From 00273b61bdfbdd8d10e02bdc58ccd3c2b61968b0 Mon Sep 17 00:00:00 2001 From: Sami Imseih Date: Tue, 3 Mar 2026 16:11:27 -0600 Subject: [PATCH v4 1/1] Clean up PREPARE query strings in multi-statement contexts When PREPARE is executed as part of a multi-statement query string, the stored query text previously included the entire multi-statement string. This caused the extra queries to be stored in the prepared statement cache, consuming unnecessary memory, and made them visible when querying pg_prepared_statements. It also caused issues with query normalization in extensions like pg_stat_statements. This commit modifies PrepareQuery() to extract only the relevant PREPARE statement using CleanQuerytext() before storing it in the CachedPlanSource. The stmt_location in the Query tree is reset to 0 since the query text stored in the plan cache now contains only the PREPARE statement, which starts at position 0. This ensures that downstream consumers like pg_stat_statements can correctly normalize the query text. Author: Julien Rouhaud Discussion: https://www.postgresql.org/message-id/flat/aUwKEWGge5jWtaRX%40jrouhaud --- contrib/auto_explain/t/001_auto_explain.pl | 8 +-- contrib/pg_stat_statements/Makefile | 1 + .../pg_stat_statements/expected/prepare.out | 53 +++++++++++++++++++ contrib/pg_stat_statements/meson.build | 1 + contrib/pg_stat_statements/sql/prepare.sql | 15 ++++++ src/backend/commands/prepare.c | 34 +++++++++++- src/test/regress/expected/prepare.out | 44 +++++++++------ src/test/regress/sql/prepare.sql | 2 +- 8 files changed, 135 insertions(+), 23 deletions(-) create mode 100644 contrib/pg_stat_statements/expected/prepare.out create mode 100644 contrib/pg_stat_statements/sql/prepare.sql diff --git a/contrib/auto_explain/t/001_auto_explain.pl b/contrib/auto_explain/t/001_auto_explain.pl index 5f673bd14c1..f2d8625f8bb 100644 --- a/contrib/auto_explain/t/001_auto_explain.pl +++ b/contrib/auto_explain/t/001_auto_explain.pl @@ -60,7 +60,7 @@ $log_contents = query_log($node, like( $log_contents, - qr/Query Text: PREPARE get_proc\(name\) AS SELECT \* FROM pg_proc WHERE proname = \$1;/, + qr/Query Text: PREPARE get_proc\(name\) AS SELECT \* FROM pg_proc WHERE proname = \$1/, "prepared query text logged, text mode"); like( @@ -82,7 +82,7 @@ $log_contents = query_log( like( $log_contents, - qr/Query Text: PREPARE get_type\(name\) AS SELECT \* FROM pg_type WHERE typname = \$1;/, + qr/Query Text: PREPARE get_type\(name\) AS SELECT \* FROM pg_type WHERE typname = \$1/, "prepared query text logged, text mode"); like( @@ -98,7 +98,7 @@ $log_contents = query_log( like( $log_contents, - qr/Query Text: PREPARE get_type\(name\) AS SELECT \* FROM pg_type WHERE typname = \$1;/, + qr/Query Text: PREPARE get_type\(name\) AS SELECT \* FROM pg_type WHERE typname = \$1/, "prepared query text logged, text mode"); unlike( @@ -164,7 +164,7 @@ $log_contents = query_log( like( $log_contents, - qr/"Query Text": "PREPARE get_class\(name\) AS SELECT \* FROM pg_class WHERE relname = \$1;"/, + qr/"Query Text": "PREPARE get_class\(name\) AS SELECT \* FROM pg_class WHERE relname = \$1"/, "prepared query text logged, json mode"); like( diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile index c27e9529bb6..ac967687796 100644 --- a/contrib/pg_stat_statements/Makefile +++ b/contrib/pg_stat_statements/Makefile @@ -36,6 +36,7 @@ REGRESS = \ parallel \ plancache \ squashing \ + prepare \ cleanup \ oldextversions diff --git a/contrib/pg_stat_statements/expected/prepare.out b/contrib/pg_stat_statements/expected/prepare.out new file mode 100644 index 00000000000..010e289c1b0 --- /dev/null +++ b/contrib/pg_stat_statements/expected/prepare.out @@ -0,0 +1,53 @@ +-- Tests for PREPARE +SELECT pg_stat_statements_reset() IS NOT NULL AS t; + t +--- + t +(1 row) + +-- Test that prepared statements in a multi-query string behaves as expected +SELECT 1\;PREPARE p1 AS SELECT 1\; PREPARE p2(int) AS SELECT 2 * $1\; SELECT 1, 1; + ?column? +---------- + 1 +(1 row) + + ?column? | ?column? +----------+---------- + 1 | 1 +(1 