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Add postgres_fdw contrib module.

Browse Source 
There's still a lot of room for improvement, but it basically works,
and we need this to be present before we can do anything much with the
writable-foreign-tables patch.  So let's commit it and get on with testing.

Shigeru Hanada, reviewed by KaiGai Kohei and Tom Lane
This commit is contained in:
Tom Lane 2013-02-21 05:26:23 -05:00
parent f435cd1d38
commit d0d75c4022
28 changed files with 4840 additions and 56 deletions
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1
contrib/Makefile
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@ -43,6 +43,7 @@ SUBDIRS = \
pgcrypto \ pgcrypto \
pgrowlocks \ pgrowlocks \
pgstattuple \ pgstattuple \
postgres_fdw \
seg \ seg \
spi \ spi \
tablefunc \ tablefunc \

4
contrib/postgres_fdw/.gitignore vendored Normal file
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@ -0,0 +1,4 @@
# Generated subdirectories
/log/
/results/
/tmp_check/

27
contrib/postgres_fdw/Makefile Normal file
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# contrib/postgres_fdw/Makefile
MODULE_big = postgres_fdw
OBJS = postgres_fdw.o option.o deparse.o connection.o
PG_CPPFLAGS = -I$(libpq_srcdir)
SHLIB_LINK = $(libpq)
SHLIB_PREREQS = submake-libpq
EXTENSION = postgres_fdw
DATA = postgres_fdw--1.0.sql
REGRESS = postgres_fdw
# the db name is hard-coded in the tests
override USE_MODULE_DB =
ifdef USE_PGXS
PG_CONFIG = pg_config
PGXS := $(shell $(PG_CONFIG) --pgxs)
include $(PGXS)
else
subdir = contrib/postgres_fdw
top_builddir = ../..
include $(top_builddir)/src/Makefile.global
include $(top_srcdir)/contrib/contrib-global.mk
endif

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contrib/postgres_fdw/connection.c Normal file
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/*-------------------------------------------------------------------------
*
* connection.c
* Connection management functions for postgres_fdw
*
* Portions Copyright (c) 2012-2013, PostgreSQL Global Development Group
*
* IDENTIFICATION
* contrib/postgres_fdw/connection.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "postgres_fdw.h"
#include "access/xact.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "utils/hsearch.h"
#include "utils/memutils.h"
/*
* Connection cache hash table entry
*
* The lookup key in this hash table is the foreign server OID plus the user
* mapping OID. (We use just one connection per user per foreign server,
* so that we can ensure all scans use the same snapshot during a query.)
*
* The "conn" pointer can be NULL if we don't currently have a live connection.
* When we do have a connection, xact_depth tracks the current depth of
* transactions and subtransactions open on the remote side. We need to issue
* commands at the same nesting depth on the remote as we're executing at
* ourselves, so that rolling back a subtransaction will kill the right
* queries and not the wrong ones.
*/
typedef struct ConnCacheKey
{
Oid serverid; /* OID of foreign server */
Oid userid; /* OID of local user whose mapping we use */
} ConnCacheKey;
typedef struct ConnCacheEntry
{
ConnCacheKey key; /* hash key (must be first) */
PGconn *conn; /* connection to foreign server, or NULL */
int xact_depth; /* 0 = no xact open, 1 = main xact open, 2 =
* one level of subxact open, etc */
} ConnCacheEntry;
/*
* Connection cache (initialized on first use)
*/
static HTAB *ConnectionHash = NULL;
/* for assigning cursor numbers */
static unsigned int cursor_number = 0;
/* tracks whether any work is needed in callback functions */
static bool xact_got_connection = false;
/* prototypes of private functions */
static PGconn *connect_pg_server(ForeignServer *server, UserMapping *user);
static void check_conn_params(const char **keywords, const char **values);
static void begin_remote_xact(ConnCacheEntry *entry);
static void pgfdw_xact_callback(XactEvent event, void *arg);
static void pgfdw_subxact_callback(SubXactEvent event,
SubTransactionId mySubid,
SubTransactionId parentSubid,
void *arg);
/*
* Get a PGconn which can be used to execute queries on the remote PostgreSQL
* server with the user's authorization. A new connection is established
* if we don't already have a suitable one, and a transaction is opened at
* the right subtransaction nesting depth if we didn't do that already.
*
* XXX Note that caching connections theoretically requires a mechanism to
* detect change of FDW objects to invalidate already established connections.
* We could manage that by watching for invalidation events on the relevant
* syscaches. For the moment, though, it's not clear that this would really
* be useful and not mere pedantry. We could not flush any active connections
* mid-transaction anyway.
*/
PGconn *
GetConnection(ForeignServer *server, UserMapping *user)
{
bool found;
ConnCacheEntry *entry;
ConnCacheKey key;
/* First time through, initialize connection cache hashtable */
if (ConnectionHash == NULL)
{
HASHCTL ctl;
MemSet(&ctl, 0, sizeof(ctl));
ctl.keysize = sizeof(ConnCacheKey);
ctl.entrysize = sizeof(ConnCacheEntry);
ctl.hash = tag_hash;
/* allocate ConnectionHash in the cache context */
ctl.hcxt = CacheMemoryContext;
ConnectionHash = hash_create("postgres_fdw connections", 8,
&ctl,
HASH_ELEM | HASH_FUNCTION | HASH_CONTEXT);
/*
* Register some callback functions that manage connection cleanup.
* This should be done just once in each backend.
*/
RegisterXactCallback(pgfdw_xact_callback, NULL);
RegisterSubXactCallback(pgfdw_subxact_callback, NULL);
}
/* Set flag that we did GetConnection during the current transaction */
xact_got_connection = true;
/* Create hash key for the entry. Assume no pad bytes in key struct */
key.serverid = server->serverid;
key.userid = user->userid;
/*
* Find or create cached entry for requested connection.
*/
entry = hash_search(ConnectionHash, &key, HASH_ENTER, &found);
if (!found)
{
/* initialize new hashtable entry (key is already filled in) */
entry->conn = NULL;
entry->xact_depth = 0;
}
/*
* We don't check the health of cached connection here, because it would
* require some overhead. Broken connection will be detected when the
* connection is actually used.
*/
/*
* If cache entry doesn't have a connection, we have to establish a new
* connection. (If connect_pg_server throws an error, the cache entry
* will be left in a valid empty state.)
*/
if (entry->conn == NULL)
{
entry->xact_depth = 0; /* just to be sure */
entry->conn = connect_pg_server(server, user);
elog(DEBUG3, "new postgres_fdw connection %p for server \"%s\"",
entry->conn, server->servername);
}
/*
* Start a new transaction or subtransaction if needed.
*/
begin_remote_xact(entry);
return entry->conn;
}
/*
* Connect to remote server using specified server and user mapping properties.
*/
static PGconn *
connect_pg_server(ForeignServer *server, UserMapping *user)
{
PGconn *volatile conn = NULL;
/*
* Use PG_TRY block to ensure closing connection on error.
*/
PG_TRY();
{
const char **keywords;
const char **values;
int n;
/*
* Construct connection params from generic options of ForeignServer
* and UserMapping. (Some of them might not be libpq options, in
* which case we'll just waste a few array slots.) Add 3 extra slots
* for fallback_application_name, client_encoding, end marker.
*/
n = list_length(server->options) + list_length(user->options) + 3;
keywords = (const char **) palloc(n * sizeof(char *));
values = (const char **) palloc(n * sizeof(char *));
n = 0;
n += ExtractConnectionOptions(server->options,
keywords + n, values + n);
n += ExtractConnectionOptions(user->options,
keywords + n, values + n);
/* Use "postgres_fdw" as fallback_application_name. */
keywords[n] = "fallback_application_name";
values[n] = "postgres_fdw";
n++;
/* Set client_encoding so that libpq can convert encoding properly. */
keywords[n] = "client_encoding";
values[n] = GetDatabaseEncodingName();
n++;
keywords[n] = values[n] = NULL;
/* verify connection parameters and make connection */
check_conn_params(keywords, values);
conn = PQconnectdbParams(keywords, values, false);
if (!conn || PQstatus(conn) != CONNECTION_OK)
{
char *connmessage;
int msglen;
/* libpq typically appends a newline, strip that */
connmessage = pstrdup(PQerrorMessage(conn));
msglen = strlen(connmessage);
if (msglen > 0 && connmessage[msglen - 1] == '\n')
connmessage[msglen - 1] = '\0';
ereport(ERROR,
(errcode(ERRCODE_SQLCLIENT_UNABLE_TO_ESTABLISH_SQLCONNECTION),
errmsg("could not connect to server \"%s\"",
server->servername),
errdetail_internal("%s", connmessage)));
}
/*
* Check that non-superuser has used password to establish connection;
* otherwise, he's piggybacking on the postgres server's user
* identity. See also dblink_security_check() in contrib/dblink.
*/
if (!superuser() && !PQconnectionUsedPassword(conn))
ereport(ERROR,
(errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
errmsg("password is required"),
errdetail("Non-superuser cannot connect if the server does not request a password."),
errhint("Target server's authentication method must be changed.")));
pfree(keywords);
pfree(values);
}
PG_CATCH();
{
/* Release PGconn data structure if we managed to create one */
if (conn)
PQfinish(conn);
PG_RE_THROW();
}
PG_END_TRY();
return conn;
}
/*
* For non-superusers, insist that the connstr specify a password. This
* prevents a password from being picked up from .pgpass, a service file,
* the environment, etc. We don't want the postgres user's passwords
* to be accessible to non-superusers. (See also dblink_connstr_check in
* contrib/dblink.)
*/
static void
check_conn_params(const char **keywords, const char **values)
{
int i;
/* no check required if superuser */
if (superuser())
return;
/* ok if params contain a non-empty password */
for (i = 0; keywords[i] != NULL; i++)
{
if (strcmp(keywords[i], "password") == 0 && values[i][0] != '\0')
return;
}
ereport(ERROR,
(errcode(ERRCODE_S_R_E_PROHIBITED_SQL_STATEMENT_ATTEMPTED),
errmsg("password is required"),
errdetail("Non-superusers must provide a password in the user mapping.")));
}
/*
* Start remote transaction or subtransaction, if needed.
*
* Note that we always use at least REPEATABLE READ in the remote session.
* This is so that, if a query initiates multiple scans of the same or
* different foreign tables, we will get snapshot-consistent results from
* those scans. A disadvantage is that we can't provide sane emulation of
* READ COMMITTED behavior --- it would be nice if we had some other way to
* control which remote queries share a snapshot.
*/
static void
begin_remote_xact(ConnCacheEntry *entry)
{
int curlevel = GetCurrentTransactionNestLevel();
PGresult *res;
/* Start main transaction if we haven't yet */
if (entry->xact_depth <= 0)
{
const char *sql;
elog(DEBUG3, "starting remote transaction on connection %p",
entry->conn);
if (XactIsoLevel == XACT_SERIALIZABLE)
sql = "START TRANSACTION ISOLATION LEVEL SERIALIZABLE";
else
sql = "START TRANSACTION ISOLATION LEVEL REPEATABLE READ";
res = PQexec(entry->conn, sql);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
pgfdw_report_error(ERROR, res, true, sql);
PQclear(res);
entry->xact_depth = 1;
}
/*
* If we're in a subtransaction, stack up savepoints to match our level.
* This ensures we can rollback just the desired effects when a
* subtransaction aborts.
*/
while (entry->xact_depth < curlevel)
{
char sql[64];
snprintf(sql, sizeof(sql), "SAVEPOINT s%d", entry->xact_depth + 1);
res = PQexec(entry->conn, sql);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
pgfdw_report_error(ERROR, res, true, sql);
PQclear(res);
entry->xact_depth++;
}
}
/*
* Release connection reference count created by calling GetConnection.
*/
void
ReleaseConnection(PGconn *conn)
{
/*
* Currently, we don't actually track connection references because all
* cleanup is managed on a transaction or subtransaction basis instead. So
* there's nothing to do here.
*/
}
/*
* Assign a "unique" number for a cursor.
*
* These really only need to be unique per connection within a transaction.
* For the moment we ignore the per-connection point and assign them across
* all connections in the transaction, but we ask for the connection to be
* supplied in case we want to refine that.
*
* Note that even if wraparound happens in a very long transaction, actual
* collisions are highly improbable; just be sure to use %u not %d to print.
*/
unsigned int
GetCursorNumber(PGconn *conn)
{
return ++cursor_number;
}
/*
* Report an error we got from the remote server.
*
* elevel: error level to use (typically ERROR, but might be less)
* res: PGresult containing the error
* clear: if true, PQclear the result (otherwise caller will handle it)
* sql: NULL, or text of remote command we tried to execute
*/
void
pgfdw_report_error(int elevel, PGresult *res, bool clear, const char *sql)
{
/* If requested, PGresult must be released before leaving this function. */
PG_TRY();
{
char *diag_sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
char *message_primary = PQresultErrorField(res, PG_DIAG_MESSAGE_PRIMARY);
char *message_detail = PQresultErrorField(res, PG_DIAG_MESSAGE_DETAIL);
char *message_hint = PQresultErrorField(res, PG_DIAG_MESSAGE_HINT);
char *message_context = PQresultErrorField(res, PG_DIAG_CONTEXT);
int sqlstate;
if (diag_sqlstate)
sqlstate = MAKE_SQLSTATE(diag_sqlstate[0],
diag_sqlstate[1],
diag_sqlstate[2],
diag_sqlstate[3],
diag_sqlstate[4]);
else
sqlstate = ERRCODE_CONNECTION_FAILURE;
ereport(elevel,
(errcode(sqlstate),
message_primary ? errmsg_internal("%s", message_primary) :
errmsg("unknown error"),
message_detail ? errdetail_internal("%s", message_detail) : 0,
message_hint ? errhint("%s", message_hint) : 0,
message_context ? errcontext("%s", message_context) : 0,
sql ? errcontext("Remote SQL command: %s", sql) : 0));
}
PG_CATCH();
{
if (clear)
PQclear(res);
PG_RE_THROW();
}
PG_END_TRY();
if (clear)
PQclear(res);
}
/*
* pgfdw_xact_callback --- cleanup at main-transaction end.
*/
static void
pgfdw_xact_callback(XactEvent event, void *arg)
{
HASH_SEQ_STATUS scan;
ConnCacheEntry *entry;
/* Quick exit if no connections were touched in this transaction. */
if (!xact_got_connection)
return;
/*
* Scan all connection cache entries to find open remote transactions, and
* close them.
*/
hash_seq_init(&scan, ConnectionHash);
while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
{
PGresult *res;
/* We only care about connections with open remote transactions */
if (entry->conn == NULL || entry->xact_depth == 0)
continue;
elog(DEBUG3, "closing remote transaction on connection %p",
entry->conn);
switch (event)
{
case XACT_EVENT_PRE_COMMIT:
/* Commit all remote transactions during pre-commit */
res = PQexec(entry->conn, "COMMIT TRANSACTION");
if (PQresultStatus(res) != PGRES_COMMAND_OK)
pgfdw_report_error(ERROR, res, true, "COMMIT TRANSACTION");
PQclear(res);
break;
case XACT_EVENT_PRE_PREPARE:
/*
* We disallow remote transactions that modified anything,
* since it's not really reasonable to hold them open until
* the prepared transaction is committed. For the moment,
* throw error unconditionally; later we might allow read-only
* cases. Note that the error will cause us to come right
* back here with event == XACT_EVENT_ABORT, so we'll clean up
* the connection state at that point.
*/
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot prepare a transaction that modified remote tables")));
break;
case XACT_EVENT_COMMIT:
case XACT_EVENT_PREPARE:
/* Should not get here -- pre-commit should have handled it */
elog(ERROR, "missed cleaning up connection during pre-commit");
break;
case XACT_EVENT_ABORT:
/* If we're aborting, abort all remote transactions too */
res = PQexec(entry->conn, "ABORT TRANSACTION");
/* Note: can't throw ERROR, it would be infinite loop */
if (PQresultStatus(res) != PGRES_COMMAND_OK)
pgfdw_report_error(WARNING, res, true,
"ABORT TRANSACTION");
else
PQclear(res);
break;
}
/* Reset state to show we're out of a transaction */
entry->xact_depth = 0;
/*
* If the connection isn't in a good idle state, discard it to
* recover. Next GetConnection will open a new connection.
*/
if (PQstatus(entry->conn) != CONNECTION_OK ||
PQtransactionStatus(entry->conn) != PQTRANS_IDLE)
{
elog(DEBUG3, "discarding connection %p", entry->conn);
PQfinish(entry->conn);
entry->conn = NULL;
}
}
/*
* Regardless of the event type, we can now mark ourselves as out of the
* transaction. (Note: if we are here during PRE_COMMIT or PRE_PREPARE,
* this saves a useless scan of the hashtable during COMMIT or PREPARE.)
*/
xact_got_connection = false;
/* Also reset cursor numbering for next transaction */
cursor_number = 0;
}
/*
* pgfdw_subxact_callback --- cleanup at subtransaction end.
*/
static void
pgfdw_subxact_callback(SubXactEvent event, SubTransactionId mySubid,
SubTransactionId parentSubid, void *arg)
{
HASH_SEQ_STATUS scan;
ConnCacheEntry *entry;
int curlevel;
/* Nothing to do at subxact start, nor after commit. */
if (!(event == SUBXACT_EVENT_PRE_COMMIT_SUB ||
event == SUBXACT_EVENT_ABORT_SUB))
return;
/* Quick exit if no connections were touched in this transaction. */
if (!xact_got_connection)
return;
/*
* Scan all connection cache entries to find open remote subtransactions
* of the current level, and close them.
*/
curlevel = GetCurrentTransactionNestLevel();
hash_seq_init(&scan, ConnectionHash);
while ((entry = (ConnCacheEntry *) hash_seq_search(&scan)))
{
PGresult *res;
char sql[100];
/*
* We only care about connections with open remote subtransactions of
* the current level.
*/
if (entry->conn == NULL || entry->xact_depth < curlevel)
continue;
if (entry->xact_depth > curlevel)
elog(ERROR, "missed cleaning up remote subtransaction at level %d",
entry->xact_depth);
if (event == SUBXACT_EVENT_PRE_COMMIT_SUB)
{
/* Commit all remote subtransactions during pre-commit */
snprintf(sql, sizeof(sql), "RELEASE SAVEPOINT s%d", curlevel);
res = PQexec(entry->conn, sql);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
pgfdw_report_error(ERROR, res, true, sql);
PQclear(res);
}
else
{
/* Rollback all remote subtransactions during abort */
snprintf(sql, sizeof(sql),
"ROLLBACK TO SAVEPOINT s%d; RELEASE SAVEPOINT s%d",
curlevel, curlevel);
res = PQexec(entry->conn, sql);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
pgfdw_report_error(WARNING, res, true, sql);
else
PQclear(res);
}
/* OK, we're outta that level of subtransaction */
entry->xact_depth--;
}
}

