Michael Lewis <mlewis@xxxxxxxxxxx> writes: >My thinking is opposite from what you have. I consider it important to very aggressive on autovacuum because it only ever does the required amount of >work. If a tiny amount of work is needed, it does only that and is done. Assuming it doesn't cause I/O concerns, do it as often as possible to minimize the> growth of bloat and maximize the reuse of the space already allocated to that relation. Excellent, I am not seeing any I/O concerns, and it seems to be keeping up now, so I will keep this setting unless someone else points out another suggestion. >On the subject of analyze, the statistics are unlikely to be impacted significantly by inserting about 24k rows to a table with almost 20 million already. >With default_statistics_target at 100, what are the chances those new rows will even be included in the sample? I don't know the math, but given each >run of analyze does the same ALL the work each and every time it runs, it seems prudent to do them a little less often than autovacuum anyway. >Regardless though, autoanalyze is a small amount of work that it does each time. I agree, this is excellent advice, I overlooked the fact that this is a sample and the new rows may not even be included in this sample. I will adjust accordingly. -----Original Message----- From: Jason Ralph <jralph@xxxxxxxxxxxxxxxxxxxxx> Sent: Friday, November 1, 2019 2:59 PM To: pgsql-general@xxxxxxxxxxxxxxxxxxxx Cc: Jason Ralph <jralph@xxxxxxxxxxxxxxxxxxxxx> Subject: Are my autovacuum settings too aggressive for this table? Hello list, DB1=# select version(); -[ RECORD 1 ]---------------------------------------------------------------------------------------------------- version | PostgreSQL 11.5 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-23), 64-bit I am sure this question has come up before, I have scoured the documentation and I think I have a good grasp on the autovacuum. I wanted to ask the team if my settings for this particular table are too aggressive, I have the following set which is producing a vacuum analyze multiple times a day. I think the defaults out of the box were not aggressive enough, so I went with the following on the global level, I will possibly move to table level if needed. I tried to show the stats below of a 10 minute interval during peak time. Any push in the right direction is appreciated, I want my tables analyzed and vacuumed but do not want to over do it. The rest of the autovacuum settings are default. I know the stats are estimates so here is my calculations. Live tuples = 19,766,480 Analyze scale factor = 0.001 Analyze thresh = 5000 Thresh + live_tuples * factor = 24,766 So an autovacuum analyze should trigger around 24K tuples modified, is this to little or too much? Same goes for autvacuum vacuum, is it too aggressive? #------------------------------------------------------------------------------ # AUTOVACUUM #------------------------------------------------------------------------------ autovacuum_naptime = 1h autovacuum_vacuum_threshold = 10000 autovacuum_analyze_threshold = 5000 autovacuum_vacuum_scale_factor = 0.002 autovacuum_analyze_scale_factor = 0.001 DB1=# \x Expanded display is on. DB1=# select now(); -[ RECORD 1 ]---------------------- now | 2019-11-01 14:35:51.893328-04 DB1=# select * from pg_stat_user_tables where relname = 'members'; -[ RECORD 1 ]-------+------------------------------ relid | 18583 schemaname | public relname | members seq_scan | 129 seq_tup_read | 2036932707 idx_scan | 546161742 idx_tup_fetch | 1670607103 n_tup_ins | 46742 n_tup_upd | 35704112 n_tup_del | 0 n_tup_hot_upd | 31106485 n_live_tup | 19766480 n_dead_tup | 1844251 n_mod_since_analyze | 15191 last_vacuum | 2019-10-13 15:42:06.043385-04 last_autovacuum | 2019-11-01 12:24:45.575283-04 last_analyze | 2019-10-13 15:42:17.370086-04 last_autoanalyze | 2019-11-01 12:25:17.181133-04 vacuum_count | 2 autovacuum_count | 15 analyze_count | 2 autoanalyze_count | 17 DB1=# select now(); -[ RECORD 1 ]---------------------- now | 2019-11-01 14:45:10.845269-04 DB1=# select * from pg_stat_user_tables where relname = 'members'; -[ RECORD 1 ]-------+------------------------------ relid | 18583 schemaname | public relname | members seq_scan | 129 seq_tup_read | 2036932707 idx_scan | 546171120 idx_tup_fetch | 1670615505 n_tup_ins | 46742 n_tup_upd | 35705068 n_tup_del | 0 n_tup_hot_upd | 31107303 n_live_tup | 19766480 n_dead_tup | 1844881 n_mod_since_analyze | 16147 last_vacuum | 2019-10-13 15:42:06.043385-04 last_autovacuum | 2019-11-01 12:24:45.575283-04 last_analyze | 2019-10-13 15:42:17.370086-04 last_autoanalyze | 2019-11-01 12:25:17.181133-04 vacuum_count | 2 autovacuum_count | 15 analyze_count | 2 autoanalyze_count | 17 Thanks for your time, Jason Ralph This message contains confidential information and is intended only for the individual named. 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