Subject: [PATCH v8 2/4] WIP: Check for volatile defaults

From: Justin Pryzby <[email-masked]>
Date: Tue, 1 Dec 2020 23:11:31 -0600

We want to check if any column *uses* a volatile default value, but after
parsing and rewriting, that information appears to be lost about which column
values are defaults and which were specified.  insertedcols doesn't appear to
be useful for this.  So add a field to track if a TargetEntry is planned with
column default.
---
 src/backend/executor/nodeModifyTable.c | 64 ++++++++++++++++++++++++--
 src/backend/nodes/copyfuncs.c          |  1 +
 src/backend/nodes/equalfuncs.c         |  1 +
 src/backend/nodes/makefuncs.c          |  1 +
 src/backend/nodes/outfuncs.c           |  1 +
 src/backend/nodes/readfuncs.c          |  1 +
 src/backend/optimizer/util/tlist.c     |  1 +
 src/backend/rewrite/rewriteHandler.c   |  3 ++
 src/include/nodes/primnodes.h          |  2 +
 9 files changed, 71 insertions(+), 4 deletions(-)

diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index 3428d9f48a..47a5271b91 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -50,6 +50,7 @@
 #include "foreign/fdwapi.h"
 #include "miscadmin.h"
 #include "nodes/nodeFuncs.h"
+#include "optimizer/optimizer.h"
 #include "rewrite/rewriteHandler.h"
 #include "storage/bufmgr.h"
 #include "storage/lmgr.h"
@@ -2258,6 +2259,61 @@ ExecModifyTable(PlanState *pstate)
 	return NULL;
 }
 
+/*
+ * Determine if a table has volatile column defaults which are used by a given
+ * planned statement (if the column is not specified or specified as DEFAULT).
+ * This works only for INSERT.
+ */
+static bool
+has_volatile_defaults(ResultRelInfo *resultRelInfo, ModifyTable *node)
+{
+	TupleDesc	tupDesc = RelationGetDescr(resultRelInfo->ri_RelationDesc);
+	Plan		*plan;
+
+	Assert(list_length(node->plans) == 1);
+	plan = linitial(node->plans);
+
+	for (int attnum = 1; attnum <= tupDesc->natts; attnum++)
+	{
+		Form_pg_attribute att = TupleDescAttr(tupDesc, attnum - 1);
+		Expr		*defexpr;
+		TargetEntry	*tle;
+
+		/* We don't need to check dropped/generated attributes */
+		if (att->attisdropped || att->attgenerated)
+			continue;
+
+		tle = list_nth(plan->targetlist, attnum - 1);
+		Assert(tle != NULL);
+		Assert(tle->resno == attnum);
+
+		/*
+		 * If the column was specified with a non-default value, then don't
+		 * check the volatility of its default
+		 */
+		if (!tle->isdefault)
+			continue;
+
+		/* Check the column's default value if one exists */
+		defexpr = (Expr *) build_column_default(resultRelInfo->ri_RelationDesc, attnum);
+		if (defexpr == NULL)
+			continue;
+
+		/* Run the expression through planner */
+		// defexpr = expression_planner(defexpr);
+		// (void) ExecInitExpr(defexpr, NULL);
+		expression_planner(defexpr);
+
+		if (contain_volatile_functions_not_nextval((Node *) defexpr))
+		{
+			elog(DEBUG1, "found volatile att %d", attnum);
+			return true;
+		}
+	}
+
+	return false;
+}
+
 /* ----------------------------------------------------------------
  *		ExecInitModifyTable
  * ----------------------------------------------------------------
@@ -2352,10 +2408,10 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 		 * are any statement level insert triggers.
 		 */
 		mtstate->miinfo = NULL;
-	else if (mtstate->rootResultRelInfo->ri_FdwRoutine != NULL
-			/* || cstate->volatile_defexprs */ )
-		// XXX contain_volatile_functions_not_nextval((Node *) defexpr);
-		/* Can't support multi-inserts to foreign tables or if there are any */
+	else if (mtstate->rootResultRelInfo->ri_FdwRoutine != NULL ||
+			has_volatile_defaults(mtstate->rootResultRelInfo, node))
+		/* Can't support multi-inserts to foreign tables or if there are any
+		 * volatile default expressions in the table. */
 		mtstate->miinfo = NULL;
 	else
 	{
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 910906f639..3bfa59f1a5 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -2177,6 +2177,7 @@ _copyTargetEntry(const TargetEntry *from)
 	COPY_SCALAR_FIELD(resorigtbl);
 	COPY_SCALAR_FIELD(resorigcol);
 	COPY_SCALAR_FIELD(resjunk);
+	COPY_SCALAR_FIELD(isdefault);
 
