sql - Why does autovacuum: VACUUM ANALYZE (to prevent wraparound) run? -
i have autovacuum vacuum analyze query running on table, , takes many hours, couple of days finish. know postgres runs autovacuum jobs perform cleanup , maintenance tasks, , it's necessary. however, tables have vacuum, not vacuum analyze.
why specific table require vacuum analyze, , how can resolve issue of taking long?
on separate note, did not notice vacuum analyze query running before few days ago. when attempting create index, , failed prematurely saying ran out of open files (or that). contribute vacuum analyze running long?
i think vacuum analyze red herring. table came due both vacuum , analyze @ same time, doing vacuum analyze, doubt analyze contributing problem @ all.
i wonder if "vacuum (to prevent wrap around)" ever finishing, or if getting interrupted part way through , therefore restarting without ever making real progress. inspection of log files should clarify (as clarify thing running out of open files about).
also, based on size of table , settings cost-based vacuuming, should able estimate how long vacuum should take , compare how long taking.
also, transaction throughput on system relevant wrap-around issues. wraparound vacuums should rare, unless database extraordinarily active.
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