Function transformAlterTableStmt

src/backend/parser/parse_utilcmd.c:4423–4826

* transformAlterTableStmt - * parse analysis for ALTER TABLE * * Returns the transformed AlterTableStmt. There may be additional actions * to be done before and after the transformed statement, which are returned * in *beforeStmts and *afterStmts as lists of utility command parsetrees. * * To avoid race conditions, it's important that this function rely only on * the passed-in relid (and

 * relation.
 */
AlterTableStmt *
transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
						const char *queryString,
						List **beforeStmts, List **afterStmts)
{
	Relation	rel;
	TupleDesc	tupdesc;
	ParseState *pstate;
	CreateStmtContext cxt;
	List	   *save_alist;
	ListCell   *lcmd,
			   *l;
	List	   *newcmds = NIL;
	bool		skipValidation = true;
	AlterTableCmd *newcmd;
	ParseNamespaceItem *nsitem;

	/*
	 * transformAlterTableStmt should not be called by QE,
	 * the QE should use the results dispatched from QD.
	 */
	Assert(Gp_role != GP_ROLE_EXECUTE);
	/*
	 * We must not scribble on the passed-in AlterTableStmt, so copy it. (This
	 * is overkill, but easy.)
	 */
	stmt = copyObject(stmt);

	/* Caller is responsible for locking the relation */
	rel = relation_open(relid, NoLock);
	tupdesc = RelationGetDescr(rel);

	/* Set up pstate */
	pstate = make_parsestate(NULL);
	pstate->p_sourcetext = queryString;
	nsitem = addRangeTableEntryForRelation(pstate,
										   rel,
										   AccessShareLock,
										   NULL,
										   false,
										   true);
	addNSItemToQuery(pstate, nsitem, false, true, true);

	/* Set up CreateStmtContext */
	cxt.pstate = pstate;
	if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
	{
		cxt.stmtType = "ALTER FOREIGN TABLE";
		cxt.isforeign = true;
	}
	else
	{
		cxt.stmtType = "ALTER TABLE";
		cxt.isforeign = false;
	}
	cxt.relation = stmt->relation;
	cxt.rel = rel;
	cxt.inhRelations = NIL;