rdelaage
/
postgresql
mirror of https://git.postgresql.org/git/postgresql.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
postgresql/src/backend/executor/execQual.c

1674 lines
42 KiB
C
Raw Blame History

/*-------------------------------------------------------------------------
*
* execQual.c
* Routines to evaluate qualification and targetlist expressions
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.50 1999/03/20 02:07:31 momjian Exp $
*
*-------------------------------------------------------------------------
*/
/*
* INTERFACE ROUTINES
* ExecEvalExpr - evaluate an expression and return a datum
* ExecQual - return true/false if qualification is satisified
* ExecTargetList - 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.
*
* ExecTargetList() 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 <string.h>
#include "postgres.h"
#include "access/heapam.h"
#include "catalog/pg_language.h"
#include "executor/execdebug.h"
#include "executor/executor.h"
#include "executor/execFlatten.h"
#include "executor/functions.h"
#include "executor/nodeSubplan.h"
#include "fmgr.h"
#include "nodes/memnodes.h"
#include "nodes/primnodes.h"
#include "nodes/relation.h"
#include "optimizer/clauses.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/fcache.h"
#include "utils/fcache2.h"
#include "utils/mcxt.h"
#include "utils/memutils.h"
/*
* externs and constants
*/
/*
* XXX Used so we can get rid of use of Const nodes in the executor.
* Currently only used by ExecHashGetBucket and set only by ExecMakeVarConst
* and by ExecEvalArrayRef.
*/
bool execConstByVal;
int execConstLen;
/* static functions decls */
static Datum ExecEvalAggref(Aggref *aggref, ExprContext *econtext, bool *isNull);
static Datum ExecEvalArrayRef(ArrayRef *arrayRef, ExprContext *econtext,
bool *isNull, bool *isDone);
static Datum ExecEvalAnd(Expr *andExpr, ExprContext *econtext, bool *isNull);
static Datum ExecEvalFunc(Expr *funcClause, ExprContext *econtext,
bool *isNull, bool *isDone);
static void ExecEvalFuncArgs(FunctionCachePtr fcache, ExprContext *econtext,
List *argList, Datum argV[], bool *argIsDone);
static Datum ExecEvalNot(Expr *notclause, ExprContext *econtext, bool *isNull);
static Datum ExecEvalOper(Expr *opClause, ExprContext *econtext,
bool *isNull);
static Datum ExecEvalOr(Expr *orExpr, ExprContext *econtext, bool *isNull);
static Datum ExecEvalVar(Var *variable, ExprContext *econtext, bool *isNull);
static Datum ExecMakeFunctionResult(Node *node, List *arguments,
ExprContext *econtext, bool *isNull, bool *isDone);
static bool ExecQualClause(Node *clause, ExprContext *econtext);
/*
* ExecEvalArrayRef
*
* This function takes an ArrayRef and returns a Const Node if it
* is an array reference or returns the changed Array Node if it is
* an array assignment.
