execqual.c

PostgreSQL7.4.6 for Linux

		/*
		 * This path is similar to ExecMakeFunctionResult.
		 */
		direct_function_call = true;

		/*
		 * Initialize function cache if first time through
		 */
		if (fcache->func.fn_oid == InvalidOid)
		{
			FuncExpr   *func = (FuncExpr *) fcache->xprstate.expr;

			init_fcache(func->funcid, fcache, econtext->ecxt_per_query_memory);
		}

		/*
		 * Evaluate the function's argument list.
		 *
		 * Note: ideally, we'd do this in the per-tuple context, but then the
		 * argument values would disappear when we reset the context in
		 * the inner loop.	So do it in caller context.  Perhaps we should
		 * make a separate context just to hold the evaluated arguments?
		 */
		MemSet(&fcinfo, 0, sizeof(fcinfo));
		fcinfo.flinfo = &(fcache->func);
		argDone = ExecEvalFuncArgs(&fcinfo, fcache->args, econtext);
		/* We don't allow sets in the arguments of the table function */
		if (argDone != ExprSingleResult)
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("set-valued function called in context that cannot accept a set")));

		/*
		 * If function is strict, and there are any NULL arguments, skip
		 * calling the function and return NULL (actually an empty set).
		 */
		if (fcache->func.fn_strict)
		{
			int			i;

			for (i = 0; i < fcinfo.nargs; i++)
			{
				if (fcinfo.argnull[i])
				{
					*returnDesc = NULL;
					return NULL;
				}
			}
		}
	}
	else
	{
		/* Treat funcexpr as a generic expression */
		direct_function_call = false;
	}

	funcrettype = exprType((Node *) funcexpr->expr);

	/*
	 * Prepare a resultinfo node for communication.  We always do this
	 * even if not expecting a set result, so that we can pass
	 * expectedDesc.  In the generic-expression case, the expression
	 * doesn't actually get to see the resultinfo, but set it up anyway
	 * because we use some of the fields as our own state variables.
	 */
	fcinfo.resultinfo = (Node *) &rsinfo;
	rsinfo.type = T_ReturnSetInfo;
	rsinfo.econtext = econtext;
	rsinfo.expectedDesc = expectedDesc;
	rsinfo.allowedModes = (int) (SFRM_ValuePerCall | SFRM_Materialize);
	rsinfo.returnMode = SFRM_ValuePerCall;
	/* isDone is filled below */
	rsinfo.setResult = NULL;
	rsinfo.setDesc = NULL;

	/*
	 * Switch to short-lived context for calling the function or
	 * expression.
	 */
	callerContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);

	/*
	 * Loop to handle the ValuePerCall protocol (which is also the same
	 * behavior needed in the generic ExecEvalExpr path).
	 */
	for (;;)
	{
		Datum		result;
		HeapTuple	tuple;

		/*
		 * reset per-tuple memory context before each call of the function
		 * or expression. This cleans up any local memory the function may
		 * leak when called.
		 */
		ResetExprContext(econtext);

		/* Call the function or expression one time */
		if (direct_function_call)
		{
			fcinfo.isnull = false;
			rsinfo.isDone = ExprSingleResult;
			result = FunctionCallInvoke(&fcinfo);
		}
		else
		{
			result = ExecEvalExpr(funcexpr, econtext,
								  &fcinfo.isnull, &rsinfo.isDone);
		}

		/* Which protocol does function want to use? */
		if (rsinfo.returnMode == SFRM_ValuePerCall)
		{
			/*
			 * Check for end of result set.
			 *
			 * Note: if function returns an empty set, we don't build a
			 * tupdesc or tuplestore (since we can't get a tupdesc in the
			 * function-returning-tuple case)
			 */
			if (rsinfo.isDone == ExprEndResult)
				break;

			/*
			 * If first time through, build tupdesc and tuplestore for
			 * result
			 */
			if (first_time)
			{
				oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
				if (funcrettype == RECORDOID ||
					get_typtype(funcrettype) == 'c')
				{
					/*
					 * Composite type, so function should have returned a
					 * TupleTableSlot; use its descriptor
					 */
					slot = (TupleTableSlot *) DatumGetPointer(result);
					if (fcinfo.isnull || !slot)
						ereport(ERROR,
								(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
								 errmsg("function returning row cannot return null value")));
					if (!IsA(slot, TupleTableSlot) ||
						!slot->ttc_tupleDescriptor)
						ereport(ERROR,
								(errcode(ERRCODE_DATATYPE_MISMATCH),
								 errmsg("function returning row did not return a valid tuple slot")));
					tupdesc = CreateTupleDescCopy(slot->ttc_tupleDescriptor);
					returnsTuple = true;
				}
				else
				{
					/*
					 * Scalar type, so make a single-column descriptor
					 */
					tupdesc = CreateTemplateTupleDesc(1, false);
					TupleDescInitEntry(tupdesc,
									   (AttrNumber) 1,
									   "column",
									   funcrettype,
									   -1,
									   0,
									   false);
				}
				tupstore = tuplestore_begin_heap(true, false, SortMem);
				MemoryContextSwitchTo(oldcontext);
				rsinfo.setResult = tupstore;
				rsinfo.setDesc = tupdesc;
			}

