diff options
| author | Noah Misch <noah@leadboat.com> | 2024-10-25 06:51:03 -0700 |
|---|---|---|
| committer | Noah Misch <noah@leadboat.com> | 2024-10-25 06:51:08 -0700 |
| commit | 1e74e31f3c93f01c2ddb1e2b25db23fb0533244c (patch) | |
| tree | a550dd00ba881daf3dd1e030a76afb5d6d3a11bb /src/backend/access/heap/README.tuplock | |
| parent | 0ea9d40a667960ad5cca5f537bb88d3bf6038379 (diff) | |
WAL-log inplace update before revealing it to other sessions.
A buffer lock won't stop a reader having already checked tuple
visibility. If a vac_update_datfrozenid() and then a crash happened
during inplace update of a relfrozenxid value, datfrozenxid could
overtake relfrozenxid. That could lead to "could not access status of
transaction" errors. Back-patch to v12 (all supported versions). In
v14 and earlier, this also back-patches the assertion removal from
commit 7fcf2faf9c7dd473208fd6d5565f88d7f733782b.
Discussion: https://postgr.es/m/20240620012908.92.nmisch@google.com
Diffstat (limited to 'src/backend/access/heap/README.tuplock')
| -rw-r--r-- | src/backend/access/heap/README.tuplock | 4 |
1 files changed, 1 insertions, 3 deletions
diff --git a/src/backend/access/heap/README.tuplock b/src/backend/access/heap/README.tuplock index 818cd7f9806..31c52ad28f9 100644 --- a/src/backend/access/heap/README.tuplock +++ b/src/backend/access/heap/README.tuplock @@ -203,6 +203,4 @@ Inplace updates create an exception to the rule that tuple data won't change under a reader holding a pin. A reader of a heap_fetch() result tuple may witness a torn read. Current inplace-updated fields are aligned and are no wider than four bytes, and current readers don't need consistency across -fields. Hence, they get by with just fetching each field once. XXX such a -caller may also read a value that has not reached WAL; see -systable_inplace_update_finish(). +fields. Hence, they get by with just fetching each field once. |