From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 15 Mar 2017 16:28:54 +0000 (-0400)
Subject: Fix failure to use clamp_row_est() for parallel joins.
X-Git-Tag: REL_10_BETA1~631
X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=1ea60ad602f9e97246958b721c8fa7c713aa86eb;p=postgresql.git

Fix failure to use clamp_row_est() for parallel joins.

Commit 0c2070cefa0e5d097b715c9a3b9b5499470019aa neglected to use
clamp_row_est() where it should have done so.

Patch by me.  Report by Amit Kapila.

Discussion: http://postgr.es/m/CAA4eK1KPm8RYa1Kun3ZmQj9pb723b-EFN70j47Pid1vn3ByquA@mail.gmail.com
---

diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index cd6dcaab190..a129d1ecb3b 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -2147,7 +2147,12 @@ final_cost_nestloop(PlannerInfo *root, NestPath *path,
 
 	/* For partial paths, scale row estimate. */
 	if (path->path.parallel_workers > 0)
-		path->path.rows /= get_parallel_divisor(&path->path);
+	{
+		double	parallel_divisor = get_parallel_divisor(&path->path);
+
+		path->path.rows =
+			clamp_row_est(path->path.rows / parallel_divisor);
+	}
 
 	/*
 	 * We could include disable_cost in the preliminary estimate, but that
@@ -2569,7 +2574,12 @@ final_cost_mergejoin(PlannerInfo *root, MergePath *path,
 
 	/* For partial paths, scale row estimate. */
 	if (path->jpath.path.parallel_workers > 0)
-		path->jpath.path.rows /= get_parallel_divisor(&path->jpath.path);
+	{
+		double	parallel_divisor = get_parallel_divisor(&path->jpath.path);
+
+		path->jpath.path.rows =
+			clamp_row_est(path->jpath.path.rows / parallel_divisor);
+	}
 
 	/*
 	 * We could include disable_cost in the preliminary estimate, but that
@@ -2952,7 +2962,12 @@ final_cost_hashjoin(PlannerInfo *root, HashPath *path,
 
 	/* For partial paths, scale row estimate. */
 	if (path->jpath.path.parallel_workers > 0)
-		path->jpath.path.rows /= get_parallel_divisor(&path->jpath.path);
+	{
+		double	parallel_divisor = get_parallel_divisor(&path->jpath.path);
+
+		path->jpath.path.rows =
+			clamp_row_est(path->jpath.path.rows / parallel_divisor);
+	}
 
 	/*
 	 * We could include disable_cost in the preliminary estimate, but that