I have a colleague that is convinced that the website is faster if enable_seqscan is turned OFF. I'm convinced of the opposite (better to leave it ON), but i would like to show it, prove it to him. Now the first query we tried, would do a bitmap heap scan instead of a seqscan when the latter were disabled, to exclude about 50% of the records (18K of 37K records). The bitmap heap scan is 3% faster, so that didn't really plea my case. The thing is that by the time we tried it, the data had been cached, so there is no penalty for the use of the index (HDD retention on random access). So it's logical that the index lookup is faster, it looks up less records.
Now i'm looking for a way to turn off the caching, so that we'll have a fair test.
It makes no sense to me to set shared_buffers really low. Any tips?
Cheers,
WBL
-- "Patriotism is the conviction that your country is superior to all others because you were born in it." -- George Bernard Shaw