From 25fe8b5f1ac93c3ec01519854e4f554b2e57a926 Mon Sep 17 00:00:00 2001
From: Robert Haas
Date: Fri, 8 Apr 2016 11:14:56 -0400
Subject: Add a 'parallel_degree' reloption.

The code that estimates what parallel degree should be uesd for the
scan of a relation is currently rather stupid, so add a parallel_degree
reloption that can be used to override the planner's rather limited
judgement.

Julien Rouhaud, reviewed by David Rowley, James Sewell, Amit Kapila,
and me.  Some further hacking by me.
---
 src/include/nodes/relation.h | 1 +
 src/include/utils/rel.h      | 9 +++++++++
 2 files changed, 10 insertions(+)

(limited to 'src/include')

diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index d430f6e9fd..e9dfb663c2 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -522,6 +522,7 @@ typedef struct RelOptInfo
 	double		allvisfrac;
 	PlannerInfo *subroot;		/* if subquery */
 	List	   *subplan_params; /* if subquery */
+	int			rel_parallel_degree;	/* wanted number of parallel workers */
 
 	/* Information about foreign tables and foreign joins */
 	Oid			serverid;		/* identifies server for the table or join */
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index 51eb27a381..c7582c2a11 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -206,6 +206,7 @@ typedef struct StdRdOptions
 	AutoVacOpts autovacuum;		/* autovacuum-related options */
 	bool		user_catalog_table;		/* use as an additional catalog
 										 * relation */
+	int			parallel_degree;	/* max number of parallel workers */
 } StdRdOptions;
 
 #define HEAP_MIN_FILLFACTOR			10
@@ -242,6 +243,14 @@ typedef struct StdRdOptions
 	((relation)->rd_options ?				\
 	 ((StdRdOptions *) (relation)->rd_options)->user_catalog_table : false)
 
+/*
+ * RelationGetParallelDegree
+ *		Returns the relation's parallel_degree.  Note multiple eval of argument!
+ */
+#define RelationGetParallelDegree(relation, defaultpd) \
+	((relation)->rd_options ? \
+	 ((StdRdOptions *) (relation)->rd_options)->parallel_degree : (defaultpd))
+
 
 /*
  * ViewOptions
-- 
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