pl_exec.c

关系型数据库 Postgresql 6.5.2

	else if (TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
		var->value = (Datum) textin("STATEMENT");
	else
		var->value = (Datum) textin("UNKNOWN");

	var = (PLpgSQL_var *) (estate.datums[func->tg_relid_varno]);
	var->isnull = false;
	var->value = (Datum) (trigdata->tg_relation->rd_id);

	var = (PLpgSQL_var *) (estate.datums[func->tg_relname_varno]);
	var->isnull = false;
	var->value = (Datum) namein(nameout(&(trigdata->tg_relation->rd_rel->relname)));

	var = (PLpgSQL_var *) (estate.datums[func->tg_nargs_varno]);
	var->isnull = false;
	var->value = (Datum) (trigdata->tg_trigger->tgnargs);

	/* ----------
	 * Put the actual call argument values into the special
	 * execution state variables
	 * ----------
	 */
	error_info_text = "while putting call arguments to local variables";
	estate.trig_nargs = trigdata->tg_trigger->tgnargs;
	if (estate.trig_nargs == 0)
		estate.trig_argv = NULL;
	else
	{
		estate.trig_argv = palloc(sizeof(Datum) * estate.trig_nargs);
		for (i = 0; i < trigdata->tg_trigger->tgnargs; i++)
			estate.trig_argv[i] = (Datum) textin(trigdata->tg_trigger->tgargs[i]);
	}

	/* ----------
	 * Initialize the other variables to NULL values for now.
	 * The default values are set when the blocks are entered.
	 * ----------
	 */
	error_info_text = "while initializing local variables to NULL";
	for (i = estate.found_varno; i < estate.ndatums; i++)
	{
		switch (estate.datums[i]->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				{
					PLpgSQL_var *var = (PLpgSQL_var *) estate.datums[i];

					var->value = 0;
					var->isnull = true;
					var->shouldfree = false;
				}
				break;

			case PLPGSQL_DTYPE_ROW:
			case PLPGSQL_DTYPE_REC:
			case PLPGSQL_DTYPE_RECFIELD:
			case PLPGSQL_DTYPE_TRIGARG:
				break;

			default:
				elog(ERROR, "unknown dtype %d in plpgsql_exec_trigger()",
					 func->datums[i]->dtype);
		}
	}

	/* ----------
	 * Set the magic variable FOUND to false
	 * ----------
	 */
	exec_set_found(&estate, false);

	/* ----------
	 * Now call the toplevel block of statements
	 * ----------
	 */
	error_info_text = NULL;
	error_info_stmt = (PLpgSQL_stmt *) (func->action);
	if (exec_stmt_block(&estate, func->action) != PLPGSQL_RC_RETURN)
	{
		error_info_stmt = NULL;
		error_info_text = "at END of toplevel PL block";
		elog(ERROR, "control reaches end of trigger procedure without RETURN");
	}

	/* ----------
	 * Check that the returned tuple structure has the same attributes,
	 * the relation that fired the trigger has.
	 *
	 * XXX This way it is possible, that the trigger returns a tuple
	 *	   where attributes don't have the correct atttypmod's length.
	 *	   It's up to the trigger's programmer to ensure that this
	 *	   doesn't happen. Jan
	 * ----------
	 */
	if (estate.retisnull)
		rettup = NULL;
	else
	{
		TupleDesc	td1 = trigdata->tg_relation->rd_att;
		TupleDesc	td2 = estate.rettupdesc;
		int			i;

		if (td1->natts != td2->natts)
			elog(ERROR, "returned tuple structure doesn't match table of trigger event");
		for (i = 1; i <= td1->natts; i++)
		{
			if (SPI_gettypeid(td1, i) != SPI_gettypeid(td2, i))
				elog(ERROR, "returned tuple structure doesn't match table of trigger event");
		}

		rettup = SPI_copytuple((HeapTuple) (estate.retval));
	}

	/* ----------
	 * Restore the previous error info and elog() jump target
	 * ----------
	 */
	error_info_func = save_efunc;
	error_info_stmt = save_estmt;
	error_info_text = save_etext;
	memcpy(&Warn_restart, &save_restart, sizeof(Warn_restart));

	/* ----------
	 * Return the triggers result
	 * ----------
	 */
	return rettup;
}


