Ron <ronljohnsonjr@xxxxxxxxx> writes: > On 6/29/21 10:41 AM, Michael Lewis wrote: >> What's an example query that uses indexes on test and does not on live? > SELECT COUNT(*) FROM sep_info_report_extract; > On prod, there's a list of "Parallel Seq Scan on xxxx_partname" records in > the EXPLAIN output, while the test system has a list of "Parallel Index Only > Scan using ..._idx" records. It'd be worth checking pg_class.relallvisible page counts for the partitions on both systems. If an IOS is possible, the main thing that might push the planner to do a seqscan instead is if it thinks that too little of the table is all-visible, which would tend to inflate the index-only scan towards the same cost as a regular index scan (which'll almost always be considered slower than seqscan). If there's a significant difference in relallvisible fractions, that would point to something different in your VACUUM housekeeping on the two systems. regards, tom lane
