Remove now-dead code in StoreAttrDefault().

StoreAttrDefault() is no longer responsible for filling
attmissingval, so remove the code for that.

Get rid of RawColumnDefault.missingMode, too, as we no longer
need that to pass information around.

While here, clean up some sloppy coding in StoreAttrDefault(),
such as failure to use XXXGetDatum macros.  These aren't bugs
but they're not good code either.

Reported-by: jian he <jian.universality@gmail.com>
Author: jian he <jian.universality@gmail.com>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/CACJufxHFssPvkP1we7WMhPD_1kwgbG52o=kQgL+TnVoX5LOyCQ@mail.gmail.com

Author: tglsfdc

src/backend/catalog/heap.c

@@ -2320,7 +2320,7 @@ StoreConstraints(Relation rel, List *cooked_constraints, bool is_internal)
 		{
 			case CONSTR_DEFAULT:
 				con->conoid = StoreAttrDefault(rel, con->attnum, con->expr,
-											   is_internal, false);
+											   is_internal);
 				break;
 			case CONSTR_CHECK:
 				con->conoid =
@@ -2447,8 +2447,7 @@ AddRelationNewConstraints(Relation rel,
 			 castNode(Const, expr)->constisnull))
 			continue;
 
-		defOid = StoreAttrDefault(rel, colDef->attnum, expr, is_internal,
-								  false);
+		defOid = StoreAttrDefault(rel, colDef->attnum, expr, is_internal);
 
 		cooked = (CookedConstraint *) palloc(sizeof(CookedConstraint));
 		cooked->contype = CONSTR_DEFAULT;

src/backend/catalog/pg_attrdef.c

@@ -14,17 +14,12 @@
  */
 #include "postgres.h"
 
-#include "access/genam.h"
 #include "access/relation.h"
 #include "access/table.h"
-#include "catalog/catalog.h"
 #include "catalog/dependency.h"
 #include "catalog/indexing.h"
 #include "catalog/objectaccess.h"
 #include "catalog/pg_attrdef.h"
-#include "executor/executor.h"
-#include "optimizer/optimizer.h"
-#include "utils/array.h"
 #include "utils/builtins.h"
 #include "utils/fmgroids.h"
 #include "utils/rel.h"
@@ -35,22 +30,16 @@
  * Store a default expression for column attnum of relation rel.
  *
  * Returns the OID of the new pg_attrdef tuple.
- *
- * add_column_mode must be true if we are storing the default for a new
- * attribute, and false if it's for an already existing attribute. The reason
- * for this is that the missing value must never be updated after it is set,
- * which can only be when a column is added to the table. Otherwise we would
- * in effect be changing existing tuples.
  */
 Oid
 StoreAttrDefault(Relation rel, AttrNumber attnum,
-				 Node *expr, bool is_internal, bool add_column_mode)
+				 Node *expr, bool is_internal)
 {
 	char	   *adbin;
 	Relation	adrel;
 	HeapTuple	tuple;
-	Datum		values[4];
-	static bool nulls[4] = {false, false, false, false};
+	Datum		values[Natts_pg_attrdef];
+	static bool nulls[Natts_pg_attrdef] = {false, false, false, false};
 	Relation	attrrel;
 	HeapTuple	atttup;
 	Form_pg_attribute attStruct;
@@ -72,8 +61,8 @@ StoreAttrDefault(Relation rel, AttrNumber attnum,
 	attrdefOid = GetNewOidWithIndex(adrel, AttrDefaultOidIndexId,
 									Anum_pg_attrdef_oid);
 	values[Anum_pg_attrdef_oid - 1] = ObjectIdGetDatum(attrdefOid);
-	values[Anum_pg_attrdef_adrelid - 1] = RelationGetRelid(rel);
-	values[Anum_pg_attrdef_adnum - 1] = attnum;
+	values[Anum_pg_attrdef_adrelid - 1] = ObjectIdGetDatum(RelationGetRelid(rel));
+	values[Anum_pg_attrdef_adnum - 1] = Int16GetDatum(attnum);
 	values[Anum_pg_attrdef_adbin - 1] = CStringGetTextDatum(adbin);
 
 	tuple = heap_form_tuple(adrel->rd_att, values, nulls);
@@ -105,71 +94,17 @@ StoreAttrDefault(Relation rel, AttrNumber attnum,
 	attgenerated = attStruct->attgenerated;
 	if (!attStruct->atthasdef)
 	{
-		Form_pg_attribute defAttStruct;
-
-		ExprState  *exprState;
-		Expr	   *expr2 = (Expr *) expr;
-		EState	   *estate = NULL;
-		ExprContext *econtext;
 		Datum		valuesAtt[Natts_pg_attribute] = {0};
 		bool		nullsAtt[Natts_pg_attribute] = {0};
 		bool		replacesAtt[Natts_pg_attribute] = {0};
-		Datum		missingval = (Datum) 0;
-		bool		missingIsNull = true;
 
-		valuesAtt[Anum_pg_attribute_atthasdef - 1] = true;
+		valuesAtt[Anum_pg_attribute_atthasdef - 1] = BoolGetDatum(true);
 		replacesAtt[Anum_pg_attribute_atthasdef - 1] = true;
 
