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Add IF NOT EXISTS for CREATE SERVER and CREATE USER MAPPING

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There is still some inconsistency with the error messages surrounding
foreign servers. Some use the word "foreign" and some don't. My
inclination is to remove all such uses of "foreign" on the basis that
the  CREATE/ALTER/DROP SERVER commands don't use the word. However, that
is left for another day. In this patch I have kept to the existing usage
in the affected commands, which omits "foreign".

Anastasia Lubennikova, reviewed by Arthur Zakirov and Ashtosh Bapat.

Discussion: http://postgr.es/m/7c2ab9b8-388a-1ce0-23a3-7acf2a0ed3c6@postgrespro.ru
This commit is contained in:
Andrew Dunstan 2017-03-20 16:40:45 -04:00
parent 839cb0649a
commit b6fb534f10
7 changed files with 93 additions and 7 deletions
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14
doc/src/sgml/ref/create_server.sgml
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@ -21,7 +21,7 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
CREATE SERVER <replaceable class="parameter">server_name</replaceable> [ TYPE '<replaceable class="parameter">server_type</replaceable>' ] [ VERSION '<replaceable class="parameter">server_version</replaceable>' ]
CREATE SERVER [IF NOT EXISTS] <replaceable class="parameter">server_name</replaceable> [ TYPE '<replaceable class="parameter">server_type</replaceable>' ] [ VERSION '<replaceable class="parameter">server_version</replaceable>' ]
FOREIGN DATA WRAPPER <replaceable class="parameter">fdw_name</replaceable>
[ OPTIONS ( <replaceable class="PARAMETER">option</replaceable> '<replaceable class="PARAMETER">value</replaceable>' [, ... ] ) ]
</synopsis>
@ -56,6 +56,18 @@ CREATE SERVER <replaceable class="parameter">server_name</replaceable> [ TYPE '<
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><literal>IF NOT EXISTS</></term>
<listitem>
<para>
Do not throw an error if a server with the same name already exists.
A notice is issued in this case. Note that there is no guarantee that
the existing server is anything like the one that would have been
created.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">server_name</replaceable></term>
<listitem>

14
doc/src/sgml/ref/create_user_mapping.sgml
View File

@ -21,7 +21,7 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
CREATE USER MAPPING FOR { <replaceable class="parameter">user_name</replaceable> | USER | CURRENT_USER | PUBLIC }
CREATE USER MAPPING [IF NOT EXISTS] FOR { <replaceable class="parameter">user_name</replaceable> | USER | CURRENT_USER | PUBLIC }
SERVER <replaceable class="parameter">server_name</replaceable>
[ OPTIONS ( <replaceable class="PARAMETER">option</replaceable> '<replaceable class="PARAMETER">value</replaceable>' [ , ... ] ) ]
</synopsis>
@ -50,6 +50,18 @@ CREATE USER MAPPING FOR { <replaceable class="parameter">user_name</replaceable>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><literal>IF NOT EXISTS</></term>
<listitem>
<para>
Do not throw an error if a mapping of the given user to the given foreign
server already exists. A notice is issued in this case. Note that there
is no guarantee that the existing user mapping is anything like the one
that would have been created.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">user_name</replaceable></term>
<listitem>

28
src/backend/commands/foreigncmds.c
View File

@ -879,12 +879,25 @@ CreateForeignServer(CreateForeignServerStmt *stmt)
/*
* Check that there is no other foreign server by this name.
* Do nothing if IF NOT EXISTS was enforced.
*/
if (GetForeignServerByName(stmt->servername, true) != NULL)
{
if (stmt->if_not_exists)
{
ereport(NOTICE,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("server \"%s\" already exists, skipping",
stmt->servername)));
heap_close(rel, RowExclusiveLock);
return InvalidObjectAddress;
}
else
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("server \"%s\" already exists",
stmt->servername)));
}
/*
* Check that the FDW exists and that we have USAGE on it. Also get the
@ -1152,12 +1165,27 @@ CreateUserMapping(CreateUserMappingStmt *stmt)
umId = GetSysCacheOid2(USERMAPPINGUSERSERVER,
ObjectIdGetDatum(useId),
ObjectIdGetDatum(srv->serverid));
if (OidIsValid(umId))
{
if (stmt->if_not_exists)
{
ereport(NOTICE,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("user mapping for \"%s\" already exists for server %s, skipping",
MappingUserName(useId),
stmt->servername)));
heap_close(rel, RowExclusiveLock);
return InvalidObjectAddress;
}
else
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("user mapping for \"%s\" already exists for server %s",
MappingUserName(useId),
stmt->servername)));
}
fdw = GetForeignDataWrapper(srv->fdwid);

