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Implement IMPORT FOREIGN SCHEMA.

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This command provides an automated way to create foreign table definitions
that match remote tables, thereby reducing tedium and chances for error.
In this patch, we provide the necessary core-server infrastructure and
implement the feature fully in the postgres_fdw foreign-data wrapper.
Other wrappers will throw a "feature not supported" error until/unless
they are updated.

Ronan Dunklau and Michael Paquier, additional work by me
This commit is contained in:
Tom Lane
2014-07-10 15:01:31 -04:00
parent 6a605cd6bd
commit 59efda3e50
29 changed files with 1239 additions and 15 deletions
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3
contrib/postgres_fdw/deparse.c
View File

@ -116,7 +116,6 @@ static void deparseReturningList(StringInfo buf, PlannerInfo *root,
static void deparseColumnRef(StringInfo buf, int varno, int varattno,
PlannerInfo *root);
static void deparseRelation(StringInfo buf, Relation rel);
static void deparseStringLiteral(StringInfo buf, const char *val);
static void deparseExpr(Expr *expr, deparse_expr_cxt *context);
static void deparseVar(Var *node, deparse_expr_cxt *context);
static void deparseConst(Const *node, deparse_expr_cxt *context);
@ -1160,7 +1159,7 @@ deparseRelation(StringInfo buf, Relation rel)
/*
* Append a SQL string literal representing "val" to buf.
*/
static void
void
deparseStringLiteral(StringInfo buf, const char *val)
{
const char *valptr;

