From bee23ea4ddc46198c95a4e73a83f453c09e04bf8 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Wed, 2 Jul 2025 08:39:25 +0900 Subject: Show sizes of FETCH queries as constants in pg_stat_statements Prior to this patch, every FETCH call would generate a unique queryId with a different size specified. Depending on the workloads, this could lead to a 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 as 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 In order to do a normalization based on the keyword used in FETCH, FetchStmt is tweaked with a new FetchDirectionKeywords. This matters for "howMany", which could be set to a negative value depending on the direction, and we want to normalize the queries with enough information about the direction keywords provided, including RELATIVE, ABSOLUTE or all the ALL variants. Author: Sami Imseih Discussion: https://postgr.es/m/CAA5RZ0tA6LbHCg2qSS+KuM850BZC_+ZgHV7Ug6BXw22TNyF+MA@mail.gmail.com --- src/backend/parser/gram.y | 50 ++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 41 insertions(+), 9 deletions(-) (limited to 'src/backend') diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y index 50f53159d58..1c11b235aa6 100644 --- a/src/backend/parser/gram.y +++ b/src/backend/parser/gram.y @@ -7477,6 +7477,8 @@ fetch_args: cursor_name n->portalname = $1; n->direction = FETCH_FORWARD; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_NONE; $$ = (Node *) n; } | from_in cursor_name @@ -7486,6 +7488,19 @@ fetch_args: cursor_name n->portalname = $2; n->direction = FETCH_FORWARD; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_NONE; + $$ = (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; $$ = (Node *) n; } | NEXT opt_from_in cursor_name @@ -7495,6 +7510,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_FORWARD; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_NEXT; $$ = (Node *) n; } | PRIOR opt_from_in cursor_name @@ -7504,6 +7521,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_BACKWARD; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_PRIOR; $$ = (Node *) n; } | FIRST_P opt_from_in cursor_name @@ -7513,6 +7532,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_ABSOLUTE; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_FIRST; $$ = (Node *) n; } | LAST_P opt_from_in cursor_name @@ -7522,6 +7543,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_ABSOLUTE; n->howMany = -1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_LAST; $$ = (Node *) n; } | ABSOLUTE_P SignedIconst opt_from_in cursor_name @@ -7531,6 +7554,8 @@ fetch_args: cursor_name n->portalname = $4; n->direction = FETCH_ABSOLUTE; n->howMany = $2; + n->location = @2; + n->direction_keyword = FETCH_KEYWORD_ABSOLUTE; $$ = (Node *) n; } | RELATIVE_P SignedIconst opt_from_in cursor_name @@ -7540,15 +7565,8 @@ 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 @@ -7558,6 +7576,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_FORWARD; n->howMany = FETCH_ALL; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_ALL; $$ = (Node *) n; } | FORWARD opt_from_in cursor_name @@ -7567,6 +7587,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_FORWARD; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_FORWARD; $$ = (Node *) n; } | FORWARD SignedIconst opt_from_in cursor_name @@ -7576,6 +7598,8 @@ fetch_args: cursor_name n->portalname = $4; n->direction = FETCH_FORWARD; n->howMany = $2; + n->location = @2; + n->direction_keyword = FETCH_KEYWORD_FORWARD; $$ = (Node *) n; } | FORWARD ALL opt_from_in cursor_name @@ -7585,6 +7609,8 @@ fetch_args: cursor_name n->portalname = $4; n->direction = FETCH_FORWARD; n->howMany = FETCH_ALL; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_FORWARD_ALL; $$ = (Node *) n; } | BACKWARD opt_from_in cursor_name @@ -7594,6 +7620,8 @@ fetch_args: cursor_name n->portalname = $3; n->direction = FETCH_BACKWARD; n->howMany = 1; + n->location = -1; + n->direction_keyword = FETCH_KEYWORD_BACKWARD; $$ = (Node *) n; } | BACKWARD SignedIconst opt_from_in cursor_name @@ -7603,6 +7631,8 @@ fetch_args: cursor_name n->portalname = $4; n->direction = FETCH_BACKWARD; n->howMany = $2; + n->location = @2; + n->direction_keyword = FETCH_KEYWORD_BACKWARD; $$ = (Node *) n; } | BACKWARD ALL opt_from_in cursor_name @@ -7612,6 +7642,8 @@ 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; } ; -- cgit v1.2.3