From c54b308feef684ea169002944241e5b8d7e2bd69 Mon Sep 17 00:00:00 2001 From: Ubuntu Date: Tue, 3 Jun 2025 17:58:19 +0000 Subject: [PATCH v4 1/1] Normalize variable fetch sizes in a FETCH command Prior to this patch, every FETCH call would generate a unique queryId. This led to significant bloat in pg_stat_statements, as repeatedly calling a specific cursor would result in a new queryId each time. For example, FETCH 1 c1; and FETCH 2 c1; would produce different queryIds. This patch improves the situation by normalizing the fetch size, so semantically similar statements generate the same queryId. As a result, statements like the below, which differ syntactically but have the same effect, will now share a single queryId: FETCH FROM c1; FETCH NEXT c1; FETCH 1 c1; Discussion: https://www.postgresql.org/message-id/flat/CAA5RZ0tA6LbHCg2qSS%2BKuM850BZC_%2BZgHV7Ug6BXw22TNyF%2BMA%40mail.gmail.com --- .../pg_stat_statements/expected/cursors.out | 4 +- .../expected/level_tracking.out | 4 +- .../pg_stat_statements/expected/utility.out | 165 +++++++++++++++++- contrib/pg_stat_statements/sql/utility.sql | 49 ++++++ src/backend/parser/gram.y | 50 +++++- src/include/nodes/parsenodes.h | 28 ++- 6 files changed, 285 insertions(+), 15 deletions(-) diff --git a/contrib/pg_stat_statements/expected/cursors.out b/contrib/pg_stat_statements/expected/cursors.out index 0fc4b2c098d..6781f99ea03 100644 --- a/contrib/pg_stat_statements/expected/cursors.out +++ b/contrib/pg_stat_statements/expected/cursors.out @@ -57,8 +57,8 @@ SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C"; 1 | 0 | COMMIT 1 | 0 | DECLARE cursor_stats_1 CURSOR WITH HOLD FOR SELECT $1 1 | 0 | DECLARE cursor_stats_2 CURSOR WITH HOLD FOR SELECT $1 - 1 | 1 | FETCH 1 IN cursor_stats_1 - 1 | 1 | FETCH 1 IN cursor_stats_2 + 1 | 1 | FETCH $1 IN cursor_stats_1 + 1 | 1 | FETCH $1 IN cursor_stats_2 1 | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t (9 rows) diff --git a/contrib/pg_stat_statements/expected/level_tracking.out b/contrib/pg_stat_statements/expected/level_tracking.out index 75e785e1719..ce4bd3a823d 100644 --- a/contrib/pg_stat_statements/expected/level_tracking.out +++ b/contrib/pg_stat_statements/expected/level_tracking.out @@ -1142,7 +1142,7 @@ SELECT toplevel, calls, query FROM pg_stat_statements t | 1 | CLOSE foocur t | 1 | COMMIT t | 1 | DECLARE FOOCUR CURSOR FOR SELECT * from stats_track_tab - t | 1 | FETCH FORWARD 1 FROM foocur + t | 1 | FETCH FORWARD $1 FROM foocur f | 1 | SELECT * from stats_track_tab t | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t (7 rows) @@ -1172,7 +1172,7 @@ SELECT toplevel, calls, query FROM pg_stat_statements t | 1 | CLOSE foocur t | 1 | COMMIT t | 1 | DECLARE FOOCUR CURSOR FOR SELECT * FROM stats_track_tab - t | 1 | FETCH FORWARD 1 FROM foocur + t | 1 | FETCH FORWARD $1 FROM foocur t | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t (6 rows) diff --git a/contrib/pg_stat_statements/expected/utility.out b/contrib/pg_stat_statements/expected/utility.out index aa4f0f7e628..5b623e0a095 100644 --- a/contrib/pg_stat_statements/expected/utility.out +++ b/contrib/pg_stat_statements/expected/utility.out @@ -702,7 +702,7 @@ SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C"; 1 | 13 | CREATE MATERIALIZED VIEW pgss_matv AS SELECT * FROM pgss_ctas 1 | 10 | CREATE TABLE