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Commitf47b33a

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author
Richard Guo
committed
Simplify create_merge_append_path for clarity
We don't currently support parameterized MergeAppend paths: there'slittle use for an ordered path on the inside of a nestloop. Giventhis, we can simplify create_merge_append_path by directly settingparam_info to NULL instead of calling get_appendrel_parampathinfo. Wecan also simplify the Assert for child paths a little bit.This change won't make any measurable difference in performance; it'sjust for clarity's sake.Author: Richard GuoReviewed-by: Alena Rybakina, Paul A JungwirthDiscussion:https://postgr.es/m/CAMbWs4_n1bgH2nACMuGsXZct3KH6PBFS0tPdQsXdstRfyxTunQ@mail.gmail.com
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‎src/backend/optimizer/util/pathnode.c

Lines changed: 10 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1423,11 +1423,16 @@ create_merge_append_path(PlannerInfo *root,
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Costinput_total_cost;
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ListCell*l;
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1426+
/*
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* We don't currently support parameterized MergeAppend paths, as
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* explained in the comments for generate_orderedappend_paths.
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*/
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Assert(bms_is_empty(rel->lateral_relids)&&bms_is_empty(required_outer));
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pathnode->path.pathtype=T_MergeAppend;
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pathnode->path.parent=rel;
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pathnode->path.pathtarget=rel->reltarget;
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pathnode->path.param_info=get_appendrel_parampathinfo(rel,
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required_outer);
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pathnode->path.param_info=NULL;
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pathnode->path.parallel_aware= false;
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pathnode->path.parallel_safe=rel->consider_parallel;
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pathnode->path.parallel_workers=0;
@@ -1453,6 +1458,9 @@ create_merge_append_path(PlannerInfo *root,
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{
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Path*subpath= (Path*)lfirst(l);
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/* All child paths should be unparameterized */
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Assert(bms_is_empty(PATH_REQ_OUTER(subpath)));
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pathnode->path.rows+=subpath->rows;
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pathnode->path.parallel_safe=pathnode->path.parallel_safe&&
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subpath->parallel_safe;
@@ -1480,9 +1488,6 @@ create_merge_append_path(PlannerInfo *root,
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input_startup_cost+=sort_path.startup_cost;
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input_total_cost+=sort_path.total_cost;
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}
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/* All child paths must have same parameterization */
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Assert(bms_equal(PATH_REQ_OUTER(subpath),required_outer));
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}
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/*

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