230
contrib/postgres_fdw/expected/postgres_fdw.out
View File

@ -2834,3 +2834,233 @@ NOTICE: NEW: (13,"test triggered !")
(0,27)
(1 row)
-- ===================================================================
-- test IMPORT FOREIGN SCHEMA
-- ===================================================================
CREATE SCHEMA import_source;
CREATE TABLE import_source.t1 (c1 int, c2 varchar NOT NULL);
CREATE TABLE import_source.t2 (c1 int default 42, c2 varchar NULL, c3 text collate "POSIX");
CREATE TYPE typ1 AS (m1 int, m2 varchar);
CREATE TABLE import_source.t3 (c1 timestamptz default now(), c2 typ1);
CREATE TABLE import_source."x 4" (c1 float8, "C 2" text, c3 varchar(42));
CREATE TABLE import_source."x 5" (c1 float8);
ALTER TABLE import_source."x 5" DROP COLUMN c1;
CREATE SCHEMA import_dest1;
IMPORT FOREIGN SCHEMA import_source FROM SERVER loopback INTO import_dest1;
\det+ import_dest1
List of foreign tables
Schema | Table | Server | FDW Options | Description
--------------+-------+----------+-------------------------------------------------+-------------
import_dest1 | t1 | loopback | (schema_name 'import_source', table_name 't1') |
import_dest1 | t2 | loopback | (schema_name 'import_source', table_name 't2') |
import_dest1 | t3 | loopback | (schema_name 'import_source', table_name 't3') |
import_dest1 | x 4 | loopback | (schema_name 'import_source', table_name 'x 4') |
import_dest1 | x 5 | loopback | (schema_name 'import_source', table_name 'x 5') |
(5 rows)
\d import_dest1.*
Foreign table "import_dest1.t1"
Column | Type | Modifiers | FDW Options
--------+-------------------+-----------+--------------------
c1 | integer | | (column_name 'c1')
c2 | character varying | not null | (column_name 'c2')
Server: loopback
FDW Options: (schema_name 'import_source', table_name 't1')
Foreign table "import_dest1.t2"
Column | Type | Modifiers | FDW Options
--------+-------------------+---------------+--------------------
c1 | integer | | (column_name 'c1')
c2 | character varying | | (column_name 'c2')
c3 | text | collate POSIX | (column_name 'c3')
Server: loopback
FDW Options: (schema_name 'import_source', table_name 't2')
Foreign table "import_dest1.t3"
Column | Type | Modifiers | FDW Options
--------+--------------------------+-----------+--------------------
c1 | timestamp with time zone | | (column_name 'c1')
c2 | typ1 | | (column_name 'c2')
Server: loopback
FDW Options: (schema_name 'import_source', table_name 't3')
Foreign table "import_dest1.x 4"
Column | Type | Modifiers | FDW Options
--------+-----------------------+-----------+---------------------
c1 | double precision | | (column_name 'c1')
C 2 | text | | (column_name 'C 2')
c3 | character varying(42) | | (column_name 'c3')
Server: loopback
FDW Options: (schema_name 'import_source', table_name 'x 4')
Foreign table "import_dest1.x 5"
Column | Type | Modifiers | FDW Options
--------+------+-----------+-------------
Server: loopback
FDW Options: (schema_name 'import_source', table_name 'x 5')
-- Options
CREATE SCHEMA import_dest2;
IMPORT FOREIGN SCHEMA import_source FROM SERVER loopback INTO import_dest2
OPTIONS (import_default 'true');
\det+ import_dest2
List of foreign tables
Schema | Table | Server | FDW Options | Description
--------------+-------+----------+-------------------------------------------------+-------------
import_dest2 | t1 | loopback | (schema_name 'import_source', table_name 't1') |
import_dest2 | t2 | loopback | (schema_name 'import_source', table_name 't2') |
import_dest2 | t3 | loopback | (schema_name 'import_source', table_name 't3') |
import_dest2 | x 4 | loopback | (schema_name 'import_source', table_name 'x 4') |
import_dest2 | x 5 | loopback | (schema_name 'import_source', table_name 'x 5') |
(5 rows)
\d import_dest2.*
Foreign table "import_dest2.t1"
Column | Type | Modifiers | FDW Options
--------+-------------------+-----------+--------------------
c1 | integer | | (column_name 'c1')
c2 | character varying | not null | (column_name 'c2')
Server: loopback
FDW Options: (schema_name 'import_source', table_name 't1')
Foreign table "import_dest2.t2"
Column | Type | Modifiers | FDW Options
--------+-------------------+---------------+--------------------
c1 | integer | default 42 | (column_name 'c1')
c2 | character varying | | (column_name 'c2')
c3 | text | collate POSIX | (column_name 'c3')
Server: loopback
FDW Options: (schema_name 'import_source', table_name 't2')
Foreign table "import_dest2.t3"
Column | Type | Modifiers | FDW Options
--------+--------------------------+---------------+--------------------
c1 | timestamp with time zone | default now() | (column_name 'c1')
c2 | typ1 | | (column_name 'c2')
Server: loopback
FDW Options: (schema_name 'import_source', table_name 't3')
Foreign table "import_dest2.x 4"
Column | Type | Modifiers | FDW Options
--------+-----------------------+-----------+---------------------
c1 | double precision | | (column_name 'c1')
C 2 | text | | (column_name 'C 2')
c3 | character varying(42) | | (column_name 'c3')
