Simple... that did it... thanks!
dev=> create index on table(code,row_id);
CREATE INDEX
Time: 38088.482 ms
dev=> explain (analyse,buffers) select row_id as last_row_id from table
where code='XX' order by row_id desc limit 1;
QUERY PLAN
> On 01 May 2015, at 13:54, David Osborne wrote:
>
> Hi,
>
> We have a query which finds the latest row_id for a particular code.
>
> We've found a backwards index scan is much slower than a forward one, to the
> extent that disabling indexscan altogether actually improves the query time.
>
Hi,
We have a query which finds the latest row_id for a particular code.
We've found a backwards index scan is much slower than a forward one, to
the extent that disabling indexscan altogether actually improves the query
time.
Can anyone suggest why this might be, and what's best to do to improv
