On Sat, 2020-02-15 at 19:04 +0800, MingJu Wu wrote: > When creating partial indexes, can postgres utilize another index for figuring which rows > should be included in the partial index, without performing a full table scan? No; it has to be a full sequential scan. > My scenario is that I have a table with 50M rows that are categorized into 10K categories. > I need to create a partial index for each category. I have created a index on the category > column, hoping that postgres can use this information when creating the partial indexes. > However, postgres always performs full table scan. There is your problem. You don't need a partial index per category, you need a single index that *contains* the category. Yours, Laurenz Albe -- Cybertec | https://www.cybertec-postgresql.com
