On Wed, 17 Jul 2019 at 07:23, Andres Freund <and...@anarazel.de> wrote: > > Hi, > > On 2019-07-15 21:12:32 -0400, Tom Lane wrote: > > But I bet that these tables forming > > an inheritance hierarchy (with multiple inheritance even) does > > have something to do with it somehow, because if this were a > > generic VACUUM bug surely we'd be seeing it elsewhere. > > It's possible that it's hidden in other cases, because of > > void > table_block_relation_estimate_size(Relation rel, int32 *attr_widths, > > BlockNumber *pages, double *tuples, > double > *allvisfrac, > Size > overhead_bytes_per_tuple, > Size > usable_bytes_per_page) > ... > * If the table has inheritance children, we don't apply this > heuristic. > * Totally empty parent tables are quite common, so we should be > willing > * to believe that they are empty. > */ > if (curpages < 10 && > relpages == 0 && > !rel->rd_rel->relhassubclass) > curpages = 10; > > which'd not make us actually take a relpages=0 into account for tables > without inheritance. A lot of these tables never get 10+ pages long, so > the heuristic would always apply...
Surely it can't be that since that just sets what *pages gets set to. Tom mentioned that following was returning 0 pages and tuples: -- Temporary hack to investigate whether extra vacuum/analyze is happening select relname, relpages, reltuples from pg_class where relname like '__star' order by relname; relname | relpages | reltuples ---------+----------+----------- a_star | 1 | 3 -- David Rowley http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services
