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From: pgsql-general-owner@xxxxxxxxxxxxxx [mailto:pgsql-general-owner@xxxxxxxxxxxxxx]
On Behalf Of Felipe Santos "Further to the point, it is self defeating to have more than one BRIN index on the table if the columns involved would have mutually non-adjacent pages." Not really, if both columns are ordered, BRIN will work "Therefore, it actually would be good to state that in the documentation, even it were just a comment." It is = "BRIN is designed
for handling very large tables in which certain columns have some natural correlation with their physical location within the table" Also, I did some tests and here are the results I got: Query with no index = completion time 43s Same Query with BRIN = completion time 14s / index size 0,5 MB Same Query without BRIN and with BTREE = completion time 10s / index size 5.000,00 MB As you can see, BRIN can save 99% of disk space for just a slightly worse performance. It seems like a huge improvement, given that your data fits BRIN's use case. Felipe, What kind of queries you used in your test? Where they based on clustering columns? Regards Igor Neyman |
