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/*-------------------------------------------------------------------------
*
* tuptable.h
* tuple table support stuff
*
*
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: tuptable.h,v 1.22 2002/06/20 20:29:49 momjian Exp $
*
* NOTES
* The tuple table interface is getting pretty ugly.
* It should be redesigned soon.
*
*-------------------------------------------------------------------------
*/
#ifndef TUPTABLE_H
#define TUPTABLE_H
#include "access/htup.h"
/* ----------------
* The executor tuple table is managed and manipulated by special
* code in executor/execTuples.c.
*
* TupleTableSlot information
*
* val current tuple, or NULL if no tuple
* shouldFree boolean - should we pfree() tuple
* descIsNew boolean - true when tupleDescriptor changes
* tupleDescriptor type information for the tuple data
* shouldFreeDesc boolean - should we free tupleDescriptor
* buffer the buffer for tuples pointing to disk pages
*
* The executor stores pointers to tuples in a ``tuple table''
* which is composed of TupleTableSlots. Sometimes the tuples
* are pointers to buffer pages, while others are pointers to
* palloc'ed memory; the shouldFree variable tells us when
* we may call pfree() on a tuple. -cim 9/23/90
*
* If buffer is not InvalidBuffer, then the slot is holding a pin
* on the indicated buffer page; drop the pin when we release the
* slot's reference to that buffer.
*
* In the implementation of nested-dot queries such as
* "retrieve (EMP.hobbies.all)", a single scan may return tuples
* of many types, so now we return pointers to tuple descriptors
* along with tuples returned via the tuple table. -cim 1/18/90
*
* shouldFreeDesc is similar to shouldFree: if it's true, then the
* tupleDescriptor is "owned" by the TupleTableSlot and should be
* freed when the slot's reference to the descriptor is dropped.
*
* See executor.h for decls of functions defined in execTuples.c
* -jolly
*
* ----------------
*/
typedef struct TupleTableSlot
{
NodeTag type;
HeapTuple val;
bool ttc_shouldFree;
bool ttc_descIsNew;
bool ttc_shouldFreeDesc;
TupleDesc ttc_tupleDescriptor;
Buffer ttc_buffer;
} TupleTableSlot;
/* ----------------
* tuple table data structure
* ----------------
*/
typedef struct TupleTableData
{
int size; /* size of the table */
int next; /* next available slot number */
TupleTableSlot *array; /* array of TupleTableSlot's */
} TupleTableData;
typedef TupleTableData *TupleTable;
#endif /* TUPTABLE_H */
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