Re-run pgindent with updated list of typedefs. (Updated README should

[pg-rex/syncrep.git] / src / include / access / htup.h

/*-------------------------------------------------------------------------
 *
 * htup.h
 *        POSTGRES heap tuple definitions.
 *
 *
 * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $PostgreSQL: pgsql/src/include/access/htup.h,v 1.97 2007/11/15 22:25:16 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef HTUP_H
#define HTUP_H

#include "storage/itemptr.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 */

/*
 * Heap tuple header.  To avoid wasting space, the fields should be
 * laid out in such a way as to avoid structure padding.
 *
 * Datums of composite types (row types) share the same general structure
 * as on-disk tuples, so that the same routines can be used to build and
 * examine them.  However the requirements are slightly different: a Datum
 * does not need any transaction visibility information, and it does need
 * a length word and some embedded type information.  We can achieve this
 * by overlaying the xmin/cmin/xmax/cmax/xvac fields of a heap tuple
 * with the fields needed in the Datum case.  Typically, all tuples built
 * in-memory will be initialized with the Datum fields; but when a tuple is
 * about to be inserted in a table, the transaction fields will be filled,
 * overwriting the datum fields.
 *
 * The overall structure of a heap tuple looks like:
 *                      fixed fields (HeapTupleHeaderData struct)
 *                      nulls bitmap (if HEAP_HASNULL is set in t_infomask)
 *                      alignment padding (as needed to make user data MAXALIGN'd)
 *                      object ID (if HEAP_HASOID is set in t_infomask)
 *                      user data fields
 *
 * We store five "virtual" fields Xmin, Cmin, Xmax, Cmax, and Xvac in three
 * physical fields.  Xmin and Xmax are always really stored, but Cmin, Cmax
 * and Xvac share a field.      This works because we know that Cmin and Cmax
 * are only interesting for the lifetime of the inserting and deleting
 * transaction respectively.  If a tuple is inserted and deleted in the same
 * transaction, we store a "combo" command id that can be mapped to the real
 * cmin and cmax, but only by use of local state within the originating
 * backend.  See combocid.c for more details.  Meanwhile, Xvac is only set
 * by VACUUM FULL, which does not have any command sub-structure and so does
 * not need either Cmin or Cmax.  (This requires that VACUUM FULL never try
 * to move a tuple whose Cmin or Cmax is still interesting, ie, an insert-
 * in-progress or delete-in-progress tuple.)
 *
 * A word about t_ctid: whenever a new tuple is stored on disk, its t_ctid
 * is initialized with its own TID (location).  If the tuple is ever updated,
 * its t_ctid is changed to point to the replacement version of the tuple.
 * Thus, a tuple is the latest version of its row iff XMAX is invalid or
 * t_ctid points to itself (in which case, if XMAX is valid, the tuple is
 * either locked or deleted).  One can follow the chain of t_ctid links
 * to find the newest version of the row.  Beware however that VACUUM might
 * erase the pointed-to (newer) tuple before erasing the pointing (older)
 * tuple.  Hence, when following a t_ctid link, it is necessary to check
 * to see if the referenced slot is empty or contains an unrelated tuple.
 * Check that the referenced tuple has XMIN equal to the referencing tuple's
 * XMAX to verify that it is actually the descendant version and not an
 * unrelated tuple stored into a slot recently freed by VACUUM.  If either
 * check fails, one may assume that there is no live descendant version.
 *
 * Following the fixed header fields, the nulls bitmap is stored (beginning
 * at t_bits).  The bitmap is *not* stored if t_infomask shows that there
 * are no nulls in the tuple.  If an OID field is present (as indicated by
 * t_infomask), then it is stored just before the user data, which begins at
 * the offset shown by t_hoff.  Note that t_hoff must be a multiple of
 * MAXALIGN.
 */

typedef struct HeapTupleFields
{
        TransactionId t_xmin;           /* inserting xact ID */
        TransactionId t_xmax;           /* deleting or locking xact ID */

        union
        {
                CommandId       t_cid;          /* inserting or deleting command ID, or both */
                TransactionId t_xvac;   /* VACUUM FULL xact ID */
        }                       t_field3;
} HeapTupleFields;

typedef struct DatumTupleFields
{
        int32           datum_len_;             /* varlena header (do not touch directly!) */

        int32           datum_typmod;   /* -1, or identifier of a record type */

        Oid                     datum_typeid;   /* composite type OID, or RECORDOID */

        /*
         * Note: field ordering is chosen with thought that Oid might someday
         * widen to 64 bits.
         */
} DatumTupleFields;

typedef struct HeapTupleHeaderData
{
        union
        {
                HeapTupleFields t_heap;
                DatumTupleFields t_datum;
        }                       t_choice;

