pg_stat_statements: Add more tests with temp tables and namespaces

These tests provide coverage for RangeTblEntry and how query jumbling
works with search_path, as well as the case where relations are
re-created, generating a different query ID as the relation OID is used
in the computation.

A patch is under discussion to switch to a different approach based on
the relation name, and there was no test coverage for this area,
including how queries are currently grouped with search_path.  This is
useful to track how the situation changes between HEAD and any patches
proposed.

Christoph has proposed the test with ON COMMIT DROP temporary tables,
and I have written the second part.

Author: Christoph Berg <myon@debian.org>
Author: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/Z9iWXKGwkm8RAC93@msg.df7cb.de

2 files changed, 309 insertions, 0 deletions

diff --git a/contrib/pg_stat_statements/expected/select.out b/contrib/pg_stat_statements/expected/select.out
index 37a30af034a..708c6b0e9c4 100644
--- a/contrib/pg_stat_statements/expected/select.out
+++ b/contrib/pg_stat_statements/expected/select.out
@@ -413,3 +413,243 @@ SELECT pg_stat_statements_reset() IS NOT NULL AS t;
  t
 (1 row)
 
+-- Temporary table with same name, re-created.
+BEGIN;
+  CREATE TEMP TABLE temp_t (id int) ON COMMIT DROP;
+  SELECT * FROM temp_t;
+ id 
+----
+(0 rows)
+
+COMMIT;
+BEGIN;
+  CREATE TEMP TABLE temp_t (id int) ON COMMIT DROP;
+  SELECT * FROM temp_t;
+ id 
+----
+(0 rows)
+
+COMMIT;
+SELECT calls, query FROM pg_stat_statements ORDER BY query COLLATE "C";
+ calls |                                 query                                  
+-------+------------------------------------------------------------------------
+     1 | SELECT * FROM temp_t
+     1 | SELECT * FROM temp_t
+     0 | SELECT calls, query FROM pg_stat_statements ORDER BY query COLLATE "C"
+     1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t
+(4 rows)
+
+SELECT pg_stat_statements_reset() IS NOT NULL AS t;
+ t 
+---
+ t
+(1 row)
+
+-- search_path with various schemas and temporary tables
+CREATE SCHEMA pgss_schema_1;
+CREATE SCHEMA pgss_schema_2;
+-- Same attributes.
+CREATE TABLE pgss_schema_1.tab_search_same (a int, b int);
+CREATE TABLE pgss_schema_2.tab_search_same (a int, b int);
+CREATE TEMP TABLE tab_search_same (a int, b int);
+-- Different number of attributes, mapping types
+CREATE TABLE pgss_schema_1.tab_search_diff_1 (a int);
+CREATE TABLE pgss_schema_2.tab_search_diff_1 (a int, b int);
+CREATE TEMP TABLE tab_search_diff_1 (a int, b int, c int);
+-- Same number of attributes, different types
+CREATE TABLE pgss_schema_1.tab_search_diff_2 (a int);
+CREATE TABLE pgss_schema_2.tab_search_diff_2 (a text);
+CREATE TEMP TABLE tab_search_diff_2 (a bigint);
+-- First permanent schema
+SET search_path = 'pgss_schema_1';
+SELECT count(*) FROM tab_search_same;
+ count 
+-------
+     0
+(1 row)
+
+SELECT a, b FROM tab_search_same;
+ a | b 
+---+---
+(0 rows)
+
+SELECT count(*) FROM tab_search_diff_1;
+ count 
+-------
+     0
+(1 row)
+
+SELECT count(*) FROM tab_search_diff_2;
+ count 
+-------
+     0
+(1 row)
+
+SELECT a FROM tab_search_diff_2 AS t1;
+ a 
+---
+(0 rows)
+
+SELECT a FROM tab_search_diff_2;
+ a 
+---
+(0 rows)
+
+SELECT a AS a1 FROM tab_search_diff_2;
+ a1 
+----
+(0 rows)
+
+-- Second permanent schema
+SET search_path = 'pgss_schema_2';
