Hi.
In coerce_to_target_type, we have comments like
/*
* Note that if there are multiple stacked CollateExprs, we just
discard all but the topmost.
*/
origexpr = expr;
while (expr && IsA(expr, CollateExpr))
expr = (Node *) ((CollateExpr *) expr)->arg;
Only the topmost CollateExpr will be used, all others will be dropped.
We can apply this to coerce_type also.
See the attached minor patch.
--
jian
https://www.enterprisedb.com/
From ff1c6eb8590bfba8e5ce2d8be70182402246d1f9 Mon Sep 17 00:00:00 2001
From: jian he <[email protected]>
Date: Mon, 29 Jun 2026 16:11:26 +0800
Subject: [PATCH v1 1/1] coerce_type
discard unncessary CollateExprs
discuccsion: https://postgr.es/m/
---
src/backend/parser/parse_coerce.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/src/backend/parser/parse_coerce.c b/src/backend/parser/parse_coerce.c
index 3b92ae2a920..f83e1933706 100644
--- a/src/backend/parser/parse_coerce.c
+++ b/src/backend/parser/parse_coerce.c
@@ -397,7 +397,10 @@ coerce_type(ParseState *pstate, Node *node,
*/
CollateExpr *coll = (CollateExpr *) node;
- result = coerce_type(pstate, (Node *) coll->arg,
+ while (node && IsA(node, CollateExpr))
+ node = (Node *) ((CollateExpr *) node)->arg;
+
+ result = coerce_type(pstate, node,
inputTypeId, targetTypeId, targetTypeMod,
ccontext, cformat, location);
if (type_is_collatable(targetTypeId))
--
2.34.1