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-- ===================================================================
-- create FDW objects
-- ===================================================================
CREATE EXTENSION postgres_fdw;
CREATE SERVER testserver1 FOREIGN DATA WRAPPER postgres_fdw;
CREATE SERVER loopback FOREIGN DATA WRAPPER postgres_fdw
OPTIONS (dbname 'contrib_regression');
CREATE USER MAPPING FOR public SERVER testserver1
OPTIONS (user 'value', password 'value');
CREATE USER MAPPING FOR CURRENT_USER SERVER loopback;
-- ===================================================================
-- create objects used through FDW loopback server
-- ===================================================================
CREATE TYPE user_enum AS ENUM ('foo', 'bar', 'buz');
CREATE SCHEMA "S 1";
CREATE TABLE "S 1"."T 1" (
"C 1" int NOT NULL,
c2 int NOT NULL,
c3 text,
c4 timestamptz,
c5 timestamp,
c6 varchar(10),
c7 char(10),
c8 user_enum,
CONSTRAINT t1_pkey PRIMARY KEY ("C 1")
);
CREATE TABLE "S 1"."T 2" (
c1 int NOT NULL,
c2 text,
CONSTRAINT t2_pkey PRIMARY KEY (c1)
);
INSERT INTO "S 1"."T 1"
SELECT id,
id % 10,
to_char(id, 'FM00000'),
'1970-01-01'::timestamptz + ((id % 100) || ' days')::interval,
'1970-01-01'::timestamp + ((id % 100) || ' days')::interval,
id % 10,
id % 10,
'foo'::user_enum
FROM generate_series(1, 1000) id;
INSERT INTO "S 1"."T 2"
SELECT id,
'AAA' || to_char(id, 'FM000')
FROM generate_series(1, 100) id;
ANALYZE "S 1"."T 1";
ANALYZE "S 1"."T 2";
-- ===================================================================
-- create foreign tables
-- ===================================================================
CREATE FOREIGN TABLE ft1 (
c0 int,
c1 int NOT NULL,
c2 int NOT NULL,
c3 text,
c4 timestamptz,
c5 timestamp,
c6 varchar(10),
c7 char(10),
c8 user_enum
) SERVER loopback;
ALTER FOREIGN TABLE ft1 DROP COLUMN c0;
CREATE FOREIGN TABLE ft2 (
c0 int,
c1 int NOT NULL,
c2 int NOT NULL,
c3 text,
c4 timestamptz,
c5 timestamp,
c6 varchar(10),
c7 char(10),
c8 user_enum
) SERVER loopback;
ALTER FOREIGN TABLE ft2 DROP COLUMN c0;
-- ===================================================================
-- tests for validator
-- ===================================================================
-- requiressl, krbsrvname and gsslib are omitted because they depend on
-- configure options
ALTER SERVER testserver1 OPTIONS (
use_remote_explain 'false',
fdw_startup_cost '123.456',
fdw_tuple_cost '0.123',
service 'value',
connect_timeout 'value',
dbname 'value',
host 'value',
hostaddr 'value',
port 'value',
--client_encoding 'value',
application_name 'value',
--fallback_application_name 'value',
keepalives 'value',
keepalives_idle 'value',
keepalives_interval 'value',
-- requiressl 'value',
sslcompression 'value',
sslmode 'value',
sslcert 'value',
sslkey 'value',
sslrootcert 'value',
sslcrl 'value'
--requirepeer 'value',
-- krbsrvname 'value',
-- gsslib 'value',
--replication 'value'
);
ALTER USER MAPPING FOR public SERVER testserver1
OPTIONS (DROP user, DROP password);
ALTER FOREIGN TABLE ft1 OPTIONS (schema_name 'S 1', table_name 'T 1');
ALTER FOREIGN TABLE ft2 OPTIONS (schema_name 'S 1', table_name 'T 1');
ALTER FOREIGN TABLE ft1 ALTER COLUMN c1 OPTIONS (column_name 'C 1');
ALTER FOREIGN TABLE ft2 ALTER COLUMN c1 OPTIONS (column_name 'C 1');
\det+
List of foreign tables
Schema | Table | Server | FDW Options | Description
--------+-------+----------+---------------------------------------+-------------
public | ft1 | loopback | (schema_name 'S 1', table_name 'T 1') |
public | ft2 | loopback | (schema_name 'S 1', table_name 'T 1') |
(2 rows)
-- Now we should be able to run ANALYZE.
-- To exercise multiple code paths, we use local stats on ft1
-- and remote_explain mode on ft2.
ANALYZE ft1;
ALTER FOREIGN TABLE ft2 OPTIONS (use_remote_explain 'true');
-- ===================================================================
-- simple queries
-- ===================================================================
-- single table, with/without alias
EXPLAIN (COSTS false) SELECT * FROM ft1 ORDER BY c3, c1 OFFSET 100 LIMIT 10;
QUERY PLAN
---------------------------------
Limit
-> Sort
Sort Key: c3, c1
-> Foreign Scan on ft1
(4 rows)
SELECT * FROM ft1 ORDER BY c3, c1 OFFSET 100 LIMIT 10;
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
-----+----+-------+------------------------------+--------------------------+----+------------+-----
101 | 1 | 00101 | Fri Jan 02 00:00:00 1970 PST | Fri Jan 02 00:00:00 1970 | 1 | 1 | foo
102 | 2 | 00102 | Sat Jan 03 00:00:00 1970 PST | Sat Jan 03 00:00:00 1970 | 2 | 2 | foo
103 | 3 | 00103 | Sun Jan 04 00:00:00 1970 PST | Sun Jan 04 00:00:00 1970 | 3 | 3 | foo
104 | 4 | 00104 | Mon Jan 05 00:00:00 1970 PST | Mon Jan 05 00:00:00 1970 | 4 | 4 | foo
105 | 5 | 00105 | Tue Jan 06 00:00:00 1970 PST | Tue Jan 06 00:00:00 1970 | 5 | 5 | foo
106 | 6 | 00106 | Wed Jan 07 00:00:00 1970 PST | Wed Jan 07 00:00:00 1970 | 6 | 6 | foo
107 | 7 | 00107 | Thu Jan 08 00:00:00 1970 PST | Thu Jan 08 00:00:00 1970 | 7 | 7 | foo
108 | 8 | 00108 | Fri Jan 09 00:00:00 1970 PST | Fri Jan 09 00:00:00 1970 | 8 | 8 | foo
109 | 9 | 00109 | Sat Jan 10 00:00:00 1970 PST | Sat Jan 10 00:00:00 1970 | 9 | 9 | foo
110 | 0 | 00110 | Sun Jan 11 00:00:00 1970 PST | Sun Jan 11 00:00:00 1970 | 0 | 0 | foo
(10 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
QUERY PLAN
-------------------------------------------------------------------------------------
Limit
Output: c1, c2, c3, c4, c5, c6, c7, c8
-> Sort
Output: c1, c2, c3, c4, c5, c6, c7, c8
Sort Key: t1.c3, t1.c1
-> Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1"
(8 rows)
SELECT * FROM ft1 t1 ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
-----+----+-------+------------------------------+--------------------------+----+------------+-----
101 | 1 | 00101 | Fri Jan 02 00:00:00 1970 PST | Fri Jan 02 00:00:00 1970 | 1 | 1 | foo
102 | 2 | 00102 | Sat Jan 03 00:00:00 1970 PST | Sat Jan 03 00:00:00 1970 | 2 | 2 | foo
103 | 3 | 00103 | Sun Jan 04 00:00:00 1970 PST | Sun Jan 04 00:00:00 1970 | 3 | 3 | foo
104 | 4 | 00104 | Mon Jan 05 00:00:00 1970 PST | Mon Jan 05 00:00:00 1970 | 4 | 4 | foo
105 | 5 | 00105 | Tue Jan 06 00:00:00 1970 PST | Tue Jan 06 00:00:00 1970 | 5 | 5 | foo
106 | 6 | 00106 | Wed Jan 07 00:00:00 1970 PST | Wed Jan 07 00:00:00 1970 | 6 | 6 | foo
107 | 7 | 00107 | Thu Jan 08 00:00:00 1970 PST | Thu Jan 08 00:00:00 1970 | 7 | 7 | foo
108 | 8 | 00108 | Fri Jan 09 00:00:00 1970 PST | Fri Jan 09 00:00:00 1970 | 8 | 8 | foo
109 | 9 | 00109 | Sat Jan 10 00:00:00 1970 PST | Sat Jan 10 00:00:00 1970 | 9 | 9 | foo
110 | 0 | 00110 | Sun Jan 11 00:00:00 1970 PST | Sun Jan 11 00:00:00 1970 | 0 | 0 | foo
(10 rows)
-- empty result
SELECT * FROM ft1 WHERE false;
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----+----+----+----+----+----+----
(0 rows)
-- with WHERE clause
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = 101 AND t1.c6 = '1' AND t1.c7 >= '1';
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE ((c7 OPERATOR(pg_catalog.>=) '1'::bpchar)) AND (("C 1" OPERATOR(pg_catalog.=) 101)) AND ((c6::text OPERATOR(pg_catalog.=) '1'::text))
(3 rows)
SELECT * FROM ft1 t1 WHERE t1.c1 = 101 AND t1.c6 = '1' AND t1.c7 >= '1';
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
-----+----+-------+------------------------------+--------------------------+----+------------+-----
101 | 1 | 00101 | Fri Jan 02 00:00:00 1970 PST | Fri Jan 02 00:00:00 1970 | 1 | 1 | foo
(1 row)
-- aggregate
SELECT COUNT(*) FROM ft1 t1;
count
-------
1000
(1 row)
-- join two tables
SELECT t1.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
c1
-----
101
102
103
104
105
106
107
108
109
110
(10 rows)
-- subquery
SELECT * FROM ft1 t1 WHERE t1.c3 IN (SELECT c3 FROM ft2 t2 WHERE c1 <= 10) ORDER BY c1;
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----+-------+------------------------------+--------------------------+----+------------+-----
1 | 1 | 00001 | Fri Jan 02 00:00:00 1970 PST | Fri Jan 02 00:00:00 1970 | 1 | 1 | foo
2 | 2 | 00002 | Sat Jan 03 00:00:00 1970 PST | Sat Jan 03 00:00:00 1970 | 2 | 2 | foo
3 | 3 | 00003 | Sun Jan 04 00:00:00 1970 PST | Sun Jan 04 00:00:00 1970 | 3 | 3 | foo
4 | 4 | 00004 | Mon Jan 05 00:00:00 1970 PST | Mon Jan 05 00:00:00 1970 | 4 | 4 | foo
5 | 5 | 00005 | Tue Jan 06 00:00:00 1970 PST | Tue Jan 06 00:00:00 1970 | 5 | 5 | foo
6 | 6 | 00006 | Wed Jan 07 00:00:00 1970 PST | Wed Jan 07 00:00:00 1970 | 6 | 6 | foo
7 | 7 | 00007 | Thu Jan 08 00:00:00 1970 PST | Thu Jan 08 00:00:00 1970 | 7 | 7 | foo
8 | 8 | 00008 | Fri Jan 09 00:00:00 1970 PST | Fri Jan 09 00:00:00 1970 | 8 | 8 | foo
9 | 9 | 00009 | Sat Jan 10 00:00:00 1970 PST | Sat Jan 10 00:00:00 1970 | 9 | 9 | foo
10 | 0 | 00010 | Sun Jan 11 00:00:00 1970 PST | Sun Jan 11 00:00:00 1970 | 0 | 0 | foo
(10 rows)
-- subquery+MAX
SELECT * FROM ft1 t1 WHERE t1.c3 = (SELECT MAX(c3) FROM ft2 t2) ORDER BY c1;
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
------+----+-------+------------------------------+--------------------------+----+------------+-----
1000 | 0 | 01000 | Thu Jan 01 00:00:00 1970 PST | Thu Jan 01 00:00:00 1970 | 0 | 0 | foo
(1 row)
-- used in CTE
WITH t1 AS (SELECT * FROM ft1 WHERE c1 <= 10) SELECT t2.c1, t2.c2, t2.c3, t2.c4 FROM t1, ft2 t2 WHERE t1.c1 = t2.c1 ORDER BY t1.c1;
c1 | c2 | c3 | c4
----+----+-------+------------------------------
1 | 1 | 00001 | Fri Jan 02 00:00:00 1970 PST
2 | 2 | 00002 | Sat Jan 03 00:00:00 1970 PST
3 | 3 | 00003 | Sun Jan 04 00:00:00 1970 PST
4 | 4 | 00004 | Mon Jan 05 00:00:00 1970 PST
5 | 5 | 00005 | Tue Jan 06 00:00:00 1970 PST
6 | 6 | 00006 | Wed Jan 07 00:00:00 1970 PST
7 | 7 | 00007 | Thu Jan 08 00:00:00 1970 PST
8 | 8 | 00008 | Fri Jan 09 00:00:00 1970 PST
9 | 9 | 00009 | Sat Jan 10 00:00:00 1970 PST
10 | 0 | 00010 | Sun Jan 11 00:00:00 1970 PST
(10 rows)
-- fixed values
SELECT 'fixed', NULL FROM ft1 t1 WHERE c1 = 1;
?column? | ?column?
----------+----------
fixed |
(1 row)
-- user-defined operator/function
CREATE FUNCTION postgres_fdw_abs(int) RETURNS int AS $$
BEGIN
RETURN abs($1);
END
$$ LANGUAGE plpgsql IMMUTABLE;
CREATE OPERATOR === (
LEFTARG = int,
RIGHTARG = int,
PROCEDURE = int4eq,
COMMUTATOR = ===,
NEGATOR = !==
);
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = postgres_fdw_abs(t1.c2);
QUERY PLAN
-------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Filter: (t1.c1 = postgres_fdw_abs(t1.c2))
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1"
(4 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 === t1.c2;
QUERY PLAN
-------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Filter: (t1.c1 === t1.c2)
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1"
(4 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = abs(t1.c2);
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) pg_catalog.abs(c2)))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = t1.c2;
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) c2))
(3 rows)
-- ===================================================================
-- WHERE with remotely-executable conditions
-- ===================================================================
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = 1; -- Var, OpExpr(b), Const