pgss_ctas AS SELECT a, $1 b FROM generate_series($2, $3) a 1 | 0 | DECLARE pgss_cursor CURSOR FOR SELECT * FROM pgss_matv - 1 | 5 | FETCH FORWARD 5 pgss_cursor + 1 | 5 | FETCH FORWARD $1 pgss_cursor 1 | 7 | FETCH FORWARD ALL pgss_cursor 1 | 1 | FETCH NEXT pgss_cursor 1 | 13 | REFRESH MATERIALIZED VIEW pgss_matv @@ -719,7 +719,170 @@ SELECT pg_stat_statements_reset() IS NOT NULL AS t; t (1 row) +-- Normalization of FETCH statements +BEGIN; +DECLARE pgss_cursor CURSOR FOR SELECT FROM generate_series(1, 50); +-- implicit directions +FETCH pgss_cursor; +-- +(1 row) + +FETCH 1 pgss_cursor; +-- +(1 row) + +FETCH 2 pgss_cursor; +-- +(2 rows) + +FETCH 3 pgss_cursor; +-- +(3 rows) + +FETCH -1 pgss_cursor; +-- +(1 row) + +-- explicit NEXT +FETCH NEXT pgss_cursor; +-- +(1 row) + +-- explicit PRIOR +FETCH PRIOR pgss_cursor; +-- +(1 row) + +-- explicit FIRST +FETCH FIRST pgss_cursor; +-- +(1 row) + +-- explicit LAST +FETCH LAST pgss_cursor; +-- +(1 row) + +-- explicit ABSOLUTE +FETCH ABSOLUTE 1 pgss_cursor; +-- +(1 row) + +FETCH ABSOLUTE 2 pgss_cursor; +-- +(1 row) + +FETCH ABSOLUTE 3 pgss_cursor; +-- +(1 row) + +FETCH ABSOLUTE -1 pgss_cursor; +-- +(1 row) + +-- explicit RELATIVE +FETCH RELATIVE 1 pgss_cursor; +-- +(0 rows) + +FETCH RELATIVE 2 pgss_cursor; +-- +(0 rows) + +FETCH RELATIVE 3 pgss_cursor; +-- +(0 rows) + +FETCH RELATIVE -1 pgss_cursor; +-- +(1 row) + +-- explicit FORWARD +FETCH ALL pgss_cursor; +-- +(0 rows) + +-- explicit FORWARD ALL +FETCH FORWARD ALL pgss_cursor; +-- +(0 rows) + +-- explicit BACKWARD ALL +FETCH BACKWARD ALL pgss_cursor; +-- +(50 rows) + +-- explicit FETCH FORWARD +FETCH FORWARD pgss_cursor; +-- +(1 row) + +FETCH FORWARD 1 pgss_cursor; +-- +(1 row) + +FETCH FORWARD 2 pgss_cursor; +-- +(2 rows) + +FETCH FORWARD 3 pgss_cursor; +-- +(3 rows) + +FETCH FORWARD -1 pgss_cursor; +-- +(1 row) + +-- explicit FETCH BACKWARD +FETCH BACKWARD pgss_cursor; +-- +(1 row) + +FETCH BACKWARD 1 pgss_cursor; +-- +(1 row) + +FETCH BACKWARD 2 pgss_cursor; +-- +(2 rows) + +FETCH BACKWARD 3 pgss_cursor; +-- +(1 row) + +FETCH BACKWARD -1 pgss_cursor; +-- +(1 row) + +COMMIT; +SELECT calls, query FROM pg_stat_statements ORDER BY query COLLATE "C"; + calls | query +-------+-------------------------------------------------------------------- + 1 | BEGIN + 1 | COMMIT + 1 | DECLARE pgss_cursor CURSOR FOR SELECT FROM generate_series($1, $2) + 4 | FETCH ABSOLUTE $1 pgss_cursor + 1 | FETCH ALL pgss_cursor + 1 | FETCH BACKWARD ALL pgss_cursor + 5 | FETCH BACKWARD pgss_cursor + 1 | FETCH FIRST pgss_cursor + 1 | FETCH FORWARD ALL pgss_cursor + 5 | FETCH FORWARD pgss_cursor + 1 | FETCH LAST pgss_cursor + 1 | FETCH NEXT pgss_cursor + 1 | FETCH PRIOR pgss_cursor + 4 | FETCH RELATIVE $1 pgss_cursor + 5 | FETCH pgss_cursor + 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t +(16 rows) + -- Special cases. Keep these ones at the end to avoid conflicts. +SELECT pg_stat_statements_reset() IS NOT NULL AS t; + t +--- + t +(1 row) + SET SCHEMA 'foo'; SET SCHEMA 'public'; RESET ALL; diff --git a/contrib/pg_stat_statements/sql/utility.sql b/contrib/pg_stat_statements/sql/utility.sql index dd97203c210..8fcd7d2983f 100644 --- a/contrib/pg_stat_statements/sql/utility.sql +++ b/contrib/pg_stat_statements/sql/utility.sql @@ -365,7 +365,56 @@ DROP TABLE pgss_select_into; SELECT pg_stat_statements_reset() IS