On 1/30/16 5:05 PM, Peter Eisentraut wrote:
When autovacuum is off, the statistics in pg_stat_sys_tables for shared
catalogs (e.g., pg_authid, pg_database) never update.  So seq_scan
doesn't update when you read the table, last_analyze doesn't update when
you run analyze, etc.

But when you shut down the server and restart it with autovacuum on, the

What about with autovacuum still off?

updated statistics magically appear right away.  So seq_scan is updated
with the number of reads you did before the shutdown, last_analyze
updates with the time of the analyze you did before the shutdown, etc.
So the data is saved, just not propagated to the view properly.

I can reproduce this back to 9.3, but not 9.2.  Any ideas?

ISTR that there's some code in the autovac launcher that ensures certain stats have been loaded from the file into memory; I'm guessing that the functions implementing the shared catalog views need something similar.
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com

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