Re: Raising stop and warn limits

From: Noah Misch <noah(at)leadboat(dot)com>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Raising stop and warn limits
Date: 2020-06-28 06:20:04
Message-ID: 20200628062004.GA3366199@rfd.leadboat.com
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On Sun, Jun 21, 2020 at 01:35:13AM -0700, Noah Misch wrote:
> In brief, I'm proposing to raise xidWrapLimit-xidStopLimit to 3M and
> xidWrapLimit-xidWarnLimit to 40M. Likewise for mxact counterparts.

Here's the patch for it.

> 1. VACUUM, to advance a limit, may assign IDs subject to one of the limits.
> VACUUM formerly consumed XIDs, not mxacts. It now consumes mxacts, not
> XIDs.

Correction: a lazy_truncate_heap() at wal_level!=minimal does assign an XID,
so XID consumption is impossible with "VACUUM (TRUNCATE false)" but possible
otherwise. "VACUUM (ANALYZE)", which a DBA might do by reflex, also assigns
XIDs. (These corrections do not affect $SUBJECT.)

Attachment Content-Type Size
stop-limits-v1.patch text/plain 7.3 KB

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