*/
static Datum
ExecEvalArrayRef(ArrayRef *arrayRef,
ExprContext *econtext,
bool *isNull,
bool *isDone)
{
bool dummy;
int i = 0,
j = 0;
ArrayType *array_scanner;
List *upperIndexpr,
*lowerIndexpr;
Node *assgnexpr;
List *elt;
IntArray upper,
lower;
int *lIndex;
char *dataPtr;
*isNull = false;
array_scanner = (ArrayType *) ExecEvalExpr(arrayRef->refexpr,
econtext,
isNull,
isDone);
if (*isNull)
return (Datum) NULL;
upperIndexpr = arrayRef->refupperindexpr;
foreach(elt, upperIndexpr)
{
upper.indx[i++] = (int32) ExecEvalExpr((Node *) lfirst(elt),
econtext,
isNull,
&dummy);
if (*isNull)
return (Datum) NULL;
}
lowerIndexpr = arrayRef->reflowerindexpr;
lIndex = NULL;
if (lowerIndexpr != NIL)
{
foreach(elt, lowerIndexpr)
{
lower.indx[j++] = (int32) ExecEvalExpr((Node *) lfirst(elt),
econtext,
isNull,
&dummy);
if (*isNull)
return (Datum) NULL;
}
if (i != j)
elog(ERROR,
"ExecEvalArrayRef: upper and lower indices mismatch");
lIndex = lower.indx;
}
assgnexpr = arrayRef->refassgnexpr;
if (assgnexpr != NULL)
{
dataPtr = (char *) ExecEvalExpr((Node *)
assgnexpr, econtext,
isNull, &dummy);
if (*isNull)
return (Datum) NULL;
execConstByVal = arrayRef->refelembyval;
execConstLen = arrayRef->refelemlength;
if (lIndex == NULL)
return (Datum) array_set(array_scanner, i, upper.indx, dataPtr,
arrayRef->refelembyval,
arrayRef->refelemlength,
arrayRef->refattrlength, isNull);
return (Datum) array_assgn(array_scanner, i, upper.indx,
lower.indx,
(ArrayType *) dataPtr,
arrayRef->refelembyval,
arrayRef->refelemlength, isNull);
}
execConstByVal = arrayRef->refelembyval;
execConstLen = arrayRef->refelemlength;
if (lIndex == NULL)
return (Datum) array_ref(array_scanner, i, upper.indx,
arrayRef->refelembyval,
arrayRef->refelemlength,
arrayRef->refattrlength, isNull);
return (Datum) array_clip(array_scanner, i, upper.indx, lower.indx,
arrayRef->refelembyval,
arrayRef->refelemlength, isNull);
}
/* ----------------------------------------------------------------
* 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)
{
*isNull = econtext->ecxt_nulls[aggref->aggno];
return econtext->ecxt_values[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;
Buffer buffer;
bool byval;
int16 len;
/*
* 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;
buffer = slot->ttc_buffer;
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.
*/
if (attnum == InvalidAttrNumber)
{
TupleTableSlot *tempSlot;
TupleDesc td;
HeapTuple tup;
tempSlot = makeNode(TupleTableSlot);
tempSlot->ttc_shouldFree = false;
tempSlot->ttc_descIsNew = true;
tempSlot->ttc_tupleDescriptor = (TupleDesc) NULL;
tempSlot->ttc_buffer = InvalidBuffer;
tempSlot->ttc_whichplan = -1;
tup = heap_copytuple(heapTuple);
td = CreateTupleDescCopy(slot->ttc_tupleDescriptor);
ExecSetSlotDescriptor(tempSlot, td);
ExecStoreTuple(tup, tempSlot, InvalidBuffer, true);
return (Datum) 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 null if att is null
*/
if (*isNull)
return (Datum) NULL;
/*
* get length and type information..
* ??? what should we do about variable length attributes
* - variable length attributes have their length stored
* in the first 4 bytes of the memory pointed to by the
* returned value.. If we can determine that the type
* is a variable length type, we can do the right thing.
* -cim 9/15/89
*/
if (attnum < 0)
{
/*
* If this is a pseudo-att, we get the type and fake the length.
* There ought to be a routine to return the real lengths, so
* we'll mark this one ... XXX -mao
*/
len = heap_sysattrlen(attnum); /* XXX see -mao above */
byval = heap_sysattrbyval(attnum); /* XXX see -mao above */
}
else
{
len = tuple_type->attrs[attnum - 1]->attlen;
byval = tuple_type->attrs[attnum - 1]->attbyval ? true : false;
}
execConstByVal = byval;
execConstLen = len;
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 = &(econtext->ecxt_param_exec_vals[thisParameterId]);
if (prm->execPlan != NULL)
ExecSetParamPlan(prm->execPlan);
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.
*/
if (paramList->isnull)
{
*isNull = true;
return (Datum) NULL;
}
if (expression->param_tlist != NIL)
{
HeapTuple tup;
Datum value;
List *tlist = expression->param_tlist;
TargetEntry *tle = (TargetEntry *) lfirst(tlist);
TupleTableSlot *slot = (TupleTableSlot *) paramList->value;
tup = slot->val;
value = ProjectAttribute(slot->ttc_tupleDescriptor,
tle, tup, isNull);
return value;
}
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().
