1/*-------------------------------------------------------------------------
2 *
3 * htup_details.h
4 * POSTGRES heap tuple header definitions.
5 *
6 *
7 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
8 * Portions Copyright (c) 1994, Regents of the University of California
9 *
10 * src/include/access/htup_details.h
11 *
12 *-------------------------------------------------------------------------
13 */
14#ifndef HTUP_DETAILS_H
15#define HTUP_DETAILS_H
16
17#include "access/htup.h"
18#include "access/tupdesc.h"
19#include "access/tupmacs.h"
20#include "access/transam.h"
21#include "storage/bufpage.h"
22
23/*
24 * MaxTupleAttributeNumber limits the number of (user) columns in a tuple.
25 * The key limit on this value is that the size of the fixed overhead for
26 * a tuple, plus the size of the null-values bitmap (at 1 bit per column),
27 * plus MAXALIGN alignment, must fit into t_hoff which is uint8. On most
28 * machines the upper limit without making t_hoff wider would be a little
29 * over 1700. We use round numbers here and for MaxHeapAttributeNumber
30 * so that alterations in HeapTupleHeaderData layout won't change the
31 * supported max number of columns.
32 */
33#define MaxTupleAttributeNumber 1664 /* 8 * 208 */
34
35/*
36 * MaxHeapAttributeNumber limits the number of (user) columns in a table.
37 * This should be somewhat less than MaxTupleAttributeNumber. It must be
38 * at least one less, else we will fail to do UPDATEs on a maximal-width
39 * table (because UPDATE has to form working tuples that include CTID).
40 * In practice we want some additional daylight so that we can gracefully
41 * support operations that add hidden "resjunk" columns, for example
42 * SELECT * FROM wide_table ORDER BY foo, bar, baz.
43 * In any case, depending on column data types you will likely be running
44 * into the disk-block-based limit on overall tuple size if you have more
45 * than a thousand or so columns. TOAST won't help.
46 */
47#define MaxHeapAttributeNumber 1600 /* 8 * 200 */
48
49/*
50 * Heap tuple header. To avoid wasting space, the fields should be
51 * laid out in such a way as to avoid structure padding.
52 *
53 * Datums of composite types (row types) share the same general structure
54 * as on-disk tuples, so that the same routines can be used to build and
55 * examine them. However the requirements are slightly different: a Datum
56 * does not need any transaction visibility information, and it does need
57 * a length word and some embedded type information. We can achieve this
58 * by overlaying the xmin/cmin/xmax/cmax/xvac fields of a heap tuple
59 * with the fields needed in the Datum case. Typically, all tuples built
60 * in-memory will be initialized with the Datum fields; but when a tuple is
61 * about to be inserted in a table, the transaction fields will be filled,
62 * overwriting the datum fields.
63 *
64 * The overall structure of a heap tuple looks like:
65 * fixed fields (HeapTupleHeaderData struct)
66 * nulls bitmap (if HEAP_HASNULL is set in t_infomask)
67 * alignment padding (as needed to make user data MAXALIGN'd)
68 * object ID (if HEAP_HASOID_OLD is set in t_infomask, not created
69 * anymore)
70 * user data fields
71 *
72 * We store five "virtual" fields Xmin, Cmin, Xmax, Cmax, and Xvac in three
73 * physical fields. Xmin and Xmax are always really stored, but Cmin, Cmax
74 * and Xvac share a field. This works because we know that Cmin and Cmax
75 * are only interesting for the lifetime of the inserting and deleting
76 * transaction respectively. If a tuple is inserted and deleted in the same
77 * transaction, we store a "combo" command id that can be mapped to the real
78 * cmin and cmax, but only by use of local state within the originating
79 * backend. See combocid.c for more details. Meanwhile, Xvac is only set by
80 * old-style VACUUM FULL, which does not have any command sub-structure and so
81 * does not need either Cmin or Cmax. (This requires that old-style VACUUM
82 * FULL never try to move a tuple whose Cmin or Cmax is still interesting,
83 * ie, an insert-in-progress or delete-in-progress tuple.)
