Re: hot updates and fillfactor
Thanks for your explanation and for the links On Tue, Mar 19, 2024 at 11:17 AM Aleksander Alekseev < aleksan...@timescale.com> wrote: > Hi Fabrice, > > > I do not understand why hot_updates value is not 0 for pg_database? > Given that reloptions is empty for this table that means it has a default > value of 100% > > Maybe I didn't entirely understand your question, but why would you > assume they are somehow related? > > According to the documentation [1][2]: > > pg_class.reloptions: > Access-method-specific options, as “keyword=value” strings > > pg_stat_all_tables.n_tup_hot_upd: > Number of rows HOT updated. These are updates where no successor > versions are required in indexes. > > The value of n_tup_hot_upd is not zero because there are tuples that > were HOT-updated. That's it. You can read more about HOT here [3]. > > [1]: https://www.postgresql.org/docs/current/catalog-pg-class.html > [2]: https://www.postgresql.org/docs/current/monitoring-stats.html > [3]: https://www.postgresql.org/docs/current/storage-hot.html > > -- > Best regards, > Aleksander Alekseev >
Re: hot updates and fillfactor
Hi Fabrice, > I do not understand why hot_updates value is not 0 for pg_database? Given > that reloptions is empty for this table that means it has a default value of > 100% Maybe I didn't entirely understand your question, but why would you assume they are somehow related? According to the documentation [1][2]: pg_class.reloptions: Access-method-specific options, as “keyword=value” strings pg_stat_all_tables.n_tup_hot_upd: Number of rows HOT updated. These are updates where no successor versions are required in indexes. The value of n_tup_hot_upd is not zero because there are tuples that were HOT-updated. That's it. You can read more about HOT here [3]. [1]: https://www.postgresql.org/docs/current/catalog-pg-class.html [2]: https://www.postgresql.org/docs/current/monitoring-stats.html [3]: https://www.postgresql.org/docs/current/storage-hot.html -- Best regards, Aleksander Alekseev
hot updates and fillfactor
Hi, I do not understand why hot_updates value is not 0 for pg_database? Given that reloptions is empty for this table that means it has a default value of 100% Regards, Fabrice SELECT relname AS table_name, seq_scan AS sequential_scans, idx_scan AS index_scans, n_tup_ins AS inserts, n_tup_upd AS updates, n_tup_hot_upd AS hot_updates FROM pg_stat_all_tables ORDER BY hot_updates DESC; table_name| sequential_scans | index_scans | inserts | updates | hot_updates -+--+-+-+-+- pg_database | 5038104 | 187427486 | 3 | 16 |* 16* postgres [1728332]=# select t.relname as table_name, t.reloptions from pg_class t join pg_namespace n on n.oid = t.relnamespace where t.relname in ('pg_database') and n.nspname = 'pg_catalog'; table_name | reloptions -+ pg_database | (1 row)