On Tue, Jan 17, 2017 at 11:49 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Mon, Jan 16, 2017 at 7:23 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> On Sat, Jan 14, 2017 at 12:07 AM, Robert Haas <rhaas(at)postgresql(dot)org> wrote:
>>> Fix cardinality estimates for parallel joins.
>>>
>>
>> + /*
>> + * In the case of a parallel plan, the row count needs to represent
>> + * the number of tuples processed per worker.
>> + */
>> + path->rows = clamp_row_est(path->rows / parallel_divisor);
>> }
>>
>> path->startup_cost = startup_cost;
>> @@ -2014,6 +1996,10 @@ final_cost_nestloop(PlannerInfo *root, NestPath *path,
>> else
>> path->path.rows = path->path.parent->rows;
>>
>> + /* For partial paths, scale row estimate. */
>> + if (path->path.parallel_workers > 0)
>> + path->path.rows /= get_parallel_divisor(&path->path);
>>
>>
>> Isn't it better to call clamp_row_est in join costing functions as we
>> are doing in cost_seqscan()? Is there a reason to keep those
>> different?
>
> No, those should probably be changed to match.
So I guess that'd look something like this?
--
Robert Haas
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