84 *
85 * A word about t_ctid: whenever a new tuple is stored on disk, its t_ctid
86 * is initialized with its own TID (location). If the tuple is ever updated,
87 * its t_ctid is changed to point to the replacement version of the tuple. Or
88 * if the tuple is moved from one partition to another, due to an update of
89 * the partition key, t_ctid is set to a special value to indicate that
90 * (see ItemPointerSetMovedPartitions). Thus, a tuple is the latest version
91 * of its row iff XMAX is invalid or
92 * t_ctid points to itself (in which case, if XMAX is valid, the tuple is
93 * either locked or deleted). One can follow the chain of t_ctid links
94 * to find the newest version of the row, unless it was moved to a different
95 * partition. Beware however that VACUUM might
96 * erase the pointed-to (newer) tuple before erasing the pointing (older)
97 * tuple. Hence, when following a t_ctid link, it is necessary to check
98 * to see if the referenced slot is empty or contains an unrelated tuple.
99 * Check that the referenced tuple has XMIN equal to the referencing tuple's
100 * XMAX to verify that it is actually the descendant version and not an
101 * unrelated tuple stored into a slot recently freed by VACUUM. If either
102 * check fails, one may assume that there is no live descendant version.
103 *
104 * t_ctid is sometimes used to store a speculative insertion token, instead
105 * of a real TID. A speculative token is set on a tuple that's being
106 * inserted, until the inserter is sure that it wants to go ahead with the
107 * insertion. Hence a token should only be seen on a tuple with an XMAX
108 * that's still in-progress, or invalid/aborted. The token is replaced with
109 * the tuple's real TID when the insertion is confirmed. One should never
110 * see a speculative insertion token while following a chain of t_ctid links,
111 * because they are not used on updates, only insertions.
112 *
113 * Following the fixed header fields, the nulls bitmap is stored (beginning
114 * at t_bits). The bitmap is *not* stored if t_infomask shows that there
115 * are no nulls in the tuple. If an OID field is present (as indicated by
116 * t_infomask), then it is stored just before the user data, which begins at
117 * the offset shown by t_hoff. Note that t_hoff must be a multiple of
118 * MAXALIGN.
119 */
120
121typedef struct HeapTupleFields
122{
123 TransactionId t_xmin; /* inserting xact ID */
124 TransactionId t_xmax; /* deleting or locking xact ID */
125
126 union
127 {
128 CommandId t_cid; /* inserting or deleting command ID, or both */
129 TransactionId t_xvac; /* old-style VACUUM FULL xact ID */
130 } t_field3;
131} HeapTupleFields;
132
133typedef struct DatumTupleFields
134{
135 int32 datum_len_; /* varlena header (do not touch directly!) */
136
137 int32 datum_typmod; /* -1, or identifier of a record type */
138
139 Oid datum_typeid; /* composite type OID, or RECORDOID */
140
141 /*
142 * datum_typeid cannot be a domain over composite, only plain composite,
143 * even if the datum is meant as a value of a domain-over-composite type.
144 * This is in line with the general principle that CoerceToDomain does not
145 * change the physical representation of the base type value.
146 *
147 * Note: field ordering is chosen with thought that Oid might someday
148 * widen to 64 bits.
