Refactor ATExecAddColumn() to use BuildDescForRelation()

BuildDescForRelation() has all the knowledge for converting a
ColumnDef into pg_attribute/tuple descriptor.  ATExecAddColumn() can
make use of that, instead of duplicating all that logic.  We just pass
a one-element list of ColumnDef and we get back exactly the data
structure we need.  Note that we don't even need to touch
BuildDescForRelation() to make this work.

Reviewed-by: Alvaro Herrera <[email protected]>
Discussion: https://www.postgresql.org/message-id/flat/52a125e4-ff9a-95f5-9f61-b87cf447e4da@eisentraut.org

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 2822b2bb440a829d82fa67ab47fd29366240b1f3..5e558fabf65a6f4c5e1ed956f7e994ea0dfaab57 100644 (file)
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -6984,22 +6984,15 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
    Relation    pgclass,
                attrdesc;
    HeapTuple   reltup;
-   FormData_pg_attribute attribute;
+   Form_pg_attribute attribute;
    int         newattnum;
    char        relkind;
-   HeapTuple   typeTuple;
-   Oid         typeOid;
-   int32       typmod;
-   Oid         collOid;
-   Form_pg_type tform;
    Expr       *defval;
    List       *children;
    ListCell   *child;
    AlterTableCmd *childcmd;
-   AclResult   aclresult;
    ObjectAddress address;
    TupleDesc   tupdesc;
-   FormData_pg_attribute *aattr[] = {&attribute};
 
    /* At top level, permission check was done in ATPrepCmd, else do it */
    if (recursing)
@@ -7121,59 +7114,21 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
                 errmsg("tables can have at most %d columns",
                        MaxHeapAttributeNumber)));
 
-   typeTuple = typenameType(NULL, colDef->typeName, &typmod);
-   tform = (Form_pg_type) GETSTRUCT(typeTuple);
-   typeOid = tform->oid;
+   /*
+    * Construct new attribute's pg_attribute entry.
+    */
+   tupdesc = BuildDescForRelation(list_make1(colDef));
 
-   aclresult = object_aclcheck(TypeRelationId, typeOid, GetUserId(), ACL_USAGE);
-   if (aclresult != ACLCHECK_OK)
-       aclcheck_error_type(aclresult, typeOid);
+   attribute = TupleDescAttr(tupdesc, 0);
 
-   collOid = GetColumnDefCollation(NULL, colDef, typeOid);
+   /* Fix up attribute number */
+   attribute->attnum = newattnum;
 
    /* make sure datatype is legal for a column */
-   CheckAttributeType(colDef->colname, typeOid, collOid,
+   CheckAttributeType(NameStr(attribute->attname), attribute->atttypid, attribute->attcollation,
                       list_make1_oid(rel->rd_rel->reltype),
                       0);
 
-   /*
-    * Construct new attribute's pg_attribute entry.  (Variable-length fields
-    * are handled by InsertPgAttributeTuples().)
-    */
-   attribute.attrelid = myrelid;
-   namestrcpy(&(attribute.attname), colDef->colname);
-   attribute.atttypid = typeOid;
-   attribute.attstattarget = -1;
-   attribute.attlen = tform->typlen;
-   attribute.attnum = newattnum;
-   if (list_length(colDef->typeName->arrayBounds) > PG_INT16_MAX)
-       ereport(ERROR,
-               errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
-               errmsg("too many array dimensions"));
-   attribute.attndims = list_length(colDef->typeName->arrayBounds);
-   attribute.atttypmod = typmod;
-   attribute.attbyval = tform->typbyval;
-   attribute.attalign = tform->typalign;
-   if (colDef->storage_name)
-       attribute.attstorage = GetAttributeStorage(typeOid, colDef->storage_name);
-   else
-       attribute.attstorage = tform->typstorage;
-   attribute.attcompression = GetAttributeCompression(typeOid,
-                                                      colDef->compression);
-   attribute.attnotnull = colDef->is_not_null;
-   attribute.atthasdef = false;
-   attribute.atthasmissing = false;
-   attribute.attidentity = colDef->identity;
-   attribute.attgenerated = colDef->generated;
-   attribute.attisdropped = false;
-   attribute.attislocal = colDef->is_local;
-   attribute.attinhcount = colDef->inhcount;
-   attribute.attcollation = collOid;
-
-   ReleaseSysCache(typeTuple);
-
-   tupdesc = CreateTupleDesc(lengthof(aattr), (FormData_pg_attribute **) &aattr);
-
    InsertPgAttributeTuples(attrdesc, tupdesc, myrelid, NULL, NULL);
 
