pl_exec.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

	PLpgSQL_dstring ds;
	ListCell   *current_param;

	plpgsql_dstring_init(&ds);
	current_param = list_head(stmt->params);

	for (cp = stmt->message; *cp; cp++)
	{
		/*
		 * Occurrences of a single % are replaced by the next parameter's
		 * external representation. Double %'s are converted to one %.
		 */
		if (cp[0] == '%')
		{
			Oid			paramtypeid;
			Datum		paramvalue;
			bool		paramisnull;
			char	   *extval;

			if (cp[1] == '%')
			{
				plpgsql_dstring_append_char(&ds, cp[1]);
				cp++;
				continue;
			}

			if (current_param == NULL)
				ereport(ERROR,
						(errcode(ERRCODE_SYNTAX_ERROR),
						 errmsg("too few parameters specified for RAISE")));

			paramvalue = exec_eval_expr(estate,
									  (PLpgSQL_expr *) lfirst(current_param),
										&paramisnull,
										&paramtypeid);

			if (paramisnull)
				extval = "<NULL>";
			else
				extval = convert_value_to_string(paramvalue, paramtypeid);
			plpgsql_dstring_append(&ds, extval);
			current_param = lnext(current_param);
			exec_eval_cleanup(estate);
			continue;
		}

		plpgsql_dstring_append_char(&ds, cp[0]);
	}

	/*
	 * If more parameters were specified than were required to process the
	 * format string, throw an error
	 */
	if (current_param != NULL)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("too many parameters specified for RAISE")));

	/*
	 * Throw the error (may or may not come back)
	 */
	estate->err_text = raise_skip_msg;	/* suppress traceback of raise */

	ereport(stmt->elog_level,
		 ((stmt->elog_level >= ERROR) ? errcode(ERRCODE_RAISE_EXCEPTION) : 0,
		  errmsg_internal("%s", plpgsql_dstring_get(&ds))));

	estate->err_text = NULL;	/* un-suppress... */

	plpgsql_dstring_free(&ds);

	return PLPGSQL_RC_OK;
}


/* ----------
 * Initialize a mostly empty execution state
 * ----------
 */
static void
plpgsql_estate_setup(PLpgSQL_execstate *estate,
					 PLpgSQL_function *func,
					 ReturnSetInfo *rsi)
{
	estate->retval = (Datum) 0;
	estate->retisnull = true;
	estate->rettype = InvalidOid;

	estate->fn_rettype = func->fn_rettype;
	estate->retistuple = func->fn_retistuple;
	estate->retisset = func->fn_retset;

	estate->readonly_func = func->fn_readonly;

	estate->rettupdesc = NULL;
	estate->exitlabel = NULL;

	estate->tuple_store = NULL;
	estate->tuple_store_cxt = NULL;
	estate->rsi = rsi;

	estate->trig_nargs = 0;
	estate->trig_argv = NULL;

	estate->found_varno = func->found_varno;
	estate->ndatums = func->ndatums;
	estate->datums = palloc(sizeof(PLpgSQL_datum *) * estate->ndatums);
	/* caller is expected to fill the datums array */

	estate->eval_tuptable = NULL;
	estate->eval_processed = 0;
	estate->eval_lastoid = InvalidOid;

	estate->err_func = func;
	estate->err_stmt = NULL;
	estate->err_text = NULL;

	/*
	 * Create an EState for evaluation of simple expressions, if there's not
	 * one already in the current transaction.	The EState is made a child of
	 * TopTransactionContext so it will have the right lifespan.
	 */
	if (simple_eval_estate == NULL)
	{
		MemoryContext oldcontext;

		oldcontext = MemoryContextSwitchTo(TopTransactionContext);
		simple_eval_estate = CreateExecutorState();
		MemoryContextSwitchTo(oldcontext);
	}

	/*
	 * Create an expression context for simple expressions. This must be a
	 * child of simple_eval_estate.
	 */
	estate->eval_econtext = CreateExprContext(simple_eval_estate);
}

/* ----------
 * Release temporary memory used by expression/subselect evaluation
 *
 * NB: the result of the evaluation is no longer valid after this is done,
 * unless it is a pass-by-value datatype.
 * ----------
 */
static void
exec_eval_cleanup(PLpgSQL_execstate *estate)
{
	/* Clear result of a full SPI_execute */
	if (estate->eval_tuptable != NULL)
		SPI_freetuptable(estate->eval_tuptable);
	estate->eval_tuptable = NULL;

	/* Clear result of exec_eval_simple_expr (but keep the econtext) */
	if (estate->eval_econtext != NULL)
		ResetExprContext(estate->eval_econtext);
}


/* ----------
 * Generate a prepared plan
 * ----------
 */
static void
exec_prepare_plan(PLpgSQL_execstate *estate,
				  PLpgSQL_expr *expr)
{
	int			i;
	_SPI_plan  *spi_plan;
	void	   *plan;
	Oid		   *argtypes;

