> Running SET STATISTICS on this particular index > Query RDB$INDICES.RDB$STATISTICS for this index
No Change: 0.0000049277592 >Also you can generate a histogram of the used values/permutation with: >select > sourcetype > , transactiontype > , refno > , count(*) >from > stk_stocktransaction >group by > sourcetype > , transactiontype > , refno >This gives you the value distribution across the entire index. Neat trick, but not sure what I should be looking at exactly. Returns about 200 000 records. The SQL I am testing with, returns no records. Interestingly though, this histogram query DOES use my index ;-) Which gave me an idea: I changed my original query to: select t.SalesOrderNo from stk_stocktransaction t where (t.SourceType = 34) and (t.TransactionType = 'EXTCST') and (t.RefNo = 'I00001') order by t.SourceType, t.TransactionType, t.RefNo This DOES use the index. BUT, it's on average 50% SLOWER than the NATURAL plan the Firebird chose to use. <scratching head>
