From 00a354a13560dc529ac34a303c85c265aaf033b7 Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Fri, 5 Nov 2021 11:22:30 -0300 Subject: [PATCH] Reword doc blurb for vacuumdb --analyze-in-stages Make users aware that using it in a database with existing stats might cause transient problems. Author: Nikolai Berkoff Discussion: https://postgr.es/m/s-kSljtWXMWgMfGTztPTPcS80R8FHdOrBxDTnrQI6GMZbT7au1A4b0fzaSFtKwCI8nwN0MhgPLfVOTvJ7DwTjkip4P3d0o4VgrMJs4OLN-o=@pm.me --- doc/src/sgml/ref/vacuumdb.sgml | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/doc/src/sgml/ref/vacuumdb.sgml b/doc/src/sgml/ref/vacuumdb.sgml index 223b986b92..d8cbf0e189 100644 --- a/doc/src/sgml/ref/vacuumdb.sgml +++ b/doc/src/sgml/ref/vacuumdb.sgml @@ -398,15 +398,19 @@ PostgreSQL documentation Only calculate statistics for use by the optimizer (no vacuum), like . Run several (currently three) - stages of analyze with different configuration settings, to produce - usable statistics faster. + stages of analyze; the first stage uses the lowest possible statistics + target (see ) + to produce usable statistics faster, and subsequent stages build the + full statistics. - This option is useful to analyze a database that was newly populated - from a restored dump or by pg_upgrade. This option - will try to create some statistics as fast as possible, to make the - database usable, and then produce full statistics in the subsequent + This option is only useful to analyze a database that current has + no statistics or wholly incorrect ones, such as if it is newly + populated from a restored dump or by pg_upgrade. + Be aware that running this option in a database with existing + statistics may cause the query optimizer choices to become + transiently worse due to the low statistics targets of the early stages.