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Sanitize IF NOT EXISTS in EXPLAIN for CTAS and matviews 

IF NOT EXISTS was ignored when specified in an EXPLAIN query for CREATE
MATERIALIZED VIEW or CREATE TABLE AS.  Hence, if this clause was
specified, the caller would get a failure if the relation already
exists instead of a success with a NOTICE message.

This commit makes the behavior of IF NOT EXISTS in EXPLAIN consistent
with the non-EXPLAIN'd DDL queries, preventing a failure with IF NOT
EXISTS if the relation to-be-created already exists.  The skip is done
before the SELECT query used for the relation is planned or executed,
and a "dummy" plan is generated instead depending on the format used by
EXPLAIN.

Author: Bharath Rupireddy
Reviewed-by: Zhijie Hou, Michael Paquier
Discussion: https://postgr.es/m/CALj2ACVa3oJ9O_wcGd+FtHWZds04dEKcakxphGz5POVgD4wC7Q@mail.gmail.com
This commit is contained in:
Michael Paquier 2020-12-30 21:23:24 +09:00
parent 0aa8a01d04
commit e665769e6d
7 changed files with 180 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
src/backend/commands/createas.c
View File

@ -239,21 +239,9 @@ ExecCreateTableAs(ParseState *pstate, CreateTableAsStmt *stmt,
PlannedStmt *plan;
QueryDesc *queryDesc;
if (stmt->if_not_exists)
{
Oid nspid;
nspid = RangeVarGetCreationNamespace(stmt->into->rel);
if (get_relname_relid(stmt->into->rel->relname, nspid))
{
ereport(NOTICE,
(errcode(ERRCODE_DUPLICATE_TABLE),
errmsg("relation \"%s\" already exists, skipping",
stmt->into->rel->relname)));
return InvalidObjectAddress;
}
}
/* Check if the relation exists or not */
if (CreateTableAsRelExists(stmt))
return InvalidObjectAddress;
/*
* Create the tuple receiver object and insert info it will need
@ -400,6 +388,41 @@ GetIntoRelEFlags(IntoClause *intoClause)
return flags;
}
/*
* CreateTableAsRelExists --- check existence of relation for CreateTableAsStmt
*
* Utility wrapper checking if the relation pending for creation in this
* CreateTableAsStmt query already exists or not. Returns true if the
* relation exists, otherwise false.
*/
bool
CreateTableAsRelExists(CreateTableAsStmt *ctas)
{
Oid nspid;
IntoClause *into = ctas->into;
nspid = RangeVarGetCreationNamespace(into->rel);
if (get_relname_relid(into->rel->relname, nspid))
{
if (!ctas->if_not_exists)
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_TABLE),
errmsg("relation \"%s\" already exists",
into->rel->relname)));
/* The relation exists and IF NOT EXISTS has been specified */
ereport(NOTICE,
(errcode(ERRCODE_DUPLICATE_TABLE),
errmsg("relation \"%s\" already exists, skipping",
into->rel->relname)));
return true;
}
/* Relation does not exist, it can be created */
return false;
}
/*
* CreateIntoRelDestReceiver -- create a suitable DestReceiver object
*

16
src/backend/commands/explain.c
View File

@ -435,6 +435,22 @@ ExplainOneUtility(Node *utilityStmt, IntoClause *into, ExplainState *es,
CreateTableAsStmt *ctas = (CreateTableAsStmt *) utilityStmt;
List *rewritten;
/*
* Check if the relation exists or not. This is done at this stage to
* avoid query planning or execution.
*/
if (CreateTableAsRelExists(ctas))
{
if (ctas->objtype == OBJECT_TABLE)
ExplainDummyGroup("CREATE TABLE AS", NULL, es);
else if (ctas->objtype == OBJECT_MATVIEW)
ExplainDummyGroup("CREATE MATERIALIZED VIEW", NULL, es);
else
elog(ERROR, "unexpected object type: %d",
(int) ctas->objtype);
return;
}
rewritten = QueryRewrite(castNode(Query, copyObject(ctas->query)));
Assert(list_length(rewritten) == 1);
ExplainOneQuery(linitial_node(Query, rewritten),