149 */
150} DatumTupleFields;
151
152struct HeapTupleHeaderData
153{
154 union
155 {
156 HeapTupleFields t_heap;
157 DatumTupleFields t_datum;
158 } t_choice;
159
160 ItemPointerData t_ctid; /* current TID of this or newer tuple (or a
161 * speculative insertion token) */
162
163 /* Fields below here must match MinimalTupleData! */
164
165#define FIELDNO_HEAPTUPLEHEADERDATA_INFOMASK2 2
166 uint16 t_infomask2; /* number of attributes + various flags */
167
168#define FIELDNO_HEAPTUPLEHEADERDATA_INFOMASK 3
169 uint16 t_infomask; /* various flag bits, see below */
170
171#define FIELDNO_HEAPTUPLEHEADERDATA_HOFF 4
172 uint8 t_hoff; /* sizeof header incl. bitmap, padding */
173
174 /* ^ - 23 bytes - ^ */
175
176#define FIELDNO_HEAPTUPLEHEADERDATA_BITS 5
177 bits8 t_bits[FLEXIBLE_ARRAY_MEMBER]; /* bitmap of NULLs */
178
179 /* MORE DATA FOLLOWS AT END OF STRUCT */
180};
181
182/* typedef appears in htup.h */
183
184#define SizeofHeapTupleHeader offsetof(HeapTupleHeaderData, t_bits)
185
186/*
187 * information stored in t_infomask:
188 */
189#define HEAP_HASNULL 0x0001 /* has null attribute(s) */
190#define HEAP_HASVARWIDTH 0x0002 /* has variable-width attribute(s) */
191#define HEAP_HASEXTERNAL 0x0004 /* has external stored attribute(s) */
192#define HEAP_HASOID_OLD 0x0008 /* has an object-id field */
193#define HEAP_XMAX_KEYSHR_LOCK 0x0010 /* xmax is a key-shared locker */
194#define HEAP_COMBOCID 0x0020 /* t_cid is a combo cid */
195#define HEAP_XMAX_EXCL_LOCK 0x0040 /* xmax is exclusive locker */
196#define HEAP_XMAX_LOCK_ONLY 0x0080 /* xmax, if valid, is only a locker */
197
198 /* xmax is a shared locker */
199#define HEAP_XMAX_SHR_LOCK (HEAP_XMAX_EXCL_LOCK | HEAP_XMAX_KEYSHR_LOCK)
200
201#define HEAP_LOCK_MASK (HEAP_XMAX_SHR_LOCK | HEAP_XMAX_EXCL_LOCK | \
202 HEAP_XMAX_KEYSHR_LOCK)
203#define HEAP_XMIN_COMMITTED 0x0100 /* t_xmin committed */
204#define HEAP_XMIN_INVALID 0x0200 /* t_xmin invalid/aborted */
205#define HEAP_XMIN_FROZEN (HEAP_XMIN_COMMITTED|HEAP_XMIN_INVALID)
206#define HEAP_XMAX_COMMITTED 0x0400 /* t_xmax committed */
207#define HEAP_XMAX_INVALID 0x0800 /* t_xmax invalid/aborted */
208#define HEAP_XMAX_IS_MULTI 0x1000 /* t_xmax is a MultiXactId */
209#define HEAP_UPDATED 0x2000 /* this is UPDATEd version of row */
210#define HEAP_MOVED_OFF 0x4000 /* moved to another place by pre-9.0
211 * VACUUM FULL; kept for binary
212 * upgrade support */
213#define HEAP_MOVED_IN 0x8000 /* moved from another place by pre-9.0
214 * VACUUM FULL; kept for binary
215 * upgrade support */
216#define HEAP_MOVED (HEAP_MOVED_OFF | HEAP_MOVED_IN)
217
218#define HEAP_XACT_MASK 0xFFF0 /* visibility-related bits */
219
220/*
221 * A tuple is only locked (i.e. not updated by its Xmax) if the
222 * HEAP_XMAX_LOCK_ONLY bit is set; or, for pg_upgrade's sake, if the Xmax is
223 * not a multi and the EXCL_LOCK bit is set.
224 *
225 * See also HeapTupleHeaderIsOnlyLocked, which also checks for a possible
226 * aborted updater transaction.
227 *
228 * Beware of multiple evaluations of the argument.
