> On Jun 3, 2025, at 6:23 PM, David Rowley <dgrowle...@gmail.com> wrote: > > On Wed, 4 Jun 2025 at 07:22, Matthew Tice <mjt...@gmail.com> wrote: >> Tue 03 Jun 2025 07:13:11 PM UTC (every 1s) >> n_dead_tup | 5038 >> autoanalyze_count | 3078 > >> Tue 03 Jun 2025 07:13:12 PM UTC (every 1s) >> n_dead_tup | 1290579 >> autoanalyze_count | 3079 > >> I don't understand where this large increase is coming from when there are >> no corresponding inserts, updates, or deletes (at the magnitude). This >> entire process repeats itself and, as mentioned, the same thing is happening >> on other observed tables. > > I imagine it's from the auto-analyze that ran. Analyze will try to > estimate the live and dead rows, but since analyze only samples some > blocks, it may come up with something that's not too accurate if the > blocks it happened to sample don't contain similar percentages of dead > rows than the entire table. > > See [1]. > > David > > [1] > https://github.com/postgres/postgres/blob/REL_15_STABLE/src/backend/commands/analyze.c#L1318
Thanks, David. This table is relatively large (1.6B records, 1.5TB, 38 columns). The `default_statistics_target` is set to 300 - so I think that 90000 may not be enough to gather accurate statistics.
