execqual.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

					/*
					 * Scalar type, so make a single-column descriptor
					 */
					tupdesc = CreateTemplateTupleDesc(1, false);
					TupleDescInitEntry(tupdesc,
									   (AttrNumber) 1,
									   "column",
									   funcrettype,
									   -1,
									   0);
				}
				tupstore = tuplestore_begin_heap(true, false, work_mem);
				MemoryContextSwitchTo(oldcontext);
				rsinfo.setResult = tupstore;
				rsinfo.setDesc = tupdesc;
			}

			/*
			 * Store current resultset item.
			 */
			if (returnsTuple)
			{
				HeapTupleHeader td;

				td = DatumGetHeapTupleHeader(result);

				/*
				 * tuplestore_puttuple needs a HeapTuple not a bare
				 * HeapTupleHeader, but it doesn't need all the fields.
				 */
				tmptup.t_len = HeapTupleHeaderGetDatumLength(td);
				tmptup.t_data = td;
				tuple = &tmptup;
			}
			else
			{
				tuple = heap_form_tuple(tupdesc, &result, &fcinfo.isnull);
			}

			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;
	}

no_function_result:

	/*
	 * If we got nothing from the function (ie, an empty-set or NULL result),
	 * we have to create the tuplestore to return, and if it's a
	 * non-set-returning function then insert a single all-nulls row.
	 */
	if (rsinfo.setResult == NULL)
	{
		MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
		tupstore = tuplestore_begin_heap(true, false, work_mem);
		rsinfo.setResult = tupstore;
		if (!returnsSet)
		{
			int			natts = expectedDesc->natts;
			Datum	   *nulldatums;
			bool	   *nullflags;
			HeapTuple	tuple;

			MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
			nulldatums = (Datum *) palloc0(natts * sizeof(Datum));
			nullflags = (bool *) palloc(natts * sizeof(bool));
			memset(nullflags, true, natts * sizeof(bool));
			tuple = heap_form_tuple(expectedDesc, nulldatums, nullflags);
			MemoryContextSwitchTo(econtext->ecxt_per_query_memory);
			tuplestore_puttuple(tupstore, tuple);
		}
	}

	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)
{
	/* This is called only the first time through */
	FuncExpr   *func = (FuncExpr *) fcache->xprstate.expr;

	/* Initialize function lookup info */
	init_fcache(func->funcid, fcache, econtext->ecxt_per_query_memory);

	/* Go directly to ExecMakeFunctionResult on subsequent uses */
	fcache->xprstate.evalfunc = (ExprStateEvalFunc) ExecMakeFunctionResult;

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

/* ----------------------------------------------------------------
 *		ExecEvalOper
 * ----------------------------------------------------------------
 */
static Datum
ExecEvalOper(FuncExprState *fcache,
			 ExprContext *econtext,
			 bool *isNull,
			 ExprDoneCond *isDone)
{
	/* This is called only the first time through */
	OpExpr	   *op = (OpExpr *) fcache->xprstate.expr;

	/* Initialize function lookup info */
	init_fcache(op->opfuncid, fcache, econtext->ecxt_per_query_memory);

	/* Go directly to ExecMakeFunctionResult on subsequent uses */
	fcache->xprstate.evalfunc = (ExprStateEvalFunc) ExecMakeFunctionResult;

	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,
				 ExprDoneCond *isDone)
{
	Datum		result;
	FunctionCallInfoData fcinfo;
	ExprDoneCond argDone;
	List	   *argList;

	/* Set default values for result flags: non-null, not a set result */
	*isNull = false;
	if (isDone)
		*isDone = ExprSingleResult;

	/*
	 * 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 */
	InitFunctionCallInfoData(fcinfo, &(fcache->func), 0, NULL, NULL);
	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, ExprDoneCond *isDone)
{
	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;

	/* Set default values for result flags: non-null, not a set result */
	*isNull = false;
	if (isDone)
		*isDone = ExprSingleResult;

	/*
	 * 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 */
	InitFunctionCallInfoData(fcinfo, &(sstate->fxprstate.func), 0, NULL, NULL);
	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)
		{
			if (DatumGetBool(thisresult))
			{
				result = BoolGetDatum(true);
				resultnull = false;
				break;			/* needn't look at any more elements */
			}
		}
		else
		{
			if (!DatumGetBool(thisresult))
			{
				result = BoolGetDatum(false);
				resultnull = false;
				break;			/* needn't look at any more elements */
			}
		}
	}

	*isNull = resultnull;
	return result;
}

/* ----------------------------------------------------------------
 *		ExecEvalNot
 *		ExecEvalOr
 *		ExecEvalAnd
 *
 *		Evaluate boolean expressions, with appropriate short-circuiting.
 *
 *		The query planner reformulates clause expressions in the
 *		qualification to conjunctive normal form.  If we ever get
 *		an AND to evaluate, we can be sure that it's not a top-level
 *		clause in the qualification, but appears lower (as a function
 *		argument, for example), or in the target list.	Not that you
 *		need to know this, mind you...
 * ----------------------------------------------------------------
 */
static Datum
ExecEvalNot(BoolExprState *notclause, ExprContext *econtext,
			bool *isNull, ExprDoneCond *isDone)
{
	ExprState  *clause = linitial(notclause->args);
	Datum		expr_value;

	if (isDone)
		*isDone = ExprSingleResult;

	expr_value = ExecEvalExpr(clause, econtext, isNull, NULL);

	/*
	 * if the expression evaluates to null, then we just cascade the null back
	 * to whoever called us.
	 */
	if (*isNull)
		return expr_value;

	/*
	 * evaluation of 'not' is simple.. expr is false, then return 'true' and
	 * vice versa.
	 */
	return BoolGetDatum(!DatumGetBool(expr_value));
}

/* ----------------------------------------------------------------
 *		ExecEvalOr
 * ----------------------------------------------------------------
 */
static Datum
ExecEvalOr(BoolExprState *orExpr, ExprContext *econtext,
		   bool *isNull, ExprDoneCond *isDone)
{
	List	   *clauses = orExpr->args;
	ListCell   *clause;
	bool		AnyNull;

	if (isDone)
		*isDone = ExprSingleResult;

	AnyNull = false;

	/*
	 * If any of the clauses is TRUE, the OR result is TRUE regardless of the
	 * states of the rest of the clauses, so we can stop evaluating and return
	 * TRUE immediately.  If none are TRUE and one or more is NULL, we return
	 * NULL; otherwise we return FALSE.  This makes sense when you interpret
	 * NULL as "don't know": if we have a TRUE then the OR is TRUE even if we
	 * aren't sure about some of the other inputs. If all the known inputs are
	 * FALSE, but we have one or more "don't knows", then we have to report
	 * that we "don't know" what the OR's result should be --- perhaps one of
	 * the "don't knows" would have been TRUE if we'd known its value.  Only
	 * when all the inputs are known to be FALSE can we state confidently that
	 * the OR's result is FALSE.
	 */
	foreach(clause, clauses)
	{
		ExprState  *clausestate = (ExprState *) lfirst(clause);