229 */
230#define HEAP_XMAX_IS_LOCKED_ONLY(infomask) \
231 (((infomask) & HEAP_XMAX_LOCK_ONLY) || \
232 (((infomask) & (HEAP_XMAX_IS_MULTI | HEAP_LOCK_MASK)) == HEAP_XMAX_EXCL_LOCK))
233
234/*
235 * A tuple that has HEAP_XMAX_IS_MULTI and HEAP_XMAX_LOCK_ONLY but neither of
236 * XMAX_EXCL_LOCK and XMAX_KEYSHR_LOCK must come from a tuple that was
237 * share-locked in 9.2 or earlier and then pg_upgrade'd.
238 *
239 * In 9.2 and prior, HEAP_XMAX_IS_MULTI was only set when there were multiple
240 * FOR SHARE lockers of that tuple. That set HEAP_XMAX_LOCK_ONLY (with a
241 * different name back then) but neither of HEAP_XMAX_EXCL_LOCK and
242 * HEAP_XMAX_KEYSHR_LOCK. That combination is no longer possible in 9.3 and
243 * up, so if we see that combination we know for certain that the tuple was
244 * locked in an earlier release; since all such lockers are gone (they cannot
245 * survive through pg_upgrade), such tuples can safely be considered not
246 * locked.
247 *
248 * We must not resolve such multixacts locally, because the result would be
249 * bogus, regardless of where they stand with respect to the current valid
250 * multixact range.
251 */
252#define HEAP_LOCKED_UPGRADED(infomask) \
253( \
254 ((infomask) & HEAP_XMAX_IS_MULTI) != 0 && \
255 ((infomask) & HEAP_XMAX_LOCK_ONLY) != 0 && \
256 (((infomask) & (HEAP_XMAX_EXCL_LOCK | HEAP_XMAX_KEYSHR_LOCK)) == 0) \
257)
258
259/*
260 * Use these to test whether a particular lock is applied to a tuple
261 */
262#define HEAP_XMAX_IS_SHR_LOCKED(infomask) \
263 (((infomask) & HEAP_LOCK_MASK) == HEAP_XMAX_SHR_LOCK)
264#define HEAP_XMAX_IS_EXCL_LOCKED(infomask) \
265 (((infomask) & HEAP_LOCK_MASK) == HEAP_XMAX_EXCL_LOCK)
266#define HEAP_XMAX_IS_KEYSHR_LOCKED(infomask) \
267 (((infomask) & HEAP_LOCK_MASK) == HEAP_XMAX_KEYSHR_LOCK)
268
269/* turn these all off when Xmax is to change */
270#define HEAP_XMAX_BITS (HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID | \
271 HEAP_XMAX_IS_MULTI | HEAP_LOCK_MASK | HEAP_XMAX_LOCK_ONLY)
272
273/*
274 * information stored in t_infomask2:
275 */
276#define HEAP_NATTS_MASK 0x07FF /* 11 bits for number of attributes */
277/* bits 0x1800 are available */
278#define HEAP_KEYS_UPDATED 0x2000 /* tuple was updated and key cols
279 * modified, or tuple deleted */
280#define HEAP_HOT_UPDATED 0x4000 /* tuple was HOT-updated */
281#define HEAP_ONLY_TUPLE 0x8000 /* this is heap-only tuple */
282
283#define HEAP2_XACT_MASK 0xE000 /* visibility-related bits */
284
285/*
286 * HEAP_TUPLE_HAS_MATCH is a temporary flag used during hash joins. It is
287 * only used in tuples that are in the hash table, and those don't need
288 * any visibility information, so we can overlay it on a visibility flag
289 * instead of using up a dedicated bit.
290 */
291#define HEAP_TUPLE_HAS_MATCH HEAP_ONLY_TUPLE /* tuple has a join match */
292
293/*
294 * HeapTupleHeader accessor macros
295 *
296 * Note: beware of multiple evaluations of "tup" argument. But the Set
297 * macros evaluate their other argument only once.