*/
/* static but gets called from external functions */
char *
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 (char *) NULL;
}
retval = heap_getattr(slot->val,
attrno,
slot->ttc_tupleDescriptor,
isNull);
if (*isNull)
return (char *) NULL;
return (char *) retval;
}
/* XXX name for catalogs */
#ifdef NOT_USED
char *
att_by_num(TupleTableSlot *slot,
AttrNumber attrno,
bool *isNull)
{
return GetAttributeByNum(slot, attrno, isNull);
}
#endif
char *
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 (char *) NULL;
}
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 (char *) NULL;
return (char *) retval;
}
/* XXX name for catalogs */
#ifdef NOT_USED
char *
att_by_name(TupleTableSlot *slot, char *attname, bool *isNull)
{
return GetAttributeByName(slot, attname, isNull);
}
#endif
static void
ExecEvalFuncArgs(FunctionCachePtr fcache,
ExprContext *econtext,
List *argList,
Datum argV[],
bool *argIsDone)
{
int i;
bool argIsNull,
*nullVect;
List *arg;
nullVect = fcache->nullVect;
i = 0;
foreach(arg, argList)
{
/*
* evaluate the expression, in general functions cannot take
* sets as arguments but we make an exception in the case of
* nested dot expressions. We have to watch out for this case
* here.
*/
argV[i] = (Datum)
ExecEvalExpr((Node *) lfirst(arg),
econtext,
&argIsNull,
argIsDone);
if (!(*argIsDone))
{
Assert(i == 0);
fcache->setArg = (char *) argV[0];
fcache->hasSetArg = true;
}
if (argIsNull)
nullVect[i] = true;
else
nullVect[i] = false;
i++;
}
}
/*
* ExecMakeFunctionResult
*/
static Datum
ExecMakeFunctionResult(Node *node,
List *arguments,
ExprContext *econtext,
bool *isNull,
bool *isDone)
{
Datum argV[MAXFMGRARGS];
FunctionCachePtr fcache;
Func *funcNode = NULL;
Oper *operNode = NULL;
bool funcisset = false;
/*
* This is kind of ugly, Func nodes now have targetlists so that we
* know when and what to project out from postquel function results.
* This means we have to pass the func node all the way down instead
* of using only the fcache struct as before. ExecMakeFunctionResult
* becomes a little bit more of a dual personality as a result.
*/
if (IsA(node, Func))
{
funcNode = (Func *) node;
fcache = funcNode->func_fcache;
}
else
{
operNode = (Oper *) node;
fcache = operNode->op_fcache;
}
/*
* arguments is a list of expressions to evaluate
* before passing to the function manager.
* We collect the results of evaluating the expressions
* into a datum array (argV) and pass this array to arrayFmgr()
*/
if (fcache->nargs != 0)
{
bool argDone;
if (fcache->nargs > MAXFMGRARGS)
elog(ERROR, "ExecMakeFunctionResult: too many arguments");
/*
* If the setArg in the fcache is set we have an argument
* returning a set of tuples (i.e. a nested dot expression). We
* don't want to evaluate the arguments again until the function
* is done. hasSetArg will always be false until we eval the args
* for the first time. We should set this in the parser.
*/
if ((fcache->hasSetArg) && fcache->setArg != NULL)
{
argV[0] = (Datum) fcache->setArg;
argDone = false;
}
else
ExecEvalFuncArgs(fcache, econtext, arguments, argV, &argDone);
if ((fcache->hasSetArg) && (argDone))
{
if (isDone)
*isDone = true;
return (Datum) NULL;
}
}
/*
* If this function is really a set, we have to diddle with things. If
* the function has already been called at least once, then the setArg
* field of the fcache holds the OID of this set in pg_proc. (This is
* not quite legit, since the setArg field is really for functions
* which take sets of tuples as input - set functions take no inputs
* at all. But it's a nice place to stash this value, for now.)