Server: loopback
FDW Options: (schema_name 'import_source', table_name 'x 4')
Foreign table "import_dest2.x 5"
Column | Type | Modifiers | FDW Options
--------+------+-----------+-------------
Server: loopback
FDW Options: (schema_name 'import_source', table_name 'x 5')
CREATE SCHEMA import_dest3;
IMPORT FOREIGN SCHEMA import_source FROM SERVER loopback INTO import_dest3
OPTIONS (import_collate 'false', import_not_null 'false');
\det+ import_dest3
List of foreign tables
Schema | Table | Server | FDW Options | Description
--------------+-------+----------+-------------------------------------------------+-------------
import_dest3 | t1 | loopback | (schema_name 'import_source', table_name 't1') |
import_dest3 | t2 | loopback | (schema_name 'import_source', table_name 't2') |
import_dest3 | t3 | loopback | (schema_name 'import_source', table_name 't3') |
import_dest3 | x 4 | loopback | (schema_name 'import_source', table_name 'x 4') |
import_dest3 | x 5 | loopback | (schema_name 'import_source', table_name 'x 5') |
(5 rows)
\d import_dest3.*
Foreign table "import_dest3.t1"
Column | Type | Modifiers | FDW Options
--------+-------------------+-----------+--------------------
c1 | integer | | (column_name 'c1')
c2 | character varying | | (column_name 'c2')
Server: loopback
FDW Options: (schema_name 'import_source', table_name 't1')
Foreign table "import_dest3.t2"
Column | Type | Modifiers | FDW Options
--------+-------------------+-----------+--------------------
c1 | integer | | (column_name 'c1')
c2 | character varying | | (column_name 'c2')
c3 | text | | (column_name 'c3')
Server: loopback
FDW Options: (schema_name 'import_source', table_name 't2')
Foreign table "import_dest3.t3"
Column | Type | Modifiers | FDW Options
--------+--------------------------+-----------+--------------------
c1 | timestamp with time zone | | (column_name 'c1')
c2 | typ1 | | (column_name 'c2')
Server: loopback
FDW Options: (schema_name 'import_source', table_name 't3')
Foreign table "import_dest3.x 4"
Column | Type | Modifiers | FDW Options
--------+-----------------------+-----------+---------------------
c1 | double precision | | (column_name 'c1')
C 2 | text | | (column_name 'C 2')
c3 | character varying(42) | | (column_name 'c3')
Server: loopback
FDW Options: (schema_name 'import_source', table_name 'x 4')
Foreign table "import_dest3.x 5"
Column | Type | Modifiers | FDW Options
--------+------+-----------+-------------
Server: loopback
FDW Options: (schema_name 'import_source', table_name 'x 5')
-- Check LIMIT TO and EXCEPT
CREATE SCHEMA import_dest4;
IMPORT FOREIGN SCHEMA import_source LIMIT TO (t1, nonesuch)
FROM SERVER loopback INTO import_dest4;
\det+ import_dest4
List of foreign tables
Schema | Table | Server | FDW Options | Description
--------------+-------+----------+------------------------------------------------+-------------
import_dest4 | t1 | loopback | (schema_name 'import_source', table_name 't1') |
(1 row)
IMPORT FOREIGN SCHEMA import_source EXCEPT (t1, "x 4", nonesuch)
FROM SERVER loopback INTO import_dest4;
\det+ import_dest4
List of foreign tables
Schema | Table | Server | FDW Options | Description
--------------+-------+----------+-------------------------------------------------+-------------
import_dest4 | t1 | loopback | (schema_name 'import_source', table_name 't1') |
import_dest4 | t2 | loopback | (schema_name 'import_source', table_name 't2') |
import_dest4 | t3 | loopback | (schema_name 'import_source', table_name 't3') |
import_dest4 | x 5 | loopback | (schema_name 'import_source', table_name 'x 5') |
(4 rows)
-- Assorted error cases
IMPORT FOREIGN SCHEMA import_source FROM SERVER loopback INTO import_dest4;
ERROR: relation "t1" already exists
CONTEXT: importing foreign table "t1"
IMPORT FOREIGN SCHEMA nonesuch FROM SERVER loopback INTO import_dest4;
ERROR: schema "nonesuch" is not present on foreign server "loopback"
IMPORT FOREIGN SCHEMA nonesuch FROM SERVER loopback INTO notthere;
ERROR: schema "notthere" does not exist
IMPORT FOREIGN SCHEMA nonesuch FROM SERVER nowhere INTO notthere;
ERROR: server "nowhere" does not exist
-- Check case of a type present only on the remote server.
-- We can fake this by dropping the type locally in our transaction.
CREATE TYPE "Colors" AS ENUM ('red', 'green', 'blue');
CREATE TABLE import_source.t5 (c1 int, c2 text collate "C", "Col" "Colors");
CREATE SCHEMA import_dest5;
BEGIN;
DROP TYPE "Colors" CASCADE;
NOTICE: drop cascades to table import_source.t5 column Col
IMPORT FOREIGN SCHEMA import_source LIMIT TO (t5)
FROM SERVER loopback INTO import_dest5; -- ERROR
ERROR: type "public.Colors" does not exist
LINE 4: "Col" public."Colors" OPTIONS (column_name 'Col')
^
QUERY: CREATE FOREIGN TABLE t5 (
c1 integer OPTIONS (column_name 'c1'),
c2 text OPTIONS (column_name 'c2') COLLATE pg_catalog."C",
"Col" public."Colors" OPTIONS (column_name 'Col')
) SERVER loopback
OPTIONS (schema_name 'import_source', table_name 't5');
CONTEXT: importing foreign table "t5"
ROLLBACK;

