| From: | Peter Geoghegan <peter(dot)geoghegan86(at)gmail(dot)com> |
|---|---|
| To: | Josh Berkus <josh(at)agliodbs(dot)com> |
| Cc: | "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: working around JSONB's lack of stats? |
| Date: | 2015-01-28 23:34:41 |
| Message-ID: | CAEYLb_VvYFj4WO4nmHHiz_JP_0qoaJ0mCejLews3oNajDr6vkg@mail.gmail.com |
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| Lists: | pgsql-performance |
On Wed, Jan 28, 2015 at 3:03 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
> We already have most_common_elem (MCE) for arrays and tsearch. What if
> we put JSONB's most common top-level keys (or array elements, depending)
> in the MCE array? Then we could still apply a simple rule for any path
> criteria below the top-level keys, say assuming that any sub-key
> criteria would match 10% of the time. While it wouldn't be perfect, it
> would be better than what we have now.
Well, the "top-level keys" would still be gathered for expression
indexes. So yeah, maybe it would work alright for arrays of "tags",
and things like that. I tend to think that that's a common enough
use-case.
--
Regards,
Peter Geoghegan
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