*
* If this is the first call of the set's function, then the call to
* ExecEvalFuncArgs above just returned the OID of the pg_proc tuple
* which defines this set. So replace the existing funcid in the
* funcnode with the set's OID. Also, we want a new fcache which
* points to the right function, so get that, now that we have the
* right OID. Also zero out the argV, since the real set doesn't take
* any arguments.
*/
if (((Func *) node)->funcid == F_SETEVAL)
{
funcisset = true;
if (fcache->setArg)
{
argV[0] = 0;
((Func *) node)->funcid = (Oid) PointerGetDatum(fcache->setArg);
}
else
{
((Func *) node)->funcid = (Oid) argV[0];
setFcache(node, argV[0], NIL, econtext);
fcache = ((Func *) node)->func_fcache;
fcache->setArg = (char *) argV[0];
argV[0] = (Datum) 0;
}
}
/*
* now return the value gotten by calling the function manager,
* passing the function the evaluated parameter values.
*/
if (fcache->language == SQLlanguageId)
{
Datum result;
Assert(funcNode);
result = postquel_function(funcNode, (char **) argV, isNull, isDone);
/*
* finagle the situation where we are iterating through all
* results in a nested dot function (whose argument function
* returns a set of tuples) and the current function finally
* finishes. We need to get the next argument in the set and run
* the function all over again. This is getting unclean.
*/
if ((*isDone) && (fcache->hasSetArg))
{
bool argDone;
ExecEvalFuncArgs(fcache, econtext, arguments, argV, &argDone);
if (argDone)
{
fcache->setArg = (char *) NULL;
*isDone = true;
result = (Datum) NULL;
}
else
result = postquel_function(funcNode,
(char **) argV,
isNull,
isDone);
}
if (funcisset)
{
/*
* reset the funcid so that next call to this routine will
* still recognize this func as a set. Note that for now we
* assume that the set function in pg_proc must be a Postquel
* function - the funcid is not reset below for C functions.
*/
((Func *) node)->funcid = F_SETEVAL;
/*
* If we're done with the results of this function, get rid of
* its func cache.
*/
if (*isDone)
((Func *) node)->func_fcache = NULL;
}
return result;
}
else
{
int i;
if (isDone)
*isDone = true;
for (i = 0; i < fcache->nargs; i++)
if (fcache->nullVect[i] == true)
*isNull = true;
return (Datum) fmgr_c(&fcache->func, (FmgrValues *) argV, isNull);
}
}
/* ----------------------------------------------------------------
* ExecEvalOper
* ExecEvalFunc
*
* Evaluate the functional result of a list of arguments by calling the
* function manager. Note that in the case of operator expressions, the
* optimizer had better have already replaced the operator OID with the
* appropriate function OID or we're hosed.
*
* old comments
* Presumably the function manager will not take null arguments, so we
* check for null arguments before sending the arguments to (fmgr).
*
* Returns the value of the functional expression.
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* ExecEvalOper
* ----------------------------------------------------------------
*/
static Datum
ExecEvalOper(Expr *opClause, ExprContext *econtext, bool *isNull)
{
Oper *op;
List *argList;
FunctionCachePtr fcache;
bool isDone;
/*
* an opclause is a list (op args). (I think)
*
* 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)
{
setFcache((Node *) op, op->opid, argList, econtext);
fcache = op->op_fcache;
}
/*
* call ExecMakeFunctionResult() with a dummy isDone that we ignore.
* We don't have operator whose arguments are sets.
*/
return ExecMakeFunctionResult((Node *) op, argList, econtext, isNull, &isDone);
}
/* ----------------------------------------------------------------
* ExecEvalFunc
* ----------------------------------------------------------------
*/
static Datum
ExecEvalFunc(Expr *funcClause,
ExprContext *econtext,
bool *isNull,
bool *isDone)
{
Func *func;
List *argList;
FunctionCachePtr fcache;
/*
* an funcclause is a list (func args). (I think)
*
* 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)
{
setFcache((Node *) func, func->funcid, argList, econtext);
fcache = func->func_fcache;
}
return ExecMakeFunctionResult((Node *) func, 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)
{
Datum expr_value;
Node *clause;
bool isDone;
clause = lfirst(notclause->args);
/*
* We don't iterate over sets in the quals, so pass in an isDone
* flag, but ignore it.
