Timeline for Can I rely on the order of columns on an index generated by database tuning advisor
Current License: CC BY-SA 3.0
7 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Apr 18, 2013 at 14:18 | vote | accept | MrMox | ||
| Apr 17, 2013 at 13:42 | comment | added | Aaron Bertrand | I've seen it do the things I've mentioned plenty of times, and not just in cases where I'm called to help when things fail. My point was simply this: use DTA with caution. | |
| Apr 17, 2013 at 13:26 | comment | added | Remus Rusanu | @AaronBertrand: I'm talking about DTA in general. Remember that you are in a position where you're called to help when things fail so you will always see a worse picture than average user sees. The countless times DTA works and gives good advice will tend to go unnoticed... | |
| Apr 17, 2013 at 13:18 | comment | added | Aaron Bertrand | Well, I don't know if I'd go so far as to say the DTA is right more often than wrong, unless you're talking specifically about the order of the key columns. It can be overly aggressive about INCLUDE columns, will often suggest redundant almost-duplicate indexes, and can be totally wrong if your input is wrong (e.g. small portion of workload). | |
| Apr 17, 2013 at 9:25 | comment | added | Remus Rusanu | You still don't explain why do you expect that. From the little info you provide, I woudl expect the order to be the one given by DTA, as low selectivity keys have little value after high selectivity keys. | |
| Apr 17, 2013 at 9:17 | comment | added | MrMox | The table is a transaction table and the recommendation is something like (TransactionStatus, Company, ReferenceId) The Company column holds only to different values (Company1 and Company2), the TransactionStatus has 5 different values, and the ReferenceId points to another table. I would expect the order to be TransactionStatus, ReferenceId, Company | |
| Apr 17, 2013 at 9:13 | history | answered | Remus Rusanu | CC BY-SA 3.0 |