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 1))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = 100 AND t1.c2 = 0; -- BoolExpr
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 100)) AND ((c2 OPERATOR(pg_catalog.=) 0))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c1 IS NULL; -- NullTest
QUERY PLAN
-------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" IS NULL))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c1 IS NOT NULL; -- NullTest
QUERY PLAN
-----------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" IS NOT NULL))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE round(abs(c1), 0) = 1; -- FuncExpr
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE ((pg_catalog.round(pg_catalog."numeric"(pg_catalog.abs("C 1")), 0) OPERATOR(pg_catalog.=) 1::numeric))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c1 = -c1; -- OpExpr(l)
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) (OPERATOR(pg_catalog.-) "C 1")))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE 1 = c1!; -- OpExpr(r)
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE ((1::numeric OPERATOR(pg_catalog.=) (pg_catalog.int8("C 1") OPERATOR(pg_catalog.!))))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE (c1 IS NOT NULL) IS DISTINCT FROM (c1 IS NOT NULL); -- DistinctExpr
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE ((("C 1" IS NOT NULL) IS DISTINCT FROM ("C 1" IS NOT NULL)))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c1 = ANY(ARRAY[c2, 1, c1 + 0]); -- ScalarArrayOpExpr
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) ANY (ARRAY[c2, 1, ("C 1" OPERATOR(pg_catalog.+) 0)])))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c1 = (ARRAY[c1,c2,3])[1]; -- ArrayRef
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) ((ARRAY["C 1", c2, 3])[1])))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c6 = E'foo''s\\bar'; -- check special chars
QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE ((c6::text OPERATOR(pg_catalog.=) E'foo''s\\bar'::text))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c8 = 'foo'; -- can't be sent to remote
QUERY PLAN
-------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Filter: (t1.c8 = 'foo'::user_enum)
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1"
(4 rows)
-- ===================================================================
-- parameterized queries
-- ===================================================================
-- simple join
PREPARE st1(int, int) AS SELECT t1.c3, t2.c3 FROM ft1 t1, ft2 t2 WHERE t1.c1 = $1 AND t2.c1 = $2;
EXPLAIN (VERBOSE, COSTS false) EXECUTE st1(1, 2);
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------
Nested Loop
Output: t1.c3, t2.c3
-> Foreign Scan on public.ft1 t1
Output: t1.c3
Remote SQL: SELECT NULL, NULL, c3, NULL, NULL, NULL, NULL, NULL FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 1))
-> Foreign Scan on public.ft2 t2
Output: t2.c3
Remote SQL: SELECT NULL, NULL, c3, NULL, NULL, NULL, NULL, NULL FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 2))
(8 rows)
EXECUTE st1(1, 1);
c3 | c3
-------+-------
00001 | 00001
(1 row)
EXECUTE st1(101, 101);
c3 | c3
-------+-------
00101 | 00101
(1 row)
-- subquery using stable function (can't be sent to remote)
PREPARE st2(int) AS SELECT * FROM ft1 t1 WHERE t1.c1 < $2 AND t1.c3 IN (SELECT c3 FROM ft2 t2 WHERE c1 > $1 AND EXTRACT(dow FROM c4) = 6) ORDER BY c1;
EXPLAIN (VERBOSE, COSTS false) EXECUTE st2(10, 20);
QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------------------------
Sort
Output: t1.c1, t1.c2, t1.c3, t1.c4, t1.c5, t1.c6, t1.c7, t1.c8
Sort Key: t1.c1
-> Nested Loop Semi Join
Output: t1.c1, t1.c2, t1.c3, t1.c4, t1.c5, t1.c6, t1.c7, t1.c8
Join Filter: (t1.c3 = t2.c3)
-> Foreign Scan on public.ft1 t1
Output: t1.c1, t1.c2, t1.c3, t1.c4, t1.c5, t1.c6, t1.c7, t1.c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.<) 20))
-> Materialize
Output: t2.c3
-> Foreign Scan on public.ft2 t2
Output: t2.c3
Filter: (date_part('dow'::text, t2.c4) = 6::double precision)
Remote SQL: SELECT NULL, NULL, c3, c4, NULL, NULL, NULL, NULL FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.>) 10))
(15 rows)
EXECUTE st2(10, 20);
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----+-------+------------------------------+--------------------------+----+------------+-----
16 | 6 | 00016 | Sat Jan 17 00:00:00 1970 PST | Sat Jan 17 00:00:00 1970 | 6 | 6 | foo
(1 row)
EXECUTE st1(101, 101);
c3 | c3
-------+-------
00101 | 00101
(1 row)
-- subquery using immutable function (can be sent to remote)
PREPARE st3(int) AS SELECT * FROM ft1 t1 WHERE t1.c1 < $2 AND t1.c3 IN (SELECT c3 FROM ft2 t2 WHERE c1 > $1 AND EXTRACT(dow FROM c5) = 6) ORDER BY c1;
EXPLAIN (VERBOSE, COSTS false) EXECUTE st3(10, 20);
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sort
Output: t1.c1, t1.c2, t1.c3, t1.c4, t1.c5, t1.c6, t1.c7, t1.c8
Sort Key: t1.c1
-> Nested Loop Semi Join
Output: t1.c1, t1.c2, t1.c3, t1.c4, t1.c5, t1.c6, t1.c7, t1.c8
Join Filter: (t1.c3 = t2.c3)
-> Foreign Scan on public.ft1 t1
Output: t1.c1, t1.c2, t1.c3, t1.c4, t1.c5, t1.c6, t1.c7, t1.c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.<) 20))
-> Materialize
Output: t2.c3
-> Foreign Scan on public.ft2 t2
Output: t2.c3
Remote SQL: SELECT NULL, NULL, c3, NULL, NULL, NULL, NULL, NULL FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.>) 10)) AND ((pg_catalog.date_part('dow'::text, c5) OPERATOR(pg_catalog.=) 6::double precision))
(14 rows)
EXECUTE st3(10, 20);
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----+-------+------------------------------+--------------------------+----+------------+-----
16 | 6 | 00016 | Sat Jan 17 00:00:00 1970 PST | Sat Jan 17 00:00:00 1970 | 6 | 6 | foo
(1 row)
EXECUTE st3(20, 30);
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----+-------+------------------------------+--------------------------+----+------------+-----
23 | 3 | 00023 | Sat Jan 24 00:00:00 1970 PST | Sat Jan 24 00:00:00 1970 | 3 | 3 | foo
(1 row)
-- custom plan should be chosen initially
PREPARE st4(int) AS SELECT * FROM ft1 t1 WHERE t1.c1 = $1;
EXPLAIN (VERBOSE, COSTS false) EXECUTE st4(1);
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 1))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) EXECUTE st4(1);
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 1))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) EXECUTE st4(1);
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 1))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) EXECUTE st4(1);
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 1))
(3 rows)
EXPLAIN (VERBOSE, COSTS false) EXECUTE st4(1);
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 1))
(3 rows)
-- once we try it enough times, should switch to generic plan
EXPLAIN (VERBOSE, COSTS false) EXECUTE st4(1);
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) $1))
(3 rows)
-- value of $1 should not be sent to remote
PREPARE st5(user_enum,int) AS SELECT * FROM ft1 t1 WHERE c8 = $1 and c1 = $2;
EXPLAIN (VERBOSE, COSTS false) EXECUTE st5('foo', 1);
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Filter: (t1.c8 = 'foo'::user_enum)
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 1))
(4 rows)
EXPLAIN (VERBOSE, COSTS false) EXECUTE st5('foo', 1);
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Filter: (t1.c8 = 'foo'::user_enum)
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 1))
(4 rows)
EXPLAIN (VERBOSE, COSTS false) EXECUTE st5('foo', 1);
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Filter: (t1.c8 = 'foo'::user_enum)
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 1))
(4 rows)
EXPLAIN (VERBOSE, COSTS false) EXECUTE st5('foo', 1);
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Filter: (t1.c8 = 'foo'::user_enum)
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 1))
(4 rows)
EXPLAIN (VERBOSE, COSTS false) EXECUTE st5('foo', 1);
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Filter: (t1.c8 = 'foo'::user_enum)
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) 1))
(4 rows)
EXPLAIN (VERBOSE, COSTS false) EXECUTE st5('foo', 1);
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------
Foreign Scan on public.ft1 t1
Output: c1, c2, c3, c4, c5, c6, c7, c8
Filter: (t1.c8 = $1)
Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" OPERATOR(pg_catalog.=) $2))
(4 rows)
EXECUTE st5('foo', 1);
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----+-------+------------------------------+--------------------------+----+------------+-----
1 | 1 | 00001 | Fri Jan 02 00:00:00 1970 PST | Fri Jan 02 00:00:00 1970 | 1 | 1 | foo
(1 row)
-- cleanup
DEALLOCATE st1;
DEALLOCATE st2;
DEALLOCATE st3;
DEALLOCATE st4;
DEALLOCATE st5;
-- ===================================================================
-- used in pl/pgsql function
-- ===================================================================
CREATE OR REPLACE FUNCTION f_test(p_c1 int) RETURNS int AS $$
DECLARE
v_c1 int;
BEGIN
SELECT c1 INTO v_c1 FROM ft1 WHERE c1 = p_c1 LIMIT 1;
PERFORM c1 FROM ft1 WHERE c1 = p_c1 AND p_c1 = v_c1 LIMIT 1;
RETURN v_c1;
END;
$$ LANGUAGE plpgsql;
SELECT f_test(100);
f_test
--------
100
(1 row)
DROP FUNCTION f_test(int);
-- ===================================================================
-- conversion error
-- ===================================================================
ALTER FOREIGN TABLE ft1 ALTER COLUMN c8 TYPE int;
SELECT * FROM ft1 WHERE c1 = 1; -- ERROR
ERROR: invalid input syntax for integer: "foo"
CONTEXT: column "c8" of foreign table "ft1"
ALTER FOREIGN TABLE ft1 ALTER COLUMN c8 TYPE user_enum;
-- ===================================================================
-- subtransaction
-- + local/remote error doesn't break cursor
-- ===================================================================
BEGIN;
DECLARE c CURSOR FOR SELECT * FROM ft1 ORDER BY c1;
FETCH c;
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----+-------+------------------------------+--------------------------+----+------------+-----
1 | 1 | 00001 | Fri Jan 02 00:00:00 1970 PST | Fri Jan 02 00:00:00 1970 | 1 | 1 | foo
(1 row)
SAVEPOINT s;
ERROR OUT; -- ERROR
ERROR: syntax error at or near "ERROR"
LINE 1: ERROR OUT;
^
ROLLBACK TO s;
FETCH c;
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----+-------+------------------------------+--------------------------+----+------------+-----
2 | 2 | 00002 | Sat Jan 03 00:00:00 1970 PST | Sat Jan 03 00:00:00 1970 | 2 | 2 | foo
(1 row)
SAVEPOINT s;
SELECT * FROM ft1 WHERE 1 / (c1 - 1) > 0; -- ERROR
ERROR: division by zero
CONTEXT: Remote SQL command: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (((1 OPERATOR(pg_catalog./) ("C 1" OPERATOR(pg_catalog.-) 1)) OPERATOR(pg_catalog.>) 0))
ROLLBACK TO s;
FETCH c;
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----+-------+------------------------------+--------------------------+----+------------+-----
3 | 3 | 00003 | Sun Jan 04 00:00:00 1970 PST | Sun Jan 04 00:00:00 1970 | 3 | 3 | foo
(1 row)
SELECT * FROM ft1 ORDER BY c1 LIMIT 1;
c1 | c2 | c3 | c4 | c5 | c6 | c7 | c8
----+----+-------+------------------------------+--------------------------+----+------------+-----
1 | 1 | 00001 | Fri Jan 02 00:00:00 1970 PST | Fri Jan 02 00:00:00 1970 | 1 | 1 | foo
(1 row)
COMMIT;

