On Mon, Jul 15, 2019 at 7:21 PM Peter Geoghegan <pg@xxxxxxx> wrote: > Sometimes B-Tree indexes can be *larger* after a REINDEX (or after > they're recreated with a CREATE INDEX). It's not that common, but it > does happen. There isn't actually a very large size difference here, > so it seems worth comparing index size in detail. A very good guess, and effectively reindexing the databases the size of the _restored_ one has shrinked being less than the original one (as I would expect in first place): % psql -U postgres -c '\x' -c "SELECT pg_database_size( 'foo' ), pg_database_size( 'bar' );" template1 Expanded display is on. -[ RECORD 1 ]----+----------- pg_database_size | 2685776543 pg_database_size | 2690269699 % vacuumdb --full foo vacuumdb: vacuuming database "foo" % psql -U postgres -c "REINDEX DATABASE foo;" foo REINDEX % vacuumdb --full bar vacuumdb: vacuuming database "bar" % psql -U postgres -c "REINDEX DATABASE bar;" bar REINDEX % psql -U postgres -c '\x' -c "SELECT pg_database_size( 'foo' ), pg_database_size( 'bar' );" template1 Expanded display is on. -[ RECORD 1 ]----+----------- pg_database_size | 2685817503 pg_database_size | 2685624835 However I still don't get why the size should not be the same after such vacuum+reindex. If my brain serves me well, in this case we have less than 0.2MB of difference, that compared to the database size (~2.5GB) is more than acceptable. Nevertheless, I would have thought that a restored database has been always smaller than the original one. Luca