+SELECT count(*) FROM tab_search_same;
+ count 
+-------
+     0
+(1 row)
+
+SELECT a, b FROM tab_search_same;
+ a | b 
+---+---
+(0 rows)
+
+SELECT count(*) FROM tab_search_diff_1;
+ count 
+-------
+     0
+(1 row)
+
+SELECT count(*) FROM tab_search_diff_2;
+ count 
+-------
+     0
+(1 row)
+
+SELECT a FROM tab_search_diff_2 AS t1;
+ a 
+---
+(0 rows)
+
+SELECT a FROM tab_search_diff_2;
+ a 
+---
+(0 rows)
+
+SELECT a AS a1 FROM tab_search_diff_2;
+ a1 
+----
+(0 rows)
+
+-- Temporary schema
+SET search_path = 'pg_temp';
+SELECT count(*) FROM tab_search_same;
+ count 
+-------
+     0
+(1 row)
+
+SELECT a, b FROM tab_search_same;
+ a | b 
+---+---
+(0 rows)
+
+SELECT count(*) FROM tab_search_diff_1;
+ count 
+-------
+     0
+(1 row)
+
+SELECT count(*) FROM tab_search_diff_2;
+ count 
+-------
+     0
+(1 row)
+
+SELECT a FROM tab_search_diff_2 AS t1;
+ a 
+---
+(0 rows)
+
+SELECT a FROM tab_search_diff_2;
+ a 
+---
+(0 rows)
+
+SELECT a AS a1 FROM tab_search_diff_2;
+ a1 
+----
+(0 rows)
+
+RESET search_path;
+-- Schema qualifications
+SELECT count(*) FROM pgss_schema_1.tab_search_same;
+ count 
+-------
+     0
+(1 row)
+
+SELECT a, b FROM pgss_schema_1.tab_search_same;
+ a | b 
+---+---
+(0 rows)
+
+SELECT count(*) FROM pgss_schema_2.tab_search_diff_1;
+ count 
+-------
+     0
+(1 row)
+
+SELECT count(*) FROM pg_temp.tab_search_diff_2;
+ count 
+-------
+     0
+(1 row)
+
+SELECT a FROM pgss_schema_2.tab_search_diff_2 AS t1;
+ a 
+---
+(0 rows)
+
+SELECT a FROM pgss_schema_2.tab_search_diff_2;
+ a 
+---
+(0 rows)
+
+SELECT a AS a1 FROM pgss_schema_2.tab_search_diff_2;
+ a1 
+----
+(0 rows)
+
+SELECT calls, query FROM pg_stat_statements ORDER BY query COLLATE "C";
+ calls |                                 query                                  
+-------+------------------------------------------------------------------------
+     3 | SELECT a FROM pgss_schema_2.tab_search_diff_2 AS t1
+     9 | SELECT a FROM tab_search_diff_2 AS t1
+     1 | SELECT a, b FROM pgss_schema_1.tab_search_same
+     3 | SELECT a, b FROM tab_search_same
+     0 | SELECT calls, query FROM pg_stat_statements ORDER BY query COLLATE "C"
+     1 | SELECT count(*) FROM pgss_schema_1.tab_search_same
+     1 | SELECT count(*) FROM pgss_schema_2.tab_search_diff_1
+     3 | SELECT count(*) FROM tab_search_diff_1
+     4 | SELECT count(*) FROM tab_search_diff_2
+     3 | SELECT count(*) FROM tab_search_same
+     1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t
+(11 rows)
+
+DROP SCHEMA pgss_schema_1 CASCADE;
+NOTICE:  drop cascades to 3 other objects
+DETAIL:  drop cascades to table pgss_schema_1.tab_search_same
+drop cascades to table pgss_schema_1.tab_search_diff_1
+drop cascades to table pgss_schema_1.tab_search_diff_2
+DROP SCHEMA pgss_schema_2 CASCADE;
+NOTICE:  drop cascades to 3 other objects
+DETAIL:  drop cascades to table pgss_schema_2.tab_search_same
+drop cascades to table pgss_schema_2.tab_search_diff_1
+drop cascades to table pgss_schema_2.tab_search_diff_2
+DROP TABLE tab_search_same, tab_search_diff_1, tab_search_diff_2;
+SELECT pg_stat_statements_reset() IS NOT NULL AS t;
+ t 
+---
+ t
+(1 row)
+
diff --git a/contrib/pg_stat_statements/sql/select.sql b/contrib/pg_stat_statements/sql/select.sql
index e0be58d5e24..9a35471b271 100644
--- a/contrib/pg_stat_statements/sql/select.sql
+++ b/contrib/pg_stat_statements/sql/select.sql
@@ -148,3 +148,72 @@ SELECT (
 
