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/*-------------------------------------------------------------------------
*
* htup.h
* POSTGRES heap tuple definitions.
*
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: htup.h,v 1.52 2002/05/27 19:53:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef HTUP_H
#define HTUP_H
#include "storage/bufpage.h"
#include "storage/relfilenode.h"
/*
* MaxTupleAttributeNumber limits the number of (user) columns in a tuple.
* The key limit on this value is that the size of the fixed overhead for
* a tuple, plus the size of the null-values bitmap (at 1 bit per column),
* plus MAXALIGN alignment, must fit into t_hoff which is uint8. On most
* machines the upper limit without making t_hoff wider would be a little
* over 1700. We use round numbers here and for MaxHeapAttributeNumber
* so that alterations in HeapTupleHeaderData layout won't change the
* supported max number of columns.
*/
#define MaxTupleAttributeNumber 1664 /* 8 * 208 */
/*----------
* MaxHeapAttributeNumber limits the number of (user) columns in a table.
* This should be somewhat less than MaxTupleAttributeNumber. It must be
* at least one less, else we will fail to do UPDATEs on a maximal-width
* table (because UPDATE has to form working tuples that include CTID).
* In practice we want some additional daylight so that we can gracefully
* support operations that add hidden "resjunk" columns, for example
* SELECT * FROM wide_table ORDER BY foo, bar, baz.
* In any case, depending on column data types you will likely be running
* into the disk-block-based limit on overall tuple size if you have more
* than a thousand or so columns. TOAST won't help.
*----------
*/
#define MaxHeapAttributeNumber 1600 /* 8 * 200 */
/*
* On-disk heap tuple header. Currently this is also used as the header
* format for tuples formed in memory, although in principle they could
* be different.
*
* To avoid wasting space, the attributes should be layed out in such a
* way to reduce structure padding. Note that t_hoff is the offset to
* the start of the user data, and so must be a multiple of MAXALIGN.
* Also note that we omit the nulls bitmap if t_infomask shows that there
* are no nulls in the tuple.
*/
typedef struct HeapTupleHeaderData
{
Oid t_oid; /* OID of this tuple -- 4 bytes */
CommandId t_cmin; /* insert CID stamp -- 4 bytes each */
CommandId t_cmax; /* delete CommandId stamp */
TransactionId t_xmin; /* insert XID stamp -- 4 bytes each */
TransactionId t_xmax; /* delete XID stamp */
ItemPointerData t_ctid; /* current TID of this or newer tuple */
int16 t_natts; /* number of attributes */
uint16 t_infomask; /* various flag bits, see below */
uint8 t_hoff; /* sizeof header incl. bitmap, padding */
/* ^ - 31 bytes - ^ */
bits8 t_bits[1]; /* bitmap of NULLs -- VARIABLE LENGTH */
/* MORE DATA FOLLOWS AT END OF STRUCT */
} HeapTupleHeaderData;
typedef HeapTupleHeaderData *HeapTupleHeader;
/*
* XLOG allows to store some information in high 4 bits of log
* record xl_info field
*/
#define XLOG_HEAP_INSERT 0x00
#define XLOG_HEAP_DELETE 0x10
#define XLOG_HEAP_UPDATE 0x20
#define XLOG_HEAP_MOVE 0x30
#define XLOG_HEAP_CLEAN 0x40
#define XLOG_HEAP_OPMASK 0x70
/*
* When we insert 1st item on new page in INSERT/UPDATE
* we can (and we do) restore entire page in redo
*/
#define XLOG_HEAP_INIT_PAGE 0x80
/*
* All what we need to find changed tuple (18 bytes)
*
* NB: on most machines, sizeof(xl_heaptid) will include some trailing pad
* bytes for alignment. We don't want to store the pad space in the XLOG,
* so use SizeOfHeapTid for space calculations. Similar comments apply for
* the other xl_FOO structs.
*/
typedef struct xl_heaptid
{
RelFileNode node;
ItemPointerData tid; /* changed tuple id */
} xl_heaptid;
#define SizeOfHeapTid (offsetof(xl_heaptid, tid) + SizeOfIptrData)
/* This is what we need to know about delete */
typedef struct xl_heap_delete
{
xl_heaptid target; /* deleted tuple id */
} xl_heap_delete;
#define SizeOfHeapDelete (offsetof(xl_heap_delete, target) + SizeOfHeapTid)
typedef struct xl_heap_header
{
Oid t_oid;
int16 t_natts;
uint8 t_hoff;
uint8 mask; /* low 8 bits of t_infomask */
} xl_heap_header;
#define SizeOfHeapHeader (offsetof(xl_heap_header, mask) + sizeof(uint8))
/* This is what we need to know about insert */
typedef struct xl_heap_insert
{
xl_heaptid target; /* inserted tuple id */
/* xl_heap_header & TUPLE DATA FOLLOWS AT END OF STRUCT */
} xl_heap_insert;
#define SizeOfHeapInsert (offsetof(xl_heap_insert, target) + SizeOfHeapTid)
/* This is what we need to know about update|move */
typedef struct xl_heap_update
{
xl_heaptid target; /* deleted tuple id */
ItemPointerData newtid; /* new inserted tuple id */
/* NEW TUPLE xl_heap_header (PLUS xmax & xmin IF MOVE OP) */
/* and TUPLE DATA FOLLOWS AT END OF STRUCT */
} xl_heap_update;
#define SizeOfHeapUpdate (offsetof(xl_heap_update, newtid) + SizeOfIptrData)
/* This is what we need to know about page cleanup */
typedef struct xl_heap_clean
{
RelFileNode node;
BlockNumber block;
/* UNUSED OFFSET NUMBERS FOLLOW AT THE END */
} xl_heap_clean;
#define SizeOfHeapClean (offsetof(xl_heap_clean, block) + sizeof(BlockNumber))
/*
* MaxTupleSize is the maximum allowed size of a tuple, including header and
* MAXALIGN alignment padding. Basically it's BLCKSZ minus the other stuff
* that has to be on a disk page. The "other stuff" includes access-method-
* dependent "special space", which we assume will be no more than
* MaxSpecialSpace bytes (currently, on heap pages it's actually zero).