        ItemPointerData t_ctid;         /* current TID of this or newer tuple */

        /* Fields below here must match MinimalTupleData! */

        uint16          t_infomask2;    /* number of attributes + various flags */

        uint16          t_infomask;             /* various flag bits, see below */

        uint8           t_hoff;                 /* sizeof header incl. bitmap, padding */

        /* ^ - 23 bytes - ^ */

        bits8           t_bits[1];              /* bitmap of NULLs -- VARIABLE LENGTH */

        /* MORE DATA FOLLOWS AT END OF STRUCT */
} HeapTupleHeaderData;

typedef HeapTupleHeaderData *HeapTupleHeader;

/*
 * information stored in t_infomask:
 */
#define HEAP_HASNULL                    0x0001  /* has null attribute(s) */
#define HEAP_HASVARWIDTH                0x0002  /* has variable-width attribute(s) */
#define HEAP_HASEXTERNAL                0x0004  /* has external stored attribute(s) */
#define HEAP_HASOID                             0x0008  /* has an object-id field */
/* bit 0x0010 is available */
#define HEAP_COMBOCID                   0x0020  /* t_cid is a combo cid */
#define HEAP_XMAX_EXCL_LOCK             0x0040  /* xmax is exclusive locker */
#define HEAP_XMAX_SHARED_LOCK   0x0080  /* xmax is shared locker */
/* if either LOCK bit is set, xmax hasn't deleted the tuple, only locked it */
#define HEAP_IS_LOCKED  (HEAP_XMAX_EXCL_LOCK | HEAP_XMAX_SHARED_LOCK)
#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_XMAX_IS_MULTI              0x1000  /* t_xmax is a MultiXactId */
#define HEAP_UPDATED                    0x2000  /* this is UPDATEd version of row */
#define HEAP_MOVED_OFF                  0x4000  /* moved to another place by VACUUM
                                                                                 * FULL */
#define HEAP_MOVED_IN                   0x8000  /* moved from another place by VACUUM
                                                                                 * FULL */
#define HEAP_MOVED (HEAP_MOVED_OFF | HEAP_MOVED_IN)

#define HEAP_XACT_MASK                  0xFFE0  /* visibility-related bits */

/*
 * information stored in t_infomask2:
 */
#define HEAP_NATTS_MASK                 0x07FF  /* 11 bits for number of attributes */
/* bits 0x3800 are available */
#define HEAP_HOT_UPDATED                0x4000  /* tuple was HOT-updated */
#define HEAP_ONLY_TUPLE                 0x8000  /* this is heap-only tuple */

#define HEAP2_XACT_MASK                 0xC000  /* visibility-related bits */

/*
 * HeapTupleHeader accessor macros
 *
 * Note: beware of multiple evaluations of "tup" argument.      But the Set
 * macros evaluate their other argument only once.
 */

#define HeapTupleHeaderGetXmin(tup) \
( \
        (tup)->t_choice.t_heap.t_xmin \
)

#define HeapTupleHeaderSetXmin(tup, xid) \
( \
        (tup)->t_choice.t_heap.t_xmin = (xid) \
)

#define HeapTupleHeaderGetXmax(tup) \
( \
        (tup)->t_choice.t_heap.t_xmax \
)

#define HeapTupleHeaderSetXmax(tup, xid) \
( \
        (tup)->t_choice.t_heap.t_xmax = (xid) \
)

/*
 * HeapTupleHeaderGetRawCommandId will give you what's in the header whether
 * it is useful or not.  Most code should use HeapTupleHeaderGetCmin or
 * HeapTupleHeaderGetCmax instead, but note that those Assert that you can
 * get a legitimate result, ie you are in the originating transaction!
 */
#define HeapTupleHeaderGetRawCommandId(tup) \
( \
        (tup)->t_choice.t_heap.t_field3.t_cid \
)

/* SetCmin is reasonably simple since we never need a combo CID */
#define HeapTupleHeaderSetCmin(tup, cid) \
do { \
        Assert(!((tup)->t_infomask & HEAP_MOVED)); \
        (tup)->t_choice.t_heap.t_field3.t_cid = (cid); \
        (tup)->t_infomask &= ~HEAP_COMBOCID; \
} while (0)