	/*
	 * We need a temporary argtypes array to load with data. (The finished
	 * plan structure will contain a copy of it.)
	 */
	argtypes = (Oid *) palloc(expr->nparams * sizeof(Oid));

	for (i = 0; i < expr->nparams; i++)
	{
		Datum		paramval;
		bool		paramisnull;

		exec_eval_datum(estate, estate->datums[expr->params[i]],
						InvalidOid,
						&argtypes[i], &paramval, &paramisnull);
	}

	/*
	 * Generate and save the plan
	 */
	plan = SPI_prepare(expr->query, expr->nparams, argtypes);
	if (plan == NULL)
	{
		/* Some SPI errors deserve specific error messages */
		switch (SPI_result)
		{
			case SPI_ERROR_COPY:
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("cannot COPY to/from client in PL/pgSQL")));
			case SPI_ERROR_CURSOR:
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					errmsg("cannot manipulate cursors directly in PL/pgSQL"),
						 errhint("Use PL/pgSQL's cursor features instead.")));
			case SPI_ERROR_TRANSACTION:
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("cannot begin/end transactions in PL/pgSQL"),
						 errhint("Use a BEGIN block with an EXCEPTION clause instead.")));
			default:
				elog(ERROR, "SPI_prepare failed for \"%s\": %s",
					 expr->query, SPI_result_code_string(SPI_result));
		}
	}
	expr->plan = SPI_saveplan(plan);
	spi_plan = (_SPI_plan *) expr->plan;
	expr->plan_argtypes = spi_plan->argtypes;
	expr->expr_simple_expr = NULL;
	exec_simple_check_plan(expr);

	SPI_freeplan(plan);
	pfree(argtypes);
}


/* ----------
 * exec_stmt_execsql			Execute an SQL statement not
 *					returning any data.
 * ----------
 */
static int
exec_stmt_execsql(PLpgSQL_execstate *estate,
				  PLpgSQL_stmt_execsql *stmt)
{
	int			i;
	Datum	   *values;
	char	   *nulls;
	int			rc;
	PLpgSQL_expr *expr = stmt->sqlstmt;

	/*
	 * On the first call for this expression generate the plan
	 */
	if (expr->plan == NULL)
		exec_prepare_plan(estate, expr);

	/*
	 * Now build up the values and nulls arguments for SPI_execute_plan()
	 */
	values = (Datum *) palloc(expr->nparams * sizeof(Datum));
	nulls = (char *) palloc(expr->nparams * sizeof(char));

	for (i = 0; i < expr->nparams; i++)
	{
		PLpgSQL_datum *datum = estate->datums[expr->params[i]];
		Oid			paramtypeid;
		bool		paramisnull;

		exec_eval_datum(estate, datum, expr->plan_argtypes[i],
						&paramtypeid, &values[i], &paramisnull);
		if (paramisnull)
			nulls[i] = 'n';
		else
			nulls[i] = ' ';
	}

	/*
	 * Execute the plan
	 */
	rc = SPI_execute_plan(expr->plan, values, nulls,
						  estate->readonly_func, 0);
	switch (rc)
	{
		case SPI_OK_UTILITY:
		case SPI_OK_SELINTO:
			break;

		case SPI_OK_INSERT:
		case SPI_OK_DELETE:
		case SPI_OK_UPDATE:

			/*
			 * If the INSERT, DELETE, or UPDATE query affected at least one
			 * tuple, set the magic 'FOUND' variable to true. This conforms
			 * with the behavior of PL/SQL.
			 */
			exec_set_found(estate, (SPI_processed != 0));
			break;

		case SPI_OK_SELECT:
			ereport(ERROR,
					(errcode(ERRCODE_SYNTAX_ERROR),
				   errmsg("SELECT query has no destination for result data"),
					 errhint("If you want to discard the results, use PERFORM instead.")));

		default:
			elog(ERROR, "SPI_execute_plan failed executing query \"%s\": %s",
				 expr->query, SPI_result_code_string(rc));
	}

	/*
	 * Release any result tuples from SPI_execute_plan (probably shouldn't be
	 * any)
	 */
	SPI_freetuptable(SPI_tuptable);

	/* Save result info for GET DIAGNOSTICS */
	estate->eval_processed = SPI_processed;
	estate->eval_lastoid = SPI_lastoid;

	pfree(values);
	pfree(nulls);

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_dynexecute			Execute a dynamic SQL query not
 *					returning any data.
 * ----------
 */
static int
exec_stmt_dynexecute(PLpgSQL_execstate *estate,
					 PLpgSQL_stmt_dynexecute *stmt)
{
	Datum		query;
	bool		isnull = false;
	Oid			restype;
	char	   *querystr;
	int			exec_res;
	PLpgSQL_rec *rec = NULL;
	PLpgSQL_row *row = NULL;

	if (stmt->rec != NULL)
		rec = (PLpgSQL_rec *) (estate->datums[stmt->rec->recno]);
	else if (stmt->row != NULL)
		row = (PLpgSQL_row *) (estate->datums[stmt->row->rowno]);

