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postgresql/src/backend/executor/execQual.c

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/*-------------------------------------------------------------------------
*
* execQual.c
* Routines to evaluate qualification and targetlist expressions
*
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.94 2002/06/20 20:29:27 momjian Exp $
*
*-------------------------------------------------------------------------
*/
/*
* INTERFACE ROUTINES
* ExecEvalExpr - evaluate an expression and return a datum
* ExecEvalExprSwitchContext - same, but switch into eval memory context
* ExecQual - return true/false if qualification is satisfied
* ExecProject - form a new tuple by projecting the given tuple
*
* NOTES
* ExecEvalExpr() and ExecEvalVar() are hotspots. making these faster
* will speed up the entire system. Unfortunately they are currently
* implemented recursively. Eliminating the recursion is bound to
* improve the speed of the executor.
*
* ExecProject() is used to make tuple projections. Rather then
* trying to speed it up, the execution plan should be pre-processed
* to facilitate attribute sharing between nodes wherever possible,
* instead of doing needless copying. -cim 5/31/91
*
*/
#include "postgres.h"
#include "access/heapam.h"
#include "executor/execdebug.h"
#include "executor/functions.h"
#include "executor/nodeSubplan.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/fcache.h"
/* static function decls */
static Datum ExecEvalAggref(Aggref *aggref, ExprContext *econtext,
bool *isNull);
static Datum ExecEvalArrayRef(ArrayRef *arrayRef, ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone);
static Datum ExecEvalVar(Var *variable, ExprContext *econtext, bool *isNull);
static Datum ExecEvalOper(Expr *opClause, ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone);
static Datum ExecEvalFunc(Expr *funcClause, ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone);
static ExprDoneCond ExecEvalFuncArgs(FunctionCallInfo fcinfo,
List *argList, ExprContext *econtext);
static Datum ExecEvalNot(Expr *notclause, ExprContext *econtext, bool *isNull);
static Datum ExecEvalAnd(Expr *andExpr, ExprContext *econtext, bool *isNull);
static Datum ExecEvalOr(Expr *orExpr, ExprContext *econtext, bool *isNull);
static Datum ExecEvalCase(CaseExpr *caseExpr, ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone);
static Datum ExecEvalNullTest(NullTest *ntest, ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone);
static Datum ExecEvalBooleanTest(BooleanTest *btest, ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone);
/*----------
* ExecEvalArrayRef
*
* This function takes an ArrayRef and returns the extracted Datum
* if it's a simple reference, or the modified array value if it's
* an array assignment (i.e., array element or slice insertion).
*
* NOTE: if we get a NULL result from a subexpression, we return NULL when
* it's an array reference, or the unmodified source array when it's an
* array assignment. This may seem peculiar, but if we return NULL (as was
* done in versions up through 7.0) then an assignment like
* UPDATE table SET arrayfield[4] = NULL
* will result in setting the whole array to NULL, which is certainly not
* very desirable. By returning the source array we make the assignment
* into a no-op, instead. (Eventually we need to redesign arrays so that
* individual elements can be NULL, but for now, let's try to protect users
* from shooting themselves in the foot.)
*
* NOTE: we deliberately refrain from applying DatumGetArrayTypeP() here,
* even though that might seem natural, because this code needs to support
* both varlena arrays and fixed-length array types. DatumGetArrayTypeP()
* only works for the varlena kind. The routines we call in arrayfuncs.c
* have to know the difference (that's what they need refattrlength for).
*----------
*/
static Datum
ExecEvalArrayRef(ArrayRef *arrayRef,
ExprContext *econtext,
bool *isNull,
ExprDoneCond *isDone)
{
ArrayType *array_source;
ArrayType *resultArray;
bool isAssignment = (arrayRef->refassgnexpr != NULL);
List *elt;
int i = 0,
j = 0;
IntArray upper,
lower;
int *lIndex;
if (arrayRef->refexpr != NULL)
{
array_source = (ArrayType *)
DatumGetPointer(ExecEvalExpr(arrayRef->refexpr,
econtext,
isNull,
isDone));
/*
* If refexpr yields NULL, result is always NULL, for now anyway.
* (This means you cannot assign to an element or slice of an
* array that's NULL; it'll just stay NULL.)
*/
if (*isNull)
return (Datum) NULL;
}
else
{
/*
* Empty refexpr indicates we are doing an INSERT into an array
* column. For now, we just take the refassgnexpr (which the
* parser will have ensured is an array value) and return it
* as-is, ignoring any subscripts that may have been supplied in
* the INSERT column list. This is a kluge, but it's not real
* clear what the semantics ought to be...
