Add support for INSERT ... ON CONFLICT DO NOTHING/UPDATE.

The newly added ON CONFLICT clause allows to specify an alternative to
raising a unique or exclusion constraint violation error when inserting.
ON CONFLICT refers to constraints that can either be specified using a
inference clause (by specifying the columns of a unique constraint) or
by naming a unique or exclusion constraint.  DO NOTHING avoids the
constraint violation, without touching the pre-existing row.  DO UPDATE
SET ... [WHERE ...] updates the pre-existing tuple, and has access to
both the tuple proposed for insertion and the existing tuple; the
optional WHERE clause can be used to prevent an update from being
executed.  The UPDATE SET and WHERE clauses have access to the tuple
proposed for insertion using the "magic" EXCLUDED alias, and to the
pre-existing tuple using the table name or its alias.

This feature is often referred to as upsert.

This is implemented using a new infrastructure called "speculative
insertion". It is an optimistic variant of regular insertion that first
does a pre-check for existing tuples and then attempts an insert.  If a
violating tuple was inserted concurrently, the speculatively inserted
tuple is deleted and a new attempt is made.  If the pre-check finds a
matching tuple the alternative DO NOTHING or DO UPDATE action is taken.
If the insertion succeeds without detecting a conflict, the tuple is
deemed inserted.

To handle the possible ambiguity between the excluded alias and a table
named excluded, and for convenience with long relation names, INSERT
INTO now can alias its target table.

Bumps catversion as stored rules change.

Author: Peter Geoghegan, with significant contributions from Heikki
    Linnakangas and Andres Freund. Testing infrastructure by Jeff Janes.
Reviewed-By: Heikki Linnakangas, Andres Freund, Robert Haas, Simon Riggs,
    Dean Rasheed, Stephen Frost and many others.

1 files changed, 15 insertions, 0 deletions

diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index dac542fbc14..210dbe4a534 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -41,6 +41,9 @@
  *		ExclusionOps		Per-column exclusion operators, or NULL if none
  *		ExclusionProcs		Underlying function OIDs for ExclusionOps
  *		ExclusionStrats		Opclass strategy numbers for ExclusionOps
+ *		UniqueOps			Theses are like Exclusion*, but for unique indexes
+ *		UniqueProcs
+ *		UniqueStrats
  *		Unique				is it a unique index?
  *		ReadyForInserts		is it valid for inserts?
  *		Concurrent			are we doing a concurrent index build?
@@ -62,6 +65,9 @@ typedef struct IndexInfo
 	Oid		   *ii_ExclusionOps;	/* array with one entry per column */
 	Oid		   *ii_ExclusionProcs;		/* array with one entry per column */
 	uint16	   *ii_ExclusionStrats;		/* array with one entry per column */
+	Oid		   *ii_UniqueOps;	/* array with one entry per column */
+	Oid		   *ii_UniqueProcs;		/* array with one entry per column */
+	uint16	   *ii_UniqueStrats;		/* array with one entry per column */
 	bool		ii_Unique;
 	bool		ii_ReadyForInserts;
 	bool		ii_Concurrent;
@@ -308,6 +314,8 @@ typedef struct JunkFilter
  *		ConstraintExprs			array of constraint-checking expr states
  *		junkFilter				for removing junk attributes from tuples
  *		projectReturning		for computing a RETURNING list
+ *		onConflictSetProj		for computing ON CONFLICT DO UPDATE SET
+ *		onConflictSetWhere		list of ON CONFLICT DO UPDATE exprs (qual)
  * ----------------
  */
 typedef struct ResultRelInfo
@@ -329,6 +337,8 @@ typedef struct ResultRelInfo
 	List	  **ri_ConstraintExprs;
 	JunkFilter *ri_junkFilter;
 	ProjectionInfo *ri_projectReturning;
+	ProjectionInfo *ri_onConflictSetProj;
+	List	   *ri_onConflictSetWhere;
 } ResultRelInfo;
 
 /* ----------------
@@ -1094,6 +1104,11 @@ typedef struct ModifyTableState
 	List	  **mt_arowmarks;	/* per-subplan ExecAuxRowMark lists */
 	EPQState	mt_epqstate;	/* for evaluating EvalPlanQual rechecks */
 	bool		fireBSTriggers; /* do we need to fire stmt triggers? */
+	OnConflictAction mt_onconflict; /* ON CONFLICT type */
+	List	   *mt_arbiterindexes;	/* unique index OIDs to arbitrate taking alt path */
+	TupleTableSlot *mt_existing; /* slot to store existing target tuple in */
+	List	   *mt_excludedtlist; /* the excluded pseudo relation's tlist  */
+	TupleTableSlot *mt_conflproj; /*  FIXME*/
 } ModifyTableState;
 
 /* ----------------