"Henry" <henry at zen.co.za> writes:
> Hello all,
>
> During an initial replication from a master to many slaves, why does slony
> perform an ANALYZE after the COPY?  For paltry tables this is OK, but for
> massive (multiple GB) tables, this is something which takes frigging
> *days* per table.
>
> Besides, what's the point of analyzing after a fresh COPY?
>
> Even if there is a valid reason to analyze after a copy, is there a way to
> disable this behavior (short of hacking the src)?  The docs don't tell me
> much.

COPY does not populate statistics in pg_statistic, so it is
*necessary* to ANALYZE the table so that you don't get pathological
awful behaviour like a default of assuming the table contains 1000
tuples so that updates may be reasonably performed via Seq Scan.

The ANALYZE is there because it is necessary.  And unless you have
been heavily hacking with "SET STATISTICS," an analyze on even a large
table shouldn't be taking painfully long - it normally scans 3000
pages, many of which ought to be _in memory_, and even if they're not,
that's still merely 24MB worth of reads.
-- 
(format nil "~S@~S" "cbbrowne" "ca.afilias.info")
<http://dba2.int.libertyrms.com/>
Christopher Browne
(416) 673-4124 (land)