| From: | Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com> |
|---|---|
| To: | Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | pg_serial early wraparound |
| Date: | 2016-11-08 22:07:42 |
| Message-ID: | CAEepm=3XfsTSxgEbEOmxu0QDiXy0o18NUg2nC89JZcCGE+XFPA@mail.gmail.com |
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| Lists: | pgsql-hackers |
Hi hackers,
The SLRU managed by predicate.c can wrap around and overwrite data if
you have more than 1 billion active XIDs. That's because when SSI was
implemented, slru.c was limited to four digit segment names, which
implied a page limit that wasn't enough for pg_serial to have space
for every possible XID. We should probably rip that code out, because
SLRUs now support five digit segment names. Something like the
attached. I'll post a test script to demonstrate correct wraparound
behaviour around in time for one of the later CFs.
--
Thomas Munro
http://www.enterprisedb.com
| Attachment | Content-Type | Size |
|---|---|---|
| ssi-slru-wraparound-v1.patch | application/octet-stream | 3.6 KB |
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