    table_close(attrdesc, RowExclusiveLock);
@@ -7203,7 +7158,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
        RawColumnDefault *rawEnt;
 
        rawEnt = (RawColumnDefault *) palloc(sizeof(RawColumnDefault));
-       rawEnt->attnum = attribute.attnum;
+       rawEnt->attnum = attribute->attnum;
        rawEnt->raw_default = copyObject(colDef->raw_default);
 
        /*
@@ -7277,7 +7232,7 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
            NextValueExpr *nve = makeNode(NextValueExpr);
 
            nve->seqid = RangeVarGetRelid(colDef->identitySequence, NoLock, false);
-           nve->typeId = typeOid;
+           nve->typeId = attribute->atttypid;
 
            defval = (Expr *) nve;
 
@@ -7285,23 +7240,23 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
            tab->rewrite |= AT_REWRITE_DEFAULT_VAL;
        }
        else
-           defval = (Expr *) build_column_default(rel, attribute.attnum);
+           defval = (Expr *) build_column_default(rel, attribute->attnum);
 
-       if (!defval && DomainHasConstraints(typeOid))
+       if (!defval && DomainHasConstraints(attribute->atttypid))
        {
            Oid         baseTypeId;
            int32       baseTypeMod;
            Oid         baseTypeColl;
 
-           baseTypeMod = typmod;
-           baseTypeId = getBaseTypeAndTypmod(typeOid, &baseTypeMod);
+           baseTypeMod = attribute->atttypmod;
+           baseTypeId = getBaseTypeAndTypmod(attribute->atttypid, &baseTypeMod);
            baseTypeColl = get_typcollation(baseTypeId);
            defval = (Expr *) makeNullConst(baseTypeId, baseTypeMod, baseTypeColl);
            defval = (Expr *) coerce_to_target_type(NULL,
                                                    (Node *) defval,
                                                    baseTypeId,
-                                                   typeOid,
-                                                   typmod,
+                                                   attribute->atttypid,
+                                                   attribute->atttypmod,
                                                    COERCION_ASSIGNMENT,
                                                    COERCE_IMPLICIT_CAST,
                                                    -1);
@@ -7314,17 +7269,17 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
            NewColumnValue *newval;
 
            newval = (NewColumnValue *) palloc0(sizeof(NewColumnValue));
-           newval->attnum = attribute.attnum;
+           newval->attnum = attribute->attnum;
            newval->expr = expression_planner(defval);
            newval->is_generated = (colDef->generated != '\0');
 
            tab->newvals = lappend(tab->newvals, newval);
        }
 
-       if (DomainHasConstraints(typeOid))
+       if (DomainHasConstraints(attribute->atttypid))
            tab->rewrite |= AT_REWRITE_DEFAULT_VAL;
 
-       if (!TupleDescAttr(rel->rd_att, attribute.attnum - 1)->atthasmissing)
+       if (!TupleDescAttr(rel->rd_att, attribute->attnum - 1)->atthasmissing)
        {
            /*
             * If the new column is NOT NULL, and there is no missing value,
@@ -7337,8 +7292,8 @@ ATExecAddColumn(List **wqueue, AlteredTableInfo *tab, Relation rel,
    /*
     * Add needed dependency entries for the new column.
     */
-   add_column_datatype_dependency(myrelid, newattnum, attribute.atttypid);
-   add_column_collation_dependency(myrelid, newattnum, attribute.attcollation);
+   add_column_datatype_dependency(myrelid, newattnum, attribute->atttypid);
+   add_column_collation_dependency(myrelid, newattnum, attribute->attcollation);
 
    /*
     * Propagate to children as appropriate.  Unlike most other ALTER