*/
array_source = NULL;
}
foreach(elt, arrayRef->refupperindexpr)
{
if (i >= MAXDIM)
elog(ERROR, "ExecEvalArrayRef: can only handle %d dimensions",
MAXDIM);
upper.indx[i++] = DatumGetInt32(ExecEvalExpr((Node *) lfirst(elt),
econtext,
isNull,
NULL));
/* If any index expr yields NULL, result is NULL or source array */
if (*isNull)
{
if (!isAssignment || array_source == NULL)
return (Datum) NULL;
*isNull = false;
return PointerGetDatum(array_source);
}
}
if (arrayRef->reflowerindexpr != NIL)
{
foreach(elt, arrayRef->reflowerindexpr)
{
if (j >= MAXDIM)
elog(ERROR, "ExecEvalArrayRef: can only handle %d dimensions",
MAXDIM);
lower.indx[j++] = DatumGetInt32(ExecEvalExpr((Node *) lfirst(elt),
econtext,
isNull,
NULL));
/*
* If any index expr yields NULL, result is NULL or source
* array
*/
if (*isNull)
{
if (!isAssignment || array_source == NULL)
return (Datum) NULL;
*isNull = false;
return PointerGetDatum(array_source);
}
}
if (i != j)
elog(ERROR,
"ExecEvalArrayRef: upper and lower indices mismatch");
lIndex = lower.indx;
}
else
lIndex = NULL;
if (isAssignment)
{
Datum sourceData = ExecEvalExpr(arrayRef->refassgnexpr,
econtext,
isNull,
NULL);
/*
* For now, can't cope with inserting NULL into an array, so make
* it a no-op per discussion above...
*/
if (*isNull)
{
if (array_source == NULL)
return (Datum) NULL;
*isNull = false;
return PointerGetDatum(array_source);
}
if (array_source == NULL)
return sourceData; /* XXX do something else? */
if (lIndex == NULL)
resultArray = array_set(array_source, i,
upper.indx,
sourceData,
arrayRef->refelembyval,
arrayRef->refelemlength,
arrayRef->refattrlength,
isNull);
else
resultArray = array_set_slice(array_source, i,
upper.indx, lower.indx,
(ArrayType *) DatumGetPointer(sourceData),
arrayRef->refelembyval,
arrayRef->refelemlength,
arrayRef->refattrlength,
isNull);
return PointerGetDatum(resultArray);
}
if (lIndex == NULL)
return array_ref(array_source, i,
upper.indx,
arrayRef->refelembyval,
arrayRef->refelemlength,
arrayRef->refattrlength,
isNull);
else
{
resultArray = array_get_slice(array_source, i,
upper.indx, lower.indx,
arrayRef->refelembyval,
arrayRef->refelemlength,
arrayRef->refattrlength,
isNull);
return PointerGetDatum(resultArray);
}
}
/* ----------------------------------------------------------------
* ExecEvalAggref
*
* Returns a Datum whose value is the value of the precomputed
* aggregate found in the given expression context.
* ----------------------------------------------------------------
*/
static Datum
ExecEvalAggref(Aggref *aggref, ExprContext *econtext, bool *isNull)
{
if (econtext->ecxt_aggvalues == NULL) /* safety check */
elog(ERROR, "ExecEvalAggref: no aggregates in this expression context");
*isNull = econtext->ecxt_aggnulls[aggref->aggno];
return econtext->ecxt_aggvalues[aggref->aggno];
}
/* ----------------------------------------------------------------
* ExecEvalVar
*
* Returns a Datum whose value is the value of a range
* variable with respect to given expression context.
*
*
* As an entry condition, we expect that the datatype the
* plan expects to get (as told by our "variable" argument) is in
* fact the datatype of the attribute the plan says to fetch (as
* seen in the current context, identified by our "econtext"
* argument).
*
* If we fetch a Type A attribute and Caller treats it as if it
* were Type B, there will be undefined results (e.g. crash).
* One way these might mismatch now is that we're accessing a
* catalog class and the type information in the pg_attribute
* class does not match the hardcoded pg_attribute information
* (in pg_attribute.h) for the class in question.
*
* We have an Assert to make sure this entry condition is met.
*
* ---------------------------------------------------------------- */
static Datum
ExecEvalVar(Var *variable, ExprContext *econtext, bool *isNull)
{
Datum result;
TupleTableSlot *slot;
AttrNumber attnum;
HeapTuple heapTuple;
TupleDesc tuple_type;
/*
* get the slot we want
*/
switch (variable->varno)
{
case INNER: /* get the tuple from the inner node */
slot = econtext->ecxt_innertuple;
break;
case OUTER: /* get the tuple from the outer node */
slot = econtext->ecxt_outertuple;
break;
default: /* get the tuple from the relation being
* scanned */
slot = econtext->ecxt_scantuple;
break;
}
/*
* extract tuple information from the slot
*/
heapTuple = slot->val;
tuple_type = slot->ttc_tupleDescriptor;
attnum = variable->varattno;
/* (See prolog for explanation of this Assert) */
Assert(attnum <= 0 ||
(attnum - 1 <= tuple_type->natts - 1 &&
tuple_type->attrs[attnum - 1] != NULL &&
variable->vartype == tuple_type->attrs[attnum - 1]->atttypid));
/*
* If the attribute number is invalid, then we are supposed to return
* the entire tuple; we give back a whole slot so that callers know
* what the tuple looks like.
*
* XXX this is a horrid crock: since the pointer to the slot might live
* longer than the current evaluation context, we are forced to copy
* the tuple and slot into a long-lived context --- we use
* TransactionCommandContext which should be safe enough. This
* represents a serious memory leak if many such tuples are processed
* in one command, however. We ought to redesign the representation
* of whole-tuple datums so that this is not necessary.
*
* We assume it's OK to point to the existing tupleDescriptor, rather
* than copy that too.