*/
expr_value = ExecEvalExpr(clause, econtext, isNull, &isDone);
/*
* 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.
*/
if (DatumGetInt32(expr_value) == 0)
return (Datum) true;
return (Datum) false;
}
/* ----------------------------------------------------------------
* ExecEvalOr
* ----------------------------------------------------------------
*/
static Datum
ExecEvalOr(Expr *orExpr, ExprContext *econtext, bool *isNull)
{
List *clauses;
List *clause;
bool isDone;
bool IsNull;
Datum const_value = 0;
IsNull = false;
clauses = orExpr->args;
/*
* we use three valued logic functions here...
* we evaluate each of the clauses in turn,
* as soon as one is true we return that
* value. If none is true and none of the
* clauses evaluate to NULL we return
* the value of the last clause evaluated (which
* should be false) with *isNull set to false else
* if none is true and at least one clause evaluated
* to NULL we set *isNull flag to true -
*/
foreach(clause, clauses)
{
/*
* We don't iterate over sets in the quals, so pass in an isDone
* flag, but ignore it.
*/
const_value = ExecEvalExpr((Node *) lfirst(clause),
econtext,
isNull,
&isDone);
/*
* if the expression evaluates to null, then we
* remember it in the local IsNull flag, if none of the
* clauses are true then we need to set *isNull
* to true again.
*/
if (*isNull)
{
IsNull = *isNull;
/*
* Many functions don't (or can't!) check if an argument is NULL
* or NOT_NULL and may return TRUE (1) with *isNull TRUE
* (an_int4_column <> 1: int4ne returns TRUE for NULLs).
* Not having time to fix the function manager I want to fix OR:
* if we had 'x <> 1 OR x isnull' then when x is NULL
* TRUE was returned by the 'x <> 1' clause ...
* but ExecQualClause says that the qualification should *fail*
* if isnull is TRUE for any value returned by ExecEvalExpr.
* So, force this rule here:
* if isnull is TRUE then the clause failed.
* Note: nullvalue() & nonnullvalue() always sets isnull to FALSE for NULLs.
* - vadim 09/22/97
*/
const_value = 0;
}
/*
* if we have a true result, then we return it.
*/
if (DatumGetInt32(const_value) != 0)
return const_value;
}
/* IsNull is true if at least one clause evaluated to NULL */
*isNull = IsNull;
return const_value;
}
/* ----------------------------------------------------------------
* ExecEvalAnd
* ----------------------------------------------------------------
*/
static Datum
ExecEvalAnd(Expr *andExpr, ExprContext *econtext, bool *isNull)
{
List *clauses;
List *clause;
Datum const_value = 0;
bool isDone;
bool IsNull;
IsNull = false;
clauses = andExpr->args;
/*
* we evaluate each of the clauses in turn,
* as soon as one is false we return that
* value. If none are false or NULL then we return
* the value of the last clause evaluated, which
* should be true.
*/
foreach(clause, clauses)
{
/*
* We don't iterate over sets in the quals, so pass in an isDone
* flag, but ignore it.
*/
const_value = ExecEvalExpr((Node *) lfirst(clause),
econtext,
isNull,
&isDone);
/*
* if the expression evaluates to null, then we
* remember it in IsNull, if none of the clauses after
* this evaluates to false we will have to set *isNull
* to true again.
*/
if (*isNull)
IsNull = *isNull;
/*
* if we have a false result, then we return it, since the
* conjunction must be false.
*/
if (DatumGetInt32(const_value) == 0)
return const_value;
}
*isNull = IsNull;
return const_value;
}
/* ----------------------------------------------------------------
* ExecEvalCase
*
* Evaluate a CASE clause. Will have boolean expressions
* inside the WHEN clauses, and will have constants
* for results.
