execqual.c

PostgreSQL7.4.6 for Linux

		char	   *thisParamName = expression->paramname;
		bool		matchFound = false;

		if (paramList != NULL)
		{
			while (paramList->kind != PARAM_INVALID && !matchFound)
			{
				if (thisParamKind == paramList->kind)
				{
					switch (thisParamKind)
					{
						case PARAM_NAMED:
							if (strcmp(paramList->name, thisParamName) == 0)
								matchFound = true;
							break;
						case PARAM_NUM:
							if (paramList->id == thisParamId)
								matchFound = true;
							break;
						default:
							elog(ERROR, "unrecognized paramkind: %d",
								 thisParamKind);
					}
				}
				if (!matchFound)
					paramList++;
			}					/* while */
		}						/* if */

		if (!matchFound)
		{
			if (thisParamKind == PARAM_NAMED)
				ereport(ERROR,
						(errcode(ERRCODE_UNDEFINED_OBJECT),
						 errmsg("no value found for parameter \"%s\"",
								thisParamName)));
			else
				ereport(ERROR,
						(errcode(ERRCODE_UNDEFINED_OBJECT),
						 errmsg("no value found for parameter %d",
								thisParamId)));
		}

		*isNull = paramList->isnull;
		return paramList->value;
	}
}


/* ----------------------------------------------------------------
 *		ExecEvalOper / ExecEvalFunc support routines
 * ----------------------------------------------------------------
 */

/*
 *		GetAttributeByName
 *		GetAttributeByNum
 *
 *		These are functions which return the value of the
 *		named attribute out of the tuple from the arg slot.  User defined
 *		C functions which take a tuple as an argument are expected
 *		to use this.  Ex: overpaid(EMP) might call GetAttributeByNum().
 */
Datum
GetAttributeByNum(TupleTableSlot *slot,
				  AttrNumber attrno,
				  bool *isNull)
{
	Datum		retval;

	if (!AttributeNumberIsValid(attrno))
		elog(ERROR, "invalid attribute number %d", attrno);

	if (isNull == (bool *) NULL)
		elog(ERROR, "a NULL isNull pointer was passed");

	if (TupIsNull(slot))
	{
		*isNull = true;
		return (Datum) 0;
	}

	retval = heap_getattr(slot->val,
						  attrno,
						  slot->ttc_tupleDescriptor,
						  isNull);
	if (*isNull)
		return (Datum) 0;

	return retval;
}

Datum
GetAttributeByName(TupleTableSlot *slot, char *attname, bool *isNull)
{
	AttrNumber	attrno;
	TupleDesc	tupdesc;
	Datum		retval;
	int			natts;
	int			i;

	if (attname == NULL)
		elog(ERROR, "invalid attribute name");

	if (isNull == (bool *) NULL)
		elog(ERROR, "a NULL isNull pointer was passed");

	if (TupIsNull(slot))
	{
		*isNull = true;
		return (Datum) 0;
	}

	tupdesc = slot->ttc_tupleDescriptor;
	natts = slot->val->t_data->t_natts;

	attrno = InvalidAttrNumber;
	for (i = 0; i < tupdesc->natts; i++)
	{
		if (namestrcmp(&(tupdesc->attrs[i]->attname), attname) == 0)
		{
			attrno = tupdesc->attrs[i]->attnum;
			break;
		}
	}

	if (attrno == InvalidAttrNumber)
		elog(ERROR, "attribute \"%s\" does not exist", attname);

	retval = heap_getattr(slot->val,
						  attrno,
						  tupdesc,
						  isNull);
	if (*isNull)
		return (Datum) 0;

	return retval;
}

/*
 * init_fcache - initialize a FuncExprState node during first use
 */
void
init_fcache(Oid foid, FuncExprState *fcache, MemoryContext fcacheCxt)
{
	AclResult	aclresult;

	/* Check permission to call function */
	aclresult = pg_proc_aclcheck(foid, GetUserId(), ACL_EXECUTE);
	if (aclresult != ACLCHECK_OK)
		aclcheck_error(aclresult, ACL_KIND_PROC, get_func_name(foid));

	/* Safety check (should never fail, as parser should check sooner) */
	if (length(fcache->args) > FUNC_MAX_ARGS)
		elog(ERROR, "too many arguments");

	/* Set up the primary fmgr lookup information */
	fmgr_info_cxt(foid, &(fcache->func), fcacheCxt);