*/
if (attnum == InvalidAttrNumber)
{
MemoryContext oldContext;
TupleTableSlot *tempSlot;
HeapTuple tup;
oldContext = MemoryContextSwitchTo(TransactionCommandContext);
tempSlot = MakeTupleTableSlot();
tup = heap_copytuple(heapTuple);
ExecStoreTuple(tup, tempSlot, InvalidBuffer, true);
ExecSetSlotDescriptor(tempSlot, tuple_type, false);
MemoryContextSwitchTo(oldContext);
return PointerGetDatum(tempSlot);
}
result = heap_getattr(heapTuple, /* tuple containing attribute */
attnum, /* attribute number of desired
* attribute */
tuple_type, /* tuple descriptor of tuple */
isNull); /* return: is attribute null? */
return result;
}
/* ----------------------------------------------------------------
* ExecEvalParam
*
* Returns the value of a parameter. A param node contains
* something like ($.name) and the expression context contains
* the current parameter bindings (name = "sam") (age = 34)...
* so our job is to replace the param node with the datum
* containing the appropriate information ("sam").
*
* Q: if we have a parameter ($.foo) without a binding, i.e.
* there is no (foo = xxx) in the parameter list info,
* is this a fatal error or should this be a "not available"
* (in which case we shoud return a Const node with the
* isnull flag) ? -cim 10/13/89
*
* Minor modification: Param nodes now have an extra field,
* `paramkind' which specifies the type of parameter
* (see params.h). So while searching the paramList for
* a paramname/value pair, we have also to check for `kind'.
*
* NOTE: The last entry in `paramList' is always an
* entry with kind == PARAM_INVALID.
* ----------------------------------------------------------------
*/
Datum
ExecEvalParam(Param *expression, ExprContext *econtext, bool *isNull)
{
char *thisParameterName;
int thisParameterKind = expression->paramkind;
AttrNumber thisParameterId = expression->paramid;
int matchFound;
ParamListInfo paramList;
if (thisParameterKind == PARAM_EXEC)
{
ParamExecData *prm;
prm = &(econtext->ecxt_param_exec_vals[thisParameterId]);
if (prm->execPlan != NULL)
{
ExecSetParamPlan(prm->execPlan, econtext);
/* ExecSetParamPlan should have processed this param... */
Assert(prm->execPlan == NULL);
}
*isNull = prm->isnull;
return prm->value;
}
thisParameterName = expression->paramname;
paramList = econtext->ecxt_param_list_info;
*isNull = false;
/*
* search the list with the parameter info to find a matching name. An
* entry with an InvalidName denotes the last element in the array.
*/
matchFound = 0;
if (paramList != NULL)
{
/*
* search for an entry in 'paramList' that matches the
* `expression'.
*/
while (paramList->kind != PARAM_INVALID && !matchFound)
{
switch (thisParameterKind)
{
case PARAM_NAMED:
if (thisParameterKind == paramList->kind &&
strcmp(paramList->name, thisParameterName) == 0)
matchFound = 1;
break;
case PARAM_NUM:
if (thisParameterKind == paramList->kind &&
paramList->id == thisParameterId)
matchFound = 1;
break;
case PARAM_OLD:
case PARAM_NEW:
if (thisParameterKind == paramList->kind &&
paramList->id == thisParameterId)
{
matchFound = 1;
/*
* sanity check
*/
if (strcmp(paramList->name, thisParameterName) != 0)
{
elog(ERROR,
"ExecEvalParam: new/old params with same id & diff names");
}
}
break;
default:
/*
* oops! this is not supposed to happen!
*/
elog(ERROR, "ExecEvalParam: invalid paramkind %d",
thisParameterKind);
}
if (!matchFound)
paramList++;
} /* while */
} /* if */
if (!matchFound)
{
/*
* ooops! we couldn't find this parameter in the parameter list.
* Signal an error
*/
elog(ERROR, "ExecEvalParam: Unknown value for parameter %s",
thisParameterName);
}
/*
* return the value.
*/
*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, "GetAttributeByNum: Invalid attribute number");
if (!AttrNumberIsForUserDefinedAttr(attrno))
elog(ERROR, "GetAttributeByNum: cannot access system attributes here");
if (isNull == (bool *) NULL)
elog(ERROR, "GetAttributeByNum: a NULL isNull flag 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, "GetAttributeByName: Invalid attribute name");
if (isNull == (bool *) NULL)
elog(ERROR, "GetAttributeByName: a NULL isNull flag 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, "GetAttributeByName: attribute %s not found", attname);
retval = heap_getattr(slot->val,
attrno,
tupdesc,
isNull);
if (*isNull)
return (Datum) 0;
return retval;
}
/*
* 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((Node *) 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)
elog(ERROR, "Functions and operators can take only one set argument");
argIsDone = thisArgIsDone;
}
i++;
}
fcinfo->nargs = i;
return argIsDone;
}
/*
* ExecMakeFunctionResult
*
* Evaluate the arguments to a function and then the function itself.
*
* NOTE: econtext is used only for evaluating the argument expressions;
* it is not passed to the function itself.
*/
Datum
ExecMakeFunctionResult(FunctionCachePtr fcache,
List *arguments,
ExprContext *econtext,
bool *isNull,
ExprDoneCond *isDone)
{
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
elog(ERROR, "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;
}
/*
* 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)
elog(ERROR, "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;
}
/*
* 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;
}
/* ----------------------------------------------------------------
* ExecEvalOper
* ExecEvalFunc
*
* Evaluate the functional result of a list of arguments by calling the
* function manager.