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/*-------------------------------------------------------------------------
*
* option.c
* FDW option handling for postgres_fdw
*
* Portions Copyright (c) 2012-2013, PostgreSQL Global Development Group
*
* IDENTIFICATION
* contrib/postgres_fdw/option.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "postgres_fdw.h"
#include "access/reloptions.h"
#include "catalog/pg_foreign_server.h"
#include "catalog/pg_foreign_table.h"
#include "catalog/pg_user_mapping.h"
#include "commands/defrem.h"
/*
* Describes the valid options for objects that this wrapper uses.
*/
typedef struct PgFdwOption
{
const char *keyword;
Oid optcontext; /* OID of catalog in which option may appear */
bool is_libpq_opt; /* true if it's used in libpq */
} PgFdwOption;
/*
* Valid options for postgres_fdw.
* Allocated and filled in InitPgFdwOptions.
*/
static PgFdwOption *postgres_fdw_options;
/*
* Valid options for libpq.
* Allocated and filled in InitPgFdwOptions.
*/
static PQconninfoOption *libpq_options;
/*
* Helper functions
*/
static void InitPgFdwOptions(void);
static bool is_valid_option(const char *keyword, Oid context);
static bool is_libpq_option(const char *keyword);
/*
* Validate the generic options given to a FOREIGN DATA WRAPPER, SERVER,
* USER MAPPING or FOREIGN TABLE that uses postgres_fdw.
*
* Raise an ERROR if the option or its value is considered invalid.
*/
extern Datum postgres_fdw_validator(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(postgres_fdw_validator);
Datum
postgres_fdw_validator(PG_FUNCTION_ARGS)
{
List *options_list = untransformRelOptions(PG_GETARG_DATUM(0));
Oid catalog = PG_GETARG_OID(1);
ListCell *cell;
/* Build our options lists if we didn't yet. */
InitPgFdwOptions();
/*
* Check that only options supported by postgres_fdw, and allowed for the
* current object type, are given.
*/
foreach(cell, options_list)
{
DefElem *def = (DefElem *) lfirst(cell);
if (!is_valid_option(def->defname, catalog))
{
/*
* Unknown option specified, complain about it. Provide a hint
* with list of valid options for the object.
*/
PgFdwOption *opt;
StringInfoData buf;
initStringInfo(&buf);
for (opt = postgres_fdw_options; opt->keyword; opt++)
{
if (catalog == opt->optcontext)
appendStringInfo(&buf, "%s%s", (buf.len > 0) ? ", " : "",
opt->keyword);
}
ereport(ERROR,
(errcode(ERRCODE_FDW_INVALID_OPTION_NAME),
errmsg("invalid option \"%s\"", def->defname),
errhint("Valid options in this context are: %s",
buf.data)));
}
/*
* Validate option value, when we can do so without any context.
*/
if (strcmp(def->defname, "use_remote_explain") == 0)
{
/* use_remote_explain accepts only boolean values */
(void) defGetBoolean(def);
}
else if (strcmp(def->defname, "fdw_startup_cost") == 0 ||
strcmp(def->defname, "fdw_tuple_cost") == 0)
{
/* these must have a non-negative numeric value */
double val;
char *endp;
val = strtod(defGetString(def), &endp);
if (*endp || val < 0)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("%s requires a non-negative numeric value",
def->defname)));
}
}
PG_RETURN_VOID();
}
/*
* Initialize option lists.
*/
static void
InitPgFdwOptions(void)
{
int num_libpq_opts;
PQconninfoOption *lopt;
PgFdwOption *popt;
/* non-libpq FDW-specific FDW options */
static const PgFdwOption non_libpq_options[] = {
{"schema_name", ForeignTableRelationId, false},
{"table_name", ForeignTableRelationId, false},
{"column_name", AttributeRelationId, false},
/* use_remote_explain is available on both server and table */
{"use_remote_explain", ForeignServerRelationId, false},
{"use_remote_explain", ForeignTableRelationId, false},
/* cost factors */
{"fdw_startup_cost", ForeignServerRelationId, false},
{"fdw_tuple_cost", ForeignServerRelationId, false},
{NULL, InvalidOid, false}
};
/* Prevent redundant initialization. */
if (postgres_fdw_options)
return;
/*
* Get list of valid libpq options.
*
* To avoid unnecessary work, we get the list once and use it throughout
* the lifetime of this backend process. We don't need to care about
* memory context issues, because PQconndefaults allocates with malloc.
*/
libpq_options = PQconndefaults();
if (!libpq_options) /* assume reason for failure is OOM */
ereport(ERROR,
(errcode(ERRCODE_FDW_OUT_OF_MEMORY),
errmsg("out of memory"),
errdetail("could not get libpq's default connection options")));
/* Count how many libpq options are available. */
num_libpq_opts = 0;
for (lopt = libpq_options; lopt->keyword; lopt++)
num_libpq_opts++;
/*
* Construct an array which consists of all valid options for
* postgres_fdw, by appending FDW-specific options to libpq options.
*
* We use plain malloc here to allocate postgres_fdw_options because it
* lives as long as the backend process does. Besides, keeping
* libpq_options in memory allows us to avoid copying every keyword
* string.
*/
postgres_fdw_options = (PgFdwOption *)
malloc(sizeof(PgFdwOption) * num_libpq_opts +
sizeof(non_libpq_options));
if (postgres_fdw_options == NULL)
ereport(ERROR,
(errcode(ERRCODE_FDW_OUT_OF_MEMORY),
errmsg("out of memory")));
popt = postgres_fdw_options;
for (lopt = libpq_options; lopt->keyword; lopt++)
{
/* Hide debug options, as well as settings we override internally. */
if (strchr(lopt->dispchar, 'D') ||
strcmp(lopt->keyword, "fallback_application_name") == 0 ||
strcmp(lopt->keyword, "client_encoding") == 0)
continue;
/* We don't have to copy keyword string, as described above. */
popt->keyword = lopt->keyword;
/*
* "user" and any secret options are allowed only on user mappings.
* Everything else is a server option.
*/
if (strcmp(lopt->keyword, "user") == 0 || strchr(lopt->dispchar, '*'))
popt->optcontext = UserMappingRelationId;
else
popt->optcontext = ForeignServerRelationId;
popt->is_libpq_opt = true;
popt++;
}
/* Append FDW-specific options and dummy terminator. */
memcpy(popt, non_libpq_options, sizeof(non_libpq_options));
}
/*
* Check whether the given option is one of the valid postgres_fdw options.
* context is the Oid of the catalog holding the object the option is for.
*/
static bool
is_valid_option(const char *keyword, Oid context)
{
PgFdwOption *opt;
Assert(postgres_fdw_options); /* must be initialized already */
for (opt = postgres_fdw_options; opt->keyword; opt++)
{
if (context == opt->optcontext && strcmp(opt->keyword, keyword) == 0)
return true;
}
return false;
}
/*
* Check whether the given option is one of the valid libpq options.
*/
static bool
is_libpq_option(const char *keyword)
{
PgFdwOption *opt;
Assert(postgres_fdw_options); /* must be initialized already */
for (opt = postgres_fdw_options; opt->keyword; opt++)
{
if (opt->is_libpq_opt && strcmp(opt->keyword, keyword) == 0)
return true;
}
return false;
}
/*
* Generate key-value arrays which include only libpq options from the
* given list (which can contain any kind of options). Caller must have
* allocated large-enough arrays. Returns number of options found.
*/
int
ExtractConnectionOptions(List *defelems, const char **keywords,
const char **values)
{
ListCell *lc;
int i;
/* Build our options lists if we didn't yet. */
InitPgFdwOptions();
i = 0;
foreach(lc, defelems)
{
DefElem *d = (DefElem *) lfirst(lc);
if (is_libpq_option(d->defname))
{
keywords[i] = d->defname;
values[i] = defGetString(d);
i++;
}
}
return i;
}