269
contrib/postgres_fdw/postgres_fdw.c
View File

@ -285,6 +285,8 @@ static void postgresExplainForeignModify(ModifyTableState *mtstate,
static bool postgresAnalyzeForeignTable(Relation relation,
AcquireSampleRowsFunc *func,
BlockNumber *totalpages);
static List *postgresImportForeignSchema(ImportForeignSchemaStmt *stmt,
Oid serverOid);
/*
* Helper functions
@ -362,6 +364,9 @@ postgres_fdw_handler(PG_FUNCTION_ARGS)
/* Support functions for ANALYZE */
routine->AnalyzeForeignTable = postgresAnalyzeForeignTable;
/* Support functions for IMPORT FOREIGN SCHEMA */
routine->ImportForeignSchema = postgresImportForeignSchema;
PG_RETURN_POINTER(routine);
}
@ -2563,6 +2568,270 @@ analyze_row_processor(PGresult *res, int row, PgFdwAnalyzeState *astate)
}
}
/*
* Import a foreign schema
*/
static List *
postgresImportForeignSchema(ImportForeignSchemaStmt *stmt, Oid serverOid)
{
List *commands = NIL;
bool import_collate = true;
bool import_default = false;
bool import_not_null = true;
ForeignServer *server;
UserMapping *mapping;
PGconn *conn;
StringInfoData buf;
PGresult *volatile res = NULL;
int numrows,
i;
ListCell *lc;
/* Parse statement options */
foreach(lc, stmt->options)
{
DefElem *def = (DefElem *) lfirst(lc);
if (strcmp(def->defname, "import_collate") == 0)
import_collate = defGetBoolean(def);
else if (strcmp(def->defname, "import_default") == 0)
import_default = defGetBoolean(def);
else if (strcmp(def->defname, "import_not_null") == 0)
import_not_null = defGetBoolean(def);
else
ereport(ERROR,
(errcode(ERRCODE_FDW_INVALID_OPTION_NAME),
errmsg("invalid option \"%s\"", def->defname)));
}
/*
* Get connection to the foreign server. Connection manager will
* establish new connection if necessary.
*/
server = GetForeignServer(serverOid);
mapping = GetUserMapping(GetUserId(), server->serverid);
conn = GetConnection(server, mapping, false);
/* Don't attempt to import collation if remote server hasn't got it */
if (PQserverVersion(conn) < 90100)
import_collate = false;
/* Create workspace for strings */
initStringInfo(&buf);
/* In what follows, do not risk leaking any PGresults. */
PG_TRY();
{
/* Check that the schema really exists */
appendStringInfoString(&buf, "SELECT 1 FROM pg_catalog.pg_namespace WHERE nspname = ");
deparseStringLiteral(&buf, stmt->remote_schema);
res = PQexec(conn, buf.data);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
pgfdw_report_error(ERROR, res, conn, false, buf.data);
if (PQntuples(res) != 1)
ereport(ERROR,
(errcode(ERRCODE_FDW_SCHEMA_NOT_FOUND),
errmsg("schema \"%s\" is not present on foreign server \"%s\"",
stmt->remote_schema, server->servername)));
PQclear(res);
res = NULL;
resetStringInfo(&buf);
/*
* Fetch all table data from this schema, possibly restricted by
* EXCEPT or LIMIT TO.
*
* Note: because we run the connection with search_path restricted to
* pg_catalog, the format_type() and pg_get_expr() outputs will always
* include a schema name for types/functions in other schemas, which
* is what we want.
*/
if (import_collate)
appendStringInfoString(&buf,
"SELECT relname, "
" attname, "
" format_type(atttypid, atttypmod), "
" attnotnull, "
" pg_get_expr(adbin, adrelid), "
" collname, "
" collnsp.nspname "
"FROM pg_class c "
" JOIN pg_namespace n ON "
" relnamespace = n.oid "
" LEFT JOIN pg_attribute a ON "
" attrelid = c.oid AND attnum > 0 "
" AND NOT attisdropped "
" LEFT JOIN pg_attrdef ad ON "
" adrelid = c.oid AND adnum = attnum "
" LEFT JOIN pg_collation coll ON "
" coll.oid = attcollation "
" LEFT JOIN pg_namespace collnsp ON "
" collnsp.oid = collnamespace ");
else
appendStringInfoString(&buf,
"SELECT relname, "
" attname, "
" format_type(atttypid, atttypmod), "
" attnotnull, "
" pg_get_expr(adbin, adrelid), "
" NULL, NULL "
"FROM pg_class c "
" JOIN pg_namespace n ON "
" relnamespace = n.oid "
