On Tue, Mar 22, 2016 at 2:27 PM, Tomas Vondra
<tomas.vondra@2ndquadrant.com> wrote:
> For example these two queries got almost 2x as slow for some data sets:
>
> SELECT a FROM numeric_test UNION SELECT a FROM numeric_test_padding
> SELECT a FROM text_test UNION SELECT a FROM text_test_padding
>
> I assume the slowdown is related to the batching (as it's only happening for
> low work_mem values), so perhaps there's an internal heuristics that we
> could tune?
Can you show trace_sort output for these cases? Both master, and patched?
Thanks
--
Peter Geoghegan