Function ProcessUtilityForAlterTable

src/backend/tcop/utility.c:2574–2615

* ProcessUtilityForAlterTable * Recursive entry from ALTER TABLE * * ALTER TABLE sometimes generates subcommands such as CREATE INDEX. * It calls this, not the main entry point ProcessUtility, to execute * such subcommands. * * stmt: the utility command to execute * context: opaque passthrough struct with the info we need * * It's caller's responsibility to do CommandCounterIncrement af

 * calling this, if needed.
 */
void
ProcessUtilityForAlterTable(Node *stmt, AlterTableUtilityContext *context)
{
	PlannedStmt *wrapper;

	/*
	 * For event triggers, we must "close" the current complex-command set,
	 * and start a new one afterwards; this is needed to ensure the ordering
	 * of command events is consistent with the way they were executed.
	 */
	EventTriggerAlterTableEnd();

	/* Create a suitable wrapper */
	wrapper = makeNode(PlannedStmt);
	wrapper->commandType = CMD_UTILITY;
	wrapper->canSetTag = false;
	wrapper->utilityStmt = stmt;
	wrapper->stmt_location = context->pstmt->stmt_location;
	wrapper->stmt_len = context->pstmt->stmt_len;

	/*
	 * We don't allow to dispatch some subcmds in ALTER TABLE before the QD has
	 * finished local execution. It causes the execution order different on QD
	 * and QEs, what's more some commands are not executed on QEs, this dispatched
	 * sub-commands will probably fail.
	 * In the end, the QD will dispatch the parse tree all in one after
	 * the QD has finished local execution, but before commit.
	 */
	HOLD_DISPATCH();
	ProcessUtility(wrapper,
				   context->queryString,
				   false,
				   PROCESS_UTILITY_SUBCOMMAND,
				   context->params,
				   context->queryEnv,
				   None_Receiver,
				   NULL);
	RESUME_DISPATCH();

	EventTriggerAlterTableStart(context->pstmt->utilityStmt);
	EventTriggerAlterTableRelid(context->relid);
}

/*
 * Dispatch function for DropStmt