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* ExecEvalOper
* ----------------------------------------------------------------
*/
static Datum
ExecEvalOper(Expr *opClause,
ExprContext *econtext,
bool *isNull,
ExprDoneCond *isDone)
{
Oper *op;
List *argList;
FunctionCachePtr fcache;
/*
* we extract the oid of the function associated with the op and then
* pass the work onto ExecMakeFunctionResult which evaluates the
* arguments and returns the result of calling the function on the
* evaluated arguments.
*/
op = (Oper *) opClause->oper;
argList = opClause->args;
/*
* get the fcache from the Oper node. If it is NULL, then initialize
* it
*/
fcache = op->op_fcache;
if (fcache == NULL)
{
fcache = init_fcache(op->opid, length(argList),
econtext->ecxt_per_query_memory);
op->op_fcache = fcache;
}
return ExecMakeFunctionResult(fcache, argList, econtext,
isNull, isDone);
}
/* ----------------------------------------------------------------
* ExecEvalFunc
* ----------------------------------------------------------------
*/
static Datum
ExecEvalFunc(Expr *funcClause,
ExprContext *econtext,
bool *isNull,
ExprDoneCond *isDone)
{
Func *func;
List *argList;
FunctionCachePtr fcache;
/*
* we extract the oid of the function associated with the func node
* and then pass the work onto ExecMakeFunctionResult which evaluates
* the arguments and returns the result of calling the function on the
* evaluated arguments.
*
* this is nearly identical to the ExecEvalOper code.
*/
func = (Func *) funcClause->oper;
argList = funcClause->args;
/*
* get the fcache from the Func node. If it is NULL, then initialize
* it
*/
fcache = func->func_fcache;
if (fcache == NULL)
{
fcache = init_fcache(func->funcid, length(argList),
econtext->ecxt_per_query_memory);
func->func_fcache = fcache;
}
return ExecMakeFunctionResult(fcache, argList, econtext,
isNull, isDone);
}
/* ----------------------------------------------------------------
* ExecEvalNot
* ExecEvalOr
* ExecEvalAnd
*
* Evaluate boolean expressions. Evaluation of 'or' is
* short-circuited when the first true (or null) value is found.
*
* 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(Expr *notclause, ExprContext *econtext, bool *isNull)
{
Node *clause;
Datum expr_value;
clause = lfirst(notclause->args);
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(Expr *orExpr, ExprContext *econtext, bool *isNull)
{
List *clauses;
List *clause;
bool AnyNull;
Datum clause_value;
clauses = orExpr->args;
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)
{
clause_value = ExecEvalExpr((Node *) lfirst(clause),
econtext, isNull, NULL);
/*
* if we have a non-null true result, then return it.
*/
if (*isNull)
AnyNull = true; /* remember we got a null */
else if (DatumGetBool(clause_value))
return clause_value;
}
/* AnyNull is true if at least one clause evaluated to NULL */
*isNull = AnyNull;
return BoolGetDatum(false);
}
/* ----------------------------------------------------------------
* ExecEvalAnd
* ----------------------------------------------------------------
*/
static Datum
ExecEvalAnd(Expr *andExpr, ExprContext *econtext, bool *isNull)
{
List *clauses;
List *clause;
bool AnyNull;
Datum clause_value;
clauses = andExpr->args;
AnyNull = false;
/*
* If any of the clauses is FALSE, the AND result is FALSE regardless
* of the states of the rest of the clauses, so we can stop evaluating
* and return FALSE immediately. If none are FALSE and one or more is
* NULL, we return NULL; otherwise we return TRUE. This makes sense
* when you interpret NULL as "don't know", using the same sort of
* reasoning as for OR, above.
*/
foreach(clause, clauses)
{
clause_value = ExecEvalExpr((Node *) lfirst(clause),
econtext, isNull, NULL);
/*
* if we have a non-null false result, then return it.
*/
if (*isNull)
AnyNull = true; /* remember we got a null */
else if (!DatumGetBool(clause_value))
return clause_value;
}
/* AnyNull is true if at least one clause evaluated to NULL */
*isNull = AnyNull;
return BoolGetDatum(!AnyNull);
}
/* ----------------------------------------------------------------
* ExecEvalCase
*
* Evaluate a CASE clause. Will have boolean expressions
* inside the WHEN clauses, and will have expressions
* for results.
* - thomas 1998-11-09
* ----------------------------------------------------------------
*/
static Datum
ExecEvalCase(CaseExpr *caseExpr, ExprContext *econtext,
bool *isNull, ExprDoneCond *isDone)
{
List *clauses;
List *clause;
Datum clause_value;
clauses = caseExpr->args;
/*
* we evaluate each of the WHEN clauses in turn, as soon as one is
* true we return the corresponding result. If none are true then we
* return the value of the default clause, or NULL if there is none.
*/
foreach(clause, clauses)
{
CaseWhen *wclause = lfirst(clause);
clause_value = ExecEvalExpr(wclause->expr,
econtext,
isNull,
NULL);
/*
* if we have a true test, then we return the result, since the
* case statement is satisfied. A NULL result from the test is
* not considered true.
