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Bruce Momjian authoredBruce Momjian authored
execJunk.c 11.00 KiB
/*-------------------------------------------------------------------------
*
* junk.c--
* Junk attribute support stuff....
*
* Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/execJunk.c,v 1.5 1997/08/26 23:31:37 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include <string.h>
#include "postgres.h"
#include "utils/palloc.h"
#include "access/heapam.h"
#include "executor/executor.h"
#include "nodes/relation.h"
#include "optimizer/tlist.h" /* for MakeTLE */
/*-------------------------------------------------------------------------
* 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 1 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.
*-------------------------------------------------------------------------
*/
JunkFilter *
ExecInitJunkFilter(List *targetList)
{
JunkFilter *junkfilter;
List *cleanTargetList;
int len, cleanLength;
TupleDesc tupType, cleanTupType;
List *t; TargetEntry *tle;
Resdom *resdom, *cleanResdom;
int resjunk;
AttrNumber cleanResno;
AttrNumber *cleanMap;
Size size;
Node *expr;
/* ---------------------
* First find the "clean" target list, i.e. all the entries
* in the original target list which have a zero '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 == 0) {
/*
* 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 = makeNode(TargetEntry);
tle->resdom = cleanResdom;
tle->expr = 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 = lcons(cleanFjoin, NIL);
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) MakeTLE(cleanResdom, (Expr) 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) MakeTLE(cleanResdom, (Expr) expr);
cleanFjList = lappend(cleanFjList, tle);
}
lappend(cleanTargetList, cleanFjList);
#endif
}
}
/* ---------------------
* Now calculate the tuple types for the original and the clean tuple
*
* XXX ExecTypeFromTL should be used sparingly. Don't we already
* have the tupType corresponding to the targetlist we are passed?
* -cim 5/31/91
* ---------------------
*/
tupType = (TupleDesc) ExecTypeFromTL(targetList);
cleanTupType = (TupleDesc) ExecTypeFromTL(cleanTargetList);
len = ExecTargetListLength(targetList);
cleanLength = ExecTargetListLength(cleanTargetList);
/* ---------------------
* Now calculate the "map" between the original tuples 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) {
size = cleanLength * sizeof(AttrNumber);
cleanMap = (AttrNumber*) palloc(size);
cleanResno = 1;
foreach (t, targetList) {
TargetEntry *tle = lfirst(t);
if (tle->resdom != NULL) {
resdom = tle->resdom;
expr = tle->expr;
resjunk = resdom->resjunk;
if (resjunk == 0) {
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.
* ---------------------
*/
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;
return(junkfilter);
}
/*-------------------------------------------------------------------------
* ExecGetJunkAttribute
*
* Given a tuple (slot), the junk filter and a junk attribute's name,
* extract & return the value of this attribute.
*
* It returns false iff no junk attribute with such name was found.
*
* NOTE: isNull might be NULL !
*-------------------------------------------------------------------------
*/
bool
ExecGetJunkAttribute(JunkFilter *junkfilter,
TupleTableSlot *slot,
char *attrName,
Datum *value,
bool *isNull)
{
List *targetList;
List *t;
Resdom *resdom;
AttrNumber resno;
char *resname;
int 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 != 0 && (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 = (TupleDesc) junkfilter->jf_tupType;
*value = (Datum)
heap_getattr(tuple, InvalidBuffer, resno, tupType, isNull);
return true;
}
/*-------------------------------------------------------------------------
* ExecRemoveJunk
*
* Construct and return a tuple with all the junk attributes removed.
*-------------------------------------------------------------------------
*/
HeapTuple
ExecRemoveJunk(JunkFilter *junkfilter, TupleTableSlot *slot)
{
HeapTuple tuple;
HeapTuple cleanTuple;
AttrNumber *cleanMap;
TupleDesc cleanTupType;
TupleDesc tupType;
int cleanLength;
bool isNull;
int i;
Size size;
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 = (TupleDesc) junkfilter->jf_tupType;
cleanTupType = (TupleDesc) 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 tuples.
* for large tuples we just use palloc.
* ---------------------
*/
if (cleanLength > 64) {
size = cleanLength * sizeof(Datum);
values = (Datum *) palloc(size);
size = cleanLength * sizeof(char);
nulls = (char *) palloc(size);
} else {
values = values_array;
nulls = nulls_array;
}
/* ---------------------
* Exctract one by one all the values of the "clean" tuple.
* ---------------------
*/
for (i=0; i<cleanLength; i++) {
Datum d = (Datum)
heap_getattr(tuple, InvalidBuffer, cleanMap[i], tupType, &isNull);
values[i] = d;
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);
}