From 6e481ebff6368cb0ab5351a5ef3463747c35af22 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 19 Apr 2013 16:14:56 -0400
Subject: [PATCH] Improve error message when an FDW doesn't support WHERE
CURRENT OF.
If an FDW fails to take special measures with a CurrentOfExpr, we will
end up trying to execute it as an ordinary qual, which was being treated
as a purely internal failure condition. Provide a more user-oriented
error message for such cases.
---
src/backend/executor/execQual.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index 330d889eba9..4ea0cbadadb 100644
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -4257,16 +4257,20 @@ ExecEvalArrayCoerceExpr(ArrayCoerceExprState *astate,
/* ----------------------------------------------------------------
* ExecEvalCurrentOfExpr
*
- * The planner must convert CURRENT OF into a TidScan qualification.
- * So, we have to be able to do ExecInitExpr on a CurrentOfExpr,
- * but we shouldn't ever actually execute it.
+ * The planner should convert CURRENT OF into a TidScan qualification, or some
+ * other special handling in a ForeignScan node. So we have to be able to do
+ * ExecInitExpr on a CurrentOfExpr, but we shouldn't ever actually execute it.
+ * If we get here, we suppose we must be dealing with CURRENT OF on a foreign
+ * table whose FDW doesn't handle it, and complain accordingly.
* ----------------------------------------------------------------
*/
static Datum
ExecEvalCurrentOfExpr(ExprState *exprstate, ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone)
{
- elog(ERROR, "CURRENT OF cannot be executed");
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("WHERE CURRENT OF is not supported for this table type")));
return 0; /* keep compiler quiet */
}
--
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