*/
if (DatumGetBool(clause_value) && !*isNull)
{
return ExecEvalExpr(wclause->result,
econtext,
isNull,
isDone);
}
}
if (caseExpr->defresult)
{
return ExecEvalExpr(caseExpr->defresult,
econtext,
isNull,
isDone);
}
*isNull = true;
return (Datum) 0;
}
/* ----------------------------------------------------------------
* ExecEvalNullTest
*
* Evaluate a NullTest node.
* ----------------------------------------------------------------
*/
static Datum
ExecEvalNullTest(NullTest *ntest,
ExprContext *econtext,
bool *isNull,
ExprDoneCond *isDone)
{
Datum result;
result = ExecEvalExpr(ntest->arg, econtext, isNull, isDone);
switch (ntest->nulltesttype)
{
case IS_NULL:
if (*isNull)
{
*isNull = false;
return BoolGetDatum(true);
}
else
return BoolGetDatum(false);
case IS_NOT_NULL:
if (*isNull)
{
*isNull = false;
return BoolGetDatum(false);
}
else
return BoolGetDatum(true);
default:
elog(ERROR, "ExecEvalNullTest: unexpected nulltesttype %d",
(int) ntest->nulltesttype);
return (Datum) 0; /* keep compiler quiet */
}
}
/* ----------------------------------------------------------------
* ExecEvalBooleanTest
*
* Evaluate a BooleanTest node.
* ----------------------------------------------------------------
*/
static Datum
ExecEvalBooleanTest(BooleanTest *btest,
ExprContext *econtext,
bool *isNull,
ExprDoneCond *isDone)
{
Datum result;
result = ExecEvalExpr(btest->arg, econtext, isNull, isDone);
switch (btest->booltesttype)
{
case IS_TRUE:
if (*isNull)
{
*isNull = false;
return BoolGetDatum(false);
}
else if (DatumGetBool(result))
return BoolGetDatum(true);
else
return BoolGetDatum(false);
case IS_NOT_TRUE:
if (*isNull)
{
*isNull = false;
return BoolGetDatum(true);
}
else if (DatumGetBool(result))
return BoolGetDatum(false);
else
return BoolGetDatum(true);
case IS_FALSE:
if (*isNull)
{
*isNull = false;
return BoolGetDatum(false);
}
else if (DatumGetBool(result))
return BoolGetDatum(false);
else
return BoolGetDatum(true);
case IS_NOT_FALSE:
if (*isNull)
{
*isNull = false;
return BoolGetDatum(true);
}
else if (DatumGetBool(result))
return BoolGetDatum(true);
else
return BoolGetDatum(false);
case IS_UNKNOWN:
if (*isNull)
{
*isNull = false;
return BoolGetDatum(true);
}
else
return BoolGetDatum(false);
case IS_NOT_UNKNOWN:
if (*isNull)
{
*isNull = false;
return BoolGetDatum(false);
}
else
return BoolGetDatum(true);
default:
elog(ERROR, "ExecEvalBooleanTest: unexpected booltesttype %d",
(int) btest->booltesttype);
return (Datum) 0; /* keep compiler quiet */
}
}
/* ----------------------------------------------------------------
* ExecEvalFieldSelect
*
* Evaluate a FieldSelect node.
* ----------------------------------------------------------------
*/
static Datum
ExecEvalFieldSelect(FieldSelect *fselect,
ExprContext *econtext,
bool *isNull,
ExprDoneCond *isDone)
{
Datum result;
TupleTableSlot *resSlot;
result = ExecEvalExpr(fselect->arg, econtext, isNull, isDone);
if (*isNull)
return result;
resSlot = (TupleTableSlot *) DatumGetPointer(result);
Assert(resSlot != NULL && IsA(resSlot, TupleTableSlot));
result = heap_getattr(resSlot->val,
fselect->fieldnum,
resSlot->ttc_tupleDescriptor,
isNull);
return result;
}
/* ----------------------------------------------------------------
* ExecEvalExpr
*
* Recursively evaluate a targetlist or qualification expression.
*
* Inputs:
* expression: the expression tree to evaluate
* econtext: evaluation context information
*
* Outputs:
* return value: Datum value of result
* *isNull: set to TRUE if result is NULL (actual return value is
* meaningless if so); set to FALSE if non-null result
* *isDone: set to indicator of set-result status
*
* A caller that can only accept a singleton (non-set) result should pass
* NULL for isDone; if the expression computes a set result then an elog()
* error will be reported. If the caller does pass an isDone pointer then
* *isDone is set to one of these three states:
* ExprSingleResult singleton result (not a set)
* ExprMultipleResult return value is one element of a set
* ExprEndResult there are no more elements in the set
* When ExprMultipleResult is returned, the caller should invoke
* ExecEvalExpr() repeatedly until ExprEndResult is returned. ExprEndResult
* is returned after the last real set element. For convenience isNull will
* always be set TRUE when ExprEndResult is returned, but this should not be
* taken as indicating a NULL element of the set. Note that these return
* conventions allow us to distinguish among a singleton NULL, a NULL element
* of a set, and an empty set.
*
* The caller should already have switched into the temporary memory
* context econtext->ecxt_per_tuple_memory. The convenience entry point
* ExecEvalExprSwitchContext() is provided for callers who don't prefer to
* do the switch in an outer loop. We do not do the switch here because
* it'd be a waste of cycles during recursive entries to ExecEvalExpr().
