Function transformCreateStmt

src/backend/parser/parse_utilcmd.c:184–449

* transformCreateStmt - * parse analysis for CREATE TABLE * * Returns a List of utility commands to be done in sequence. One of these * will be the transformed CreateStmt, but there may be additional actions * to be done before and after the actual DefineRelation() call. * In addition to normal utility commands such as AlterTableStmt and * IndexStmt, the result list may contain TableLike

 *	  - thomas 1997-12-02
 */
List *
transformCreateStmt(CreateStmt *stmt, const char *queryString)
{
	ParseState *pstate;
	CreateStmtContext cxt;
	List	   *result;
	List	   *save_alist;
	ListCell   *elements;
	Oid			namespaceid;
	Oid			existing_relid;
	ParseCallbackState pcbstate;

	DistributedBy *likeDistributedBy = NULL;
	bool		bQuiet = false;		/* shut up transformDistributedBy messages */

 	/*
	 * We don't normally care much about the memory consumption of parsing,
	 * because any memory leaked is leaked into MessageContext which is
	 * reset between each command. But if a table is heavily partitioned,
	 * the CREATE TABLE statement can be expanded into hundreds or even
	 * thousands of CreateStmts, so the leaks start to add up. To reduce
	 * the memory consumption, we use a temporary memory context that's
	 * destroyed after processing the CreateStmt for some parts of the
	 * processing.
	 */
	cxt.tempCtx =
		AllocSetContextCreate(CurrentMemoryContext,
							  "CreateStmt analyze context",
							  ALLOCSET_DEFAULT_MINSIZE,
							  ALLOCSET_DEFAULT_INITSIZE,
							  ALLOCSET_DEFAULT_MAXSIZE);

	/*
	 * We must not scribble on the passed-in CreateStmt, so copy it.  (This is
	 * overkill, but easy.)
	 */
	stmt = copyObject(stmt);


	/* Set up pstate */
	pstate = make_parsestate(NULL);
	pstate->p_sourcetext = queryString;

	/*
	 * Look up the creation namespace.  This also checks permissions on the
	 * target namespace, locks it against concurrent drops, checks for a
	 * preexisting relation in that namespace with the same name, and updates
	 * stmt->relation->relpersistence if the selected namespace is temporary.
	 */
	setup_parser_errposition_callback(&pcbstate, pstate,
									  stmt->relation->location);
	namespaceid =
		RangeVarGetAndCheckCreationNamespace(stmt->relation, NoLock,
											 &existing_relid);
	cancel_parser_errposition_callback(&pcbstate);

	/*
	 * If the relation already exists and the user specified "IF NOT EXISTS",