NOT NULL AS t; +-- Normalization of FETCH statements +BEGIN; +DECLARE pgss_cursor CURSOR FOR SELECT FROM generate_series(1, 50); +-- implicit directions +FETCH pgss_cursor; +FETCH 1 pgss_cursor; +FETCH 2 pgss_cursor; +FETCH 3 pgss_cursor; +FETCH -1 pgss_cursor; +-- explicit NEXT +FETCH NEXT pgss_cursor; +-- explicit PRIOR +FETCH PRIOR pgss_cursor; +-- explicit FIRST +FETCH FIRST pgss_cursor; +-- explicit LAST +FETCH LAST pgss_cursor; +-- explicit ABSOLUTE +FETCH ABSOLUTE 1 pgss_cursor; +FETCH ABSOLUTE 2 pgss_cursor; +FETCH ABSOLUTE 3 pgss_cursor; +FETCH ABSOLUTE -1 pgss_cursor; +-- explicit RELATIVE +FETCH RELATIVE 1 pgss_cursor; +FETCH RELATIVE 2 pgss_cursor; +FETCH RELATIVE 3 pgss_cursor; +FETCH RELATIVE -1 pgss_cursor; +-- explicit FORWARD +FETCH ALL pgss_cursor; +-- explicit FORWARD ALL +FETCH FORWARD ALL pgss_cursor; +-- explicit BACKWARD ALL +FETCH BACKWARD ALL pgss_cursor; +-- explicit FETCH FORWARD +FETCH FORWARD pgss_cursor; +FETCH FORWARD 1 pgss_cursor; +FETCH FORWARD 2 pgss_cursor; +FETCH FORWARD 3 pgss_cursor; +FETCH FORWARD -1 pgss_cursor; +-- explicit FETCH BACKWARD +FETCH BACKWARD pgss_cursor; +FETCH BACKWARD 1 pgss_cursor; +FETCH BACKWARD 2 pgss_cursor; +FETCH BACKWARD 3 pgss_cursor; +FETCH BACKWARD -1 pgss_cursor; +COMMIT; +SELECT calls, query FROM pg_stat_statements ORDER BY query COLLATE "C"; + -- Special cases. Keep these ones at the end to avoid conflicts. +SELECT pg_stat_statements_reset() IS NOT NULL AS t; SET SCHEMA 'foo'; SET SCHEMA 'public'; RESET ALL; diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y index 0b5652071d1..0dfcdbfb310 100644 --- a/src/backend/parser/gram.y +++ b/src/backend/parser/gram.y @@ -7479,6 +7479,8 @@ fetch_args: cursor_name n->portalname = $1; n->direction = FETCH_FORWARD; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_NONE; $$ = (Node *) n; } | from_in cursor_name @@ -7488,6 +7490,19 @@ fetch_args: cursor_name n->portalname = $2; n->direction = FETCH_FORWARD; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_NONE; + $$ = (Node *) n; + } + | SignedIconst opt_from_in cursor_name + { + FetchStmt *n = makeNode(FetchStmt); + + n->portalname = $3; + n->direction = FETCH_FORWARD; + n->howMany = $1; + n->location = @1; + n->direction_keyword = FETCH_KEYWORD_NONE; $$ = (Node *) n; } | NEXT opt_from_in cursor_name @@ -7497,6 +7512,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_FORWARD; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_NEXT; $$ = (Node *) n; } | PRIOR opt_from_in cursor_name @@ -7506,6 +7523,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_BACKWARD; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_PRIOR; $$ = (Node *) n; } | FIRST_P opt_from_in cursor_name @@ -7515,6 +7534,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_ABSOLUTE; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_FIRST; $$ = (Node *) n; } | LAST_P opt_from_in cursor_name @@ -7524,6 +7545,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_ABSOLUTE; n->howMany = -1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_LAST; $$ = (Node *) n; } | ABSOLUTE_P SignedIconst opt_from_in cursor_name @@ -7533,6 +7556,8 @@ fetch_args: cursor_name n->portalname = $4; n->direction = FETCH_ABSOLUTE; n->howMany = $2; + n->location = @2; + n->direction_keyword = FETCH_KEYWORD_ABSOLUTE; $$ = (Node *) n; } | RELATIVE_P