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/*-------------------------------------------------------------------------
*
* junk.c
* Junk attribute support stuff....
*
* 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/execJunk.c,v 1.32 2002/09/04 20:31:17 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/heapam.h"
#include "executor/executor.h"
#include "nodes/makefuncs.h"
/*-------------------------------------------------------------------------
* XXX this stuff should be rewritten to take advantage
* of ExecProject() and the ProjectionInfo node.
* -cim 6/3/91
*
* An attribute of a tuple living inside the executor, can be
* either a normal attribute or a "junk" attribute. "junk" attributes
* never make it out of the executor, i.e. they are never printed,
* returned or stored in disk. Their only purpose in life is to
* store some information useful only to the executor, mainly the values
* of some system attributes like "ctid" or rule locks.
*
* The general idea is the following: A target list consists of a list of
* Resdom nodes & expression pairs. Each Resdom node has an attribute
* called 'resjunk'. If the value of this attribute is true then the
* corresponding attribute is a "junk" attribute.
*
* When we initialize a plan we call 'ExecInitJunkFilter' to create
* and store the appropriate information in the 'es_junkFilter' attribute of
* EState.
*
* We then execute the plan ignoring the "resjunk" attributes.
*
* Finally, when at the top level we get back a tuple, we can call
* 'ExecGetJunkAttribute' to retrieve the value of the junk attributes we
* are interested in, and 'ExecRemoveJunk' to remove all the junk attributes
* from a tuple. This new "clean" tuple is then printed, replaced, deleted
* or inserted.
*
*-------------------------------------------------------------------------
*/
/*-------------------------------------------------------------------------
* ExecInitJunkFilter
*
* Initialize the Junk filter.
*
* The initial targetlist and associated tuple descriptor are passed in.
* An optional resultSlot can be passed as well.
*-------------------------------------------------------------------------
*/
JunkFilter *
ExecInitJunkFilter(List *targetList, TupleDesc tupType,
TupleTableSlot *slot)
{
MemoryContext oldContext;
MemoryContext junkContext;
JunkFilter *junkfilter;
List *cleanTargetList;
int len,
cleanLength;
TupleDesc cleanTupType;
List *t;
TargetEntry *tle;
Resdom *resdom,
*cleanResdom;
bool resjunk;
AttrNumber cleanResno;
AttrNumber *cleanMap;
Node *expr;
/*
* Make a memory context that will hold the JunkFilter as well as all
* the subsidiary structures we are about to create. We use smaller-
* than-default sizing parameters since we don't expect a very large
* volume of stuff here.
*/
junkContext = AllocSetContextCreate(CurrentMemoryContext,
"JunkFilterContext",
1024,
1024,
ALLOCSET_DEFAULT_MAXSIZE);
oldContext = MemoryContextSwitchTo(junkContext);
/*
* First find the "clean" target list, i.e. all the entries in the
* original target list which have a false 'resjunk' NOTE: make copy
* of the Resdom nodes, because we have to change the 'resno's...
*/
cleanTargetList = NIL;
cleanResno = 1;
foreach(t, targetList)
{
TargetEntry *rtarget = lfirst(t);
if (rtarget->resdom != NULL)
{
resdom = rtarget->resdom;
expr = rtarget->expr;
resjunk = resdom->resjunk;
if (!resjunk)
{
/*
* make a copy of the resdom node, changing its resno.
*/
cleanResdom = (Resdom *) copyObject(resdom);
cleanResdom->resno = cleanResno;
cleanResno++;
/*
* create a new target list entry
*/
tle = makeTargetEntry(cleanResdom, expr);
cleanTargetList = lappend(cleanTargetList, tle);
}
}
else
{
#ifdef SETS_FIXED
List *fjListP;
Fjoin *cleanFjoin;
List *cleanFjList;
List *fjList = lfirst(t);
Fjoin *fjNode = (Fjoin *) tl_node(fjList);
cleanFjoin = (Fjoin) copyObject((Node) fjNode);
cleanFjList = makeList1(cleanFjoin);
resdom = (Resdom) lfirst(get_fj_innerNode(fjNode));
expr = lsecond(get_fj_innerNode(fjNode));
cleanResdom = (Resdom) copyObject((Node) resdom);
set_resno(cleanResdom, cleanResno);
cleanResno++;
tle = (List) makeTargetEntry(cleanResdom, (Node *) expr);
set_fj_innerNode(cleanFjoin, tle);
foreach(fjListP, lnext(fjList))
{
TargetEntry *tle = lfirst(fjListP);
resdom = tle->resdom;
expr = tle->expr;
cleanResdom = (Resdom *) copyObject((Node) resdom);
cleanResno++;
cleanResdom->Resno = cleanResno;
/*
* create a new target list entry
*/
tle = (List) makeTargetEntry(cleanResdom, (Node *) expr);
cleanFjList = lappend(cleanFjList, tle);
}
lappend(cleanTargetList, cleanFjList);
#endif
}
}
/*
* Now calculate the tuple type for the cleaned tuple (we were already
* given the type for the original targetlist).
*/
cleanTupType = ExecTypeFromTL(cleanTargetList, tupType->tdhasoid);
len = ExecTargetListLength(targetList);
cleanLength = ExecTargetListLength(cleanTargetList);
/*
* Now calculate the "map" between the original tuple's attributes and
* the "clean" tuple's attributes.
*
* The "map" is an array of "cleanLength" attribute numbers, i.e. one
* entry for every attribute of the "clean" tuple. The value of this
* entry is the attribute number of the corresponding attribute of the
* "original" tuple.
