Improve representation of PlanRowMark.

This patch fixes two inadequacies of the PlanRowMark representation.

First, that the original LockingClauseStrength isn't stored (and cannot be
inferred for foreign tables, which always get ROW_MARK_COPY).  Since some
PlanRowMarks are created out of whole cloth and don't actually have an
ancestral RowMarkClause, this requires adding a dummy LCS_NONE value to
enum LockingClauseStrength, which is fairly annoying but the alternatives
seem worse.  This fix allows getting rid of the use of get_parse_rowmark()
in FDWs (as per the discussion around commits 462bd95705a0c23b and
8ec8760fc87ecde0), and it simplifies some things elsewhere.

Second, that the representation assumed that all child tables in an
inheritance hierarchy would use the same RowMarkType.  That's true today
but will soon not be true.  We add an "allMarkTypes" field that identifies
the union of mark types used in all a parent table's children, and use
that where appropriate (currently, only in preprocess_targetlist()).

In passing fix a couple of minor infelicities left over from the SKIP
LOCKED patch, notably that _outPlanRowMark still thought waitPolicy
is a bool.

Catversion bump is required because the numeric values of enum
LockingClauseStrength can appear in on-disk rules.

Extracted from a much larger patch to support foreign table inheritance;
it seemed worth breaking this out, since it's a separable concern.

Shigeru Hanada and Etsuro Fujita, somewhat modified by me

2 files changed, 9 insertions, 2 deletions

diff --git a/src/include/nodes/lockoptions.h b/src/include/nodes/lockoptions.h
index 55324baf40f..2e55622b043 100644
--- a/src/include/nodes/lockoptions.h
+++ b/src/include/nodes/lockoptions.h
@@ -20,6 +20,7 @@
  */
 typedef enum LockClauseStrength
 {
+	LCS_NONE,					/* no such clause - only used in PlanRowMark */
 	LCS_FORKEYSHARE,			/* FOR KEY SHARE */
 	LCS_FORSHARE,				/* FOR SHARE */
 	LCS_FORNOKEYUPDATE,			/* FOR NO KEY UPDATE */
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index af44ddf5dc5..21cbfa8cf0f 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -820,7 +820,7 @@ typedef enum RowMarkType
 	ROW_MARK_NOKEYEXCLUSIVE,	/* obtain no-key exclusive tuple lock */
 	ROW_MARK_SHARE,				/* obtain shared tuple lock */
 	ROW_MARK_KEYSHARE,			/* obtain keyshare tuple lock */
-	ROW_MARK_REFERENCE,			/* just fetch the TID */
+	ROW_MARK_REFERENCE,			/* just fetch the TID, don't lock it */
 	ROW_MARK_COPY				/* physically copy the row value */
 } RowMarkType;
 
@@ -841,7 +841,9 @@ typedef enum RowMarkType
  * list for each child relation (including the target rel itself in its role
  * as a child).  The child entries have rti == child rel's RT index and
  * prti == parent's RT index, and can therefore be recognized as children by
- * the fact that prti != rti.
+ * the fact that prti != rti.  The parent's allMarkTypes field gets the OR
+ * of (1<<markType) across all its children (this definition allows children
+ * to use different markTypes).
  *
  * The planner also adds resjunk output columns to the plan that carry
  * information sufficient to identify the locked or fetched rows.  For
@@ -851,6 +853,8 @@ typedef enum RowMarkType
  * The tableoid column is only present for an inheritance hierarchy.
  * When markType == ROW_MARK_COPY, there is instead a single column named
  *		wholerow%u			whole-row value of relation
+ * (An inheritance hierarchy could have all three resjunk output columns,
+ * if some children use a different markType than others.)
  * In all three cases, %u represents the rowmark ID number (rowmarkId).
  * This number is unique within a plan tree, except that child relation
  * entries copy their parent's rowmarkId.  (Assigning unique numbers
@@ -867,6 +871,8 @@ typedef struct PlanRowMark
 	Index		prti;			/* range table index of parent relation */
 	Index		rowmarkId;		/* unique identifier for resjunk columns */
 	RowMarkType markType;		/* see enum above */
+	int			allMarkTypes;	/* OR of (1<<markType) for all children */
+	LockClauseStrength strength;	/* LockingClause's strength, or LCS_NONE */
 	LockWaitPolicy waitPolicy;	/* NOWAIT and SKIP LOCKED options */
 	bool		isParent;		/* true if this is a "dummy" parent entry */
 } PlanRowMark;