			/*
			 * Store current resultset item.
			 */
			if (returnsTuple)
			{
				slot = (TupleTableSlot *) DatumGetPointer(result);
				if (fcinfo.isnull ||
					!slot ||
					!IsA(slot, TupleTableSlot) ||
					TupIsNull(slot))
					ereport(ERROR,
							(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
							 errmsg("function returning row cannot return null value")));
				tuple = slot->val;
			}
			else
			{
				char		nullflag;

				nullflag = fcinfo.isnull ? 'n' : ' ';
				tuple = heap_formtuple(tupdesc, &result, &nullflag);
			}

			oldcontext = MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
			tuplestore_puttuple(tupstore, tuple);
			MemoryContextSwitchTo(oldcontext);

			/*
			 * Are we done?
			 */
			if (rsinfo.isDone != ExprMultipleResult)
				break;
		}
		else if (rsinfo.returnMode == SFRM_Materialize)
		{
			/* check we're on the same page as the function author */
			if (!first_time || rsinfo.isDone != ExprSingleResult)
				ereport(ERROR,
						(errcode(ERRCODE_E_R_I_E_SRF_PROTOCOL_VIOLATED),
						 errmsg("table-function protocol for materialize mode was not followed")));
			/* Done evaluating the set result */
			break;
		}
		else
			ereport(ERROR,
					(errcode(ERRCODE_E_R_I_E_SRF_PROTOCOL_VIOLATED),
					 errmsg("unrecognized table-function returnMode: %d",
							(int) rsinfo.returnMode)));

		first_time = false;
	}

	MemoryContextSwitchTo(callerContext);

	/* The returned pointers are those in rsinfo */
	*returnDesc = rsinfo.setDesc;
	return rsinfo.setResult;
}


/* ----------------------------------------------------------------
 *		ExecEvalFunc
 *		ExecEvalOper
 *
 *		Evaluate the functional result of a list of arguments by calling the
 *		function manager.
 * ----------------------------------------------------------------
 */

/* ----------------------------------------------------------------
 *		ExecEvalFunc
 * ----------------------------------------------------------------
 */
static Datum
ExecEvalFunc(FuncExprState *fcache,
			 ExprContext *econtext,
			 bool *isNull,
			 ExprDoneCond *isDone)
{
	/*
	 * Initialize function cache if first time through
	 */
	if (fcache->func.fn_oid == InvalidOid)
	{
		FuncExpr   *func = (FuncExpr *) fcache->xprstate.expr;

		init_fcache(func->funcid, fcache, econtext->ecxt_per_query_memory);
	}

	return ExecMakeFunctionResult(fcache, econtext, isNull, isDone);
}

/* ----------------------------------------------------------------
 *		ExecEvalOper
 * ----------------------------------------------------------------
 */
static Datum
ExecEvalOper(FuncExprState *fcache,
			 ExprContext *econtext,
			 bool *isNull,
			 ExprDoneCond *isDone)
{
	/*
	 * Initialize function cache if first time through
	 */
	if (fcache->func.fn_oid == InvalidOid)
	{
		OpExpr	   *op = (OpExpr *) fcache->xprstate.expr;

		init_fcache(op->opfuncid, fcache, econtext->ecxt_per_query_memory);
	}

	return ExecMakeFunctionResult(fcache, econtext, isNull, isDone);
}

/* ----------------------------------------------------------------
 *		ExecEvalDistinct
 *
 * IS DISTINCT FROM must evaluate arguments to determine whether
 * they are NULL; if either is NULL then the result is already
 * known. If neither is NULL, then proceed to evaluate the
 * function. Note that this is *always* derived from the equals
 * operator, but since we need special processing of the arguments
 * we can not simply reuse ExecEvalOper() or ExecEvalFunc().
 * ----------------------------------------------------------------
 */
static Datum
ExecEvalDistinct(FuncExprState *fcache,
				 ExprContext *econtext,
				 bool *isNull)
{
	Datum		result;
	FunctionCallInfoData fcinfo;
	ExprDoneCond argDone;
	List	   *argList;

	/*
	 * Initialize function cache if first time through
	 */
	if (fcache->func.fn_oid == InvalidOid)
	{
		DistinctExpr *op = (DistinctExpr *) fcache->xprstate.expr;

		init_fcache(op->opfuncid, fcache, econtext->ecxt_per_query_memory);
		Assert(!fcache->func.fn_retset);
	}

	/*
	 * extract info from fcache
	 */
	argList = fcache->args;