/* SetCmax must be used after HeapTupleHeaderAdjustCmax; see combocid.c */
#define HeapTupleHeaderSetCmax(tup, cid, iscombo) \
do { \
        Assert(!((tup)->t_infomask & HEAP_MOVED)); \
        (tup)->t_choice.t_heap.t_field3.t_cid = (cid); \
        if (iscombo) \
                (tup)->t_infomask |= HEAP_COMBOCID; \
        else \
                (tup)->t_infomask &= ~HEAP_COMBOCID; \
} while (0)

#define HeapTupleHeaderGetXvac(tup) \
( \
        ((tup)->t_infomask & HEAP_MOVED) ? \
                (tup)->t_choice.t_heap.t_field3.t_xvac \
        : \
                InvalidTransactionId \
)

#define HeapTupleHeaderSetXvac(tup, xid) \
do { \
        Assert((tup)->t_infomask & HEAP_MOVED); \
        (tup)->t_choice.t_heap.t_field3.t_xvac = (xid); \
} while (0)

#define HeapTupleHeaderGetDatumLength(tup) \
        VARSIZE(tup)

#define HeapTupleHeaderSetDatumLength(tup, len) \
        SET_VARSIZE(tup, len)

#define HeapTupleHeaderGetTypeId(tup) \
( \
        (tup)->t_choice.t_datum.datum_typeid \
)

#define HeapTupleHeaderSetTypeId(tup, typeid) \
( \
        (tup)->t_choice.t_datum.datum_typeid = (typeid) \
)

#define HeapTupleHeaderGetTypMod(tup) \
( \
        (tup)->t_choice.t_datum.datum_typmod \
)

#define HeapTupleHeaderSetTypMod(tup, typmod) \
( \
        (tup)->t_choice.t_datum.datum_typmod = (typmod) \
)

#define HeapTupleHeaderGetOid(tup) \
( \
        ((tup)->t_infomask & HEAP_HASOID) ? \
                *((Oid *) ((char *)(tup) + (tup)->t_hoff - sizeof(Oid))) \
        : \
                InvalidOid \
)

#define HeapTupleHeaderSetOid(tup, oid) \
do { \
        Assert((tup)->t_infomask & HEAP_HASOID); \
        *((Oid *) ((char *)(tup) + (tup)->t_hoff - sizeof(Oid))) = (oid); \
} while (0)

/*
 * Note that we stop considering a tuple HOT-updated as soon as it is known
 * aborted or the would-be updating transaction is known aborted.  For best
 * efficiency, check tuple visibility before using this macro, so that the
 * INVALID bits will be as up to date as possible.
 */
#define HeapTupleHeaderIsHotUpdated(tup) \
( \
        ((tup)->t_infomask2 & HEAP_HOT_UPDATED) != 0 && \
        ((tup)->t_infomask & (HEAP_XMIN_INVALID | HEAP_XMAX_INVALID)) == 0 \
)

#define HeapTupleHeaderSetHotUpdated(tup) \
( \
        (tup)->t_infomask2 |= HEAP_HOT_UPDATED \
)

#define HeapTupleHeaderClearHotUpdated(tup) \
( \
        (tup)->t_infomask2 &= ~HEAP_HOT_UPDATED \
)

#define HeapTupleHeaderIsHeapOnly(tup) \
( \
  (tup)->t_infomask2 & HEAP_ONLY_TUPLE \
)

#define HeapTupleHeaderSetHeapOnly(tup) \
( \
  (tup)->t_infomask2 |= HEAP_ONLY_TUPLE \
)

#define HeapTupleHeaderClearHeapOnly(tup) \
( \
  (tup)->t_infomask2 &= ~HEAP_ONLY_TUPLE \
)

#define HeapTupleHeaderGetNatts(tup) \
        ((tup)->t_infomask2 & HEAP_NATTS_MASK)

#define HeapTupleHeaderSetNatts(tup, natts) \
( \
        (tup)->t_infomask2 = ((tup)->t_infomask2 & ~HEAP_NATTS_MASK) | (natts) \
)


/*
 * BITMAPLEN(NATTS) -
 *              Computes size of null bitmap given number of data columns.
 */
#define BITMAPLEN(NATTS)        (((int)(NATTS) + 7) / 8)

