Re: Ignore hash indices on replicas

On Mon, Aug 20, 2012 at 10:29 AM, Steven Schlansker <steven(at)likeness(dot)com> wrote:
>
> On Aug 19, 2012, at 2:37 PM, Jeff Davis <pgsql(at)j-davis(dot)com> wrote:
>
>> On Tue, 2012-07-10 at 00:09 -0700, Steven Schlansker wrote:
>>> show that our particular application is faster by quite a bit when a
>>> hash index is available.
>>
>> Can you publish the results somewhere? It might provoke some interest.
>
> I might be able to spend some time looking at making this public, but the general parameters are:
>
> 122M rows, lookup key is a UUID type. Lookups are ~1000 random keys at a time (as in, a giant SELECT * FROM table WHERE key IN (?,?,?,?,…)

How well cached is the data?

If it has to be read from disk, then a bitmap index scan on a btree
index with effective_io_concurrency set high might do quite well,
assuming you can convince the planner to use one.

Cheers,

Jeff