	/* Need to prep callinfo structure */
	MemSet(&fcinfo, 0, sizeof(fcinfo));
	fcinfo.flinfo = &(fcache->func);
	argDone = ExecEvalFuncArgs(&fcinfo, argList, econtext);
	if (argDone != ExprSingleResult)
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
			 errmsg("IS DISTINCT FROM does not support set arguments")));
	Assert(fcinfo.nargs == 2);

	if (fcinfo.argnull[0] && fcinfo.argnull[1])
	{
		/* Both NULL? Then is not distinct... */
		result = BoolGetDatum(FALSE);
	}
	else if (fcinfo.argnull[0] || fcinfo.argnull[1])
	{
		/* Only one is NULL? Then is distinct... */
		result = BoolGetDatum(TRUE);
	}
	else
	{
		fcinfo.isnull = false;
		result = FunctionCallInvoke(&fcinfo);
		*isNull = fcinfo.isnull;
		/* Must invert result of "=" */
		result = BoolGetDatum(!DatumGetBool(result));
	}

	return result;
}

/*
 * ExecEvalScalarArrayOp
 *
 * Evaluate "scalar op ANY/ALL (array)".  The operator always yields boolean,
 * and we combine the results across all array elements using OR and AND
 * (for ANY and ALL respectively).	Of course we short-circuit as soon as
 * the result is known.
 */
static Datum
ExecEvalScalarArrayOp(ScalarArrayOpExprState *sstate,
					  ExprContext *econtext, bool *isNull)
{
	ScalarArrayOpExpr *opexpr = (ScalarArrayOpExpr *) sstate->fxprstate.xprstate.expr;
	bool		useOr = opexpr->useOr;
	ArrayType  *arr;
	int			nitems;
	Datum		result;
	bool		resultnull;
	FunctionCallInfoData fcinfo;
	ExprDoneCond argDone;
	int			i;
	int16		typlen;
	bool		typbyval;
	char		typalign;
	char	   *s;

	/*
	 * Initialize function cache if first time through
	 */
	if (sstate->fxprstate.func.fn_oid == InvalidOid)
	{
		init_fcache(opexpr->opfuncid, &sstate->fxprstate,
					econtext->ecxt_per_query_memory);
		Assert(!sstate->fxprstate.func.fn_retset);
	}

	/* Need to prep callinfo structure */
	MemSet(&fcinfo, 0, sizeof(fcinfo));
	fcinfo.flinfo = &(sstate->fxprstate.func);
	argDone = ExecEvalFuncArgs(&fcinfo, sstate->fxprstate.args, econtext);
	if (argDone != ExprSingleResult)
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
		   errmsg("op ANY/ALL (array) does not support set arguments")));
	Assert(fcinfo.nargs == 2);

	/*
	 * If the array is NULL then we return NULL --- it's not very
	 * meaningful to do anything else, even if the operator isn't strict.
	 */
	if (fcinfo.argnull[1])
	{
		*isNull = true;
		return (Datum) 0;
	}
	/* Else okay to fetch and detoast the array */
	arr = DatumGetArrayTypeP(fcinfo.arg[1]);

	/*
	 * If the array is empty, we return either FALSE or TRUE per the useOr
	 * flag.  This is correct even if the scalar is NULL; since we would
	 * evaluate the operator zero times, it matters not whether it would
	 * want to return NULL.
	 */
	nitems = ArrayGetNItems(ARR_NDIM(arr), ARR_DIMS(arr));
	if (nitems <= 0)
		return BoolGetDatum(!useOr);

	/*
	 * If the scalar is NULL, and the function is strict, return NULL.
	 * This is just to avoid having to test for strictness inside the
	 * loop.  (XXX but if arrays could have null elements, we'd need a
	 * test anyway.)
	 */
	if (fcinfo.argnull[0] && sstate->fxprstate.func.fn_strict)
	{
		*isNull = true;
		return (Datum) 0;
	}

	/*
	 * We arrange to look up info about the element type only once per
	 * series of calls, assuming the element type doesn't change
	 * underneath us.
	 */
	if (sstate->element_type != ARR_ELEMTYPE(arr))
	{
		get_typlenbyvalalign(ARR_ELEMTYPE(arr),
							 &sstate->typlen,
							 &sstate->typbyval,
							 &sstate->typalign);
		sstate->element_type = ARR_ELEMTYPE(arr);
	}
	typlen = sstate->typlen;
	typbyval = sstate->typbyval;
	typalign = sstate->typalign;

	result = BoolGetDatum(!useOr);
	resultnull = false;

	/* Loop over the array elements */
	s = (char *) ARR_DATA_PTR(arr);
	for (i = 0; i < nitems; i++)
	{
		Datum		elt;
		Datum		thisresult;

		/* Get array element */
		elt = fetch_att(s, typbyval, typlen);

		s = att_addlength(s, typlen, PointerGetDatum(s));
		s = (char *) att_align(s, typalign);

		/* Call comparison function */
		fcinfo.arg[1] = elt;
		fcinfo.argnull[1] = false;
		fcinfo.isnull = false;
		thisresult = FunctionCallInvoke(&fcinfo);

		/* Combine results per OR or AND semantics */
		if (fcinfo.isnull)
			resultnull = true;
		else if (useOr)