*
* NOTE: we do not need to count an ItemId for the tuple because
* sizeof(PageHeaderData) includes the first ItemId on the page.
*/
#define MaxSpecialSpace 32
#define MaxTupleSize \
(BLCKSZ - MAXALIGN(sizeof(PageHeaderData) + MaxSpecialSpace))
/*
* MaxAttrSize is a somewhat arbitrary upper limit on the declared size of
* data fields of char(n) and similar types. It need not have anything
* directly to do with the *actual* upper limit of varlena values, which
* is currently 1Gb (see struct varattrib in postgres.h). I've set it
* at 10Mb which seems like a reasonable number --- tgl 8/6/00.
*/
#define MaxAttrSize (10 * 1024 * 1024)
/*
* Attribute numbers for the system-defined attributes
*/
#define SelfItemPointerAttributeNumber (-1)
#define ObjectIdAttributeNumber (-2)
#define MinTransactionIdAttributeNumber (-3)
#define MinCommandIdAttributeNumber (-4)
#define MaxTransactionIdAttributeNumber (-5)
#define MaxCommandIdAttributeNumber (-6)
#define TableOidAttributeNumber (-7)
#define FirstLowInvalidHeapAttributeNumber (-8)
/*
* HeapTupleData is an in-memory data structure that points to a tuple.
*
* This new HeapTuple for version >= 6.5 and this is why it was changed:
*
* 1. t_len moved off on-disk tuple data - ItemIdData is used to get len;
* 2. t_ctid above is not self tuple TID now - it may point to
* updated version of tuple (required by MVCC);
* 3. someday someone let tuple to cross block boundaries -
* he have to add something below...
*
* Change for 7.0:
* Up to now t_data could be NULL, the memory location directly following
* HeapTupleData, or pointing into a buffer. Now, it could also point to
* a separate allocation that was done in the t_datamcxt memory context.
*/
typedef struct HeapTupleData
{
uint32 t_len; /* length of *t_data */
ItemPointerData t_self; /* SelfItemPointer */
Oid t_tableOid; /* table the tuple came from */
MemoryContext t_datamcxt; /* memory context of allocation */
HeapTupleHeader t_data; /* -> tuple header and data */
} HeapTupleData;
typedef HeapTupleData *HeapTuple;
#define HEAPTUPLESIZE MAXALIGN(sizeof(HeapTupleData))
/* ----------------
* support macros
* ----------------
*/
#define GETSTRUCT(TUP) (((char *)((HeapTuple)(TUP))->t_data) + \
((HeapTuple)(TUP))->t_data->t_hoff)
/*
* BITMAPLEN(NATTS) -
* Computes size of null bitmap given number of data columns.
*/
#define BITMAPLEN(NATTS) (((int)(NATTS) + 7) / 8)
/*
* HeapTupleIsValid
* True iff the heap tuple is valid.
*/
#define HeapTupleIsValid(tuple) PointerIsValid(tuple)
/*
* information stored in t_infomask:
*/
#define HEAP_HASNULL 0x0001 /* has null attribute(s) */
#define HEAP_HASVARLENA 0x0002 /* has variable length
* attribute(s) */
#define HEAP_HASEXTERNAL 0x0004 /* has external stored
* attribute(s) */
#define HEAP_HASCOMPRESSED 0x0008 /* has compressed stored
* attribute(s) */
#define HEAP_HASEXTENDED 0x000C /* the two above combined */
#define HEAP_XMAX_UNLOGGED 0x0080 /* to lock tuple for update
* without logging */
#define HEAP_XMIN_COMMITTED 0x0100 /* t_xmin committed */
#define HEAP_XMIN_INVALID 0x0200 /* t_xmin invalid/aborted */
#define HEAP_XMAX_COMMITTED 0x0400 /* t_xmax committed */
#define HEAP_XMAX_INVALID 0x0800 /* t_xmax invalid/aborted */
#define HEAP_MARKED_FOR_UPDATE 0x1000 /* marked for UPDATE */
#define HEAP_UPDATED 0x2000 /* this is UPDATEd version of row */
#define HEAP_MOVED_OFF 0x4000 /* moved to another place by
* vacuum */
#define HEAP_MOVED_IN 0x8000 /* moved from another place by
* vacuum */
#define HEAP_XACT_MASK 0xFFF0 /* visibility-related bits */
#define HeapTupleNoNulls(tuple) \
(!(((HeapTuple) (tuple))->t_data->t_infomask & HEAP_HASNULL))
#define HeapTupleAllFixed(tuple) \
(!(((HeapTuple) (tuple))->t_data->t_infomask & HEAP_HASVARLENA))
#define HeapTupleHasExternal(tuple) \
((((HeapTuple)(tuple))->t_data->t_infomask & HEAP_HASEXTERNAL) != 0)
#define HeapTupleHasCompressed(tuple) \
((((HeapTuple)(tuple))->t_data->t_infomask & HEAP_HASCOMPRESSED) != 0)
#define HeapTupleHasExtended(tuple) \
((((HeapTuple)(tuple))->t_data->t_infomask & HEAP_HASEXTENDED) != 0)
#endif /* HTUP_H */