2
src/include/commands/createas.h
View File

@ -29,4 +29,6 @@ extern int GetIntoRelEFlags(IntoClause *intoClause);
extern DestReceiver *CreateIntoRelDestReceiver(IntoClause *intoClause);
extern bool CreateTableAsRelExists(CreateTableAsStmt *ctas);
#endif /* CREATEAS_H */

38
src/test/regress/expected/matview.out
View File

@ -630,3 +630,41 @@ drop cascades to materialized view matview_schema.mv_withdata2
drop cascades to materialized view matview_schema.mv_nodata1
drop cascades to materialized view matview_schema.mv_nodata2
DROP USER regress_matview_user;
-- CREATE MATERIALIZED VIEW ... IF NOT EXISTS
CREATE MATERIALIZED VIEW matview_ine_tab AS SELECT 1;
CREATE MATERIALIZED VIEW matview_ine_tab AS SELECT 1 / 0; -- error
ERROR: relation "matview_ine_tab" already exists
CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
SELECT 1 / 0; -- ok
NOTICE: relation "matview_ine_tab" already exists, skipping
CREATE MATERIALIZED VIEW matview_ine_tab AS
SELECT 1 / 0 WITH NO DATA; -- error
ERROR: relation "matview_ine_tab" already exists
CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
SELECT 1 / 0 WITH NO DATA; -- ok
NOTICE: relation "matview_ine_tab" already exists, skipping
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE MATERIALIZED VIEW matview_ine_tab AS
SELECT 1 / 0; -- error
ERROR: relation "matview_ine_tab" already exists
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
SELECT 1 / 0; -- ok
NOTICE: relation "matview_ine_tab" already exists, skipping
QUERY PLAN
------------
(0 rows)
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE MATERIALIZED VIEW matview_ine_tab AS
SELECT 1 / 0 WITH NO DATA; -- error
ERROR: relation "matview_ine_tab" already exists
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
SELECT 1 / 0 WITH NO DATA; -- ok
NOTICE: relation "matview_ine_tab" already exists, skipping
QUERY PLAN
------------
(0 rows)
DROP MATERIALIZED VIEW matview_ine_tab;

42
src/test/regress/expected/select_into.out
View File

@ -178,3 +178,45 @@ INSERT INTO b SELECT 1 INTO f;
ERROR: SELECT ... INTO is not allowed here
LINE 1: INSERT INTO b SELECT 1 INTO f;
^
-- Test CREATE TABLE AS ... IF NOT EXISTS
CREATE TABLE ctas_ine_tbl AS SELECT 1;
CREATE TABLE ctas_ine_tbl AS SELECT 1 / 0; -- error
ERROR: relation "ctas_ine_tbl" already exists
CREATE TABLE IF NOT EXISTS ctas_ine_tbl AS SELECT 1 / 0; -- ok
NOTICE: relation "ctas_ine_tbl" already exists, skipping
CREATE TABLE ctas_ine_tbl AS SELECT 1 / 0 WITH NO DATA; -- error
ERROR: relation "ctas_ine_tbl" already exists
CREATE TABLE IF NOT EXISTS ctas_ine_tbl AS SELECT 1 / 0 WITH NO DATA; -- ok
NOTICE: relation "ctas_ine_tbl" already exists, skipping
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE TABLE ctas_ine_tbl AS SELECT 1 / 0; -- error
ERROR: relation "ctas_ine_tbl" already exists
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE TABLE IF NOT EXISTS ctas_ine_tbl AS SELECT 1 / 0; -- ok
NOTICE: relation "ctas_ine_tbl" already exists, skipping
QUERY PLAN
------------
(0 rows)
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE TABLE ctas_ine_tbl AS SELECT 1 / 0 WITH NO DATA; -- error
ERROR: relation "ctas_ine_tbl" already exists
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE TABLE IF NOT EXISTS ctas_ine_tbl AS SELECT 1 / 0 WITH NO DATA; -- ok
NOTICE: relation "ctas_ine_tbl" already exists, skipping
QUERY PLAN
------------
(0 rows)
PREPARE ctas_ine_query AS SELECT 1 / 0;
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE TABLE ctas_ine_tbl AS EXECUTE ctas_ine_query; -- error
ERROR: relation "ctas_ine_tbl" already exists
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE TABLE IF NOT EXISTS ctas_ine_tbl AS EXECUTE ctas_ine_query; -- ok
NOTICE: relation "ctas_ine_tbl" already exists, skipping
QUERY PLAN
------------
(0 rows)
DROP TABLE ctas_ine_tbl;

