On 2020-Jul-13, Andres Freund wrote:
> Hi,
>
> On 2020-07-13 17:12:18 -0400, Robert Haas wrote:
> > 1. There's nothing to identify the tuple that has the problem, and no
> > way to know how many more of them there might be. Back-patching
> > b61d161c146328ae6ba9ed937862d66e5c8b035a would help with the first
> > part of this.
>
> Not fully, I'm afraid. Afaict it doesn't currently tell you the item
> pointer offset, just the block numer, right? We probably should extend
> it to also include the offset...
Just having the block number is already a tremendous step forward; with
that you can ask the customer to set a pageinspect dump of tuple
headers, and then the problem is obvious. Now if you want to add block
number to that, by all means do so.
FWIW I do support the idea of backpatching the vacuum errcontext commit.
One useful thing to do is to mark a tuple frozen unconditionally if it's
marked hinted XMIN_COMMITTED; no need to consult pg_clog in that case.
The attached (for 9.6) does that; IIRC it would have helped in a couple
of cases.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
>From 2d5574e4e3caa0299d27d77f0fc319463fc84162 Mon Sep 17 00:00:00 2001
From: Alvaro Herrera <alvhe...@alvh.no-ip.org>
Date: Thu, 18 Jul 2019 12:50:11 -0400
Subject: [PATCH] Don't test for xact commit if tuple is hinted
---
src/backend/access/heap/heapam.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index fe3e83b489..d42bc6502c 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -6724,7 +6724,8 @@ heap_prepare_freeze_tuple(HeapTupleHeader tuple,
if (TransactionIdPrecedes(xid, cutoff_xid))
{
- if (!TransactionIdDidCommit(xid))
+ if (!HeapTupleHeaderXminCommitted(xid) &&
+ !TransactionIdDidCommit(xid))
ereport(ERROR,
(errcode(ERRCODE_DATA_CORRUPTED),
errmsg_internal("uncommitted xmin %u from before xid cutoff %u needs to be frozen",
--
2.20.1
