Yes and no. The process of finding the dups will extremely slow without the index.
You can drop the indexes on the columns not in the using clause. You can also drop the indexes on the least unique columns in the using clause That will speed things up. To put it another way, one of your columns in the using clause should be indexed, preferably the most unique column. Dennis McGrath ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Thursday, August 06, 2009 3:54 PM To: RBASE-L Mailing List Subject: [RBASE-L] - Re: Deleting dups Interesting ... You would think there would be tons of overhead to update the index file everytime one row is deleted ... I'll leave the indexes in there and maybe do a time comparison to see if there's any difference (although this is a 6.5 database so wouldn't be currently relevant). Karen About the DELETE DUPLICATES Command Use DELETE DUPLICATES to delete duplicate rows from a table. A duplicate row is a row where the values for each column are exactly the same as those in another row in the table. This command deletes all but the first row for each set of duplicate rows. DELETEDUPLICATES processes faster when the table contains an indexed column and the USING collist option is used. Rules for Column Deletion And I thought line "DELETE DUPLICATES processes faster when the table contains an indexed column and the USING collist option is used." Was right. Sincerely, Paul D.
