Re: Enabling Checksums - Mailing list pgsql-hackers

From Josh Berkus
Subject Re: Enabling Checksums
Date
Msg-id 5137958B.3080404@agliodbs.com
Whole thread Raw
In response to Re: Enabling Checksums  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: Enabling Checksums  (Robert Haas <robertmhaas@gmail.com>)
Re: Enabling Checksums  (Jim Nasby <jim@nasby.net>)
List pgsql-hackers
> There may be good reasons to reject this patch.  Or there may not.
> But I completely disagree with the idea that asking them to solve the
> problem at the filesystem level is sensible.

Yes, can we get back to the main issues with the patch?

1) argument over whether the checksum is sufficient to detect most
errors, or if it will give users false confidence.

2) performance overhead.

Based on Smith's report, I consider (2) to be a deal-killer right now.
The level of overhead reported by him would prevent the users I work
with from ever employing checksums on production systems.

Specifically, the writing checksums for a read-only query is a defect I
think is prohibitively bad.  When we first talked about this feature for
9.2, we were going to exclude hint bits from checksums, in order to
avoid this issue; what happened to that?

(FWIW, I still support the idea of moving hint bits to a separate
filehandle, as we do with the FSM, but clearly that's not happening for
9.3 ...)

-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com



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