From: Heikki Linnakangas Date: Mon, 19 May 2025 15:50:26 +0000 (+0300) Subject: Fix deparsing FETCH FIRST ROWS WITH TIES X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;ds=inline;p=postgresql.git Fix deparsing FETCH FIRST ROWS WITH TIES In the grammar, is a c_expr, which accepts only a limited set of integer literals and simple expressions without parens. The deparsing logic didn't quite match the grammar rule, and failed to use parens e.g. for "5::bigint". To fix, always surround the expression with parens. Would be nice to omit the parens in simple cases, but unfortunately it's non-trivial to detect such simple cases. Even if the expression is a simple literal 123 in the original query, after parse analysis it becomes a FuncExpr with COERCE_IMPLICIT_CAST rather than a simple Const. Reported-by: yonghao lee Backpatch-through: 13 Discussion: https://www.postgresql.org/message-id/18929-077d6b7093b176e2@postgresql.org --- diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c index 467b08198b8..3d6e6bdbfd2 100644 --- a/src/backend/utils/adt/ruleutils.c +++ b/src/backend/utils/adt/ruleutils.c @@ -5956,9 +5956,19 @@ get_select_query_def(Query *query, deparse_context *context) { if (query->limitOption == LIMIT_OPTION_WITH_TIES) { + /* + * The limitCount arg is a c_expr, so it needs parens. Simple + * literals and function expressions would not need parens, but + * unfortunately it's hard to tell if the expression will be + * printed as a simple literal like 123 or as a typecast + * expression, like '-123'::int4. The grammar accepts the former + * without quoting, but not the latter. + */ appendContextKeyword(context, " FETCH FIRST ", -PRETTYINDENT_STD, PRETTYINDENT_STD, 0); + appendStringInfoChar(buf, '('); get_rule_expr(query->limitCount, context, false); + appendStringInfoChar(buf, ')'); appendStringInfoString(buf, " ROWS WITH TIES"); } else diff --git a/src/test/regress/expected/limit.out b/src/test/regress/expected/limit.out index f4267c002d7..e3bcc680653 100644 --- a/src/test/regress/expected/limit.out +++ b/src/test/regress/expected/limit.out @@ -647,7 +647,7 @@ View definition: WHERE thousand < 995 ORDER BY thousand OFFSET 10 - FETCH FIRST 5 ROWS WITH TIES; + FETCH FIRST (5) ROWS WITH TIES; CREATE VIEW limit_thousand_v_2 AS SELECT thousand FROM onek WHERE thousand < 995 ORDER BY thousand OFFSET 10 FETCH FIRST 5 ROWS ONLY; @@ -679,15 +679,29 @@ View definition: FROM onek WHERE thousand < 995 ORDER BY thousand - FETCH FIRST (NULL::integer + 1) ROWS WITH TIES; + FETCH FIRST ((NULL::integer + 1)) ROWS WITH TIES; CREATE VIEW limit_thousand_v_4 AS SELECT thousand FROM onek WHERE thousand < 995 - ORDER BY thousand FETCH FIRST NULL ROWS ONLY; + ORDER BY thousand FETCH FIRST (5::bigint) ROWS WITH TIES; \d+ limit_thousand_v_4 View "public.limit_thousand_v_4" Column | Type | Collation | Nullable | Default | Storage | Description ----------+---------+-----------+----------+---------+---------+------------- thousand | integer | | | | plain | +View definition: + SELECT thousand + FROM onek + WHERE thousand < 995 + ORDER BY thousand + FETCH FIRST (5::bigint) ROWS WITH TIES; + +CREATE VIEW limit_thousand_v_5 AS SELECT thousand FROM onek WHERE thousand < 995 + ORDER BY thousand FETCH FIRST NULL ROWS ONLY; +\d+ limit_thousand_v_5 + View "public.limit_thousand_v_5" + Column | Type | Collation | Nullable | Default | Storage | Description +----------+---------+-----------+----------+---------+---------+------------- + thousand | integer | | | | plain | View definition: SELECT thousand FROM onek diff --git a/src/test/regress/sql/limit.sql b/src/test/regress/sql/limit.sql index 6f0cda98701..603910fe6d1 100644 --- a/src/test/regress/sql/limit.sql +++ b/src/test/regress/sql/limit.sql @@ -196,6 +196,9 @@ CREATE VIEW limit_thousand_v_3 AS SELECT thousand FROM onek WHERE thousand < 995 ORDER BY thousand FETCH FIRST (NULL+1) ROWS WITH TIES; \d+ limit_thousand_v_3 CREATE VIEW limit_thousand_v_4 AS SELECT thousand FROM onek WHERE thousand < 995 - ORDER BY thousand FETCH FIRST NULL ROWS ONLY; + ORDER BY thousand FETCH FIRST (5::bigint) ROWS WITH TIES; \d+ limit_thousand_v_4 +CREATE VIEW limit_thousand_v_5 AS SELECT thousand FROM onek WHERE thousand < 995 + ORDER BY thousand FETCH FIRST NULL ROWS ONLY; +\d+ limit_thousand_v_5 -- leave these views