*/
if (cleanLength > 0)
{
cleanMap = (AttrNumber *) palloc(cleanLength * sizeof(AttrNumber));
cleanResno = 1;
foreach(t, targetList)
{
TargetEntry *tle = lfirst(t);
if (tle->resdom != NULL)
{
resdom = tle->resdom;
expr = tle->expr;
resjunk = resdom->resjunk;
if (!resjunk)
{
cleanMap[cleanResno - 1] = resdom->resno;
cleanResno++;
}
}
else
{
#ifdef SETS_FIXED
List fjListP;
List fjList = lfirst(t);
Fjoin fjNode = (Fjoin) lfirst(fjList);
/* what the hell is this????? */
resdom = (Resdom) lfirst(get_fj_innerNode(fjNode));
#endif
cleanMap[cleanResno - 1] = tle->resdom->resno;
cleanResno++;
#ifdef SETS_FIXED
foreach(fjListP, lnext(fjList))
{
TargetEntry *tle = lfirst(fjListP);
resdom = tle->resdom;
cleanMap[cleanResno - 1] = resdom->resno;
cleanResno++;
}
#endif
}
}
}
else
cleanMap = NULL;
/*
* Finally create and initialize the JunkFilter struct.
*/
junkfilter = makeNode(JunkFilter);
junkfilter->jf_targetList = targetList;
junkfilter->jf_length = len;
junkfilter->jf_tupType = tupType;
junkfilter->jf_cleanTargetList = cleanTargetList;
junkfilter->jf_cleanLength = cleanLength;
junkfilter->jf_cleanTupType = cleanTupType;
junkfilter->jf_cleanMap = cleanMap;
junkfilter->jf_junkContext = junkContext;
junkfilter->jf_resultSlot = slot;
if (slot)
ExecSetSlotDescriptor(slot, cleanTupType, false);
MemoryContextSwitchTo(oldContext);
return junkfilter;
}
/*-------------------------------------------------------------------------
* ExecFreeJunkFilter
*
* Release the data structures created by ExecInitJunkFilter.
*-------------------------------------------------------------------------
*/
void
ExecFreeJunkFilter(JunkFilter *junkfilter)
{
/*
* Since the junkfilter is inside its own context, we just have to
* delete the context and we're set.
*/
MemoryContextDelete(junkfilter->jf_junkContext);
}
/*-------------------------------------------------------------------------
* ExecGetJunkAttribute
*
* Given a tuple (slot), the junk filter and a junk attribute's name,
* extract & return the value and isNull flag of this attribute.
*
* It returns false iff no junk attribute with such name was found.
*-------------------------------------------------------------------------
*/
bool
ExecGetJunkAttribute(JunkFilter *junkfilter,
TupleTableSlot *slot,
char *attrName,
Datum *value,
bool *isNull)
{
List *targetList;
List *t;
Resdom *resdom;
AttrNumber resno;
char *resname;
bool resjunk;
TupleDesc tupType;
HeapTuple tuple;
/*
* first look in the junkfilter's target list for an attribute with
* the given name
*/
resno = InvalidAttrNumber;
targetList = junkfilter->jf_targetList;
foreach(t, targetList)
{
TargetEntry *tle = lfirst(t);
resdom = tle->resdom;
resname = resdom->resname;
resjunk = resdom->resjunk;
if (resjunk && (strcmp(resname, attrName) == 0))
{
/* We found it ! */
resno = resdom->resno;
break;
}
}
if (resno == InvalidAttrNumber)
{
/* Ooops! We couldn't find this attribute... */
return false;
}
/*
* Now extract the attribute value from the tuple.
*/
tuple = slot->val;
tupType = junkfilter->jf_tupType;
*value = heap_getattr(tuple, resno, tupType, isNull);
return true;
}
/*-------------------------------------------------------------------------
* ExecRemoveJunk
*
* Construct and return a tuple with all the junk attributes removed.
*
* Note: for historical reasons, this does not store the constructed
* tuple into the junkfilter's resultSlot. The caller should do that
* if it wants to.
*-------------------------------------------------------------------------
*/
HeapTuple
ExecRemoveJunk(JunkFilter *junkfilter, TupleTableSlot *slot)
{
HeapTuple tuple;
HeapTuple cleanTuple;
AttrNumber *cleanMap;
TupleDesc cleanTupType;
TupleDesc tupType;
int cleanLength;
bool isNull;
int i;
Datum *values;
char *nulls;
Datum values_array[64];
char nulls_array[64];
/*
* get info from the slot and the junk filter
*/
tuple = slot->val;
tupType = junkfilter->jf_tupType;
cleanTupType = junkfilter->jf_cleanTupType;
cleanLength = junkfilter->jf_cleanLength;
cleanMap = junkfilter->jf_cleanMap;
/*
* Handle the trivial case first.
*/
if (cleanLength == 0)
return (HeapTuple) NULL;
/*
* Create the arrays that will hold the attribute values and the null
* information for the new "clean" tuple.
*
* Note: we use memory on the stack to optimize things when we are
* dealing with a small number of attributes. for large tuples we just
* use palloc.
*/
if (cleanLength > 64)
{
values = (Datum *) palloc(cleanLength * sizeof(Datum));
nulls = (char *) palloc(cleanLength * sizeof(char));
}
else
{
values = values_array;
nulls = nulls_array;
}
/*
* Exctract one by one all the values of the "clean" tuple.
*/
for (i = 0; i < cleanLength; i++)
{
values[i] = heap_getattr(tuple, cleanMap[i], tupType, &isNull);
if (isNull)
nulls[i] = 'n';
else
nulls[i] = ' ';
}
/*
* Now form the new tuple.
*/
cleanTuple = heap_formtuple(cleanTupType,
values,
nulls);
/*
* We are done. Free any space allocated for 'values' and 'nulls' and
* return the new tuple.
*/
if (cleanLength > 64)
{
pfree(values);
pfree(nulls);
}
return cleanTuple;
}
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