 SELECT COUNT(*) FROM pg_stat_statements WHERE query LIKE '%SELECT GROUPING%';
 SELECT pg_stat_statements_reset() IS NOT NULL AS t;
+
+-- Temporary table with same name, re-created.
+BEGIN;
+  CREATE TEMP TABLE temp_t (id int) ON COMMIT DROP;
+  SELECT * FROM temp_t;
+COMMIT;
+BEGIN;
+  CREATE TEMP TABLE temp_t (id int) ON COMMIT DROP;
+  SELECT * FROM temp_t;
+COMMIT;
+SELECT calls, query FROM pg_stat_statements ORDER BY query COLLATE "C";
+SELECT pg_stat_statements_reset() IS NOT NULL AS t;
+
+-- search_path with various schemas and temporary tables
+CREATE SCHEMA pgss_schema_1;
+CREATE SCHEMA pgss_schema_2;
+-- Same attributes.
+CREATE TABLE pgss_schema_1.tab_search_same (a int, b int);
+CREATE TABLE pgss_schema_2.tab_search_same (a int, b int);
+CREATE TEMP TABLE tab_search_same (a int, b int);
+-- Different number of attributes, mapping types
+CREATE TABLE pgss_schema_1.tab_search_diff_1 (a int);
+CREATE TABLE pgss_schema_2.tab_search_diff_1 (a int, b int);
+CREATE TEMP TABLE tab_search_diff_1 (a int, b int, c int);
+-- Same number of attributes, different types
+CREATE TABLE pgss_schema_1.tab_search_diff_2 (a int);
+CREATE TABLE pgss_schema_2.tab_search_diff_2 (a text);
+CREATE TEMP TABLE tab_search_diff_2 (a bigint);
+-- First permanent schema
+SET search_path = 'pgss_schema_1';
+SELECT count(*) FROM tab_search_same;
+SELECT a, b FROM tab_search_same;
+SELECT count(*) FROM tab_search_diff_1;
+SELECT count(*) FROM tab_search_diff_2;
+SELECT a FROM tab_search_diff_2 AS t1;
+SELECT a FROM tab_search_diff_2;
+SELECT a AS a1 FROM tab_search_diff_2;
+-- Second permanent schema
+SET search_path = 'pgss_schema_2';
+SELECT count(*) FROM tab_search_same;
+SELECT a, b FROM tab_search_same;
+SELECT count(*) FROM tab_search_diff_1;
+SELECT count(*) FROM tab_search_diff_2;
+SELECT a FROM tab_search_diff_2 AS t1;
+SELECT a FROM tab_search_diff_2;
+SELECT a AS a1 FROM tab_search_diff_2;
+-- Temporary schema
+SET search_path = 'pg_temp';
+SELECT count(*) FROM tab_search_same;
+SELECT a, b FROM tab_search_same;
+SELECT count(*) FROM tab_search_diff_1;
+SELECT count(*) FROM tab_search_diff_2;
+SELECT a FROM tab_search_diff_2 AS t1;
+SELECT a FROM tab_search_diff_2;
+SELECT a AS a1 FROM tab_search_diff_2;
+RESET search_path;
+-- Schema qualifications
+SELECT count(*) FROM pgss_schema_1.tab_search_same;
+SELECT a, b FROM pgss_schema_1.tab_search_same;
+SELECT count(*) FROM pgss_schema_2.tab_search_diff_1;
+SELECT count(*) FROM pg_temp.tab_search_diff_2;
+SELECT a FROM pgss_schema_2.tab_search_diff_2 AS t1;
+SELECT a FROM pgss_schema_2.tab_search_diff_2;
+SELECT a AS a1 FROM pgss_schema_2.tab_search_diff_2;
+SELECT calls, query FROM pg_stat_statements ORDER BY query COLLATE "C";
+DROP SCHEMA pgss_schema_1 CASCADE;
+DROP SCHEMA pgss_schema_2 CASCADE;
+DROP TABLE tab_search_same, tab_search_diff_1, tab_search_diff_2;
+SELECT pg_stat_statements_reset() IS NOT NULL AS t;