*
* This routine is an inner loop routine and must be as fast as possible.
* ----------------------------------------------------------------
*/
Datum
ExecEvalExpr(Node *expression,
ExprContext *econtext,
bool *isNull,
ExprDoneCond *isDone)
{
Datum retDatum;
/* Set default values for result flags: non-null, not a set result */
*isNull = false;
if (isDone)
*isDone = ExprSingleResult;
/* Is this still necessary? Doubtful... */
if (expression == NULL)
{
*isNull = true;
return (Datum) 0;
}
/*
* here we dispatch the work to the appropriate type of function given
* the type of our expression.
*/
switch (nodeTag(expression))
{
case T_Var:
retDatum = ExecEvalVar((Var *) expression, econtext, isNull);
break;
case T_Const:
{
Const *con = (Const *) expression;
retDatum = con->constvalue;
*isNull = con->constisnull;
break;
}
case T_Param:
retDatum = ExecEvalParam((Param *) expression, econtext, isNull);
break;
case T_Aggref:
retDatum = ExecEvalAggref((Aggref *) expression, econtext, isNull);
break;
case T_ArrayRef:
retDatum = ExecEvalArrayRef((ArrayRef *) expression,
econtext,
isNull,
isDone);
break;
case T_Expr:
{
Expr *expr = (Expr *) expression;
switch (expr->opType)
{
case OP_EXPR:
retDatum = ExecEvalOper(expr, econtext,
isNull, isDone);
break;
case FUNC_EXPR:
retDatum = ExecEvalFunc(expr, econtext,
isNull, isDone);
break;
case OR_EXPR:
retDatum = ExecEvalOr(expr, econtext, isNull);
break;
case AND_EXPR:
retDatum = ExecEvalAnd(expr, econtext, isNull);
break;
case NOT_EXPR:
retDatum = ExecEvalNot(expr, econtext, isNull);
break;
case SUBPLAN_EXPR:
retDatum = ExecSubPlan((SubPlan *) expr->oper,
expr->args, econtext,
isNull);
break;
default:
elog(ERROR, "ExecEvalExpr: unknown expression type %d",
expr->opType);
retDatum = 0; /* keep compiler quiet */
break;
}
break;
}
case T_FieldSelect:
retDatum = ExecEvalFieldSelect((FieldSelect *) expression,
econtext,
isNull,
isDone);
break;
case T_RelabelType:
retDatum = ExecEvalExpr(((RelabelType *) expression)->arg,
econtext,
isNull,
isDone);
break;
case T_CaseExpr:
retDatum = ExecEvalCase((CaseExpr *) expression,
econtext,
isNull,
isDone);
break;
case T_NullTest:
retDatum = ExecEvalNullTest((NullTest *) expression,
econtext,
isNull,
isDone);
break;
case T_BooleanTest:
retDatum = ExecEvalBooleanTest((BooleanTest *) expression,
econtext,
isNull,
isDone);
break;
default:
elog(ERROR, "ExecEvalExpr: unknown expression type %d",
nodeTag(expression));
retDatum = 0; /* keep compiler quiet */
break;
}
return retDatum;
} /* ExecEvalExpr() */
/*
* Same as above, but get into the right allocation context explicitly.
*/
Datum
ExecEvalExprSwitchContext(Node *expression,
ExprContext *econtext,
bool *isNull,
ExprDoneCond *isDone)
{
Datum retDatum;
MemoryContext oldContext;
oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
retDatum = ExecEvalExpr(expression, econtext, isNull, isDone);
MemoryContextSwitchTo(oldContext);
return retDatum;
}
/* ----------------------------------------------------------------
* ExecQual / ExecTargetList / ExecProject
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* ExecQual
*
* Evaluates a conjunctive boolean expression (qual list) and
* returns true iff none of the subexpressions are false.
* (We also return true if the list is empty.)
*
* If some of the subexpressions yield NULL but none yield FALSE,
* then the result of the conjunction is NULL (ie, unknown)
* according to three-valued boolean logic. In this case,
* we return the value specified by the "resultForNull" parameter.
*
* Callers evaluating WHERE clauses should pass resultForNull=FALSE,
* since SQL specifies that tuples with null WHERE results do not
* get selected. On the other hand, callers evaluating constraint
* conditions should pass resultForNull=TRUE, since SQL also specifies
* that NULL constraint conditions are not failures.
*
* NOTE: it would not be correct to use this routine to evaluate an
* AND subclause of a boolean expression; for that purpose, a NULL
* result must be returned as NULL so that it can be properly treated
* in the next higher operator (cf. ExecEvalAnd and ExecEvalOr).
* This routine is only used in contexts where a complete expression
* is being evaluated and we know that NULL can be treated the same
* as one boolean result or the other.
*
* ----------------------------------------------------------------
*/
bool
ExecQual(List *qual, ExprContext *econtext, bool resultForNull)
{
bool result;
MemoryContext oldContext;
List *qlist;
/*
* debugging stuff
*/
EV_printf("ExecQual: qual is ");
EV_nodeDisplay(qual);
EV_printf("\n");
IncrProcessed();
/*
* Run in short-lived per-tuple context while computing expressions.