23
src/test/regress/sql/matview.sql
View File

@ -264,3 +264,26 @@ ALTER DEFAULT PRIVILEGES FOR ROLE regress_matview_user
DROP SCHEMA matview_schema CASCADE;
DROP USER regress_matview_user;
-- CREATE MATERIALIZED VIEW ... IF NOT EXISTS
CREATE MATERIALIZED VIEW matview_ine_tab AS SELECT 1;
CREATE MATERIALIZED VIEW matview_ine_tab AS SELECT 1 / 0; -- error
CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
SELECT 1 / 0; -- ok
CREATE MATERIALIZED VIEW matview_ine_tab AS
SELECT 1 / 0 WITH NO DATA; -- error
CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
SELECT 1 / 0 WITH NO DATA; -- ok
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE MATERIALIZED VIEW matview_ine_tab AS
SELECT 1 / 0; -- error
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
SELECT 1 / 0; -- ok
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE MATERIALIZED VIEW matview_ine_tab AS
SELECT 1 / 0 WITH NO DATA; -- error
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE MATERIALIZED VIEW IF NOT EXISTS matview_ine_tab AS
SELECT 1 / 0 WITH NO DATA; -- ok
DROP MATERIALIZED VIEW matview_ine_tab;

21
src/test/regress/sql/select_into.sql
View File

@ -115,3 +115,24 @@ COPY (SELECT 1 INTO frak UNION SELECT 2) TO 'blob';
SELECT * FROM (SELECT 1 INTO f) bar;
CREATE VIEW foo AS SELECT 1 INTO b;
INSERT INTO b SELECT 1 INTO f;
-- Test CREATE TABLE AS ... IF NOT EXISTS
CREATE TABLE ctas_ine_tbl AS SELECT 1;
CREATE TABLE ctas_ine_tbl AS SELECT 1 / 0; -- error
CREATE TABLE IF NOT EXISTS ctas_ine_tbl AS SELECT 1 / 0; -- ok
CREATE TABLE ctas_ine_tbl AS SELECT 1 / 0 WITH NO DATA; -- error
CREATE TABLE IF NOT EXISTS ctas_ine_tbl AS SELECT 1 / 0 WITH NO DATA; -- ok
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE TABLE ctas_ine_tbl AS SELECT 1 / 0; -- error
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE TABLE IF NOT EXISTS ctas_ine_tbl AS SELECT 1 / 0; -- ok
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE TABLE ctas_ine_tbl AS SELECT 1 / 0 WITH NO DATA; -- error
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE TABLE IF NOT EXISTS ctas_ine_tbl AS SELECT 1 / 0 WITH NO DATA; -- ok
PREPARE ctas_ine_query AS SELECT 1 / 0;
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE TABLE ctas_ine_tbl AS EXECUTE ctas_ine_query; -- error
EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
CREATE TABLE IF NOT EXISTS ctas_ine_tbl AS EXECUTE ctas_ine_query; -- ok
DROP TABLE ctas_ine_tbl;