* - thomas 1998-11-09
* ----------------------------------------------------------------
*/
static Datum
ExecEvalCase(CaseExpr *caseExpr, ExprContext *econtext, bool *isNull)
{
List *clauses;
List *clause;
CaseWhen *wclause;
Datum const_value = 0;
bool isDone;
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.
*/
foreach(clause, clauses)
{
/*
* We don't iterate over sets in the quals, so pass in an isDone
* flag, but ignore it.
*/
wclause = lfirst(clause);
const_value = ExecEvalExpr((Node *) wclause->expr,
econtext,
isNull,
&isDone);
/*
* if we have a true test, then we return the result,
* since the case statement is satisfied.
*/
if (DatumGetInt32(const_value) != 0)
{
const_value = ExecEvalExpr((Node *) wclause->result,
econtext,
isNull,
&isDone);
return (Datum) const_value;
}
}
if (caseExpr->defresult)
{
const_value = ExecEvalExpr((Node *) caseExpr->defresult,
econtext,
isNull,
&isDone);
}
else
{
*isNull = true;
}
return const_value;
}
/* ----------------------------------------------------------------
* ExecEvalExpr
*
* Recursively evaluate a targetlist or qualification expression.
*
* This routine is an inner loop routine and should be as fast
* as possible.
*
* Node comparison functions were replaced by macros for speed and to plug
* memory leaks incurred by using the planner's Lispy stuff for
* comparisons. Order of evaluation of node comparisons IS IMPORTANT;
* the macros do no checks. Order of evaluation:
*
* o an isnull check, largely to avoid coredumps since greg doubts this
* routine is called with a null ptr anyway in proper operation, but is
* not completely sure...
* o ExactNodeType checks.
* o clause checks or other checks where we look at the lfirst of something.
* ----------------------------------------------------------------
*/
Datum
ExecEvalExpr(Node *expression,
ExprContext *econtext,
bool *isNull,
bool *isDone)
{
Datum retDatum = 0;
*isNull = false;
/*
* Some callers don't care about is done and only want 1 result. They
* indicate this by passing NULL
*/
if (isDone)
*isDone = true;
/*
* here we dispatch the work to the appropriate type
* of function given the type of our expression.
*/
if (expression == NULL)
{
*isNull = true;
return (Datum) true;
}
switch (nodeTag(expression))
{
case T_Var:
retDatum = (Datum) ExecEvalVar((Var *) expression, econtext, isNull);
break;
case T_Const:
{
Const *con = (Const *) expression;
if (con->constisnull)
*isNull = true;
retDatum = con->constvalue;
break;
}
case T_Param:
retDatum = (Datum) ExecEvalParam((Param *) expression, econtext, isNull);
break;
case T_Iter:
retDatum = (Datum) ExecEvalIter((Iter *) expression,
econtext,
isNull,
isDone);
break;
case T_Aggref:
retDatum = (Datum) ExecEvalAggref((Aggref *) expression,
econtext,
isNull);
break;
case T_ArrayRef:
retDatum = (Datum) ExecEvalArrayRef((ArrayRef *) expression,
econtext,
isNull,
isDone);
break;
case T_Expr:
{
Expr *expr = (Expr *) expression;
switch (expr->opType)
{
case OP_EXPR:
retDatum = (Datum) ExecEvalOper(expr, econtext, isNull);
break;
case FUNC_EXPR:
retDatum = (Datum) ExecEvalFunc(expr, econtext, isNull, isDone);
break;
case OR_EXPR:
retDatum = (Datum) ExecEvalOr(expr, econtext, isNull);
break;
case AND_EXPR:
retDatum = (Datum) ExecEvalAnd(expr, econtext, isNull);
break;
case NOT_EXPR:
retDatum = (Datum) ExecEvalNot(expr, econtext, isNull);
break;
case SUBPLAN_EXPR:
retDatum = (Datum) ExecSubPlan((SubPlan *) expr->oper, expr->args, econtext);
break;
default:
elog(ERROR, "ExecEvalExpr: unknown expression type %d", expr->opType);
break;
}
break;
}
case T_CaseExpr:
retDatum = (Datum) ExecEvalCase((CaseExpr *) expression, econtext, isNull);
break;
default:
elog(ERROR, "ExecEvalExpr: unknown expression type %d", nodeTag(expression));
break;
}
return retDatum;
} /* ExecEvalExpr() */
/* ----------------------------------------------------------------
* ExecQual / ExecTargetList
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* ExecQualClause
*
* this is a workhorse for ExecQual. ExecQual has to deal
* with a list of qualifications, so it passes each qualification
* in the list to this function one at a time. ExecQualClause
* returns true when the qualification *fails* and false if
* the qualification succeeded (meaning we have to test the
* rest of the qualification)
* ----------------------------------------------------------------
*/
static bool
ExecQualClause(Node *clause, ExprContext *econtext)
{
Datum expr_value;
bool isNull;
bool isDone;
/* when there is a null clause, consider the qualification to be true */
if (clause == NULL)
return true;
/*
* pass isDone, but ignore it. We don't iterate over multiple returns
* in the qualifications.
