Hi, On Thu, Nov 1, 2018 at 2:28 PM Yura Sokolov <funny.fal...@gmail.com> wrote: > > Excuse me for being noisy. > > Increasing vacuum's ring buffer improves vacuum upto 6 times. > https://www.postgresql.org/message-id/flat/20170720190405.GM1769%40tamriel.snowman.net > This is one-line change. > > How much improvement parallel vacuum gives?
It depends on hardware resources you can use. In current design the scanning heap and vacuuming heap are procesed with parallel workers at block level (using parallel sequential scan) and the vacuuming indexes are also processed with parallel worker at index-level. So even if a table is not large enough the more a table has indexes you can get better performance. The performance test result (I attached) I did before shows that parallel vacuum is up to almost 10 times faster than single-process vacuum in a case. The test used not-large table (4GB table) with many indexes but it would be insteresting to test with large table. Regards, -- Masahiko Sawada NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center
