On Thu, Feb 01, 2007 at 09:17:51PM -0500, Tom Lane wrote: > "michael" <[EMAIL PROTECTED]> writes: > > can these be executed with index seek like what MS SQL does? > > select * from account_category > > where account_category_full_description <> 'MICHAEL' > > What for? A query like that is generally going to fetch the majority of > the table, so an indexscan would be counterproductive. > > It could potentially be a win if a very large fraction of the rows had > the exact value MICHAEL ... but the recommended way to deal with that is > to create a partial index with "full_description <> 'MICHAEL'" as the > WHERE clause.
Just FYI, the reason that MSSQL does this is most likely that you have a covering, clustered index on that column. First of all, if you have a clustered index on that table, SQLServer wil always do an indexscan - because there is no way to heap-scan such a table. And second, since SQLServer has covering indexes, they can use indexes in cases where it returns even a significant portion of the table. //Magnus ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
