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Commit7ee0091

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Fix deparsing FETCH FIRST <expr> ROWS WITH TIES
In the grammar, <expr> is a c_expr, which accepts only a limited setof simple constants and expressions without parens. The deparsinglogic didn't quite match the grammar rule, and failed to use parense.g. for "5::bigint".To fix, always surround the expression with parens. Would be nice toomit the parens in simple cases, but unfortunately it's non-trivial todetect such simple cases. Even if the expression is a simple literal123 in the original query, after parse analysis it becomes a FuncExprwith COERCE_IMPLICIT_CAST rather than a simple Const.Reported-by: yonghao leeBackpatch-through: 13Discussion:https://www.postgresql.org/message-id/18929-077d6b7093b176e2@postgresql.org
1 parente323d9d commit7ee0091

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3 files changed

+31
-4
lines changed

3 files changed

+31
-4
lines changed

‎src/backend/utils/adt/ruleutils.c

Lines changed: 10 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -5300,9 +5300,19 @@ get_select_query_def(Query *query, deparse_context *context,
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{
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if (query->limitOption==LIMIT_OPTION_WITH_TIES)
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{
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/*
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* The limitCount arg is a c_expr, so it needs parens. Simple
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* literals and function expressions would not need parens, but
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* unfortunately it's hard to tell if the expression will be
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* printed as a simple literal like 123 or as a typecast
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* expression, like '-123'::int4. The grammar accepts the former
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* without quoting, but not the latter.
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*/
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appendContextKeyword(context," FETCH FIRST ",
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-PRETTYINDENT_STD,PRETTYINDENT_STD,0);
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appendStringInfoChar(buf,'(');
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get_rule_expr(query->limitCount,context, false);
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appendStringInfoChar(buf,')');
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appendStringInfo(buf," ROWS WITH TIES");
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}
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else

‎src/test/regress/expected/limit.out

Lines changed: 17 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -643,7 +643,7 @@ View definition:
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WHERE onek.thousand < 995
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ORDER BY onek.thousand
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OFFSET 10
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FETCH FIRST5 ROWS WITH TIES;
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FETCH FIRST(5) ROWS WITH TIES;
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CREATE VIEW limit_thousand_v_2 AS SELECT thousand FROM onek WHERE thousand < 995
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ORDER BY thousand OFFSET 10 FETCH FIRST 5 ROWS ONLY;
@@ -675,15 +675,29 @@ View definition:
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FROM onek
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WHERE onek.thousand < 995
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ORDER BY onek.thousand
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FETCH FIRST (NULL::integer + 1) ROWS WITH TIES;
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FETCH FIRST ((NULL::integer + 1)) ROWS WITH TIES;
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CREATE VIEW limit_thousand_v_4 AS SELECT thousand FROM onek WHERE thousand < 995
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ORDER BY thousand FETCH FIRSTNULL ROWSONLY;
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ORDER BY thousand FETCH FIRST(5::bigint) ROWSWITH TIES;
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\d+ limit_thousand_v_4
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View "public.limit_thousand_v_4"
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Column | Type | Collation | Nullable | Default | Storage | Description
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----------+---------+-----------+----------+---------+---------+-------------
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thousand | integer | | | | plain |
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View definition:
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SELECT onek.thousand
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FROM onek
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WHERE onek.thousand < 995
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ORDER BY onek.thousand
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FETCH FIRST (5::bigint) ROWS WITH TIES;
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CREATE VIEW limit_thousand_v_5 AS SELECT thousand FROM onek WHERE thousand < 995
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ORDER BY thousand FETCH FIRST NULL ROWS ONLY;
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\d+ limit_thousand_v_5
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View "public.limit_thousand_v_5"
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Column | Type | Collation | Nullable | Default | Storage | Description
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----------+---------+-----------+----------+---------+---------+-------------
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thousand | integer | | | | plain |
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View definition:
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SELECT onek.thousand
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FROM onek

‎src/test/regress/sql/limit.sql

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -196,6 +196,9 @@ CREATE VIEW limit_thousand_v_3 AS SELECT thousand FROM onek WHERE thousand < 995
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ORDER BY thousand FETCH FIRST (NULL+1) ROWS WITH TIES;
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\d+ limit_thousand_v_3
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CREATEVIEWlimit_thousand_v_4ASSELECT thousandFROM onekWHERE thousand<995
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ORDER BY thousand FETCH FIRSTNULL ROWSONLY;
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ORDER BY thousand FETCH FIRST(5::bigint) ROWSWITH TIES;
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\d+ limit_thousand_v_4
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CREATEVIEWlimit_thousand_v_5ASSELECT thousandFROM onekWHERE thousand<995
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ORDER BY thousand FETCH FIRSTNULL ROWS ONLY;
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\d+ limit_thousand_v_5
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-- leave these views

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