/* ----------
 * Support functions for copying local execution variables
 * ----------
 */
static PLpgSQL_var *
copy_var(PLpgSQL_var * var)
{
	PLpgSQL_var *new = palloc(sizeof(PLpgSQL_var));

	memcpy(new, var, sizeof(PLpgSQL_var));

	return new;
}


static PLpgSQL_rec *
copy_rec(PLpgSQL_rec * rec)
{
	PLpgSQL_rec *new = palloc(sizeof(PLpgSQL_rec));

	memcpy(new, rec, sizeof(PLpgSQL_rec));

	return new;
}


/* ----------
 * exec_stmt_block			Execute a block of statements
 * ----------
 */
static int
exec_stmt_block(PLpgSQL_execstate * estate, PLpgSQL_stmt_block * block)
{
	int			rc;
	int			i;
	int			n;

	/* ----------
	 * First initialize all variables declared in this block
	 * ----------
	 */
	for (i = 0; i < block->n_initvars; i++)
	{
		n = block->initvarnos[i];

		switch (estate->datums[n]->dtype)
		{
			case PLPGSQL_DTYPE_VAR:
				{
					PLpgSQL_var *var = (PLpgSQL_var *) (estate->datums[n]);

					if (!var->isconst || var->isnull)
					{
						if (var->default_val == NULL)
						{
							var->value = (Datum) 0;
							var->isnull = true;
							if (var->notnull)
								elog(ERROR, "variable '%s' declared NOT NULL cannot default to NULL", var->refname);
						}
						else
						{
							exec_assign_expr(estate, (PLpgSQL_datum *) var,
											 var->default_val);
						}
					}
				}
				break;

			case PLPGSQL_DTYPE_REC:
				{
					PLpgSQL_rec *rec = (PLpgSQL_rec *) (estate->datums[n]);

					rec->tup = NULL;
					rec->tupdesc = NULL;
				}
				break;

			case PLPGSQL_DTYPE_RECFIELD:
				break;

			default:
				elog(ERROR, "unknown dtype %d in exec_stmt_block()", estate->datums[n]->dtype);
		}

	}

	/* ----------
	 * Execute the statements in the block's body
	 * ----------
	 */
	rc = exec_stmts(estate, block->body);

	/* ----------
	 * Handle the return code.
	 * ----------
	 */
	switch (rc)
	{
		case PLPGSQL_RC_OK:
			return PLPGSQL_RC_OK;

		case PLPGSQL_RC_EXIT:
			if (estate->exitlabel == NULL)
				return PLPGSQL_RC_OK;
			if (block->label == NULL)
				return PLPGSQL_RC_EXIT;
			if (strcmp(block->label, estate->exitlabel))
				return PLPGSQL_RC_EXIT;
			estate->exitlabel = NULL;
			return PLPGSQL_RC_OK;

		case PLPGSQL_RC_RETURN:
			return PLPGSQL_RC_RETURN;

		default:
			elog(ERROR, "unknown rc %d from exec_stmt()", rc);
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmts			Iterate over a list of statements
 *				as long as their return code is OK
 * ----------
 */
static int
exec_stmts(PLpgSQL_execstate * estate, PLpgSQL_stmts * stmts)
{
	int			rc;
	int			i;

	for (i = 0; i < stmts->stmts_used; i++)
	{
		rc = exec_stmt(estate, (PLpgSQL_stmt *) (stmts->stmts[i]));
		if (rc != PLPGSQL_RC_OK)
			return rc;
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt			Distribute one statement to the statements
 *				type specific execution function.
 * ----------
 */
static int
exec_stmt(PLpgSQL_execstate * estate, PLpgSQL_stmt * stmt)
{
	PLpgSQL_stmt *save_estmt;
	int			rc = -1;

	save_estmt = error_info_stmt;
	error_info_stmt = stmt;

	switch (stmt->cmd_type)
	{
		case PLPGSQL_STMT_BLOCK:
			rc = exec_stmt_block(estate, (PLpgSQL_stmt_block *) stmt);
			break;

		case PLPGSQL_STMT_ASSIGN:
			rc = exec_stmt_assign(estate, (PLpgSQL_stmt_assign *) stmt);
			break;

		case PLPGSQL_STMT_IF:
			rc = exec_stmt_if(estate, (PLpgSQL_stmt_if *) stmt);
			break;

