From e665769e6d1e84b6650f53ed297058fc11152f7f Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Wed, 30 Dec 2020 21:23:24 +0900 Subject: [PATCH] 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 --- src/backend/commands/createas.c | 53 ++++++++++++++++------- src/backend/commands/explain.c | 16 +++++++ src/include/commands/createas.h | 2 + src/test/regress/expected/matview.out | 38 ++++++++++++++++ src/test/regress/expected/select_into.out | 42 ++++++++++++++++++ src/test/regress/sql/matview.sql | 23 ++++++++++ src/test/regress/sql/select_into.sql | 21 +++++++++ 7 files changed, 180 insertions(+), 15 deletions(-) diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c index 6bf6c5a310..009896bcee 100644 --- a/src/backend/commands/createas.c +++ b/src/backend/commands/createas.c @@ -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 * diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c index 43f9b01e83..d797b5f53e 100644 --- a/src/backend/commands/explain.c +++ b/src/backend/commands/explain.c @@ -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), diff --git a/src/include/commands/createas.h b/src/include/commands/createas.h index 7629230254..d8cfb62522 100644 --- a/src/include/commands/createas.h +++ b/src/include/commands/createas.h @@ -29,4 +29,6 @@ extern int GetIntoRelEFlags(IntoClause *intoClause); extern DestReceiver *CreateIntoRelDestReceiver(IntoClause *intoClause); +extern bool CreateTableAsRelExists(CreateTableAsStmt *ctas); + #endif /* CREATEAS_H */ diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out index 2c0760404d..4b3a2e0cb7 100644 --- a/src/test/regress/expected/matview.out +++ b/src/test/regress/expected/matview.out @@ -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; diff --git a/src/test/regress/expected/select_into.out b/src/test/regress/expected/select_into.out index bf5c6bea04..43b8209d22 100644 --- a/src/test/regress/expected/select_into.out +++ b/src/test/regress/expected/select_into.out @@ -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; diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql index 70c4954d89..4a4bd0d6b6 100644 --- a/src/test/regress/sql/matview.sql +++ b/src/test/regress/sql/matview.sql @@ -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; diff --git a/src/test/regress/sql/select_into.sql b/src/test/regress/sql/select_into.sql index 6c170ef968..7e903c339a 100644 --- a/src/test/regress/sql/select_into.sql +++ b/src/test/regress/sql/select_into.sql @@ -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;