On Tue, Jan 17, 2017 at 11:49 AM, Robert Haas <robertmh...@gmail.com> wrote: > On Mon, Jan 16, 2017 at 7:23 AM, Amit Kapila <amit.kapil...@gmail.com> wrote: >> On Sat, Jan 14, 2017 at 12:07 AM, Robert Haas <rh...@postgresql.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 EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
clamp-parallel-join-est.patch
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