I have this table and index: create table t(id int, hash int); create index idx_t on t(hash); The value of the hash column, which is indexed, is a pseudo-random number. I load the table and measure the time per insert. What I've observed is that inserts slow down as the table grows to 1,000,000 records. Observing the pg_stat* tables, I see that the data page reads per unit time stay steady, but that index page reads grow quickly, (shared_buffers was set to 2000). I'm guessing that this is because inserts will append to data pages, but there is a random probe to the btree to maintain the index. This is a test program, but I'm wondering about my application that will need row counts much beyond 1,000,000. Questions: - Am I reasoning about the data and index costs correctly? - In order to keep insert times from dropping too much, do I simply need to increase shared_buffers in order to accomodate more of the index? - Assuming I'm willing to buy enough RAM and set shmmax high enough, are there practical limits on how big shared_buffers can be that will limit how far I can pursue such a strategy? Jack Orenstein
