Re: Adding an index caused problems!
From: Axel Schwenke <axel.schwenke_at_gmx.de>
Date: Thu, 23 May 2019 10:23:31 +0200
Message-ID: <qc5la3$7nm$1_at_dont-email.me>
Date: Thu, 23 May 2019 10:23:31 +0200
Message-ID: <qc5la3$7nm$1_at_dont-email.me>
[Quoted] On 22.05.2019 22:38, Richard Ryan wrote:
> Found it interesting that adding something as seemingly innocuous as an index can cripple a query that ran previously in a reasonable amount of time.
[Quoted] On the contrary. The database chooses an execution plan for a query based on the available indexes. Different indexes will (quite likely) give different plans. You might want to learn about EXPLAIN.
There is however something broken here. Since your query has to read *all* rows in the table, no index should ever be used. Either you have enabled some strange optimizer switch or you discovered a bug.
[Quoted] This is impossible. No such version ever existed. Received on Thu May 23 2019 - 10:23:31 CEST