On 2016-07-29 11:41, Jean CAVALLO wrote: > They may be useful in some cases, I just wanted to point out that in the > particular case you gave they do not. > > See http://dba.stackexchange.com/questions/27481/is-a-composite-index-also-good-for-queries-on-the-first-field > and http://dba.stackexchange.com/questions/6115/working-of-indexes-in-postgresql > > The scheduler will use the composite index for the first column and it > will be as efficient as having an extra index only on this column. > This allows to create less indexes and save some space :) Not necessary, such composite index could be bigger and so more expensive to load. So as my previous link shows, there are legitimate use case to have "duplicate" indexes so a warning will be annoying. > Regarding the reverse, I agree it should not be a rule, but IMHO in > 90-95% of the case it should be set. Even on small tables, where the > cost of adding the index is minimal. No, index on small table is just a waste of resources.
|2016-07-29 12:35:07||ced||set||recipients: + albertca, pokoli, jcavallo|
|2016-07-29 12:35:06||ced||link||issue5757 messages|
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