" LEFT JOIN pg_attribute a ON "
" attrelid = c.oid AND attnum > 0 "
" AND NOT attisdropped "
" LEFT JOIN pg_attrdef ad ON "
" adrelid = c.oid AND adnum = attnum ");
appendStringInfoString(&buf,
"WHERE c.relkind IN ('r', 'v', 'f', 'm') "
" AND n.nspname = ");
deparseStringLiteral(&buf, stmt->remote_schema);
/* Apply restrictions for LIMIT TO and EXCEPT */
if (stmt->list_type == FDW_IMPORT_SCHEMA_LIMIT_TO ||
stmt->list_type == FDW_IMPORT_SCHEMA_EXCEPT)
{
bool first_item = true;
appendStringInfoString(&buf, " AND c.relname ");
if (stmt->list_type == FDW_IMPORT_SCHEMA_EXCEPT)
appendStringInfoString(&buf, "NOT ");
appendStringInfoString(&buf, "IN (");
/* Append list of table names within IN clause */
foreach(lc, stmt->table_list)
{
RangeVar *rv = (RangeVar *) lfirst(lc);
if (first_item)
first_item = false;
else
appendStringInfoString(&buf, ", ");
deparseStringLiteral(&buf, rv->relname);
}
appendStringInfoString(&buf, ")");
}
/* Append ORDER BY at the end of query to ensure output ordering */
appendStringInfo(&buf, " ORDER BY c.relname, a.attnum");
/* Fetch the data */
res = PQexec(conn, buf.data);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
pgfdw_report_error(ERROR, res, conn, false, buf.data);
/* Process results */
numrows = PQntuples(res);
/* note: incrementation of i happens in inner loop's while() test */
for (i = 0; i < numrows;)
{
char *tablename = PQgetvalue(res, i, 0);
bool first_item = true;
resetStringInfo(&buf);
appendStringInfo(&buf, "CREATE FOREIGN TABLE %s (\n",
quote_identifier(tablename));
/* Scan all rows for this table */
do
{
char *attname;
char *typename;
char *attnotnull;
char *attdefault;
char *collname;
char *collnamespace;
/* If table has no columns, we'll see nulls here */
if (PQgetisnull(res, i, 1))
continue;
attname = PQgetvalue(res, i, 1);
typename = PQgetvalue(res, i, 2);
attnotnull = PQgetvalue(res, i, 3);
attdefault = PQgetisnull(res, i, 4) ? (char *) NULL :
PQgetvalue(res, i, 4);
collname = PQgetisnull(res, i, 5) ? (char *) NULL :
PQgetvalue(res, i, 5);
collnamespace = PQgetisnull(res, i, 6) ? (char *) NULL :
PQgetvalue(res, i, 6);
if (first_item)
first_item = false;
else
appendStringInfoString(&buf, ",\n");
/* Print column name and type */
appendStringInfo(&buf, " %s %s",
quote_identifier(attname),
typename);
/*
* Add column_name option so that renaming the foreign table's
* column doesn't break the association to the underlying
* column.
*/
appendStringInfoString(&buf, " OPTIONS (column_name ");
deparseStringLiteral(&buf, attname);
appendStringInfoString(&buf, ")");
/* Add COLLATE if needed */
if (import_collate && collname != NULL && collnamespace != NULL)
appendStringInfo(&buf, " COLLATE %s.%s",
quote_identifier(collnamespace),
quote_identifier(collname));
/* Add DEFAULT if needed */
if (import_default && attdefault != NULL)
appendStringInfo(&buf, " DEFAULT %s", attdefault);
/* Add NOT NULL if needed */
if (import_not_null && attnotnull[0] == 't')
appendStringInfoString(&buf, " NOT NULL");
}
while (++i < numrows &&
strcmp(PQgetvalue(res, i, 0), tablename) == 0);
/*
* Add server name and table-level options. We specify remote
* schema and table name as options (the latter to ensure that
* renaming the foreign table doesn't break the association).
*/
appendStringInfo(&buf, "\n) SERVER %s\nOPTIONS (",
quote_identifier(server->servername));
appendStringInfoString(&buf, "schema_name ");
deparseStringLiteral(&buf, stmt->remote_schema);
appendStringInfoString(&buf, ", table_name ");
deparseStringLiteral(&buf, tablename);
appendStringInfoString(&buf, ");");
commands = lappend(commands, pstrdup(buf.data));
}
/* Clean up */
PQclear(res);
res = NULL;
}
PG_CATCH();
{
if (res)
PQclear(res);
PG_RE_THROW();
}
PG_END_TRY();
ReleaseConnection(conn);
return commands;
}
/*
* Create a tuple from the specified row of the PGresult.
*

