Re: index-only scans

Jeff Janes <jeff.janes@gmail.com>

From: Jeff Janes <jeff.janes@gmail.com>

To: Tom Lane <tgl@sss.pgh.pa.us>

Cc: Robert Haas <robertmhaas@gmail.com>, pgsql-hackers@postgresql.org

Date: 2011-10-15T21:16:05Z

Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Reduce the alignment requirement of type "name" from int to char, and arrange
- 5f6f840e93a3 8.4.0 cited

On Fri, Oct 7, 2011 at 11:40 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> Please find attached a patch implementing a basic version of
>> index-only scans.
>
> I'm making some progress with this, but I notice what seems like a
> missing feature: there needs to be a way to turn it off.  Otherwise
> performance comparisons will be difficult to impossible.
>
> The most obvious solution is a planner control GUC, perhaps
> "enable_indexonlyscan".  Anyone object, or want to bikeshed the name?
>

Currently I can't force an indexonlyscan over an indexscan, because of
the way the enable_* variables work.

Should setting enable_indexscan=off also disable index-only scans (the
current behavior) in addition to plain index scans?

By way of precedent, enable_indexscan=off does not disable Bitmap Index Scan.

Cheers,

Jeff