-		/*
-		 * Note: this code is dead so far as core Postgres is concerned,
-		 * because no caller passes add_column_mode = true anymore.  We keep
-		 * it in back branches on the slight chance that some extension is
-		 * depending on it.
-		 */
-		if (rel->rd_rel->relkind == RELKIND_RELATION && add_column_mode &&
-			!attgenerated)
-		{
-			expr2 = expression_planner(expr2);
-			estate = CreateExecutorState();
-			exprState = ExecPrepareExpr(expr2, estate);
-			econtext = GetPerTupleExprContext(estate);
-
-			missingval = ExecEvalExpr(exprState, econtext,
-									  &missingIsNull);
-
-			FreeExecutorState(estate);
-
-			defAttStruct = TupleDescAttr(rel->rd_att, attnum - 1);
-
-			if (missingIsNull)
-			{
-				/* if the default evaluates to NULL, just store a NULL array */
-				missingval = (Datum) 0;
-			}
-			else
-			{
-				/* otherwise make a one-element array of the value */
-				missingval = PointerGetDatum(construct_array(&missingval,
-															 1,
-															 defAttStruct->atttypid,
-															 defAttStruct->attlen,
-															 defAttStruct->attbyval,
-															 defAttStruct->attalign));
-			}
-
-			valuesAtt[Anum_pg_attribute_atthasmissing - 1] = !missingIsNull;
-			replacesAtt[Anum_pg_attribute_atthasmissing - 1] = true;
-			valuesAtt[Anum_pg_attribute_attmissingval - 1] = missingval;
-			replacesAtt[Anum_pg_attribute_attmissingval - 1] = true;
-			nullsAtt[Anum_pg_attribute_attmissingval - 1] = missingIsNull;
-		}
 		atttup = heap_modify_tuple(atttup, RelationGetDescr(attrrel),
 								   valuesAtt, nullsAtt, replacesAtt);
 
 		CatalogTupleUpdate(attrrel, &atttup->t_self, atttup);
-
-		if (!missingIsNull)
-			pfree(DatumGetPointer(missingval));
 	}
 	table_close(attrrel, RowExclusiveLock);
 	heap_freetuple(atttup);

src/backend/commands/tablecmds.c

@@ -967,7 +967,6 @@ DefineRelation(CreateStmt *stmt, char relkind, Oid ownerId,
 			rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
 			rawEnt->attnum = attnum;
 			rawEnt->raw_default = colDef->raw_default;
-			rawEnt->missingMode = false;
 			rawEnt->generated = colDef->generated;
 			rawDefaults = lappend(rawDefaults, rawEnt);
 			attr->atthasdef = true;
@@ -7321,7 +7320,6 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
 		rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
 		rawEnt->attnum = attribute->attnum;
 		rawEnt->raw_default = copyObject(colDef->raw_default);
-		rawEnt->missingMode = false;	/* XXX vestigial */
 		rawEnt->generated = colDef->generated;
 
 		/*
@@ -8077,7 +8075,6 @@ ATExecColumnDefault(Relation rel, const char *colName,
 		rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
 		rawEnt->attnum = attnum;
 		rawEnt->raw_default = newDefault;
-		rawEnt->missingMode = false;
 		rawEnt->generated = '\0';
 
 		/*
@@ -8115,7 +8112,7 @@ ATExecCookedColumnDefault(Relation rel, AttrNumber attnum,
 	RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, false,
 					  true);
 
-	(void) StoreAttrDefault(rel, attnum, newDefault, true, false);
+	(void) StoreAttrDefault(rel, attnum, newDefault, true);
 
 	ObjectAddressSubSet(address, RelationRelationId,
 						RelationGetRelid(rel), attnum);
@@ -8578,7 +8575,6 @@ ATExecSetExpression(AlteredTableInfo *tab, Relation rel, const char *colName,
 	rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
 	rawEnt->attnum = attnum;
 	rawEnt->raw_default = newExpr;
-	rawEnt->missingMode = false;
 	rawEnt->generated = attgenerated;
 
 	/* Store the generated expression */
@@ -14130,7 +14126,7 @@ ATExecAlterColumnType(AlteredTableInfo *tab, Relation rel,
 		RemoveAttrDefault(RelationGetRelid(rel), attnum, DROP_RESTRICT, true,
 						  true);
 
-		StoreAttrDefault(rel, attnum, defaultexpr, true, false);
+		(void) StoreAttrDefault(rel, attnum, defaultexpr, true);
 	}
 
 	ObjectAddressSubSet(address, RelationRelationId,

src/include/catalog/heap.h

@@ -29,7 +29,6 @@ typedef struct RawColumnDefault
 {
 	AttrNumber	attnum;			/* attribute to attach default to */
 	Node	   *raw_default;	/* default value (untransformed parse tree) */
-	bool		missingMode;	/* obsolete, no longer used */
 	char		generated;		/* attgenerated setting */
 } RawColumnDefault;
 

src/include/catalog/pg_attrdef.h

@@ -57,8 +57,7 @@ DECLARE_FOREIGN_KEY((adrelid, adnum), pg_attribute, (attrelid, attnum));
 
 
 extern Oid	StoreAttrDefault(Relation rel, AttrNumber attnum,
-							 Node *expr, bool is_internal,
-							 bool add_column_mode);
+							 Node *expr, bool is_internal);
 extern void RemoveAttrDefault(Oid relid, AttrNumber attnum,
 							  DropBehavior behavior,
 							  bool complain, bool internal);