David Brown <[EMAIL PROTECTED]> writes: > Actually, I'm surprised the planner came up with such a low cost for the > single column index, unless ... perhaps correlation statistics aren't > used when determining costs for multi-column indexes?
The correlation calculation for multi-column indexes is pretty whacked out pre-8.0. I don't think it's that great in 8.0 either --- we really need to make ANALYZE calculate the correlation explicitly for each index, probably, rather than trying to use per-column correlations. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match