[GENERAL] does vacuum rebuild index?
hi, we have a 34 million row table. after many inserts, updates, deletes the performance degraded so we vacuumed the table. the output indicated that the index was also vacuumed but the size didn't change. it was still 80m so we dropped and recreated it reducing it to 20m. no big deal but is it common for a vacuum to "miss" the index, so to speak? i saw that someone else asked a similar question on 6/4 in the general archives but i found no reply to it. is this a common occurrence or am i doing something wrong or maybe should be doing something different? this is a 7 column index on an 11 column table. xxx1 | varchar(15) | xxx2 | bigint | xxx3 | varchar(15) | xxx4 | varchar(15) | xxx5 | bigint | xxx6 | float8 | xxx7 | float8 | xxx8 | float8 | xxx9 | date| xxx10| integer | xxx11| bigint | the index is on columns 1-5,10,11 thanks, mikeo
Re: [GENERAL] does vacuum rebuild index?
mikeo [EMAIL PROTECTED] writes: we have a 34 million row table. after many inserts, updates, deletes the performance degraded so we vacuumed the table. the output indicated that the index was also vacuumed but the size didn't change. it was still 80m so we dropped and recreated it reducing it to 20m. This is in the FAQ isn't it? VACUUM removes unused index entries but it doesn't reduce the physical size of the index file. There's an item on the TODO list to fix that, but for now a lot of people are in the habit of doing drop indexes; vacuum; recreate indexes; This is often faster than what vacuum does, so there's been talk of changing vacuum to work that way, but there's concern about what happens if vacuum crashes before it's rebuilt the indexes... at least with the delete-unused-entries approach you aren't left with an incomplete index. regards, tom lane
