Hi.
I'm routinely bulk inserting data to a PostgreSQL table and then
analyzing a single column of the table, because it contains data which
significantly changes histogram of this column values - for example
something like adding rows with "todo=true" column, when all rows before
bulk insert have "todo=false".
This column has rather small "statistics" value, so analyze of it is
fairly fast, which is important as I'm doing it often and also in
parallel (and analyze blocks - only one can run at the time). The full
analyze of this large table would take a lot of time (20 times more
actually), and I can't perform it after each bulk insert.
But I've noticed that a standard automatic analyze, which should work in
background, never runs. I've noticed that this fast analyze of one
column resets pg_stat_user_tables(n_mod_since_analyze) counter.
I suppose that the decision to analyze the whole table is based on these
values from pg_stat_user_tables and autovacuum_analyze_threshold and
autovacuum_analyze_scale_factor settings. And in this case this highly
updated table never reaches these values.
I suppose this is a bug - an analyze, which does not analyze all
columns, should not reset pg_stat_user_tables(n_mod_since_analyze). What
do you think?
--
Tomasz "Tometzky" Ostrowski