1
contrib/postgres_fdw/postgres_fdw.h
View File

@ -73,5 +73,6 @@ extern void deparseDeleteSql(StringInfo buf, PlannerInfo *root,
extern void deparseAnalyzeSizeSql(StringInfo buf, Relation rel);
extern void deparseAnalyzeSql(StringInfo buf, Relation rel,
List **retrieved_attrs);
extern void deparseStringLiteral(StringInfo buf, const char *val);
#endif /* POSTGRES_FDW_H */

57
contrib/postgres_fdw/sql/postgres_fdw.sql
View File

@ -609,3 +609,60 @@ UPDATE rem1 SET f2 = 'testo';
-- Test returning a system attribute
INSERT INTO rem1(f2) VALUES ('test') RETURNING ctid;
-- ===================================================================
-- test IMPORT FOREIGN SCHEMA
-- ===================================================================
CREATE SCHEMA import_source;
CREATE TABLE import_source.t1 (c1 int, c2 varchar NOT NULL);
CREATE TABLE import_source.t2 (c1 int default 42, c2 varchar NULL, c3 text collate "POSIX");
CREATE TYPE typ1 AS (m1 int, m2 varchar);
CREATE TABLE import_source.t3 (c1 timestamptz default now(), c2 typ1);
CREATE TABLE import_source."x 4" (c1 float8, "C 2" text, c3 varchar(42));
CREATE TABLE import_source."x 5" (c1 float8);
ALTER TABLE import_source."x 5" DROP COLUMN c1;
CREATE SCHEMA import_dest1;
IMPORT FOREIGN SCHEMA import_source FROM SERVER loopback INTO import_dest1;
\det+ import_dest1
\d import_dest1.*
-- Options
CREATE SCHEMA import_dest2;
IMPORT FOREIGN SCHEMA import_source FROM SERVER loopback INTO import_dest2
OPTIONS (import_default 'true');
\det+ import_dest2
\d import_dest2.*
CREATE SCHEMA import_dest3;
IMPORT FOREIGN SCHEMA import_source FROM SERVER loopback INTO import_dest3
OPTIONS (import_collate 'false', import_not_null 'false');
\det+ import_dest3
\d import_dest3.*
-- Check LIMIT TO and EXCEPT
CREATE SCHEMA import_dest4;
IMPORT FOREIGN SCHEMA import_source LIMIT TO (t1, nonesuch)
FROM SERVER loopback INTO import_dest4;
\det+ import_dest4
IMPORT FOREIGN SCHEMA import_source EXCEPT (t1, "x 4", nonesuch)
FROM SERVER loopback INTO import_dest4;
\det+ import_dest4
-- Assorted error cases
IMPORT FOREIGN SCHEMA import_source FROM SERVER loopback INTO import_dest4;
IMPORT FOREIGN SCHEMA nonesuch FROM SERVER loopback INTO import_dest4;
IMPORT FOREIGN SCHEMA nonesuch FROM SERVER loopback INTO notthere;
IMPORT FOREIGN SCHEMA nonesuch FROM SERVER nowhere INTO notthere;
-- Check case of a type present only on the remote server.
-- We can fake this by dropping the type locally in our transaction.
CREATE TYPE "Colors" AS ENUM ('red', 'green', 'blue');
CREATE TABLE import_source.t5 (c1 int, c2 text collate "C", "Col" "Colors");
CREATE SCHEMA import_dest5;
BEGIN;
DROP TYPE "Colors" CASCADE;
IMPORT FOREIGN SCHEMA import_source LIMIT TO (t5)
FROM SERVER loopback INTO import_dest5; -- ERROR
ROLLBACK;