18
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/* contrib/postgres_fdw/postgres_fdw--1.0.sql */
-- complain if script is sourced in psql, rather than via CREATE EXTENSION
\echo Use "CREATE EXTENSION postgres_fdw" to load this file. \quit
CREATE FUNCTION postgres_fdw_handler()
RETURNS fdw_handler
AS 'MODULE_PATHNAME'
LANGUAGE C STRICT;
CREATE FUNCTION postgres_fdw_validator(text[], oid)
RETURNS void
AS 'MODULE_PATHNAME'
LANGUAGE C STRICT;
CREATE FOREIGN DATA WRAPPER postgres_fdw
HANDLER postgres_fdw_handler
VALIDATOR postgres_fdw_validator;

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5
contrib/postgres_fdw/postgres_fdw.control Normal file
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# postgres_fdw extension
comment = 'foreign-data wrapper for remote PostgreSQL servers'
default_version = '1.0'
module_pathname = '$libdir/postgres_fdw'
relocatable = true

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/*-------------------------------------------------------------------------
*
* postgres_fdw.h
* Foreign-data wrapper for remote PostgreSQL servers
*
* Portions Copyright (c) 2012-2013, PostgreSQL Global Development Group
*
* IDENTIFICATION
* contrib/postgres_fdw/postgres_fdw.h
*
*-------------------------------------------------------------------------
*/
#ifndef POSTGRES_FDW_H
#define POSTGRES_FDW_H
#include "foreign/foreign.h"
#include "lib/stringinfo.h"
#include "nodes/relation.h"
#include "utils/rel.h"
#include "libpq-fe.h"
/* in connection.c */
extern PGconn *GetConnection(ForeignServer *server, UserMapping *user);
extern void ReleaseConnection(PGconn *conn);
extern unsigned int GetCursorNumber(PGconn *conn);
extern void pgfdw_report_error(int elevel, PGresult *res, bool clear,
const char *sql);
/* in option.c */
extern int ExtractConnectionOptions(List *defelems,
const char **keywords,
const char **values);
/* in deparse.c */
extern void classifyConditions(PlannerInfo *root,
RelOptInfo *baserel,
List **remote_conds,
List **param_conds,
List **local_conds,
List **param_numbers);
extern void deparseSimpleSql(StringInfo buf,
PlannerInfo *root,
RelOptInfo *baserel,
List *local_conds);
extern void appendWhereClause(StringInfo buf,
bool has_where,
List *exprs,
PlannerInfo *root);
extern void deparseAnalyzeSql(StringInfo buf, Relation rel);
#endif /* POSTGRES_FDW_H */