298 */
299
300/*
301 * HeapTupleHeaderGetRawXmin returns the "raw" xmin field, which is the xid
302 * originally used to insert the tuple. However, the tuple might actually
303 * be frozen (via HeapTupleHeaderSetXminFrozen) in which case the tuple's xmin
304 * is visible to every snapshot. Prior to PostgreSQL 9.4, we actually changed
305 * the xmin to FrozenTransactionId, and that value may still be encountered
306 * on disk.
307 */
308#define HeapTupleHeaderGetRawXmin(tup) \
309( \
310 (tup)->t_choice.t_heap.t_xmin \
311)
312
313#define HeapTupleHeaderGetXmin(tup) \
314( \
315 HeapTupleHeaderXminFrozen(tup) ? \
316 FrozenTransactionId : HeapTupleHeaderGetRawXmin(tup) \
317)
318
319#define HeapTupleHeaderSetXmin(tup, xid) \
320( \
321 (tup)->t_choice.t_heap.t_xmin = (xid) \
322)
323
324#define HeapTupleHeaderXminCommitted(tup) \
325( \
326 ((tup)->t_infomask & HEAP_XMIN_COMMITTED) != 0 \
327)
328
329#define HeapTupleHeaderXminInvalid(tup) \
330( \
331 ((tup)->t_infomask & (HEAP_XMIN_COMMITTED|HEAP_XMIN_INVALID)) == \
332 HEAP_XMIN_INVALID \
333)
334
335#define HeapTupleHeaderXminFrozen(tup) \
336( \
337 ((tup)->t_infomask & (HEAP_XMIN_FROZEN)) == HEAP_XMIN_FROZEN \
338)
339
340#define HeapTupleHeaderSetXminCommitted(tup) \
341( \
342 AssertMacro(!HeapTupleHeaderXminInvalid(tup)), \
343 ((tup)->t_infomask |= HEAP_XMIN_COMMITTED) \
344)
345
346#define HeapTupleHeaderSetXminInvalid(tup) \
347( \
348 AssertMacro(!HeapTupleHeaderXminCommitted(tup)), \
349 ((tup)->t_infomask |= HEAP_XMIN_INVALID) \
350)
351
352#define HeapTupleHeaderSetXminFrozen(tup) \
353( \
354 AssertMacro(!HeapTupleHeaderXminInvalid(tup)), \
355 ((tup)->t_infomask |= HEAP_XMIN_FROZEN) \
356)
357
358/*
359 * HeapTupleHeaderGetRawXmax gets you the raw Xmax field. To find out the Xid
360 * that updated a tuple, you might need to resolve the MultiXactId if certain
361 * bits are set. HeapTupleHeaderGetUpdateXid checks those bits and takes care
362 * to resolve the MultiXactId if necessary. This might involve multixact I/O,
363 * so it should only be used if absolutely necessary.
364 */
365#define HeapTupleHeaderGetUpdateXid(tup) \
366( \
367 (!((tup)->t_infomask & HEAP_XMAX_INVALID) && \
368 ((tup)->t_infomask & HEAP_XMAX_IS_MULTI) && \
369 !((tup)->t_infomask & HEAP_XMAX_LOCK_ONLY)) ? \
370 HeapTupleGetUpdateXid(tup) \
371 : \
372 HeapTupleHeaderGetRawXmax(tup) \
373)
374
375#define HeapTupleHeaderGetRawXmax(tup) \
376( \
377 (tup)->t_choice.t_heap.t_xmax \
378)
379
380#define HeapTupleHeaderSetXmax(tup, xid) \
381( \
382 (tup)->t_choice.t_heap.t_xmax = (xid) \
383)
384
385/*
386 * HeapTupleHeaderGetRawCommandId will give you what's in the header whether
387 * it is useful or not. Most code should use HeapTupleHeaderGetCmin or
388 * HeapTupleHeaderGetCmax instead, but note that those Assert that you can
389 * get a legitimate result, ie you are in the originating transaction!