/*
 * MaxHeapTupleSize is the maximum allowed size of a heap tuple, including
 * header and MAXALIGN alignment padding.  Basically it's BLCKSZ minus the
 * other stuff that has to be on a disk page.  Since heap pages use no
 * "special space", there's no deduction for that.
 *
 * NOTE: we do not need to count an ItemId for the tuple because
 * sizeof(PageHeaderData) includes the first ItemId on the page.  But beware
 * of assuming that, say, you can fit 2 tuples of size MaxHeapTupleSize/2
 * on the same page.
 */
#define MaxHeapTupleSize  (BLCKSZ - MAXALIGN(sizeof(PageHeaderData)))

/*
 * MaxHeapTuplesPerPage is an upper bound on the number of tuples that can
 * fit on one heap page.  (Note that indexes could have more, because they
 * use a smaller tuple header.)  We arrive at the divisor because each tuple
 * must be maxaligned, and it must have an associated item pointer.
 *
 * Note: with HOT, there could theoretically be more line pointers (not actual
 * tuples) than this on a heap page.  However we constrain the number of line
 * pointers to this anyway, to avoid excessive line-pointer bloat and not
 * require increases in the size of work arrays.
 */
#define MaxHeapTuplesPerPage    \
        ((int) ((BLCKSZ - offsetof(PageHeaderData, pd_linp)) / \
                        (MAXALIGN(offsetof(HeapTupleHeaderData, t_bits)) + sizeof(ItemIdData))))

/*
 * 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 TOAST structures 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)


/*
 * MinimalTuple is an alternative representation that is used for transient
 * tuples inside the executor, in places where transaction status information
 * is not required, the tuple rowtype is known, and shaving off a few bytes
 * is worthwhile because we need to store many tuples.  The representation
 * is chosen so that tuple access routines can work with either full or
 * minimal tuples via a HeapTupleData pointer structure.  The access routines
 * see no difference, except that they must not access the transaction status
 * or t_ctid fields because those aren't there.
 *
 * For the most part, MinimalTuples should be accessed via TupleTableSlot
 * routines.  These routines will prevent access to the "system columns"
 * and thereby prevent accidental use of the nonexistent fields.
 *
 * MinimalTupleData contains a length word, some padding, and fields matching
 * HeapTupleHeaderData beginning with t_infomask2. The padding is chosen so
 * that offsetof(t_infomask2) is the same modulo MAXIMUM_ALIGNOF in both
 * structs.   This makes data alignment rules equivalent in both cases.
 *
 * When a minimal tuple is accessed via a HeapTupleData pointer, t_data is
 * set to point MINIMAL_TUPLE_OFFSET bytes before the actual start of the
 * minimal tuple --- that is, where a full tuple matching the minimal tuple's
 * data would start.  This trick is what makes the structs seem equivalent.
 *
 * Note that t_hoff is computed the same as in a full tuple, hence it includes
 * the MINIMAL_TUPLE_OFFSET distance.  t_len does not include that, however.
 */
#define MINIMAL_TUPLE_OFFSET \
        ((offsetof(HeapTupleHeaderData, t_infomask2) - sizeof(uint32)) / MAXIMUM_ALIGNOF * MAXIMUM_ALIGNOF)
#define MINIMAL_TUPLE_PADDING \
        ((offsetof(HeapTupleHeaderData, t_infomask2) - sizeof(uint32)) % MAXIMUM_ALIGNOF)

typedef struct MinimalTupleData
{
        uint32          t_len;                  /* actual length of minimal tuple */

        char            mt_padding[MINIMAL_TUPLE_PADDING];

        /* Fields below here must match HeapTupleHeaderData! */

        uint16          t_infomask2;    /* number of attributes + various flags */

        uint16          t_infomask;             /* various flag bits, see below */

        uint8           t_hoff;                 /* sizeof header incl. bitmap, padding */

        /* ^ - 23 bytes - ^ */

        bits8           t_bits[1];              /* bitmap of NULLs -- VARIABLE LENGTH */

        /* MORE DATA FOLLOWS AT END OF STRUCT */
} MinimalTupleData;

typedef MinimalTupleData *MinimalTuple;