	/*
	 * First we evaluate the string expression after the EXECUTE keyword. It's
	 * result is the querystring we have to execute.
	 */
	query = exec_eval_expr(estate, stmt->query, &isnull, &restype);
	if (isnull)
		ereport(ERROR,
				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
				 errmsg("cannot EXECUTE a null querystring")));

	/* Get the C-String representation */
	querystr = convert_value_to_string(query, restype);

	exec_eval_cleanup(estate);

	/*
	 * Call SPI_execute() without preparing a saved plan. The returncode can
	 * be any standard OK.	Note that while a SELECT is allowed, its results
	 * will be discarded unless an INTO clause is specified.
	 */
	exec_res = SPI_execute(querystr, estate->readonly_func, 0);

	/* Assign to INTO variable */
	if (rec || row)
	{
		if (exec_res != SPI_OK_SELECT)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("EXECUTE ... INTO is only for SELECT")));
		else
		{
			if (SPI_processed == 0)
				exec_move_row(estate, rec, row, NULL, SPI_tuptable->tupdesc);
			else
				exec_move_row(estate, rec, row,
							  SPI_tuptable->vals[0], SPI_tuptable->tupdesc);
		}
	}

	switch (exec_res)
	{
		case SPI_OK_SELECT:
		case SPI_OK_INSERT:
		case SPI_OK_UPDATE:
		case SPI_OK_DELETE:
		case SPI_OK_UTILITY:
			break;

		case 0:

			/*
			 * Also allow a zero return, which implies the querystring
			 * contained no commands.
			 */
			break;

		case SPI_OK_SELINTO:

			/*
			 * We want to disallow SELECT INTO for now, because its behavior
			 * is not consistent with SELECT INTO in a normal plpgsql context.
			 * (We need to reimplement EXECUTE to parse the string as a
			 * plpgsql command, not just feed it to SPI_execute.) However,
			 * CREATE AS should be allowed ... and since it produces the same
			 * parsetree as SELECT INTO, there's no way to tell the difference
			 * except to look at the source text.  Wotta kluge!
			 */
			{
				char	   *ptr;

				for (ptr = querystr; *ptr; ptr++)
					if (!isspace((unsigned char) *ptr))
						break;
				if (*ptr == 'S' || *ptr == 's')
					ereport(ERROR,
							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
							 errmsg("EXECUTE of SELECT ... INTO is not implemented yet")));
				break;
			}

			/* Some SPI errors deserve specific error messages */
		case SPI_ERROR_COPY:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("cannot COPY to/from client in PL/pgSQL")));
		case SPI_ERROR_CURSOR:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("cannot manipulate cursors directly in PL/pgSQL"),
					 errhint("Use PL/pgSQL's cursor features instead.")));
		case SPI_ERROR_TRANSACTION:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("cannot begin/end transactions in PL/pgSQL"),
			errhint("Use a BEGIN block with an EXCEPTION clause instead.")));

		default:
			elog(ERROR, "SPI_execute failed executing query \"%s\": %s",
				 querystr, SPI_result_code_string(exec_res));
			break;
	}

	/* Release any result from SPI_execute, as well as the querystring */
	SPI_freetuptable(SPI_tuptable);
	pfree(querystr);

	/* Save result info for GET DIAGNOSTICS */
	estate->eval_processed = SPI_processed;
	estate->eval_lastoid = SPI_lastoid;

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_dynfors			Execute a dynamic query, assign each
 *					tuple to a record or row and
 *					execute a group of statements
 *					for it.
 * ----------
 */
static int
exec_stmt_dynfors(PLpgSQL_execstate *estate, PLpgSQL_stmt_dynfors *stmt)
{
	Datum		query;
	bool		isnull;
	Oid			restype;
	char	   *querystr;
	PLpgSQL_rec *rec = NULL;
	PLpgSQL_row *row = NULL;
	SPITupleTable *tuptab;
	int			n;
	void	   *plan;
	Portal		portal;
	bool		found = false;

	/*
	 * Determine if we assign to a record or a row
	 */
	if (stmt->rec != NULL)
		rec = (PLpgSQL_rec *) (estate->datums[stmt->rec->recno]);
	else if (stmt->row != NULL)
		row = (PLpgSQL_row *) (estate->datums[stmt->row->rowno]);
	else
		elog(ERROR, "unsupported target");

	/*
	 * Evaluate the string expression after the EXECUTE keyword. It's result
	 * is the querystring we have to execute.
	 */
	query = exec_eval_expr(estate, stmt->query, &isnull, &restype);
	if (isnull)
		ereport(ERROR,
				(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
				 errmsg("cannot EXECUTE a null querystring")));

	/* Get the C-String representation */
	querystr = convert_value_to_string(query, restype);

	exec_eval_cleanup(estate);

	/*
	 * Prepare a plan and open an implicit cursor for the query
	 */
	plan = SPI_prepare(querystr, 0, NULL);
	if