Hi hackers,
Attached is a small cleanup patch for extended statistics.
lookup_var_attr_stats() assigns tupDesc to VacAttrStats entries created
for expressions. That appears to be obsolete: make_build_data() uses
tupDesc only when fetching values for regular columns, while expressions
are handled separately using VacAttrStats entries created by
examine_expression().
The old comment also points at statext_mcv_build(), but this does not
seem to match the current code anymore. If some future code needs a
tuple descriptor for expression entries here, it should probably set up
that dependency explicitly rather than rely on copying vacatts[0]->tupDesc.
The patch removes the assignment and the outdated XXX comment.
Best regards,
Denis Rodionov
Tantor Labs LLC,
https://tantorlabs.com/
From 5c092b86955f9df47e02e393c1ee5a4bf6e6c79c Mon Sep 17 00:00:00 2001
From: Denis Rodionov <[email protected]>
Date: Thu, 28 May 2026 17:56:09 +0300
Subject: [PATCH v1] Remove obsolete tupDesc assignment in extended statistics
lookup_var_attr_stats() assigns tupDesc to VacAttrStats entries built for
expressions. This appears to be obsolete.
make_build_data() uses tupDesc only for regular columns, when fetching
attribute values from sample rows. For expressions, it creates separate
VacAttrStats entries with examine_expression(), so the entries built by
lookup_var_attr_stats() do not need tupDesc.
Remove the assignment and the outdated XXX comment.
---
src/backend/statistics/extended_stats.c | 8 --------
1 file changed, 8 deletions(-)
diff --git a/src/backend/statistics/extended_stats.c b/src/backend/statistics/extended_stats.c
index 2b83355d26e..049933896b4 100644
--- a/src/backend/statistics/extended_stats.c
+++ b/src/backend/statistics/extended_stats.c
@@ -785,14 +785,6 @@ lookup_var_attr_stats(Bitmapset *attrs, List *exprs,
return NULL;
}
- /*
- * XXX We need tuple descriptor later, and we just grab it from
- * stats[0]->tupDesc (see e.g. statext_mcv_build). But as coded
- * examine_attribute does not set that, so just grab it from the first
- * vacatts element.
- */
- stats[i]->tupDesc = vacatts[0]->tupDesc;
-
i++;
}
--
2.34.1
