On Fri, Oct 19, 2018 at 07:19:12AM +0000, Yavuz Selim Sertoglu wrote: > I have a problem with my query. Query always using parallel bitmap heap scan. > I've created an index with all where conditions and id but query does not > this index and continue to use bitmapscan. So I decided disable bitmap scan > for testing. And after that, things became strange. Cost is higher, execution > time is lower. > But I want to use index_only_scan because index have all column that query > need. No need to access table. > It is doing index_only_scan when disabling bitmap scan but I cannot disable > bitmap scan for cluster wide. There are other queries...
My first comment is that bitmap IOS is supported on PG11, which was released..yesterday: https://www.postgresql.org/docs/11/static/release-11.html |Allow bitmap scans to perform index-only scans when possible (Alexander Kuzmenkov) Also, I wonder whether parallel query is helping here or hurting (SET max_parallel_workers_per_gather=0)? If it's hurting, should you adjust cost parameters or perhaps disable it globally ? Justin