*/
expr_value = (Datum)
ExecEvalExpr(clause, econtext, &isNull, &isDone);
/*
* this is interesting behaviour here. When a clause evaluates
* to null, then we consider this as passing the qualification.
* it seems kind of like, if the qual is NULL, then there's no
* qual..
*/
if (isNull)
return true;
/*
* remember, we return true when the qualification fails..
*/
if (DatumGetInt32(expr_value) == 0)
return true;
return false;
}
/* ----------------------------------------------------------------
* ExecQual
*
* Evaluates a conjunctive boolean expression and returns t
* iff none of the subexpressions are false (or null).
* ----------------------------------------------------------------
*/
bool
ExecQual(List *qual, ExprContext *econtext)
{
List *clause;
bool result;
/*
* debugging stuff
*/
EV_printf("ExecQual: qual is ");
EV_nodeDisplay(qual);
EV_printf("\n");
IncrProcessed();
/*
* return true immediately if no qual
*/
if (qual == NIL)
return true;
/*
* a "qual" is a list of clauses. To evaluate the
* qual, we evaluate each of the clauses in the list.
*
* ExecQualClause returns true when we know the qualification
* *failed* so we just pass each clause in qual to it until
* we know the qual failed or there are no more clauses.
*/
result = false;
foreach(clause, qual)
{
result = ExecQualClause((Node *) lfirst(clause), econtext);
if (result == true)
break;
}
/*
* if result is true, then it means a clause failed so we
* return false. if result is false then it means no clause
* failed so we return true.
*/
if (result == true)
return false;
return true;
}
int
ExecTargetListLength(List *targetlist)
{
int len;
List *tl;
TargetEntry *curTle;
len = 0;
foreach(tl, targetlist)
{
curTle = lfirst(tl);
if (curTle->resdom != NULL)
len++;
else
len += curTle->fjoin->fj_nNodes;
}
return len;
}
/* ----------------------------------------------------------------
* ExecTargetList
*
* Evaluates a targetlist with respect to the current
* expression context and return a tuple.
* ----------------------------------------------------------------
*/
static HeapTuple
ExecTargetList(List *targetlist,
int nodomains,
TupleDesc targettype,
Datum *values,
ExprContext *econtext,
bool *isDone)
{
char nulls_array[64];
bool fjNullArray[64];
bool *fjIsNull;
char *null_head;
List *tl;
TargetEntry *tle;
Node *expr;
Resdom *resdom;
AttrNumber resind;
Datum constvalue;
HeapTuple newTuple;
bool isNull;
/*
* debugging stuff
*/
EV_printf("ExecTargetList: tl is ");
EV_nodeDisplay(targetlist);
EV_printf("\n");
/*
* Return a dummy tuple if the targetlist is empty.
* the dummy tuple is necessary to differentiate
* between passing and failing the qualification.