SignedIconst opt_from_in cursor_name @@ -7542,15 +7567,8 @@ fetch_args: cursor_name n->portalname = $4; n->direction = FETCH_RELATIVE; n->howMany = $2; - $$ = (Node *) n; - } - | SignedIconst opt_from_in cursor_name - { - FetchStmt *n = makeNode(FetchStmt); - - n->portalname = $3; - n->direction = FETCH_FORWARD; - n->howMany = $1; + n->location = @2; + n->direction_keyword = FETCH_KEYWORD_RELATIVE; $$ = (Node *) n; } | ALL opt_from_in cursor_name @@ -7560,6 +7578,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_FORWARD; n->howMany = FETCH_ALL; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_ALL; $$ = (Node *) n; } | FORWARD opt_from_in cursor_name @@ -7569,6 +7589,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_FORWARD; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_FORWARD; $$ = (Node *) n; } | FORWARD SignedIconst opt_from_in cursor_name @@ -7578,6 +7600,8 @@ fetch_args: cursor_name n->portalname = $4; n->direction = FETCH_FORWARD; n->howMany = $2; + n->location = @2; + n->direction_keyword = FETCH_KEYWORD_FORWARD; $$ = (Node *) n; } | FORWARD ALL opt_from_in cursor_name @@ -7587,6 +7611,8 @@ fetch_args: cursor_name n->portalname = $4; n->direction = FETCH_FORWARD; n->howMany = FETCH_ALL; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_FORWARD_ALL; $$ = (Node *) n; } | BACKWARD opt_from_in cursor_name @@ -7596,6 +7622,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_BACKWARD; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_BACKWARD; $$ = (Node *) n; } | BACKWARD SignedIconst opt_from_in cursor_name @@ -7605,6 +7633,8 @@ fetch_args: cursor_name n->portalname = $4; n->direction = FETCH_BACKWARD; n->howMany = $2; + n->location = @2; + n->direction_keyword = FETCH_KEYWORD_BACKWARD; $$ = (Node *) n; } | BACKWARD ALL opt_from_in cursor_name @@ -7614,6 +7644,8 @@ fetch_args: cursor_name n->portalname = $4; n->direction = FETCH_BACKWARD; n->howMany = FETCH_ALL; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_BACKWARD_ALL; $$ = (Node *) n; } ; diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h index dd00ab420b8..9fb050c0705 100644 --- a/src/include/nodes/parsenodes.h +++ b/src/include/nodes/parsenodes.h @@ -3422,15 +3422,41 @@ typedef enum FetchDirection FETCH_RELATIVE, } FetchDirection; +typedef enum FetchDirectionKeywords +{ + FETCH_KEYWORD_NONE, + FETCH_KEYWORD_NEXT, + FETCH_KEYWORD_PRIOR, + FETCH_KEYWORD_FIRST, + FETCH_KEYWORD_LAST, + FETCH_KEYWORD_ABSOLUTE, + FETCH_KEYWORD_RELATIVE, + FETCH_KEYWORD_ALL, + FETCH_KEYWORD_FORWARD, + FETCH_KEYWORD_FORWARD_ALL, + FETCH_KEYWORD_BACKWARD, + FETCH_KEYWORD_BACKWARD_ALL, +} FetchDirectionKeywords; + #define FETCH_ALL LONG_MAX typedef struct FetchStmt { NodeTag type; FetchDirection direction; /* see above */ - long howMany; /* number of rows, or position argument */ + /* number of rows, or position argument */ + long howMany pg_node_attr(query_jumble_ignore); char *portalname; /* name of portal (cursor) */ bool ismove; /* true if MOVE */ + + /* + * If an direction_keyword (i.e., FETCH FORWARD) is used, set this field + * to distinguish it from its numeric counterpart (i.e., FETCH 1). This + * value is set only within gram.y. + */ + FetchDirectionKeywords direction_keyword; + + ParseLoc location pg_node_attr(query_jumble_location); } FetchStmt; /* ---------------------- -- 2.43.0