"Tom Lane" <tgl@xxxxxxxxxxxxx> writes: > This rule works for all the locales I have installed ... but I don't > have any Far Eastern locales installed. Also, my test cases are only > covering ASCII characters, and I believe many locales have some non-ASCII > letters that sort after 'Z'. I'm not sure how hard we need to try to > cover those corner cases, though. It is ultimately only an estimate... If I understand correctly what we're talking about it's generating estimates for LIKE 'foo%' using the algorithm which makes sense for C locale which means generating the next range of values which start with 'foo%'. It seems to me the problematic situations is when the most-frequent-values come into play. Being off slightly in the histogram isn't going to generate very inaccurate estimates but including or not a most-frequent-value could throw off the estimate severely. Could we not use the bogus range to calculate the histogram estimate but apply the LIKE pattern directly to the most-frequent-values instead of applying the bogus range? Or would that be too much code re-organization for now? -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Get trained by Bruce Momjian - ask me about EnterpriseDB's PostgreSQL training! ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
