On 2/19/20, Olivier Mascia <o...@integral.be> wrote: > Hello, > > As part of a rare database "maintenance"... > Does VACUUM, in essence, implies whatever actions REINDEX would do? > Would REINDEX before VACUUM make any more sense? > > And what about ANALYZE? Would it be wise or useless, to run it after VACUUM?
VACUUM does not imply REINDEX. Those are separate actions. VACUUM repacks all the content in to minimal space, and thus (probably) makes the database file a little smaller. It also reorganizes the pages so that tables are grouped together and are in search order, which might make table scans faster, depending on the underlying filesystem. REINDEX rebuilds an index from scratch based on the original table data. This amounts to a big sort. REINDEX was invented so that if you change the definition of a collating function, you can run REINDEX on all indexes that use that collating function and it will reorder the indexes into the new correct order. REINDEX will also fix any index corruption. But if you have index corruption, that is a symptom of deeper problems which should be addressed. You should not paper-over such problems by running REINDEX. VACUUM is independent of ANALYZE. The information computed by ANALYZE is the same before and after VACUUM. There is no benefit to running ANALYZE after running VACUUM if the ANALYZE data (the content of the sqlite_stat1 table) is still up-to-date. -- D. Richard Hipp d...@sqlite.org _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