390 */
391#define HeapTupleHeaderGetRawCommandId(tup) \
392( \
393 (tup)->t_choice.t_heap.t_field3.t_cid \
394)
395
396/* SetCmin is reasonably simple since we never need a combo CID */
397#define HeapTupleHeaderSetCmin(tup, cid) \
398do { \
399 Assert(!((tup)->t_infomask & HEAP_MOVED)); \
400 (tup)->t_choice.t_heap.t_field3.t_cid = (cid); \
401 (tup)->t_infomask &= ~HEAP_COMBOCID; \
402} while (0)
403
404/* SetCmax must be used after HeapTupleHeaderAdjustCmax; see combocid.c */
405#define HeapTupleHeaderSetCmax(tup, cid, iscombo) \
406do { \
407 Assert(!((tup)->t_infomask & HEAP_MOVED)); \
408 (tup)->t_choice.t_heap.t_field3.t_cid = (cid); \
409 if (iscombo) \
410 (tup)->t_infomask |= HEAP_COMBOCID; \
411 else \
412 (tup)->t_infomask &= ~HEAP_COMBOCID; \
413} while (0)
414
415#define HeapTupleHeaderGetXvac(tup) \
416( \
417 ((tup)->t_infomask & HEAP_MOVED) ? \
418 (tup)->t_choice.t_heap.t_field3.t_xvac \
419 : \
420 InvalidTransactionId \
421)
422
423#define HeapTupleHeaderSetXvac(tup, xid) \
424do { \
425 Assert((tup)->t_infomask & HEAP_MOVED); \
426 (tup)->t_choice.t_heap.t_field3.t_xvac = (xid); \
427} while (0)
428
429#define HeapTupleHeaderIsSpeculative(tup) \
430( \
431 (ItemPointerGetOffsetNumberNoCheck(&(tup)->t_ctid) == SpecTokenOffsetNumber) \
432)
433
434#define HeapTupleHeaderGetSpeculativeToken(tup) \
435( \
436 AssertMacro(HeapTupleHeaderIsSpeculative(tup)), \
437 ItemPointerGetBlockNumber(&(tup)->t_ctid) \
438)
439
440#define HeapTupleHeaderSetSpeculativeToken(tup, token) \
441( \
442 ItemPointerSet(&(tup)->t_ctid, token, SpecTokenOffsetNumber) \
443)
444
445#define HeapTupleHeaderIndicatesMovedPartitions(tup) \
446 (ItemPointerGetOffsetNumber(&(tup)->t_ctid) == MovedPartitionsOffsetNumber && \
447 ItemPointerGetBlockNumberNoCheck(&(tup)->t_ctid) == MovedPartitionsBlockNumber)
448
449#define HeapTupleHeaderSetMovedPartitions(tup) \
450 ItemPointerSet(&(tup)->t_ctid, MovedPartitionsBlockNumber, MovedPartitionsOffsetNumber)
451
452#define HeapTupleHeaderGetDatumLength(tup) \
453 VARSIZE(tup)
454
455#define HeapTupleHeaderSetDatumLength(tup, len) \
456 SET_VARSIZE(tup, len)
457
458#define HeapTupleHeaderGetTypeId(tup) \
459( \
460 (tup)->t_choice.t_datum.datum_typeid \
461)
462
463#define HeapTupleHeaderSetTypeId(tup, typeid) \
464( \
465 (tup)->t_choice.t_datum.datum_typeid = (typeid) \
466)
467
468#define HeapTupleHeaderGetTypMod(tup) \
469( \
470 (tup)->t_choice.t_datum.datum_typmod \
471)
472
473#define HeapTupleHeaderSetTypMod(tup, typmod) \
474( \
475 (tup)->t_choice.t_datum.datum_typmod = (typmod) \
476)
477
478/*
479 * Note that we stop considering a tuple HOT-updated as soon as it is known
480 * aborted or the would-be updating transaction is known aborted. For best
481 * efficiency, check tuple visibility before using this macro, so that the
482 * INVALID bits will be as up to date as possible.