		case PLPGSQL_STMT_LOOP:
			rc = exec_stmt_loop(estate, (PLpgSQL_stmt_loop *) stmt);
			break;

		case PLPGSQL_STMT_WHILE:
			rc = exec_stmt_while(estate, (PLpgSQL_stmt_while *) stmt);
			break;

		case PLPGSQL_STMT_FORI:
			rc = exec_stmt_fori(estate, (PLpgSQL_stmt_fori *) stmt);
			break;

		case PLPGSQL_STMT_FORS:
			rc = exec_stmt_fors(estate, (PLpgSQL_stmt_fors *) stmt);
			break;

		case PLPGSQL_STMT_SELECT:
			rc = exec_stmt_select(estate, (PLpgSQL_stmt_select *) stmt);
			break;

		case PLPGSQL_STMT_EXIT:
			rc = exec_stmt_exit(estate, (PLpgSQL_stmt_exit *) stmt);
			break;

		case PLPGSQL_STMT_RETURN:
			rc = exec_stmt_return(estate, (PLpgSQL_stmt_return *) stmt);
			break;

		case PLPGSQL_STMT_RAISE:
			rc = exec_stmt_raise(estate, (PLpgSQL_stmt_raise *) stmt);
			break;

		case PLPGSQL_STMT_EXECSQL:
			rc = exec_stmt_execsql(estate, (PLpgSQL_stmt_execsql *) stmt);
			break;

		default:
			error_info_stmt = save_estmt;
			elog(ERROR, "unknown cmdtype %d in exec_stmt",
				 stmt->cmd_type);
	}

	error_info_stmt = save_estmt;

	return rc;
}


/* ----------
 * exec_stmt_assign			Evaluate an expression and
 *					put the result into a variable.
 * ----------
 */
static int
exec_stmt_assign(PLpgSQL_execstate * estate, PLpgSQL_stmt_assign * stmt)
{
	if (stmt->varno < 0)
		exec_assign_expr(estate, NULL, stmt->expr);
	else
		exec_assign_expr(estate, estate->datums[stmt->varno], stmt->expr);

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_if				Evaluate a bool expression and
 *					execute the true or false body
 *					conditionally.
 * ----------
 */
static int
exec_stmt_if(PLpgSQL_execstate * estate, PLpgSQL_stmt_if * stmt)
{
	Datum		value;
	Oid			valtype;
	bool		isnull = false;

	value = exec_eval_expr(estate, stmt->cond, &isnull, &valtype);

	if (value)
	{
		if (stmt->true_body != NULL)
			return exec_stmts(estate, stmt->true_body);
	}
	else
	{
		if (stmt->false_body != NULL)
			return exec_stmts(estate, stmt->false_body);
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_loop			Loop over statements until
 *					an exit occurs.
 * ----------
 */
static int
exec_stmt_loop(PLpgSQL_execstate * estate, PLpgSQL_stmt_loop * stmt)
{
	int			rc;

	for (;;)
	{
		rc = exec_stmts(estate, stmt->body);

		switch (rc)
		{
			case PLPGSQL_RC_OK:
				break;

			case PLPGSQL_RC_EXIT:
				if (estate->exitlabel == NULL)
					return PLPGSQL_RC_OK;
				if (stmt->label == NULL)
					return PLPGSQL_RC_EXIT;
				if (strcmp(stmt->label, estate->exitlabel))
					return PLPGSQL_RC_EXIT;
				estate->exitlabel = NULL;
				return PLPGSQL_RC_OK;

			case PLPGSQL_RC_RETURN:
				return PLPGSQL_RC_RETURN;

			default:
				elog(ERROR, "unknown rc %d from exec_stmts()", rc);
		}
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_while			Loop over statements as long
 *					as an expression evaluates to
 *					true or an exit occurs.
 * ----------
 */
static int
exec_stmt_while(PLpgSQL_execstate * estate, PLpgSQL_stmt_while * stmt)
{
	Datum		value;
	Oid			valtype;
	bool		isnull = false;
	int			rc;

	for (;;)
	{
		value = exec_eval_expr(estate, stmt->cond, &isnull, &valtype);
		if (!value)
			break;

		rc = exec_stmts(estate, stmt->body);

		switch (rc)
		{
			case PLPGSQL_RC_OK:
				break;