/*
 * HeapTupleData is an in-memory data structure that points to a tuple.
 *
 * There are several ways in which this data structure is used:
 *
 * * Pointer to a tuple in a disk buffer: t_data points directly into the
 *       buffer (which the code had better be holding a pin on, but this is not
 *       reflected in HeapTupleData itself).
 *
 * * Pointer to nothing: t_data is NULL.  This is used as a failure indication
 *       in some functions.
 *
 * * Part of a palloc'd tuple: the HeapTupleData itself and the tuple
 *       form a single palloc'd chunk.  t_data points to the memory location
 *       immediately following the HeapTupleData struct (at offset HEAPTUPLESIZE).
 *       This is the output format of heap_form_tuple and related routines.
 *
 * * Separately allocated tuple: t_data points to a palloc'd chunk that
 *       is not adjacent to the HeapTupleData.  (This case is deprecated since
 *       it's difficult to tell apart from case #1.  It should be used only in
 *       limited contexts where the code knows that case #1 will never apply.)
 *
 * * Separately allocated minimal tuple: t_data points MINIMAL_TUPLE_OFFSET
 *       bytes before the start of a MinimalTuple.      As with the previous case,
 *       this can't be told apart from case #1 by inspection; code setting up
 *       or destroying this representation has to know what it's doing.
 *
 * t_len should always be valid, except in the pointer-to-nothing case.
 * t_self and t_tableOid should be valid if the HeapTupleData points to
 * a disk buffer, or if it represents a copy of a tuple on disk.  They
 * should be explicitly set invalid in manufactured tuples.
 */
typedef struct HeapTupleData
{
        uint32          t_len;                  /* length of *t_data */
        ItemPointerData t_self;         /* SelfItemPointer */
        Oid                     t_tableOid;             /* table the tuple came from */
        HeapTupleHeader t_data;         /* -> tuple header and data */
} HeapTupleData;

typedef HeapTupleData *HeapTuple;

#define HEAPTUPLESIZE   MAXALIGN(sizeof(HeapTupleData))

/*
 * GETSTRUCT - given a HeapTuple pointer, return address of the user data
 */
#define GETSTRUCT(TUP) ((char *) ((TUP)->t_data) + (TUP)->t_data->t_hoff)

/*
 * Accessor macros to be used with HeapTuple pointers.
 */
#define HeapTupleIsValid(tuple) PointerIsValid(tuple)

#define HeapTupleHasNulls(tuple) \
                (((tuple)->t_data->t_infomask & HEAP_HASNULL) != 0)

#define HeapTupleNoNulls(tuple) \
                (!((tuple)->t_data->t_infomask & HEAP_HASNULL))

#define HeapTupleHasVarWidth(tuple) \
                (((tuple)->t_data->t_infomask & HEAP_HASVARWIDTH) != 0)

#define HeapTupleAllFixed(tuple) \
                (!((tuple)->t_data->t_infomask & HEAP_HASVARWIDTH))

#define HeapTupleHasExternal(tuple) \
                (((tuple)->t_data->t_infomask & HEAP_HASEXTERNAL) != 0)

#define HeapTupleIsHotUpdated(tuple) \
                HeapTupleHeaderIsHotUpdated((tuple)->t_data)

#define HeapTupleSetHotUpdated(tuple) \
                HeapTupleHeaderSetHotUpdated((tuple)->t_data)

#define HeapTupleClearHotUpdated(tuple) \
                HeapTupleHeaderClearHotUpdated((tuple)->t_data)

#define HeapTupleIsHeapOnly(tuple) \
                HeapTupleHeaderIsHeapOnly((tuple)->t_data)

#define HeapTupleSetHeapOnly(tuple) \
                HeapTupleHeaderSetHeapOnly((tuple)->t_data)

#define HeapTupleClearHeapOnly(tuple) \
                HeapTupleHeaderClearHeapOnly((tuple)->t_data)

#define HeapTupleGetOid(tuple) \
                HeapTupleHeaderGetOid((tuple)->t_data)

#define HeapTupleSetOid(tuple, oid) \
                HeapTupleHeaderSetOid((tuple)->t_data, (oid))


/*
 * WAL record definitions for heapam.c's WAL operations
 *
 * XLOG allows to store some information in high 4 bits of log
 * record xl_info field.  We use 3 for opcode and one for init bit.
 */
#define XLOG_HEAP_INSERT                0x00
#define XLOG_HEAP_DELETE                0x10
#define XLOG_HEAP_UPDATE                0x20
#define XLOG_HEAP_MOVE                  0x30
#define XLOG_HEAP_HOT_UPDATE    0x40
#define XLOG_HEAP_NEWPAGE               0x50
#define XLOG_HEAP_LOCK                  0x60
#define XLOG_HEAP_INPLACE               0x70