	/* Initialize additional info */
	fcache->setArgsValid = false;
	fcache->shutdown_reg = false;
	fcache->func.fn_expr = (Node *) fcache->xprstate.expr;
}

/*
 * callback function in case a FuncExpr returning a set needs to be shut down
 * before it has been run to completion
 */
static void
ShutdownFuncExpr(Datum arg)
{
	FuncExprState *fcache = (FuncExprState *) DatumGetPointer(arg);

	/* Clear any active set-argument state */
	fcache->setArgsValid = false;

	/* execUtils will deregister the callback... */
	fcache->shutdown_reg = false;
}

/*
 * Evaluate arguments for a function.
 */
static ExprDoneCond
ExecEvalFuncArgs(FunctionCallInfo fcinfo,
				 List *argList,
				 ExprContext *econtext)
{
	ExprDoneCond argIsDone;
	int			i;
	List	   *arg;

	argIsDone = ExprSingleResult;		/* default assumption */

	i = 0;
	foreach(arg, argList)
	{
		ExprDoneCond thisArgIsDone;

		fcinfo->arg[i] = ExecEvalExpr((ExprState *) lfirst(arg),
									  econtext,
									  &fcinfo->argnull[i],
									  &thisArgIsDone);

		if (thisArgIsDone != ExprSingleResult)
		{
			/*
			 * We allow only one argument to have a set value; we'd need
			 * much more complexity to keep track of multiple set
			 * arguments (cf. ExecTargetList) and it doesn't seem worth
			 * it.
			 */
			if (argIsDone != ExprSingleResult)
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("functions and operators can take at most one set argument")));
			argIsDone = thisArgIsDone;
		}
		i++;
	}

	fcinfo->nargs = i;

	return argIsDone;
}

/*
 *		ExecMakeFunctionResult
 *
 * Evaluate the arguments to a function and then the function itself.
 */
Datum
ExecMakeFunctionResult(FuncExprState *fcache,
					   ExprContext *econtext,
					   bool *isNull,
					   ExprDoneCond *isDone)
{
	List	   *arguments = fcache->args;
	Datum		result;
	FunctionCallInfoData fcinfo;
	ReturnSetInfo rsinfo;		/* for functions returning sets */
	ExprDoneCond argDone;
	bool		hasSetArg;
	int			i;

	/*
	 * arguments is a list of expressions to evaluate before passing to
	 * the function manager.  We skip the evaluation if it was already
	 * done in the previous call (ie, we are continuing the evaluation of
	 * a set-valued function).	Otherwise, collect the current argument
	 * values into fcinfo.
	 */
	if (!fcache->setArgsValid)
	{
		/* Need to prep callinfo structure */
		MemSet(&fcinfo, 0, sizeof(fcinfo));
		fcinfo.flinfo = &(fcache->func);
		argDone = ExecEvalFuncArgs(&fcinfo, arguments, econtext);
		if (argDone == ExprEndResult)
		{
			/* input is an empty set, so return an empty set. */
			*isNull = true;
			if (isDone)
				*isDone = ExprEndResult;
			else
				ereport(ERROR,
						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
						 errmsg("set-valued function called in context that cannot accept a set")));
			return (Datum) 0;
		}
		hasSetArg = (argDone != ExprSingleResult);
	}
	else
	{
		/* Copy callinfo from previous evaluation */
		memcpy(&fcinfo, &fcache->setArgs, sizeof(fcinfo));
		hasSetArg = fcache->setHasSetArg;
		/* Reset flag (we may set it again below) */
		fcache->setArgsValid = false;
	}

	/*
	 * If function returns set, prepare a resultinfo node for
	 * communication
	 */
	if (fcache->func.fn_retset)
	{
		fcinfo.resultinfo = (Node *) &rsinfo;
		rsinfo.type = T_ReturnSetInfo;
		rsinfo.econtext = econtext;
		rsinfo.expectedDesc = NULL;
		rsinfo.allowedModes = (int) SFRM_ValuePerCall;
		rsinfo.returnMode = SFRM_ValuePerCall;
		/* isDone is filled below */
		rsinfo.setResult = NULL;
		rsinfo.setDesc = NULL;
	}

	/*
	 * now return the value gotten by calling the function manager,
	 * passing the function the evaluated parameter values.
	 */
	if (fcache->func.fn_retset || hasSetArg)
	{
		/*
		 * We need to return a set result.	Complain if caller not ready
		 * to accept one.
		 */
		if (isDone == NULL)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("set-valued function called in context that cannot accept a set")));