row) + +SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C"; + calls | rows | query +-------+------+---------------------------------------------------- + 1 | 1 | SELECT $1 + 1 | 1 | SELECT $1, $2 + 1 | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t +(3 rows) + +SELECT pg_stat_statements_reset() IS NOT NULL AS t; + t +--- + t +(1 row) + +EXECUTE p1; + ?column? +---------- + 1 +(1 row) + +EXECUTE p2(0); + ?column? +---------- + 0 +(1 row) + +SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C"; + calls | rows | query +-------+------+---------------------------------------------------- + 1 | 1 | PREPARE p1 AS SELECT 1 + 1 | 1 | PREPARE p2(int) AS SELECT 2 * $1 + 1 | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t +(3 rows) + diff --git a/contrib/pg_stat_statements/meson.build b/contrib/pg_stat_statements/meson.build index 9d78cb88b7d..c9e1d446d39 100644 --- a/contrib/pg_stat_statements/meson.build +++ b/contrib/pg_stat_statements/meson.build @@ -58,6 +58,7 @@ tests += { 'parallel', 'plancache', 'squashing', + 'prepare', 'cleanup', 'oldextversions', ], diff --git a/contrib/pg_stat_statements/sql/prepare.sql b/contrib/pg_stat_statements/sql/prepare.sql new file mode 100644 index 00000000000..a6bc5de4430 --- /dev/null +++ b/contrib/pg_stat_statements/sql/prepare.sql @@ -0,0 +1,15 @@ +-- Tests for PREPARE + +SELECT pg_stat_statements_reset() IS NOT NULL AS t; + +-- Test that prepared statements in a multi-query string behaves as expected +SELECT 1\;PREPARE p1 AS SELECT 1\; PREPARE p2(int) AS SELECT 2 * $1\; SELECT 1, 1; + +SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C"; + +SELECT pg_stat_statements_reset() IS NOT NULL AS t; + +EXECUTE p1; +EXECUTE p2(0); + +SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C"; diff --git a/src/backend/commands/prepare.c b/src/backend/commands/prepare.c index 5b86a727587..8a392f6a2f8 100644 --- a/src/backend/commands/prepare.c +++ b/src/backend/commands/prepare.c @@ -27,6 +27,7 @@ #include "commands/prepare.h" #include "funcapi.h" #include "nodes/nodeFuncs.h" +#include "nodes/queryjumble.h" #include "parser/parse_coerce.h" #include "parser/parse_collate.h" #include "parser/parse_expr.h" @@ -64,6 +65,8 @@ PrepareQuery(ParseState *pstate, PrepareStmt *stmt, Oid *argtypes = NULL; int nargs; List *query_list; + const char *new_query; + ListCell *lc; /* * Disallow empty-string statement name (conflicts with protocol-level @@ -82,12 +85,29 @@ PrepareQuery(ParseState *pstate, PrepareStmt *stmt, rawstmt->stmt = stmt->query; rawstmt->stmt_location = stmt_location; rawstmt->stmt_len = stmt_len; + new_query = pstate->p_sourcetext; + + /* + * If we have a multi-statement string, extract only the PREPARE statement + * for storage in the plan cache. + */ + if (stmt_location >= 0) + { + const char *cleaned; + char *tmp; + + cleaned = CleanQuerytext(pstate->p_sourcetext, &rawstmt->stmt_location, &rawstmt->stmt_len); + + tmp = palloc(rawstmt->stmt_len + 1); + strlcpy(tmp, cleaned, rawstmt->stmt_len + 1); + new_query = tmp; + } /* * Create the CachedPlanSource before we do parse analysis, since it needs * to see the unmodified raw parse tree. */ - plansource = CreateCachedPlan(rawstmt, pstate->p_sourcetext, + plansource = CreateCachedPlan(rawstmt, new_query, CreateCommandTag(stmt->query)); /* Transform list of TypeNames to array of type OIDs */ @@ -119,6 +139,18 @@ PrepareQuery(ParseState *pstate, PrepareStmt *stmt, query_list = pg_analyze_and_rewrite_varparams(rawstmt, pstate->p_sourcetext, &argtypes, &nargs, NULL); + /* + * Reset stmt_location to 0 since the query text stored in the plan cache + * now contains only the PREPARE statement. + */ + foreach(lc, query_list) + { + Query *query = lfirst_node(Query, lc); + + if (query->stmt_location > 0) + query->stmt_location = 0; + } + /* Finish filling in the CachedPlanSource */ CompleteCachedPlan(plansource, query_list, diff --git a/src/test/regress/expected/prepare.out b/src/test/regress/expected/prepare.out index 5815e17b39c..c645a4e5d0e 100644 --- a/src/test/regress/expected/prepare.out +++ b/src/test/regress/expected/prepare.out @@ -6,7 +6,17 @@ SELECT name, statement, parameter_types, result_types FROM pg_prepared_statement ------+-----------+-----------------+-------------- (0 rows) -PREPARE q1 AS SELECT 1 AS a; +SELECT 'bingo'\; PREPARE q1 AS SELECT 1 AS a \; SELECT 42; + ?column? +---------- + bingo +(1 row) + + ?column? +---------- + 42 +(1 row) + EXECUTE q1; a --- @@ -14,9 +24,9 @@ EXECUTE q1; (1 row) SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements; - name | statement | parameter_types | result_types -------+------------------------------+-----------------+-------------- - q1 | PREPARE q1 AS SELECT 1 AS a; | {} | {integer} + name | statement | parameter_types | result_types +------+-----------------------------+-----------------+-------------- + q1 | PREPARE q1 AS SELECT 1 AS a | {} | {integer} (1 row) -- should fail @@ -33,18 +43,18 @@ EXECUTE q1; PREPARE q2 AS SELECT 2 AS b; SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements; - name | statement | parameter_types | result_types -------+------------------------------+-----------------+-------------- - q1 | PREPARE q1 AS SELECT 2; | {} | {integer} - q2 | PREPARE q2 AS SELECT 2 AS b; | {} | {integer} + name | statement | parameter_types | result_types +------+-----------------------------+-----------------+-------------- + q1 | PREPARE q1 AS SELECT 2 | {} | {integer} + q2 | PREPARE q2 AS SELECT 2 AS b | {} | {integer} (2 rows) -- sql92 syntax DEALLOCATE PREPARE q1; SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements; - name | statement | parameter_types | result_types -------+------------------------------+-----------------+-------------- - q2 | PREPARE q2 AS SELECT 2 AS b; | {} | {integer} + name | statement | parameter_types | result_types +------+-----------------------------+-----------------+-------------- + q2 | PREPARE q2 AS SELECT 2 AS b | {} | {integer} (1 row) DEALLOCATE PREPARE q2; @@ -168,20 +178,20 @@ SELECT name, statement, parameter_types, result_types FROM pg_prepared_statement ------+------------------------------------------------------------------+----------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------- q2 | PREPARE q2(text) AS +| {text} | {name,boolean,boolean} | SELECT datname, datistemplate, datallowconn +| | - | FROM pg_database WHERE datname = $1; | | + | FROM pg_database WHERE datname = $1 | | q3 | PREPARE q3(text, int, float, boolean, smallint) AS +| {text,integer,"double precision",boolean,smallint} | {integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,name,name,name} | SELECT * FROM tenk1 WHERE string4 = $1 AND (four = $2 OR+| | | ten = $3::bigint OR true = $4 OR odd = $5::int) +| | - | ORDER BY unique1; | | + | ORDER BY unique1 | | q5 | PREPARE q5(int, text) AS +| {integer,text} | {integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,name,name,name} | SELECT * FROM tenk1 WHERE unique1 = $1 OR stringu1 = $2 +| | - | ORDER BY unique1; | | + | ORDER BY unique1 | | q6 | PREPARE q6 AS +| {integer,name} | {integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,integer,name,name,name} - | SELECT * FROM tenk1 WHERE unique1 = $1 AND stringu1 = $2; | | + | SELECT * FROM tenk1 WHERE unique1 = $1 AND stringu1 = $2 | | q7 | PREPARE q7(unknown) AS +| {path} | {text,path} - | SELECT * FROM road WHERE thepath = $1; | | + | SELECT * FROM road WHERE thepath = $1 | | q8 | PREPARE q8 AS +| {integer,name} | - | UPDATE tenk1 SET stringu1 = $2 WHERE unique1 = $1; | | + | UPDATE tenk1 SET stringu1 = $2 WHERE unique1 = $1 | | (6 rows) -- test DEALLOCATE ALL; diff --git a/src/test/regress/sql/prepare.sql b/src/test/regress/sql/prepare.sql index c6098dc95ce..0e7fe44725e 100644 --- a/src/test/regress/sql/prepare.sql +++ b/src/test/regress/sql/prepare.sql @@ -4,7 +4,7 @@ SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements; -PREPARE q1 AS SELECT 1 AS a; +SELECT 'bingo'\; PREPARE q1 AS SELECT 1 AS a \; SELECT 42; EXECUTE q1; SELECT name, statement, parameter_types, result_types FROM pg_prepared_statements; -- 2.50.1 (Apple Git-155)