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-- ===================================================================
-- create FDW objects
-- ===================================================================
CREATE EXTENSION postgres_fdw;
CREATE SERVER testserver1 FOREIGN DATA WRAPPER postgres_fdw;
CREATE SERVER loopback FOREIGN DATA WRAPPER postgres_fdw
OPTIONS (dbname 'contrib_regression');
CREATE USER MAPPING FOR public SERVER testserver1
OPTIONS (user 'value', password 'value');
CREATE USER MAPPING FOR CURRENT_USER SERVER loopback;
-- ===================================================================
-- create objects used through FDW loopback server
-- ===================================================================
CREATE TYPE user_enum AS ENUM ('foo', 'bar', 'buz');
CREATE SCHEMA "S 1";
CREATE TABLE "S 1"."T 1" (
"C 1" int NOT NULL,
c2 int NOT NULL,
c3 text,
c4 timestamptz,
c5 timestamp,
c6 varchar(10),
c7 char(10),
c8 user_enum,
CONSTRAINT t1_pkey PRIMARY KEY ("C 1")
);
CREATE TABLE "S 1"."T 2" (
c1 int NOT NULL,
c2 text,
CONSTRAINT t2_pkey PRIMARY KEY (c1)
);
INSERT INTO "S 1"."T 1"
SELECT id,
id % 10,
to_char(id, 'FM00000'),
'1970-01-01'::timestamptz + ((id % 100) || ' days')::interval,
'1970-01-01'::timestamp + ((id % 100) || ' days')::interval,
id % 10,
id % 10,
'foo'::user_enum
FROM generate_series(1, 1000) id;
INSERT INTO "S 1"."T 2"
SELECT id,
'AAA' || to_char(id, 'FM000')
FROM generate_series(1, 100) id;
ANALYZE "S 1"."T 1";
ANALYZE "S 1"."T 2";
-- ===================================================================
-- create foreign tables
-- ===================================================================
CREATE FOREIGN TABLE ft1 (
c0 int,
c1 int NOT NULL,
c2 int NOT NULL,
c3 text,
c4 timestamptz,
c5 timestamp,
c6 varchar(10),
c7 char(10),
c8 user_enum
) SERVER loopback;
ALTER FOREIGN TABLE ft1 DROP COLUMN c0;
CREATE FOREIGN TABLE ft2 (
c0 int,
c1 int NOT NULL,
c2 int NOT NULL,
c3 text,
c4 timestamptz,
c5 timestamp,
c6 varchar(10),
c7 char(10),
c8 user_enum
) SERVER loopback;
ALTER FOREIGN TABLE ft2 DROP COLUMN c0;
-- ===================================================================
-- tests for validator
-- ===================================================================
-- requiressl, krbsrvname and gsslib are omitted because they depend on
-- configure options
ALTER SERVER testserver1 OPTIONS (
use_remote_explain 'false',
fdw_startup_cost '123.456',
fdw_tuple_cost '0.123',
service 'value',
connect_timeout 'value',
dbname 'value',
host 'value',
hostaddr 'value',
port 'value',
--client_encoding 'value',
application_name 'value',
--fallback_application_name 'value',
keepalives 'value',
keepalives_idle 'value',
keepalives_interval 'value',
-- requiressl 'value',
sslcompression 'value',
sslmode 'value',
sslcert 'value',
sslkey 'value',
sslrootcert 'value',
sslcrl 'value'
--requirepeer 'value',
-- krbsrvname 'value',
-- gsslib 'value',
--replication 'value'
);
ALTER USER MAPPING FOR public SERVER testserver1
OPTIONS (DROP user, DROP password);
ALTER FOREIGN TABLE ft1 OPTIONS (schema_name 'S 1', table_name 'T 1');
ALTER FOREIGN TABLE ft2 OPTIONS (schema_name 'S 1', table_name 'T 1');
ALTER FOREIGN TABLE ft1 ALTER COLUMN c1 OPTIONS (column_name 'C 1');
ALTER FOREIGN TABLE ft2 ALTER COLUMN c1 OPTIONS (column_name 'C 1');
\det+
-- Now we should be able to run ANALYZE.
-- To exercise multiple code paths, we use local stats on ft1
-- and remote_explain mode on ft2.
ANALYZE ft1;
ALTER FOREIGN TABLE ft2 OPTIONS (use_remote_explain 'true');
-- ===================================================================
-- simple queries
-- ===================================================================
-- single table, with/without alias
EXPLAIN (COSTS false) SELECT * FROM ft1 ORDER BY c3, c1 OFFSET 100 LIMIT 10;
SELECT * FROM ft1 ORDER BY c3, c1 OFFSET 100 LIMIT 10;
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
SELECT * FROM ft1 t1 ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
-- empty result
SELECT * FROM ft1 WHERE false;
-- with WHERE clause
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = 101 AND t1.c6 = '1' AND t1.c7 >= '1';
SELECT * FROM ft1 t1 WHERE t1.c1 = 101 AND t1.c6 = '1' AND t1.c7 >= '1';
-- aggregate
SELECT COUNT(*) FROM ft1 t1;
-- join two tables
SELECT t1.c1 FROM ft1 t1 JOIN ft2 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c3, t1.c1 OFFSET 100 LIMIT 10;
-- subquery
SELECT * FROM ft1 t1 WHERE t1.c3 IN (SELECT c3 FROM ft2 t2 WHERE c1 <= 10) ORDER BY c1;
-- subquery+MAX
SELECT * FROM ft1 t1 WHERE t1.c3 = (SELECT MAX(c3) FROM ft2 t2) ORDER BY c1;
-- used in CTE
WITH t1 AS (SELECT * FROM ft1 WHERE c1 <= 10) SELECT t2.c1, t2.c2, t2.c3, t2.c4 FROM t1, ft2 t2 WHERE t1.c1 = t2.c1 ORDER BY t1.c1;
-- fixed values
SELECT 'fixed', NULL FROM ft1 t1 WHERE c1 = 1;
-- user-defined operator/function
CREATE FUNCTION postgres_fdw_abs(int) RETURNS int AS $$
BEGIN
RETURN abs($1);
END
$$ LANGUAGE plpgsql IMMUTABLE;
CREATE OPERATOR === (
LEFTARG = int,
RIGHTARG = int,
PROCEDURE = int4eq,
COMMUTATOR = ===,
NEGATOR = !==
);
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = postgres_fdw_abs(t1.c2);
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 === t1.c2;
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = abs(t1.c2);
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = t1.c2;
-- ===================================================================
-- WHERE with remotely-executable conditions
-- ===================================================================
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = 1; -- Var, OpExpr(b), Const
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE t1.c1 = 100 AND t1.c2 = 0; -- BoolExpr
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c1 IS NULL; -- NullTest
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c1 IS NOT NULL; -- NullTest
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE round(abs(c1), 0) = 1; -- FuncExpr
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c1 = -c1; -- OpExpr(l)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE 1 = c1!; -- OpExpr(r)
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE (c1 IS NOT NULL) IS DISTINCT FROM (c1 IS NOT NULL); -- DistinctExpr
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c1 = ANY(ARRAY[c2, 1, c1 + 0]); -- ScalarArrayOpExpr
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c1 = (ARRAY[c1,c2,3])[1]; -- ArrayRef
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c6 = E'foo''s\\bar'; -- check special chars
EXPLAIN (VERBOSE, COSTS false) SELECT * FROM ft1 t1 WHERE c8 = 'foo'; -- can't be sent to remote
-- ===================================================================
-- parameterized queries
-- ===================================================================
-- simple join
PREPARE st1(int, int) AS SELECT t1.c3, t2.c3 FROM ft1 t1, ft2 t2 WHERE t1.c1 = $1 AND t2.c1 = $2;
EXPLAIN (VERBOSE, COSTS false) EXECUTE st1(1, 2);
EXECUTE st1(1, 1);
EXECUTE st1(101, 101);
-- subquery using stable function (can't be sent to remote)
PREPARE st2(int) AS SELECT * FROM ft1 t1 WHERE t1.c1 < $2 AND t1.c3 IN (SELECT c3 FROM ft2 t2 WHERE c1 > $1 AND EXTRACT(dow FROM c4) = 6) ORDER BY c1;
EXPLAIN (VERBOSE, COSTS false) EXECUTE st2(10, 20);
EXECUTE st2(10, 20);
EXECUTE st1(101, 101);
-- subquery using immutable function (can be sent to remote)
PREPARE st3(int) AS SELECT * FROM ft1 t1 WHERE t1.c1 < $2 AND t1.c3 IN (SELECT c3 FROM ft2 t2 WHERE c1 > $1 AND EXTRACT(dow FROM c5) = 6) ORDER BY c1;
EXPLAIN (VERBOSE, COSTS false) EXECUTE st3(10, 20);
EXECUTE st3(10, 20);
EXECUTE st3(20, 30);
-- custom plan should be chosen initially
PREPARE st4(int) AS SELECT * FROM ft1 t1 WHERE t1.c1 = $1;
EXPLAIN (VERBOSE, COSTS false) EXECUTE st4(1);
EXPLAIN (VERBOSE, COSTS false) EXECUTE st4(1);
EXPLAIN (VERBOSE, COSTS false) EXECUTE st4(1);
EXPLAIN (VERBOSE, COSTS false) EXECUTE st4(1);
EXPLAIN (VERBOSE, COSTS false) EXECUTE st4(1);
-- once we try it enough times, should switch to generic plan
EXPLAIN (VERBOSE, COSTS false) EXECUTE st4(1);
-- value of $1 should not be sent to remote
PREPARE st5(user_enum,int) AS SELECT * FROM ft1 t1 WHERE c8 = $1 and c1 = $2;
EXPLAIN (VERBOSE, COSTS false) EXECUTE st5('foo', 1);
EXPLAIN (VERBOSE, COSTS false) EXECUTE st5('foo', 1);
EXPLAIN (VERBOSE, COSTS false) EXECUTE st5('foo', 1);
EXPLAIN (VERBOSE, COSTS false) EXECUTE st5('foo', 1);
EXPLAIN (VERBOSE, COSTS false) EXECUTE st5('foo', 1);
EXPLAIN (VERBOSE, COSTS false) EXECUTE st5('foo', 1);
EXECUTE st5('foo', 1);
-- cleanup
DEALLOCATE st1;
DEALLOCATE st2;
DEALLOCATE st3;
DEALLOCATE st4;
DEALLOCATE st5;
-- ===================================================================
-- used in pl/pgsql function
-- ===================================================================
CREATE OR REPLACE FUNCTION f_test(p_c1 int) RETURNS int AS $$
DECLARE
v_c1 int;
BEGIN
SELECT c1 INTO v_c1 FROM ft1 WHERE c1 = p_c1 LIMIT 1;
PERFORM c1 FROM ft1 WHERE c1 = p_c1 AND p_c1 = v_c1 LIMIT 1;
RETURN v_c1;
END;
$$ LANGUAGE plpgsql;
SELECT f_test(100);
DROP FUNCTION f_test(int);
-- ===================================================================
-- conversion error
-- ===================================================================
ALTER FOREIGN TABLE ft1 ALTER COLUMN c8 TYPE int;
SELECT * FROM ft1 WHERE c1 = 1; -- ERROR
ALTER FOREIGN TABLE ft1 ALTER COLUMN c8 TYPE user_enum;
-- ===================================================================
-- subtransaction
-- + local/remote error doesn't break cursor
-- ===================================================================
BEGIN;
DECLARE c CURSOR FOR SELECT * FROM ft1 ORDER BY c1;
FETCH c;
SAVEPOINT s;
ERROR OUT; -- ERROR
ROLLBACK TO s;
FETCH c;
SAVEPOINT s;
SELECT * FROM ft1 WHERE 1 / (c1 - 1) > 0; -- ERROR
ROLLBACK TO s;
FETCH c;
SELECT * FROM ft1 ORDER BY c1 LIMIT 1;
COMMIT;

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doc/src/sgml/client-auth.sgml
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@ -1098,7 +1098,7 @@ omicron bryanh guest1
<replaceable>servicename</> can be set on the server side using the <replaceable>servicename</> can be set on the server side using the
<xref linkend="guc-krb-srvname"> configuration parameter, and on the <xref linkend="guc-krb-srvname"> configuration parameter, and on the
client side using the <literal>krbsrvname</> connection parameter. (See client side using the <literal>krbsrvname</> connection parameter. (See
also <xref linkend="libpq-connect">.) The installation default can be also <xref linkend="libpq-paramkeywords">.) The installation default can be
changed from the default <literal>postgres</literal> at build time using changed from the default <literal>postgres</literal> at build time using
<literal>./configure --with-krb-srvnam=</><replaceable>whatever</>. <literal>./configure --with-krb-srvnam=</><replaceable>whatever</>.
In most environments, In most environments,

1
doc/src/sgml/contrib.sgml
View File

@ -132,6 +132,7 @@ CREATE EXTENSION <replaceable>module_name</> FROM unpackaged;
&pgstatstatements; &pgstatstatements;
&pgstattuple; &pgstattuple;
&pgtrgm; &pgtrgm;
&postgres-fdw;
&seg; &seg;
&sepgsql; &sepgsql;
&contrib-spi; &contrib-spi;

26
doc/src/sgml/dblink.sgml
View File

@ -8,11 +8,16 @@
</indexterm> </indexterm>
<para> <para>
<filename>dblink</> is a module which supports connections to <filename>dblink</> is a module that supports connections to
other <productname>PostgreSQL</> databases from within a database other <productname>PostgreSQL</> databases from within a database
session. session.
</para> </para>
<para>
See also <xref linkend="postgres-fdw">, which provides roughly the same
functionality using a more modern and standards-compliant infrastructure.
</para>
<refentry id="CONTRIB-DBLINK-CONNECT"> <refentry id="CONTRIB-DBLINK-CONNECT">
<refmeta> <refmeta>
<refentrytitle>dblink_connect</refentrytitle> <refentrytitle>dblink_connect</refentrytitle>
@ -47,12 +52,10 @@ dblink_connect(text connname, text connstr) returns text
<para> <para>
The connection string may also be the name of an existing foreign The connection string may also be the name of an existing foreign
server. It is recommended to use the foreign-data wrapper server. It is recommended to use the foreign-data wrapper
<literal>dblink_fdw</literal> when defining the corresponding foreign <literal>dblink_fdw</literal> when defining the foreign
server. See the example below, as well as the following: server. See the example below, as well as
<simplelist type="inline"> <xref linkend="sql-createserver"> and
<member><xref linkend="sql-createserver"></member> <xref linkend="sql-createusermapping">.
<member><xref linkend="sql-createusermapping"></member>
</simplelist>
</para> </para>
</refsect1> </refsect1>
@ -77,8 +80,8 @@ dblink_connect(text connname, text connstr) returns text
<para><application>libpq</>-style connection info string, for example <para><application>libpq</>-style connection info string, for example
<literal>hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres <literal>hostaddr=127.0.0.1 port=5432 dbname=mydb user=postgres
password=mypasswd</>. password=mypasswd</>.
For details see <function>PQconnectdb</> in For details see <xref linkend="libpq-connstring">.
<xref linkend="libpq-connect">. Alternatively, the name of a foreign server.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -133,9 +136,10 @@ SELECT dblink_connect('myconn', 'dbname=postgres');
-- ERROR: password is required -- ERROR: password is required
-- DETAIL: Non-superuser cannot connect if the server does not request a password. -- DETAIL: Non-superuser cannot connect if the server does not request a password.
-- HINT: Target server's authentication method must be changed. -- HINT: Target server's authentication method must be changed.
CREATE USER dblink_regression_test WITH PASSWORD 'secret';
CREATE SERVER fdtest FOREIGN DATA WRAPPER dblink_fdw OPTIONS (hostaddr '127.0.0.1', dbname 'contrib_regression'); CREATE SERVER fdtest FOREIGN DATA WRAPPER dblink_fdw OPTIONS (hostaddr '127.0.0.1', dbname 'contrib_regression');
CREATE USER dblink_regression_test WITH PASSWORD 'secret';
CREATE USER MAPPING FOR dblink_regression_test SERVER fdtest OPTIONS (user 'dblink_regression_test', password 'secret'); CREATE USER MAPPING FOR dblink_regression_test SERVER fdtest OPTIONS (user 'dblink_regression_test', password 'secret');
GRANT USAGE ON FOREIGN SERVER fdtest TO dblink_regression_test; GRANT USAGE ON FOREIGN SERVER fdtest TO dblink_regression_test;
GRANT SELECT ON TABLE foo TO dblink_regression_test; GRANT SELECT ON TABLE foo TO dblink_regression_test;
@ -166,7 +170,7 @@ SELECT * FROM dblink('myconn','SELECT * FROM foo') AS t(a int, b text, c text[])
\c - :ORIGINAL_USER \c - :ORIGINAL_USER
REVOKE USAGE ON FOREIGN SERVER fdtest FROM dblink_regression_test; REVOKE USAGE ON FOREIGN SERVER fdtest FROM dblink_regression_test;
REVOKE SELECT ON TABLE foo FROM dblink_regression_test; REVOKE SELECT ON TABLE foo FROM dblink_regression_test;
DROP USER MAPPING FOR dblink_regression_test SERVER fdtest; DROP USER MAPPING FOR dblink_regression_test SERVER fdtest;
DROP USER dblink_regression_test; DROP USER dblink_regression_test;
DROP SERVER fdtest; DROP SERVER fdtest;

