Re: Planner not choosing GIN index

[Corey Huinker <corey.huinker@xxxxxxxxx>]

On Wed, Mar 13, 2019 at 5:11 AM Flo Rance <trourance@xxxxxxxxx> wrote:

It is an expected behavior. You can see the list of array operators with which a GIN index can be used in the doc:

https://www.postgresql.org/docs/current/indexes-types.html

And a very good and detailed explanation about any operator here:

https://stackoverflow.com/questions/4058731/can-postgresql-index-array-columns/29245753#29245753

Regards,

Flo

On Wed, Mar 13, 2019 at 2:44 AM Corey Huinker <corey.huinker@xxxxxxxxx> wrote:

A client had an issue with a where that had a where clause something like this:

WHERE 123456 = ANY(integer_array_column)

I was surprised that this didn't use the pre-existing GIN index on integer_array_column, whereas recoding as

WHERE ARRAY[123456] <@ integer_array_column

did cause the GIN index to be used. Is this a known/expected behavior? If so, is there any logical reason why we couldn't have the planner pick up on that?

Thanks. I'll bring the question of why-cant-we over to the hackers list.