From: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> |
---|---|
To: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Parallel Bitmap Heap Scans segfaults due to (tbm->dsa==NULL) on PostgreSQL 10 |
Date: | 2017-10-12 11:01:24 |
Message-ID: | 50e89684-8ad9-dead-8767-c9545bafd3b6@2ndquadrant.com |
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Lists: | pgsql-hackers |
Hi,
It seems that Q19 from TPC-H is consistently failing with segfaults due
to calling tbm_prepare_shared_iterate() with (tbm->dsa==NULL).
I'm not very familiar with how the dsa is initialized and passed around,
but I only see the failures when the bitmap is constructed by a mix of
BitmapAnd and BitmapOr operations.
Another interesting observation is that setting force_parallel_mode=on
may not be enough - there really need to be multiple parallel workers,
which is why the simple query does cpu_tuple_cost=1.
Attached is a bunch of files:
1) details for "full" query:
* query.sql
* plan.txt
* backtrace.txt
2) details for the "minimal" query triggering the issue:
* query-minimal.sql
* plan-minimal.txt
* backtrace-minimal.txt
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
Attachment | Content-Type | Size |
---|---|---|
backtrace-simple.txt | text/plain | 3.0 KB |
plan-simple.txt | text/plain | 1.6 KB |
query-simple.txt | text/plain | 347 bytes |
query.sql | application/sql | 1.1 KB |
plan.txt | text/plain | 5.8 KB |
backtrace.txt | text/plain | 4.0 KB |
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