1
doc/src/sgml/filelist.sgml
View File

@ -134,6 +134,7 @@
<!ENTITY pgtesttiming SYSTEM "pgtesttiming.sgml"> <!ENTITY pgtesttiming SYSTEM "pgtesttiming.sgml">
<!ENTITY pgtrgm SYSTEM "pgtrgm.sgml"> <!ENTITY pgtrgm SYSTEM "pgtrgm.sgml">
<!ENTITY pgupgrade SYSTEM "pgupgrade.sgml"> <!ENTITY pgupgrade SYSTEM "pgupgrade.sgml">
<!ENTITY postgres-fdw SYSTEM "postgres-fdw.sgml">
<!ENTITY seg SYSTEM "seg.sgml"> <!ENTITY seg SYSTEM "seg.sgml">
<!ENTITY contrib-spi SYSTEM "contrib-spi.sgml"> <!ENTITY contrib-spi SYSTEM "contrib-spi.sgml">
<!ENTITY sepgsql SYSTEM "sepgsql.sgml"> <!ENTITY sepgsql SYSTEM "sepgsql.sgml">

2
doc/src/sgml/libpq.sgml
View File

@ -6941,7 +6941,7 @@ myEventProc(PGEventId evtId, void *evtInfo, void *passThrough)
<para> <para>
The file uses an <quote>INI file</quote> format where the section The file uses an <quote>INI file</quote> format where the section
name is the service name and the parameters are connection name is the service name and the parameters are connection
parameters; see <xref linkend="libpq-connect"> for a list. For parameters; see <xref linkend="libpq-paramkeywords"> for a list. For
example: example:
<programlisting> <programlisting>
# comment # comment

325
doc/src/sgml/postgres-fdw.sgml Normal file
View File

@ -0,0 +1,325 @@
<!-- doc/src/sgml/postgres-fdw.sgml -->
<sect1 id="postgres-fdw" xreflabel="postgres_fdw">
<title>postgres_fdw</title>
<indexterm zone="postgres-fdw">
<primary>postgres_fdw</primary>
</indexterm>
<para>
The <filename>postgres_fdw</> module provides the foreign-data wrapper
<literal>postgres_fdw</literal>, which can be used to access data
stored in external <productname>PostgreSQL</productname> servers.
</para>
<para>
The functionality provided by this module overlaps substantially
with the functionality of the older <xref linkend="dblink"> module.
But <filename>postgres_fdw</> provides more transparent and
standards-compliant syntax for accessing remote tables, and can give
better performance in many cases.
</para>
<para>
To prepare for remote access using <filename>postgres_fdw</>:
<orderedlist spacing="compact">
<listitem>
<para>
Install the <filename>postgres_fdw</> extension using <xref
linkend="sql-createextension">.
</para>
</listitem>
<listitem>
<para>
Create a foreign server object, using <xref linkend="sql-createserver">,
to represent each remote database you want to connect to.
Specify connection information, except <literal>user</literal> and
<literal>password</literal>, as options of the server object.
</para>
</listitem>
<listitem>
<para>
Create a user mapping, using <xref linkend="sql-createusermapping">, for
each database user you want to allow to access each foreign server.
Specify the remote user name and password to use as
<literal>user</literal> and <literal>password</literal> options of the
user mapping.
</para>
</listitem>
<listitem>
<para>
Create a foreign table, using <xref linkend="sql-createforeigntable">,
for each remote table you want to access. The columns of the foreign
table must match the referenced remote table. You can, however, use
table and/or column names different from the remote table's, if you
specify the correct remote names as options of the foreign table object.
</para>
</listitem>
</orderedlist>
</para>
<para>
Now you need only <command>SELECT</> from a foreign table to access
the data stored in its underlying remote table.
</para>
<para>
It is generally recommended that the columns of a foreign table be declared
with exactly the same data types, and collations if applicable, as the
referenced columns of the remote table. Although <filename>postgres_fdw</>
is currently rather forgiving about performing data type conversions at
need, surprising semantic anomalies may arise when types or collations do
not match, due to the remote server interpreting <literal>WHERE</> clauses
slightly differently from the local server.
</para>
<para>
Note that a foreign table can be declared with fewer columns, or with a
different column order, than its underlying remote table has. Matching
of columns to the remote table is by name, not position.
</para>
<sect2>
<title>FDW Options of postgres_fdw</title>
<sect3>
<title>Connection Options</title>
<para>
A foreign server using the <filename>postgres_fdw</> foreign data wrapper
can have the same options that <application>libpq</> accepts in
connection strings, as described in <xref linkend="libpq-paramkeywords">,
except that these options are not allowed:
<itemizedlist spacing="compact">
<listitem>
<para>
<literal>user</literal> and <literal>password</literal> (specify these
for a user mapping, instead)
</para>
</listitem>
<listitem>
<para>
<literal>client_encoding</> (this is automatically set from the local
server encoding)
</para>
</listitem>
<listitem>
<para>
<literal>fallback_application_name</> (always set to
<literal>postgres_fdw</>)
</para>
</listitem>
</itemizedlist>
</para>
<para>
Only superusers may connect to foreign servers without password
authentication, so always specify the <literal>password</literal> option
for user mappings belonging to non-superusers.
</para>
</sect3>
<sect3>
<title>Object Name Options</title>
<para>
These options can be used to control the names used in SQL statements
sent to the remote <productname>PostgreSQL</productname> server. These
options are needed when a foreign table is created with names different
from the underlying remote table's names.
</para>
<variablelist>
<varlistentry>
<term><literal>schema_name</literal></term>
<listitem>
<para>
This option, which can be specified for a foreign table, gives the
schema name to use for the foreign table on the remote server. If this
option is omitted, the name of the foreign table's schema is used.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>table_name</literal></term>
<listitem>
<para>
This option, which can be specified for a foreign table, gives the
table name to use for the foreign table on the remote server. If this
option is omitted, the foreign table's name is used.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>column_name</literal></term>
<listitem>
<para>
This option, which can be specified for a column of a foreign table,
gives the column name to use for the column on the remote server.
If this option is omitted, the column's name is used.
</para>
</listitem>
</varlistentry>
</variablelist>
</sect3>
<sect3>
<title>Cost Estimation Options</title>
<para>
<filename>postgres_fdw</> retrieves remote data by executing queries
against remote servers, so ideally the estimated cost of scanning a
foreign table should be whatever it costs to be done on the remote
server, plus some overhead for communication. The most reliable way to
get such an estimate is to ask the remote server and then add something
for overhead &mdash; but for simple queries, it may not be worth the cost
of an additional remote query to get a cost estimate.
So <filename>postgres_fdw</> provides the following options to control
how cost estimation is done:
</para>
<variablelist>
<varlistentry>
<term><literal>use_remote_estimate</literal></term>
<listitem>
<para>
This option, which can be specified for a foreign table or a foreign
server, controls whether <filename>postgres_fdw</> issues remote
<command>EXPLAIN</command> commands to obtain cost estimates.
A setting for a foreign table overrides any setting for its server,
but only for that table.
The default is <literal>false</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>fdw_startup_cost</literal></term>
<listitem>
<para>
This option, which can be specified for a foreign server, is a numeric
value that is added to the estimated startup cost of any foreign-table
scan on that server. This represents the additional overhead of
establishing a connection, parsing and planning the query on the
remote side, etc.
The default value is <literal>100</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>fdw_tuple_cost</literal></term>
<listitem>
<para>
This option, which can be specified for a foreign server, is a numeric
value that is used as extra cost per-tuple for foreign-table
scans on that server. This represents the additional overhead of
data transfer between servers. You might increase or decrease this
number to reflect higher or lower network delay to the remote server.
The default value is <literal>0.01</literal>.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
When <literal>use_remote_estimate</literal> is true,
<filename>postgres_fdw</> obtains rowcount and cost estimates from the
remote server and then adds <literal>fdw_startup_cost</literal> and
<literal>fdw_tuple_cost</literal> to the cost estimates. When
<literal>use_remote_estimate</literal> is false,
<filename>postgres_fdw</> performs local rowcount and cost estimation
and then adds <literal>fdw_startup_cost</literal> and
<literal>fdw_tuple_cost</literal> to the cost estimates. This local
estimation is unlikely to be very accurate unless local copies of the
remote table's statistics are available. Running
<xref linkend="sql-analyze"> on the foreign table is the way to update
the local statistics; this will perform a scan of the remote table and
then calculate and store statistics just as though the table were local.
Keeping local statistics can be a useful way to reduce per-query planning
overhead for a remote table &mdash; but if the remote table is
frequently updated, the local statistics will soon be obsolete.
</para>
</sect3>
</sect2>
<sect2>
<title>Connection Management</title>
<para>
<filename>postgres_fdw</filename> establishes a connection to a
foreign server during the first query that uses a foreign table
associated with the foreign server. This connection is kept and
re-used for subsequent queries in the same session. However, if
multiple user identities (user mappings) are used to access the foreign
server, a connection is established for each user mapping.
</para>
</sect2>
<sect2>
<title>Transaction Management</title>
<para>
During a query that references any remote tables on a foreign server,
<filename>postgres_fdw</filename> opens a transaction on the
remote server if one is not already open corresponding to the current
local transaction. The remote transaction is committed or aborted when
the local transaction commits or aborts. Savepoints are similarly
managed by creating corresponding remote savepoints.
</para>
<para>
The remote transaction uses <literal>SERIALIZABLE</>
isolation level when the local transaction has <literal>SERIALIZABLE</>
isolation level; otherwise it uses <literal>REPEATABLE READ</>
isolation level. This choice ensures that if a query performs multiple
table scans on the remote server, it will get snapshot-consistent results
for all the scans. A consequence is that successive queries within a
single transaction will see the same data from the remote server, even if
concurrent updates are occurring on the remote server due to other
activities. That behavior would be expected anyway if the local
transaction uses <literal>SERIALIZABLE</> or <literal>REPEATABLE READ</>
isolation level, but it might be surprising for a <literal>READ
COMMITTED</> local transaction. A future
<productname>PostgreSQL</productname> release might modify these rules.
</para>
</sect2>
<sect2>
<title>Remote Query Optimization</title>
<para>
<filename>postgres_fdw</> attempts to optimize remote queries to reduce
the amount of data transferred from foreign servers. This is done by
sending query <literal>WHERE</> clauses to the remote server for
execution, and by not retrieving table columns that are not needed for
the current query. To reduce the risk of misexecution of queries,
<literal>WHERE</> clauses are not sent to the remote server unless they use
only built-in data types, operators, and functions. Operators and
functions in the clauses must be <literal>IMMUTABLE</> as well.
</para>
<para>
The query that is actually sent to the remote server for execution can
be examined using <command>EXPLAIN VERBOSE</>.
</para>
</sect2>
<sect2>
<title>Author</title>
<para>
Shigeru Hanada <email>shigeru.hanada@gmail.com</email>
</para>
</sect2>
</sect1>

