From c8f78b616167bf8e24bc5dc69112c37755ed3058 Mon Sep 17 00:00:00 2001
From: Amit Kapila
Date: Thu, 18 Mar 2021 07:25:27 +0530
Subject: Add a new GUC and a reloption to enable inserts in parallel-mode.

Commit 05c8482f7f added the implementation of parallel SELECT for
"INSERT INTO ... SELECT ..." which may incur non-negligible overhead in
the additional parallel-safety checks that it performs, even when, in the
end, those checks determine that parallelism can't be used. This is
normally only ever a problem in the case of when the target table has a
large number of partitions.

A new GUC option "enable_parallel_insert" is added, to allow insert in
parallel-mode. The default is on.

In addition to the GUC option, the user may want a mechanism to allow
inserts in parallel-mode with finer granularity at table level. The new
table option "parallel_insert_enabled" allows this. The default is true.

Author: "Hou, Zhijie"
Reviewed-by: Greg Nancarrow, Amit Langote, Takayuki Tsunakawa, Amit Kapila
Discussion: https://postgr.es/m/CAA4eK1K-cW7svLC2D7DHoGHxdAdg3P37BLgebqBOC2ZLc9a6QQ%40mail.gmail.com
Discussion: https://postgr.es/m/CAJcOf-cXnB5cnMKqWEp2E2z7Mvcd04iLVmV=qpFJrR3AcrTS3g@mail.gmail.com
---
 src/include/utils/rel.h | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

(limited to 'src/include/utils')

diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index 10b63982c0a..5375a37dd19 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -306,6 +306,8 @@ typedef struct StdRdOptions
 	int			parallel_workers;	/* max number of parallel workers */
 	bool		vacuum_index_cleanup;	/* enables index vacuuming and cleanup */
 	bool		vacuum_truncate;	/* enables vacuum to truncate a relation */
+	bool		parallel_insert_enabled;	/* enables planner's use of
+											 * parallel insert */
 } StdRdOptions;
 
 #define HEAP_MIN_FILLFACTOR			10
@@ -423,6 +425,29 @@ typedef struct ViewOptions
 	 ((ViewOptions *) (relation)->rd_options)->check_option ==				\
 	  VIEW_OPTION_CHECK_OPTION_CASCADED)
 
+/*
+ * PartitionedTableRdOptions
+ *		Contents of rd_options for partitioned tables
+ */
+typedef struct PartitionedTableRdOptions
+{
+	int32		vl_len_;		/* varlena header (do not touch directly!) */
+	bool		parallel_insert_enabled;	/* enables planner's use of
+											 * parallel insert */
+} PartitionedTableRdOptions;
+
+/*
+ * RelationGetParallelInsert
+ *		Returns the relation's parallel_insert_enabled reloption setting.
+ *		Note multiple eval of argument!
+ */
+#define RelationGetParallelInsert(relation, defaultpd) 						\
+	((relation)->rd_options ?												\
+	 (relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE ?				\
+	 ((PartitionedTableRdOptions *) (relation)->rd_options)->parallel_insert_enabled : \
+	 ((StdRdOptions *) (relation)->rd_options)->parallel_insert_enabled) :		\
+	 (defaultpd))
+
 /*
  * RelationIsValid
  *		True iff relation descriptor is valid.
-- 
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