Running --analyze-in-stages on a database with statistics causes the statistics to become significantly worse before they are improved. This could be made clearer in the documentation.
diff --git i/doc/src/sgml/ref/vacuumdb.sgml w/doc/src/sgml/ref/vacuumdb.sgml
index 223b986..d76c18e 100644
--- i/doc/src/sgml/ref/vacuumdb.sgml
+++ w/doc/src/sgml/ref/vacuumdb.sgml
@@ -403,9 +403,10 @@ PostgreSQL documentation
</para>
<para>
- This option is useful to analyze a database that was newly populated
+ This option is useful to analyze a database that current has no,
+ or bad, statistics e.g. it was newly populated
from a restored dump or by <command>pg_upgrade</command>. This option
- will try to create some statistics as fast as possible, to make the
+ will create coarse statistics as fast as possible, to make the
database usable, and then produce full statistics in the subsequent
stages.
</para>
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