			case PLPGSQL_RC_EXIT:
				if (estate->exitlabel == NULL)
					return PLPGSQL_RC_OK;
				if (stmt->label == NULL)
					return PLPGSQL_RC_EXIT;
				if (strcmp(stmt->label, estate->exitlabel))
					return PLPGSQL_RC_EXIT;
				estate->exitlabel = NULL;
				return PLPGSQL_RC_OK;

			case PLPGSQL_RC_RETURN:
				return PLPGSQL_RC_RETURN;

			default:
				elog(ERROR, "unknown rc %d from exec_stmts()", rc);
		}
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_fori			Iterate an integer variable
 *					from a lower to an upper value.
 *					Loop can be left with exit.
 * ----------
 */
static int
exec_stmt_fori(PLpgSQL_execstate * estate, PLpgSQL_stmt_fori * stmt)
{
	PLpgSQL_var *var;
	Datum		value;
	Oid			valtype;
	bool		isnull = false;
	int			rc;

	/* ----------
	 * Get the value of the lower bound into the loop var
	 * ----------
	 */
	value = exec_eval_expr(estate, stmt->lower, &isnull, &valtype);
	var = (PLpgSQL_var *) (estate->datums[stmt->var->varno]);

	value = exec_cast_value(value, valtype, var->datatype->typoid,
							&(var->datatype->typinput),
							var->datatype->atttypmod, &isnull);
	if (isnull)
		elog(ERROR, "lower bound of FOR loop cannot be NULL");
	var->value = value;
	var->isnull = false;

	/* ----------
	 * Get the value of the upper bound
	 * ----------
	 */
	value = exec_eval_expr(estate, stmt->upper, &isnull, &valtype);
	value = exec_cast_value(value, valtype, var->datatype->typoid,
							&(var->datatype->typinput),
							var->datatype->atttypmod, &isnull);
	if (isnull)
		elog(ERROR, "upper bound of FOR loop cannot be NULL");

	/* ----------
	 * Now do the loop
	 * ----------
	 */
	exec_set_found(estate, false);
	for (;;)
	{
		/* ----------
		 * Check bounds
		 * ----------
		 */
		if (stmt->reverse)
		{
			if ((int4) (var->value) < (int4) value)
				break;
		}
		else
		{
			if ((int4) (var->value) > (int4) value)
				break;
		}
		exec_set_found(estate, true);

		/* ----------
		 * Execute the statements
		 * ----------
		 */
		rc = exec_stmts(estate, stmt->body);

		/* ----------
		 * Check returncode
		 * ----------
		 */
		switch (rc)
		{
			case PLPGSQL_RC_OK:
				break;

			case PLPGSQL_RC_EXIT:
				if (estate->exitlabel == NULL)
					return PLPGSQL_RC_OK;
				if (stmt->label == NULL)
					return PLPGSQL_RC_EXIT;
				if (strcmp(stmt->label, estate->exitlabel))
					return PLPGSQL_RC_EXIT;
				estate->exitlabel = NULL;
				return PLPGSQL_RC_OK;

			case PLPGSQL_RC_RETURN:
				return PLPGSQL_RC_RETURN;

			default:
				elog(ERROR, "unknown rc %d from exec_stmts()", rc);
		}

		/* ----------
		 * Increase/decrease loop var
		 * ----------
		 */
		if (stmt->reverse)
			var->value--;
		else
			var->value++;
	}

	return PLPGSQL_RC_OK;
}


/* ----------
 * exec_stmt_fors			Execute a query, assign each
 *					tuple to a record or row and
 *					execute a group of statements
 *					for it.
 * ----------
 */
static int
exec_stmt_fors(PLpgSQL_execstate * estate, PLpgSQL_stmt_fors * stmt)
{
	PLpgSQL_rec *rec = NULL;
	PLpgSQL_row *row = NULL;
	SPITupleTable *tuptab;
	int			rc;
	int			i;
	int			n;

	/* ----------
	 * Initialize the global found variable to false
	 * ----------
	 */
	exec_set_found(estate, 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 in exec_stmt_fors()");
	}

	/* ----------
	 * Run the query
	 * ----------
	 */
	exec_run_select(estate, stmt->query, 0);
	n = SPI_processed;

	/* ----------
	 * If the query didn't return any row, set the target
	 * to NULL and return.
	 * ----------
	 */
	if (n == 0)
	{
		exec_move_row(estate, rec, row, NULL, NULL);
		return PLPGSQL_RC_OK;