#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
/*
 * We ran out of opcodes, so heapam.c now has a second RmgrId.  These opcodes
 * are associated with RM_HEAP2_ID, but are not logically different from
 * the ones above associated with RM_HEAP_ID.  We apply XLOG_HEAP_OPMASK,
 * although currently XLOG_HEAP_INIT_PAGE is not used for any of these.
 */
#define XLOG_HEAP2_FREEZE               0x00
#define XLOG_HEAP2_CLEAN                0x10
#define XLOG_HEAP2_CLEAN_MOVE   0x20

/*
 * All what we need to find changed tuple
 *
 * 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)

/*
 * We don't store the whole fixed part (HeapTupleHeaderData) of an inserted
 * or updated tuple in WAL; we can save a few bytes by reconstructing the
 * fields that are available elsewhere in the WAL record, or perhaps just
 * plain needn't be reconstructed.  These are the fields we must store.
 * NOTE: t_hoff could be recomputed, but we may as well store it because
 * it will come for free due to alignment considerations.
 */
typedef struct xl_heap_header
{
        uint16          t_infomask2;
        uint16          t_infomask;
        uint8           t_hoff;
} xl_heap_header;

#define SizeOfHeapHeader        (offsetof(xl_heap_header, t_hoff) + 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|hot_update */
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 vacuum page cleanup/redirect
 *
 * The array of OffsetNumbers following the fixed part of the record contains:
 *      * for each redirected item: the item offset, then the offset redirected to
 *      * for each now-dead item: the item offset
 *      * for each now-unused item: the item offset
 * The total number of OffsetNumbers is therefore 2*nredirected+ndead+nunused.
 * Note that nunused is not explicitly stored, but may be found by reference
 * to the total record length.
 *
 * If the opcode is CLEAN_MOVE instead of CLEAN, then each redirection pair
 * should be interpreted as physically moving the "to" item pointer to the
 * "from" slot, rather than placing a redirection item in the "from" slot.
 * The moved pointers should be replaced by LP_UNUSED items (there will not
 * be explicit entries in the "now-unused" list for this).      Also, the
 * HEAP_ONLY bit in the moved tuples must be turned off.
 */
typedef struct xl_heap_clean
{
        RelFileNode node;
        BlockNumber block;
        uint16          nredirected;
        uint16          ndead;
        /* OFFSET NUMBERS FOLLOW */
} xl_heap_clean;

#define SizeOfHeapClean (offsetof(xl_heap_clean, ndead) + sizeof(uint16))

/* This is for replacing a page's contents in toto */
/* NB: this is used for indexes as well as heaps */
typedef struct xl_heap_newpage
{
        RelFileNode node;
        BlockNumber blkno;                      /* location of new page */
        /* entire page contents follow at end of record */
} xl_heap_newpage;

#define SizeOfHeapNewpage       (offsetof(xl_heap_newpage, blkno) + sizeof(BlockNumber))

/* This is what we need to know about lock */
typedef struct xl_heap_lock
{
        xl_heaptid      target;                 /* locked tuple id */
        TransactionId locking_xid;      /* might be a MultiXactId not xid */
        bool            xid_is_mxact;   /* is it? */
        bool            shared_lock;    /* shared or exclusive row lock? */
} xl_heap_lock;

#define SizeOfHeapLock  (offsetof(xl_heap_lock, shared_lock) + sizeof(bool))

/* This is what we need to know about in-place update */
typedef struct xl_heap_inplace
{
        xl_heaptid      target;                 /* updated tuple id */
        /* TUPLE DATA FOLLOWS AT END OF STRUCT */
} xl_heap_inplace;

#define SizeOfHeapInplace       (offsetof(xl_heap_inplace, target) + SizeOfHeapTid)

/* This is what we need to know about tuple freezing during vacuum */
typedef struct xl_heap_freeze
{
        RelFileNode node;
        BlockNumber block;
        TransactionId cutoff_xid;
        /* TUPLE OFFSET NUMBERS FOLLOW AT THE END */
} xl_heap_freeze;

#define SizeOfHeapFreeze (offsetof(xl_heap_freeze, cutoff_xid) + sizeof(TransactionId))

/* HeapTupleHeader functions implemented in utils/time/combocid.c */
extern CommandId HeapTupleHeaderGetCmin(HeapTupleHeader tup);
extern CommandId HeapTupleHeaderGetCmax(HeapTupleHeader tup);
extern void HeapTupleHeaderAdjustCmax(HeapTupleHeader tup,
                                                  CommandId *cmax,
                                                  bool *iscombo);

#endif   /* HTUP_H */