*/
oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
/*
* Evaluate the qual conditions one at a time. If we find a FALSE
* result, we can stop evaluating and return FALSE --- the AND result
* must be FALSE. Also, if we find a NULL result when resultForNull
* is FALSE, we can stop and return FALSE --- the AND result must be
* FALSE or NULL in that case, and the caller doesn't care which.
*
* If we get to the end of the list, we can return TRUE. This will
* happen when the AND result is indeed TRUE, or when the AND result
* is NULL (one or more NULL subresult, with all the rest TRUE) and
* the caller has specified resultForNull = TRUE.
*/
result = true;
foreach(qlist, qual)
{
Node *clause = (Node *) lfirst(qlist);
Datum expr_value;
bool isNull;
expr_value = ExecEvalExpr(clause, econtext, &isNull, NULL);
if (isNull)
{
if (resultForNull == false)
{
result = false; /* treat NULL as FALSE */
break;
}
}
else
{
if (!DatumGetBool(expr_value))
{
result = false; /* definitely FALSE */
break;
}
}
}
MemoryContextSwitchTo(oldContext);
return result;
}
/*
* Number of items in a tlist (including any resjunk items!)
*/
int
ExecTargetListLength(List *targetlist)
{
int len = 0;
List *tl;
foreach(tl, targetlist)
{
TargetEntry *curTle = (TargetEntry *) lfirst(tl);
if (curTle->resdom != NULL)
len++;
else
len += curTle->fjoin->fj_nNodes;
}
return len;
}
/*
* Number of items in a tlist, not including any resjunk items
*/
int
ExecCleanTargetListLength(List *targetlist)
{
int len = 0;
List *tl;
foreach(tl, targetlist)
{
TargetEntry *curTle = (TargetEntry *) lfirst(tl);
if (curTle->resdom != NULL)
{
if (!curTle->resdom->resjunk)
len++;
}
else
len += curTle->fjoin->fj_nNodes;
}
return len;
}
/* ----------------------------------------------------------------
* ExecTargetList
*
* Evaluates a targetlist with respect to the current
* expression context and return a tuple.
*
* As with ExecEvalExpr, the caller should pass isDone = NULL if not
* prepared to deal with sets of result tuples. Otherwise, a return
* of *isDone = ExprMultipleResult signifies a set element, and a return
* of *isDone = ExprEndResult signifies end of the set of tuple.
* ----------------------------------------------------------------
*/
static HeapTuple
ExecTargetList(List *targetlist,
int nodomains,
TupleDesc targettype,
Datum *values,
ExprContext *econtext,
ExprDoneCond *isDone)
{
MemoryContext oldContext;
#define NPREALLOCDOMAINS 64
char nullsArray[NPREALLOCDOMAINS];
bool fjIsNullArray[NPREALLOCDOMAINS];
ExprDoneCond itemIsDoneArray[NPREALLOCDOMAINS];
char *nulls;
bool *fjIsNull;
ExprDoneCond *itemIsDone;
List *tl;
TargetEntry *tle;
AttrNumber resind;
HeapTuple newTuple;
bool isNull;
bool haveDoneSets;
static struct tupleDesc NullTupleDesc; /* we assume this inits to
* zeroes */
/*
* debugging stuff
*/
EV_printf("ExecTargetList: tl is ");
EV_nodeDisplay(targetlist);
EV_printf("\n");
/*
* Run in short-lived per-tuple context while computing expressions.
*/
oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
/*
* There used to be some klugy and demonstrably broken code here that
* special-cased the situation where targetlist == NIL. Now we just
* fall through and return an empty-but-valid tuple. We do, however,
* have to cope with the possibility that targettype is NULL ---
* heap_formtuple won't like that, so pass a dummy descriptor with
* natts = 0 to deal with it.
*/
if (targettype == NULL)
targettype = &NullTupleDesc;
/*
* allocate an array of char's to hold the "null" information only if
* we have a really large targetlist. otherwise we use the stack.
*
* We also allocate a bool array that is used to hold fjoin result state,
* and another array that holds the isDone status for each targetlist
* item. The isDone status is needed so that we can iterate,
* generating multiple tuples, when one or more tlist items return
* sets. (We expect the caller to call us again if we return:
*
* isDone = ExprMultipleResult.)