		/*
		 * This loop handles the situation where we have both a set
		 * argument and a set-valued function.	Once we have exhausted the
		 * function's value(s) for a particular argument value, we have to
		 * get the next argument value and start the function over again.
		 * We might have to do it more than once, if the function produces
		 * an empty result set for a particular input value.
		 */
		for (;;)
		{
			/*
			 * If function is strict, and there are any NULL arguments,
			 * skip calling the function (at least for this set of args).
			 */
			bool		callit = true;

			if (fcache->func.fn_strict)
			{
				for (i = 0; i < fcinfo.nargs; i++)
				{
					if (fcinfo.argnull[i])
					{
						callit = false;
						break;
					}
				}
			}

			if (callit)
			{
				fcinfo.isnull = false;
				rsinfo.isDone = ExprSingleResult;
				result = FunctionCallInvoke(&fcinfo);
				*isNull = fcinfo.isnull;
				*isDone = rsinfo.isDone;
			}
			else
			{
				result = (Datum) 0;
				*isNull = true;
				*isDone = ExprEndResult;
			}

			if (*isDone != ExprEndResult)
			{
				/*
				 * Got a result from current argument.	If function itself
				 * returns set, save the current argument values to re-use
				 * on the next call.
				 */
				if (fcache->func.fn_retset)
				{
					memcpy(&fcache->setArgs, &fcinfo, sizeof(fcinfo));
					fcache->setHasSetArg = hasSetArg;
					fcache->setArgsValid = true;
					/* Register cleanup callback if we didn't already */
					if (!fcache->shutdown_reg)
					{
						RegisterExprContextCallback(econtext,
													ShutdownFuncExpr,
													PointerGetDatum(fcache));
						fcache->shutdown_reg = true;
					}
				}

				/*
				 * Make sure we say we are returning a set, even if the
				 * function itself doesn't return sets.
				 */
				*isDone = ExprMultipleResult;
				break;
			}

			/* Else, done with this argument */
			if (!hasSetArg)
				break;			/* input not a set, so done */

			/* Re-eval args to get the next element of the input set */
			argDone = ExecEvalFuncArgs(&fcinfo, arguments, econtext);

			if (argDone != ExprMultipleResult)
			{
				/* End of argument set, so we're done. */
				*isNull = true;
				*isDone = ExprEndResult;
				result = (Datum) 0;
				break;
			}

			/*
			 * If we reach here, loop around to run the function on the
			 * new argument.
			 */
		}
	}
	else
	{
		/*
		 * Non-set case: much easier.
		 *
		 * If function is strict, and there are any NULL arguments, skip
		 * calling the function and return NULL.
		 */
		if (fcache->func.fn_strict)
		{
			for (i = 0; i < fcinfo.nargs; i++)
			{
				if (fcinfo.argnull[i])
				{
					*isNull = true;
					return (Datum) 0;
				}
			}
		}
		fcinfo.isnull = false;
		result = FunctionCallInvoke(&fcinfo);
		*isNull = fcinfo.isnull;
	}

	return result;
}


/*
 *		ExecMakeTableFunctionResult
 *
 * Evaluate a table function, producing a materialized result in a Tuplestore
 * object.	(If function returns an empty set, we just return NULL instead.)
 */
Tuplestorestate *
ExecMakeTableFunctionResult(ExprState *funcexpr,
							ExprContext *econtext,
							TupleDesc expectedDesc,
							TupleDesc *returnDesc)
{
	Tuplestorestate *tupstore = NULL;
	TupleDesc	tupdesc = NULL;
	Oid			funcrettype;
	FunctionCallInfoData fcinfo;
	ReturnSetInfo rsinfo;
	MemoryContext callerContext;
	MemoryContext oldcontext;
	TupleTableSlot *slot;
	bool		direct_function_call;
	bool		first_time = true;
	bool		returnsTuple = false;

	/*
	 * Normally the passed expression tree will be a FuncExprState, since
	 * the grammar only allows a function call at the top level of a table
	 * function reference.	However, if the function doesn't return set
	 * then the planner might have replaced the function call via
	 * constant-folding or inlining.  So if we see any other kind of
	 * expression node, execute it via the general ExecEvalExpr() code;
	 * the only difference is that we don't get a chance to pass a special
	 * ReturnSetInfo to any functions buried in the expression.
	 */
	if (funcexpr && IsA(funcexpr, FuncExprState) &&
		IsA(funcexpr->expr, FuncExpr))
	{
		FuncExprState *fcache = (FuncExprState *) funcexpr;
		ExprDoneCond argDone;