 	return newnode;
 }
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 687609f59e..84530468b8 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -769,6 +769,7 @@ _equalTargetEntry(const TargetEntry *a, const TargetEntry *b)
 	COMPARE_SCALAR_FIELD(resorigtbl);
 	COMPARE_SCALAR_FIELD(resorigcol);
 	COMPARE_SCALAR_FIELD(resjunk);
+	COMPARE_SCALAR_FIELD(isdefault);
 
 	return true;
 }
diff --git a/src/backend/nodes/makefuncs.c b/src/backend/nodes/makefuncs.c
index ee033ae779..1cd14fed3d 100644
--- a/src/backend/nodes/makefuncs.c
+++ b/src/backend/nodes/makefuncs.c
@@ -254,6 +254,7 @@ makeTargetEntry(Expr *expr,
 	tle->ressortgroupref = 0;
 	tle->resorigtbl = InvalidOid;
 	tle->resorigcol = 0;
+	tle->isdefault = false;
 
 	tle->resjunk = resjunk;
 
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 9c73c605a4..ef6d14e072 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -1660,6 +1660,7 @@ _outTargetEntry(StringInfo str, const TargetEntry *node)
 	WRITE_OID_FIELD(resorigtbl);
 	WRITE_INT_FIELD(resorigcol);
 	WRITE_BOOL_FIELD(resjunk);
+	WRITE_BOOL_FIELD(isdefault);
 }
 
 static void
diff --git a/src/backend/nodes/readfuncs.c b/src/backend/nodes/readfuncs.c
index 169d5581b9..ba2288f7b0 100644
--- a/src/backend/nodes/readfuncs.c
+++ b/src/backend/nodes/readfuncs.c
@@ -1274,6 +1274,7 @@ _readTargetEntry(void)
 	READ_OID_FIELD(resorigtbl);
 	READ_INT_FIELD(resorigcol);
 	READ_BOOL_FIELD(resjunk);
+	READ_BOOL_FIELD(isdefault);
 
 	READ_DONE();
 }
diff --git a/src/backend/optimizer/util/tlist.c b/src/backend/optimizer/util/tlist.c
index 02a3c6b165..1043ee7b66 100644
--- a/src/backend/optimizer/util/tlist.c
+++ b/src/backend/optimizer/util/tlist.c
@@ -354,6 +354,7 @@ apply_tlist_labeling(List *dest_tlist, List *src_tlist)
 		dest_tle->resorigtbl = src_tle->resorigtbl;
 		dest_tle->resorigcol = src_tle->resorigcol;
 		dest_tle->resjunk = src_tle->resjunk;
+		dest_tle->isdefault = src_tle->isdefault;
 	}
 }
 
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
index c25012f325..9998db2268 100644
--- a/src/backend/rewrite/rewriteHandler.c
+++ b/src/backend/rewrite/rewriteHandler.c
@@ -986,10 +986,13 @@ rewriteTargetListIU(List *targetList,
 			}
 
 			if (new_expr)
+			{
 				new_tle = makeTargetEntry((Expr *) new_expr,
 										  attrno,
 										  pstrdup(NameStr(att_tup->attname)),
 										  false);
+				new_tle->isdefault = true;
+			}
 		}
 
 		/*
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index cdbe781c73..c5e626f175 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -1428,6 +1428,8 @@ typedef struct TargetEntry
 	AttrNumber	resorigcol;		/* column's number in source table */
 	bool		resjunk;		/* set to true to eliminate the attribute from
 								 * final target list */
+	bool		isdefault;		/* true if using the column default, either
+								 * by "DEFAULT" or omission of the column */
 } TargetEntry;

-- 
2.17.0

--AZuoSAvZwvV/ife4
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 filename="v8-0003-COPY-flush-multi-insert-buffer-based-on-accumulat.patch"