23
src/backend/parser/gram.y
View File

@ -4621,6 +4621,19 @@ CreateForeignServerStmt: CREATE SERVER name opt_type opt_foreign_server_version
n->version = $5;
n->fdwname = $9;
n->options = $10;
n->if_not_exists = false;
$$ = (Node *) n;
}
| CREATE SERVER IF_P NOT EXISTS name opt_type opt_foreign_server_version
FOREIGN DATA_P WRAPPER name create_generic_options
{
CreateForeignServerStmt *n = makeNode(CreateForeignServerStmt);
n->servername = $6;
n->servertype = $7;
n->version = $8;
n->fdwname = $12;
n->options = $13;
n->if_not_exists = true;
$$ = (Node *) n;
}
;
@ -4853,6 +4866,16 @@ CreateUserMappingStmt: CREATE USER MAPPING FOR auth_ident SERVER name create_gen
n->user = $5;
n->servername = $7;
n->options = $8;
n->if_not_exists = false;
$$ = (Node *) n;
}
| CREATE USER MAPPING IF_P NOT EXISTS FOR auth_ident SERVER name create_generic_options
{
CreateUserMappingStmt *n = makeNode(CreateUserMappingStmt);
n->user = $8;
n->servername = $10;
n->options = $11;
n->if_not_exists = true;
$$ = (Node *) n;
}
;

2
src/include/nodes/parsenodes.h
View File

@ -2154,6 +2154,7 @@ typedef struct CreateForeignServerStmt
char *servertype; /* optional server type */
char *version; /* optional server version */
char *fdwname; /* FDW name */
bool if_not_exists; /* just do nothing if it already exists? */
List *options; /* generic options to server */
} CreateForeignServerStmt;
@ -2188,6 +2189,7 @@ typedef struct CreateUserMappingStmt
NodeTag type;
RoleSpec *user; /* user role */
char *servername; /* server name */
bool if_not_exists; /* just do nothing if it already exists? */
List *options; /* generic options to server */
} CreateUserMappingStmt;

6
src/test/regress/expected/foreign_data.out
View File

@ -221,6 +221,10 @@ CREATE FOREIGN DATA WRAPPER foo;
CREATE SERVER s1 FOREIGN DATA WRAPPER foo;
COMMENT ON SERVER s1 IS 'foreign server';
CREATE USER MAPPING FOR current_user SERVER s1;
CREATE USER MAPPING FOR current_user SERVER s1; -- ERROR
ERROR: user mapping for "regress_foreign_data_user" already exists for server s1
CREATE USER MAPPING IF NOT EXISTS FOR current_user SERVER s1; -- NOTICE
NOTICE: user mapping for "regress_foreign_data_user" already exists for server s1, skipping
\dew+
List of foreign-data wrappers
Name | Owner | Handler | Validator | Access privileges | FDW Options | Description
@ -284,6 +288,8 @@ CREATE FOREIGN DATA WRAPPER foo OPTIONS ("test wrapper" 'true');
CREATE SERVER s1 FOREIGN DATA WRAPPER foo;
CREATE SERVER s1 FOREIGN DATA WRAPPER foo; -- ERROR
ERROR: server "s1" already exists
CREATE SERVER IF NOT EXISTS s1 FOREIGN DATA WRAPPER foo; -- No ERROR, just NOTICE
NOTICE: server "s1" already exists, skipping
CREATE SERVER s2 FOREIGN DATA WRAPPER foo OPTIONS (host 'a', dbname 'b');
CREATE SERVER s3 TYPE 'oracle' FOREIGN DATA WRAPPER foo;
CREATE SERVER s4 TYPE 'oracle' FOREIGN DATA WRAPPER foo OPTIONS (host 'a', dbname 'b');

3
src/test/regress/sql/foreign_data.sql
View File

@ -104,6 +104,8 @@ CREATE FOREIGN DATA WRAPPER foo;
CREATE SERVER s1 FOREIGN DATA WRAPPER foo;
COMMENT ON SERVER s1 IS 'foreign server';
CREATE USER MAPPING FOR current_user SERVER s1;
CREATE USER MAPPING FOR current_user SERVER s1; -- ERROR
CREATE USER MAPPING IF NOT EXISTS FOR current_user SERVER s1; -- NOTICE
\dew+
\des+
\deu+
@ -121,6 +123,7 @@ CREATE SERVER s1 FOREIGN DATA WRAPPER foo; -- ERROR
CREATE FOREIGN DATA WRAPPER foo OPTIONS ("test wrapper" 'true');
CREATE SERVER s1 FOREIGN DATA WRAPPER foo;
CREATE SERVER s1 FOREIGN DATA WRAPPER foo; -- ERROR
CREATE SERVER IF NOT EXISTS s1 FOREIGN DATA WRAPPER foo; -- No ERROR, just NOTICE
CREATE SERVER s2 FOREIGN DATA WRAPPER foo OPTIONS (host 'a', dbname 'b');
CREATE SERVER s3 TYPE 'oracle' FOREIGN DATA WRAPPER foo;
CREATE SERVER s4 TYPE 'oracle' FOREIGN DATA WRAPPER foo OPTIONS (host 'a', dbname 'b');