2
doc/src/sgml/queries.sgml
View File

@ -699,7 +699,7 @@ SELECT *
WHERE proname LIKE 'bytea%'; WHERE proname LIKE 'bytea%';
</programlisting> </programlisting>
The <xref linkend="CONTRIB-DBLINK-FUNCTION"> function The <xref linkend="CONTRIB-DBLINK-FUNCTION"> function
(part of the <xref linkend="dblink"> module>) executes (part of the <xref linkend="dblink"> module) executes
a remote query. It is declared to return a remote query. It is declared to return
<type>record</> since it might be used for any kind of query. <type>record</> since it might be used for any kind of query.
The actual column set must be specified in the calling query so The actual column set must be specified in the calling query so

3
doc/src/sgml/recovery-config.sgml
View File

@ -314,8 +314,7 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
<para> <para>
Specifies a connection string to be used for the standby server Specifies a connection string to be used for the standby server
to connect with the primary. This string is in the format to connect with the primary. This string is in the format
accepted by the libpq <function>PQconnectdb</function> function, described in <xref linkend="libpq-connstring">. If any option is
described in <xref linkend="libpq-connect">. If any option is
unspecified in this string, then the corresponding environment unspecified in this string, then the corresponding environment
variable (see <xref linkend="libpq-envars">) is checked. If the variable (see <xref linkend="libpq-envars">) is checked. If the
environment variable is not set either, then environment variable is not set either, then

8
doc/src/sgml/ref/create_foreign_data_wrapper.sgml
View File

@ -121,14 +121,6 @@ CREATE FOREIGN DATA WRAPPER <replaceable class="parameter">name</replaceable>
There is no support for updating a foreign table, and optimization of There is no support for updating a foreign table, and optimization of
queries is primitive (and mostly left to the wrapper, too). queries is primitive (and mostly left to the wrapper, too).
</para> </para>
<para>
There is one built-in foreign-data wrapper validator function
provided:
<filename>postgresql_fdw_validator</filename>, which accepts
options corresponding to <application>libpq</> connection
parameters.
</para>
</refsect1> </refsect1>
<refsect1> <refsect1>

12
doc/src/sgml/ref/create_foreign_table.sgml
View File

@ -32,7 +32,7 @@ CREATE FOREIGN TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name
<title>Description</title> <title>Description</title>
<para> <para>
<command>CREATE FOREIGN TABLE</command> will create a new foreign table <command>CREATE FOREIGN TABLE</command> creates a new foreign table
in the current database. The table will be owned by the user issuing the in the current database. The table will be owned by the user issuing the
command. command.
</para> </para>
@ -54,8 +54,9 @@ CREATE FOREIGN TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name
</para> </para>
<para> <para>
To be able to create a table, you must have <literal>USAGE</literal> To be able to create a foreign table, you must have <literal>USAGE</literal>
privilege on all column types. privilege on the foreign server, as well as <literal>USAGE</literal>
privilege on all column types used in the table.
</para> </para>
</refsect1> </refsect1>
@ -134,7 +135,7 @@ CREATE FOREIGN TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name
<term><replaceable class="PARAMETER">server_name</replaceable></term> <term><replaceable class="PARAMETER">server_name</replaceable></term>
<listitem> <listitem>
<para> <para>
The name of an existing server for the foreign table. The name of an existing foreign server to use for the foreign table.
For details on defining a server, see <xref For details on defining a server, see <xref
linkend="SQL-CREATESERVER">. linkend="SQL-CREATESERVER">.
</para> </para>
@ -164,7 +165,8 @@ CREATE FOREIGN TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name
<title>Examples</title> <title>Examples</title>
<para> <para>
Create foreign table <structname>films</> with <structname>film_server</>: Create foreign table <structname>films</>, which will be accessed through
the server <structname>film_server</>:
<programlisting> <programlisting>
CREATE FOREIGN TABLE films ( CREATE FOREIGN TABLE films (

24
doc/src/sgml/ref/create_server.sgml
View File

@ -110,11 +110,10 @@ CREATE SERVER <replaceable class="parameter">server_name</replaceable> [ TYPE '<
<title>Notes</title> <title>Notes</title>
<para> <para>
When using the <application>dblink</application> module When using the <xref linkend="dblink"> module,
(see <xref linkend="dblink">), the foreign server name can be used a foreign server's name can be used
as an argument of the <xref linkend="contrib-dblink-connect"> as an argument of the <xref linkend="contrib-dblink-connect">
function to indicate the connection parameters. See also there for function to indicate the connection parameters. It is necessary to have
more examples. It is necessary to have
the <literal>USAGE</literal> privilege on the foreign server to be the <literal>USAGE</literal> privilege on the foreign server to be
able to use it in this way. able to use it in this way.
</para> </para>
@ -123,20 +122,14 @@ CREATE SERVER <replaceable class="parameter">server_name</replaceable> [ TYPE '<
<refsect1> <refsect1>
<title>Examples</title> <title>Examples</title>
<para>
Create a server <literal>foo</> that uses the built-in foreign-data
wrapper <literal>default</>:
<programlisting>
CREATE SERVER foo FOREIGN DATA WRAPPER "default";
</programlisting>
</para>
<para> <para>
Create a server <literal>myserver</> that uses the Create a server <literal>myserver</> that uses the
foreign-data wrapper <literal>pgsql</>: foreign-data wrapper <literal>postgres_fdw</>:
<programlisting> <programlisting>
CREATE SERVER myserver FOREIGN DATA WRAPPER pgsql OPTIONS (host 'foo', dbname 'foodb', port '5432'); CREATE SERVER myserver FOREIGN DATA WRAPPER postgres_fdw OPTIONS (host 'foo', dbname 'foodb', port '5432');
</programlisting></para> </programlisting>
See <xref linkend="postgres-fdw"> for more details.
</para>
</refsect1> </refsect1>
<refsect1> <refsect1>
@ -154,6 +147,7 @@ CREATE SERVER myserver FOREIGN DATA WRAPPER pgsql OPTIONS (host 'foo', dbname 'f
<member><xref linkend="sql-alterserver"></member> <member><xref linkend="sql-alterserver"></member>
<member><xref linkend="sql-dropserver"></member> <member><xref linkend="sql-dropserver"></member>
<member><xref linkend="sql-createforeigndatawrapper"></member> <member><xref linkend="sql-createforeigndatawrapper"></member>
<member><xref linkend="sql-createforeigntable"></member>
<member><xref linkend="sql-createusermapping"></member> <member><xref linkend="sql-createusermapping"></member>
</simplelist> </simplelist>
</refsect1> </refsect1>

7
doc/src/sgml/ref/grant.sgml
View File

@ -357,10 +357,9 @@ GRANT <replaceable class="PARAMETER">role_name</replaceable> [, ...] TO <replace
to create new servers using that foreign-data wrapper. to create new servers using that foreign-data wrapper.
</para> </para>
<para> <para>
For servers, this privilege enables the grantee to create, For servers, this privilege enables the grantee to create foreign
alter, and drop his own user's user mappings associated with tables using the server, and also to create, alter, or drop his own
that server. Also, it enables the grantee to query the options user's user mappings associated with that server.
of the server and associated user mappings.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>

3
doc/src/sgml/ref/pg_isready.sgml
View File

@ -54,7 +54,8 @@ PostgreSQL documentation
with a valid <acronym>URI</acronym> prefix with a valid <acronym>URI</acronym> prefix
(<literal>postgresql://</literal> (<literal>postgresql://</literal>
or <literal>postgres://</literal>), it is treated as a or <literal>postgres://</literal>), it is treated as a
<parameter>conninfo</parameter> string. See <xref linkend="libpq-connect"> for more information. <parameter>conninfo</parameter> string. See <xref
linkend="libpq-connstring"> for more information.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>

9
doc/src/sgml/ref/psql-ref.sgml
View File

@ -120,7 +120,8 @@ PostgreSQL documentation
with a valid <acronym>URI</acronym> prefix with a valid <acronym>URI</acronym> prefix
(<literal>postgresql://</literal> (<literal>postgresql://</literal>
or <literal>postgres://</literal>), it is treated as a or <literal>postgres://</literal>), it is treated as a
<parameter>conninfo</parameter> string. See <xref linkend="libpq-connect"> for more information. <parameter>conninfo</parameter> string. See <xref
linkend="libpq-connstring"> for more information.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
@ -608,9 +609,9 @@ PostgreSQL documentation
$ <userinput>psql "service=myservice sslmode=require"</userinput> $ <userinput>psql "service=myservice sslmode=require"</userinput>
$ <userinput>psql postgresql://dbmaster:5433/mydb?sslmode=require</userinput> $ <userinput>psql postgresql://dbmaster:5433/mydb?sslmode=require</userinput>
</programlisting> </programlisting>
This way you can also use <acronym>LDAP</acronym> for connection parameter lookup as This way you can also use <acronym>LDAP</acronym> for connection
described in <xref linkend="libpq-ldap">. parameter lookup as described in <xref linkend="libpq-ldap">.
See <xref linkend="libpq-connect"> for more information on all the See <xref linkend="libpq-paramkeywords"> for more information on all the
available connection options. available connection options.
</para> </para>

2
doc/src/sgml/runtime.sgml
View File

@ -1751,7 +1751,7 @@ pg_dumpall -p 5432 | psql -d postgres -p 5433
(<xref linkend="ssl-tcp">). The TCP client must connect using (<xref linkend="ssl-tcp">). The TCP client must connect using
<literal>sslmode=verify-ca</> or <literal>sslmode=verify-ca</> or
<literal>verify-full</> and have the appropriate root certificate <literal>verify-full</> and have the appropriate root certificate
file installed (<xref linkend="libpq-connect">). file installed (<xref linkend="libq-ssl-certificates">).
</para> </para>
</sect1> </sect1>

8
src/backend/foreign/foreign.c
View File

@ -485,11 +485,15 @@ is_conninfo_option(const char *option, Oid context)
/* /*
* Validate the generic option given to SERVER or USER MAPPING. * Validate the generic option given to SERVER or USER MAPPING.
* Raise an ERROR if the option or its value is considered * Raise an ERROR if the option or its value is considered invalid.
* invalid.
* *
* Valid server options are all libpq conninfo options except * Valid server options are all libpq conninfo options except
* user and password -- these may only appear in USER MAPPING options. * user and password -- these may only appear in USER MAPPING options.
*
* Caution: this function is deprecated, and is now meant only for testing
* purposes, because the list of options it knows about doesn't necessarily
* square with those known to whichever libpq instance you might be using.
* Inquire of libpq itself, instead.
*/ */
Datum Datum
postgresql_fdw_validator(PG_FUNCTION_ARGS) postgresql_fdw_validator(PG_FUNCTION_ARGS)