*/
if (targetlist == NIL)
{
/*
* I now think that the only time this makes
* any sense is when we run a delete query. Then
* we need to return something other than nil
* so we know to delete the tuple associated
* with the saved tupleid.. see what ExecutePlan
* does with the returned tuple.. -cim 9/21/89
*
* It could also happen in queries like:
* retrieve (foo.all) where bar.a = 3
*
* is this a new phenomenon? it might cause bogus behavior
* if we try to free this tuple later!! I put a hook in
* ExecProject to watch out for this case -mer 24 Aug 1992
*
* We must return dummy tuple!!! Try
* select t1.x from t1, t2 where t1.y = 1 and t2.y = 1
* - t2 scan target list will be empty and so no one tuple
* will be returned! But Mer was right - dummy tuple
* must be palloced... - vadim 03/01/1999
*/
*isDone = true;
return (HeapTuple) palloc(1);
}
/*
* allocate an array of char's to hold the "null" information
* only if we have a really large targetlist. otherwise we use
* the stack.
*/
if (nodomains > 64)
{
null_head = (char *) palloc(nodomains + 1);
fjIsNull = (bool *) palloc(nodomains + 1);
}
else
{
null_head = &nulls_array[0];
fjIsNull = &fjNullArray[0];
}
/*
* evaluate all the expressions in the target list
*/
EV_printf("ExecTargetList: setting target list values\n");
*isDone = true;
foreach(tl, targetlist)
{
/*
* remember, a target list is a list of lists:
*
* ((<resdom | fjoin> expr) (<resdom | fjoin> expr) ...)
*
* tl is a pointer to successive cdr's of the targetlist
* tle is a pointer to the target list entry in tl
*/
tle = lfirst(tl);
if (tle->resdom != NULL)
{
expr = tle->expr;
resdom = tle->resdom;
resind = resdom->resno - 1;
constvalue = (Datum) ExecEvalExpr(expr,
econtext,
&isNull,
isDone);
if ((IsA(expr, Iter)) && (*isDone))
return (HeapTuple) NULL;
values[resind] = constvalue;
if (!isNull)
null_head[resind] = ' ';
else
null_head[resind] = 'n';
}
else
{
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);
if (*isDone)
return (HeapTuple) NULL;
/*
* get the result from the inner node
*/
fjRes = (Resdom *) fjNode->fj_innerNode;
resind = fjRes->resno - 1;
if (fjIsNull[0])
null_head[resind] = 'n';
else
{
null_head[resind] = ' ';
values[resind] = results[0];
}
/*
* Get results from all of the outer nodes
*/
for (curNode = 1;
curNode < nNodes;
curNode++, fjTlist = lnext(fjTlist))
{
#ifdef NOT_USED /* what is this?? */
Node *outernode = lfirst(fjTlist);
fjRes = (Resdom *) outernode->iterexpr;
#endif
resind = fjRes->resno - 1;
if (fjIsNull[curNode])
null_head[resind] = 'n';
else
{
null_head[resind] = ' ';
values[resind] = results[curNode];
}
}
}
}
/*
* form the new result tuple (in the "normal" context)
*/
newTuple = (HeapTuple) heap_formtuple(targettype, values, null_head);
/*
* free the nulls array if we allocated one..
*/
if (nodomains > 64)
{
pfree(null_head);
pfree(fjIsNull);
}
return newTuple;
}
/* ----------------------------------------------------------------
* ExecProject
*
* projects a tuple based in 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, bool *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
*/
newTuple = ExecTargetList(targetlist,
len,
tupType,
tupValue,
econtext,
isDone);
/*
* store the tuple in the projection slot and return the slot.
*
* If there's no projection target list we don't want to pfree
* the bogus tuple that ExecTargetList passes back to us.
* -mer 24 Aug 1992
*/
return (TupleTableSlot *)
ExecStoreTuple(newTuple,/* tuple to store */
slot, /* slot to store in */
InvalidBuffer, /* tuple has no buffer */
true);
}
Reference in New Issue View Git Blame Copy Permalink