*/
if (nodomains > NPREALLOCDOMAINS)
{
nulls = (char *) palloc(nodomains * sizeof(char));
fjIsNull = (bool *) palloc(nodomains * sizeof(bool));
itemIsDone = (ExprDoneCond *) palloc(nodomains * sizeof(ExprDoneCond));
}
else
{
nulls = nullsArray;
fjIsNull = fjIsNullArray;
itemIsDone = itemIsDoneArray;
}
/*
* evaluate all the expressions in the target list
*/
if (isDone)
*isDone = ExprSingleResult; /* until proven otherwise */
haveDoneSets = false; /* any exhausted set exprs in tlist? */
foreach(tl, targetlist)
{
tle = lfirst(tl);
if (tle->resdom != NULL)
{
resind = tle->resdom->resno - 1;
values[resind] = ExecEvalExpr(tle->expr,
econtext,
&isNull,
&itemIsDone[resind]);
nulls[resind] = isNull ? 'n' : ' ';
if (itemIsDone[resind] != ExprSingleResult)
{
/* We have a set-valued expression in the tlist */
if (isDone == NULL)
elog(ERROR, "Set-valued function called in context that cannot accept a set");
if (itemIsDone[resind] == ExprMultipleResult)
{
/* we have undone sets in the tlist, set flag */
*isDone = ExprMultipleResult;
}
else
{
/* we have done sets in the tlist, set flag for that */
haveDoneSets = true;
}
}
}
else
{
#ifdef SETS_FIXED
int curNode;
Resdom *fjRes;
List *fjTlist = (List *) tle->expr;
Fjoin *fjNode = tle->fjoin;
int nNodes = fjNode->fj_nNodes;
DatumPtr results = fjNode->fj_results;
ExecEvalFjoin(tle, econtext, fjIsNull, isDone);
/*
* XXX this is wrong, but since fjoin code is completely
* broken anyway, I'm not going to worry about it now --- tgl
* 8/23/00
*/
if (isDone && *isDone == ExprEndResult)
{
MemoryContextSwitchTo(oldContext);
newTuple = NULL;
goto exit;
}
/*
* get the result from the inner node
*/
fjRes = (Resdom *) fjNode->fj_innerNode;
resind = fjRes->resno - 1;
values[resind] = results[0];
nulls[resind] = fjIsNull[0] ? 'n' : ' ';
/*
* Get results from all of the outer nodes
*/
for (curNode = 1;
curNode < nNodes;
curNode++, fjTlist = lnext(fjTlist))
{
Node *outernode = lfirst(fjTlist);
fjRes = (Resdom *) outernode->iterexpr;
resind = fjRes->resno - 1;
values[resind] = results[curNode];
nulls[resind] = fjIsNull[curNode] ? 'n' : ' ';
}
#else
elog(ERROR, "ExecTargetList: fjoin nodes not currently supported");
#endif
}
}
if (haveDoneSets)
{
/*
* note: can't get here unless we verified isDone != NULL
*/
if (*isDone == ExprSingleResult)
{
/*
* all sets are done, so report that tlist expansion is
* complete.
*/
*isDone = ExprEndResult;
MemoryContextSwitchTo(oldContext);
newTuple = NULL;
goto exit;
}
else
{
/*
* We have some done and some undone sets. Restart the done
* ones so that we can deliver a tuple (if possible).
*/
foreach(tl, targetlist)
{
tle = lfirst(tl);
if (tle->resdom != NULL)
{
resind = tle->resdom->resno - 1;
if (itemIsDone[resind] == ExprEndResult)
{
values[resind] = ExecEvalExpr(tle->expr,
econtext,
&isNull,
&itemIsDone[resind]);
nulls[resind] = isNull ? 'n' : ' ';
if (itemIsDone[resind] == ExprEndResult)
{
/*
* Oh dear, this item is returning an empty
* set. Guess we can't make a tuple after all.
*/
*isDone = ExprEndResult;
break;
}
}
}
}
/*
* If we cannot make a tuple because some sets are empty, we
* still have to cycle the nonempty sets to completion, else
* resources will not be released from subplans etc.
*/
if (*isDone == ExprEndResult)
{
foreach(tl, targetlist)
{
tle = lfirst(tl);
if (tle->resdom != NULL)
{
resind = tle->resdom->resno - 1;
while (itemIsDone[resind] == ExprMultipleResult)
{
(void) ExecEvalExpr(tle->expr,
econtext,
&isNull,
&itemIsDone[resind]);
}
}
}
MemoryContextSwitchTo(oldContext);
newTuple = NULL;
goto exit;
}
}
}
/*
* form the new result tuple (in the caller's memory context!)
*/
MemoryContextSwitchTo(oldContext);
newTuple = (HeapTuple) heap_formtuple(targettype, values, nulls);
exit:
/*
* free the status arrays if we palloc'd them
*/
if (nodomains > NPREALLOCDOMAINS)
{
pfree(nulls);
pfree(fjIsNull);
pfree(itemIsDone);
}
return newTuple;
}
/* ----------------------------------------------------------------
* ExecProject
*
* projects a tuple based on projection info and stores
* it in the specified tuple table slot.
*
* Note: someday soon the executor can be extended to eliminate
* redundant projections by storing pointers to datums
* in the tuple table and then passing these around when
* possible. this should make things much quicker.
* -cim 6/3/91
* ----------------------------------------------------------------
*/
TupleTableSlot *
ExecProject(ProjectionInfo *projInfo, ExprDoneCond *isDone)
{
TupleTableSlot *slot;
List *targetlist;
int len;
TupleDesc tupType;
Datum *tupValue;
ExprContext *econtext;
HeapTuple newTuple;
/*
* sanity checks
*/
if (projInfo == NULL)
return (TupleTableSlot *) NULL;
/*
* get the projection info we want
*/
slot = projInfo->pi_slot;
targetlist = projInfo->pi_targetlist;
len = projInfo->pi_len;
tupType = slot->ttc_tupleDescriptor;
tupValue = projInfo->pi_tupValue;
econtext = projInfo->pi_exprContext;
/*
* form a new result tuple (if possible --- result can be NULL)
*/
newTuple = ExecTargetList(targetlist,
len,
tupType,
tupValue,
econtext,
isDone);
/*
* store the tuple in the projection slot and return the slot.
*/
return ExecStoreTuple(newTuple, /* tuple to store */
slot, /* slot to store in */
InvalidBuffer, /* tuple has no buffer */
true);
}
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