From 95caaebd3be099b924dc60ab3805b429406d4eb1 Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Wed, 3 Jan 2018 22:32:27 -0500 Subject: [PATCH] Code review for Parallel Append. - Remove unnecessary #include mistakenly added in execnodes.h. - Fix mistake in comment in choose_next_subplan_for_leader. - Adjust row estimates in cost_append for a possibly-different parallel divisor. - Clamp row estimates in cost_append after operations that may not produce integers. Amit Kapila, with cosmetic adjustments by me. Discussion: http://postgr.es/m/CAA4eK1+qcbeai3coPpRW=GFCzFeLUsuY4T-AKHqMjxpEGZBPQg@mail.gmail.com --- src/backend/executor/nodeAppend.c | 7 +++---- src/backend/optimizer/path/costsize.c | 16 ++++++++++++---- src/include/nodes/execnodes.h | 1 - 3 files changed, 15 insertions(+), 9 deletions(-) diff --git a/src/backend/executor/nodeAppend.c b/src/backend/executor/nodeAppend.c index 4245d8afaf..64a17fb032 100644 --- a/src/backend/executor/nodeAppend.c +++ b/src/backend/executor/nodeAppend.c @@ -446,10 +446,9 @@ choose_next_subplan_for_leader(AppendState *node) * * We start from the first plan and advance through the list; * when we get back to the end, we loop back to the first - * nonpartial plan. This assigns the non-partial plans first - * in order of descending cost and then spreads out the - * workers as evenly as possible across the remaining partial - * plans. + * partial plan. This assigns the non-partial plans first in + * order of descending cost and then spreads out the workers + * as evenly as possible across the remaining partial plans. * ---------------------------------------------------------------- */ static bool diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c index 7903b2cb16..8679b14b29 100644 --- a/src/backend/optimizer/path/costsize.c +++ b/src/backend/optimizer/path/costsize.c @@ -1883,18 +1883,26 @@ cost_append(AppendPath *apath) subpath->startup_cost); /* - * Apply parallel divisor to non-partial subpaths. Also add the - * cost of partial paths to the total cost, but ignore non-partial - * paths for now. + * Apply parallel divisor to subpaths. Scale the number of rows + * for each partial subpath based on the ratio of the parallel + * divisor originally used for the subpath to the one we adopted. + * Also add the cost of partial paths to the total cost, but + * ignore non-partial paths for now. */ if (i < apath->first_partial_path) apath->path.rows += subpath->rows / parallel_divisor; else { - apath->path.rows += subpath->rows; + double subpath_parallel_divisor; + + subpath_parallel_divisor = get_parallel_divisor(subpath); + apath->path.rows += subpath->rows * (subpath_parallel_divisor / + parallel_divisor); apath->path.total_cost += subpath->total_cost; } + apath->path.rows = clamp_row_est(apath->path.rows); + i++; } diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h index b121e16688..3ad58cdfe7 100644 --- a/src/include/nodes/execnodes.h +++ b/src/include/nodes/execnodes.h @@ -21,7 +21,6 @@ #include "lib/pairingheap.h" #include "nodes/params.h" #include "nodes/plannodes.h" -#include "storage/spin.h" #include "utils/hsearch.h" #include "utils/queryenvironment.h" #include "utils/reltrigger.h" -- 2.13.5 (Apple Git-94)