Re: when do I analyze after concurrent index creation?

Would a simple multi-column index be considered an 'expression' in this context, meaning that an ANALYZE should be issued after the creation of such an index?

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Pete Yunker
Vice President of Data Products
Home Junction, Inc.

On Oct 18, 2013, at 11:42 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> dinesh kumar <dineshkumar02(at)gmail(dot)com> writes:
>> When we create an index, i believe the postgres engine it self update it's
>> catalog about the index availability.
>
> ANALYZE normally collects statistics about the contents of table columns.
> Thus, adding (or removing) an index does not create any reason to
> re-ANALYZE.
>
> However ... if you have an index on an expression (not just a simple
> column value), that cues ANALYZE to collect statistics about the values of
> that expression. So re-analyzing is useful after creating such an index,
> to give the planner a better idea of when to use that index.
>
> Whether you used CREATE INDEX CONCURRENTLY or some other way of creating
> the index doesn't matter at all.
>
> regards, tom lane
>
>
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