3 ms·
Yes but the fact that they are an optimization fence is a major drawback.
by jboggan 8y ago
Yes but the fact that they are an optimization fence is a major drawback.
- paddy_m 8y agoNot always. I use them to force hash joins. This way you can filter table A on an index, and filter table B on an index, then join them with a hash join. In a straight join postgres would try to use the same index for all of the joins. At least that was my experience. Maybe I'm not understanding the docs properly or using the correct terminology. I know that the end result was 10x faster than any index I could come up with.