483 */
484#define HeapTupleHeaderIsHotUpdated(tup) \
485( \
486 ((tup)->t_infomask2 & HEAP_HOT_UPDATED) != 0 && \
487 ((tup)->t_infomask & HEAP_XMAX_INVALID) == 0 && \
488 !HeapTupleHeaderXminInvalid(tup) \
489)
490
491#define HeapTupleHeaderSetHotUpdated(tup) \
492( \
493 (tup)->t_infomask2 |= HEAP_HOT_UPDATED \
494)
495
496#define HeapTupleHeaderClearHotUpdated(tup) \
497( \
498 (tup)->t_infomask2 &= ~HEAP_HOT_UPDATED \
499)
500
501#define HeapTupleHeaderIsHeapOnly(tup) \
502( \
503 ((tup)->t_infomask2 & HEAP_ONLY_TUPLE) != 0 \
504)
505
506#define HeapTupleHeaderSetHeapOnly(tup) \
507( \
508 (tup)->t_infomask2 |= HEAP_ONLY_TUPLE \
509)
510
511#define HeapTupleHeaderClearHeapOnly(tup) \
512( \
513 (tup)->t_infomask2 &= ~HEAP_ONLY_TUPLE \
514)
515
516#define HeapTupleHeaderHasMatch(tup) \
517( \
518 ((tup)->t_infomask2 & HEAP_TUPLE_HAS_MATCH) != 0 \
519)
520
521#define HeapTupleHeaderSetMatch(tup) \
522( \
523 (tup)->t_infomask2 |= HEAP_TUPLE_HAS_MATCH \
524)
525
526#define HeapTupleHeaderClearMatch(tup) \
527( \
528 (tup)->t_infomask2 &= ~HEAP_TUPLE_HAS_MATCH \
529)
530
531#define HeapTupleHeaderGetNatts(tup) \
532 ((tup)->t_infomask2 & HEAP_NATTS_MASK)
533
534#define HeapTupleHeaderSetNatts(tup, natts) \
535( \
536 (tup)->t_infomask2 = ((tup)->t_infomask2 & ~HEAP_NATTS_MASK) | (natts) \
537)
538
539#define HeapTupleHeaderHasExternal(tup) \
540 (((tup)->t_infomask & HEAP_HASEXTERNAL) != 0)
541
542
543/*
544 * BITMAPLEN(NATTS) -
545 * Computes size of null bitmap given number of data columns.
546 */
547#define BITMAPLEN(NATTS) (((int)(NATTS) + 7) / 8)
548
549/*
550 * MaxHeapTupleSize is the maximum allowed size of a heap tuple, including
551 * header and MAXALIGN alignment padding. Basically it's BLCKSZ minus the
552 * other stuff that has to be on a disk page. Since heap pages use no
553 * "special space", there's no deduction for that.
554 *
555 * NOTE: we allow for the ItemId that must point to the tuple, ensuring that
556 * an otherwise-empty page can indeed hold a tuple of this size. Because
557 * ItemIds and tuples have different alignment requirements, don't assume that
558 * you can, say, fit 2 tuples of size MaxHeapTupleSize/2 on the same page.
559 */
560#define MaxHeapTupleSize (BLCKSZ - MAXALIGN(SizeOfPageHeaderData + sizeof(ItemIdData)))
561#define MinHeapTupleSize MAXALIGN(SizeofHeapTupleHeader)
562
563/*
564 * MaxHeapTuplesPerPage is an upper bound on the number of tuples that can
565 * fit on one heap page. (Note that indexes could have more, because they
566 * use a smaller tuple header.) We arrive at the divisor because each tuple
567 * must be maxaligned, and it must have an associated line pointer.
568 *
569 * Note: with HOT, there could theoretically be more line pointers (not actual
570 * tuples) than this on a heap page. However we constrain the number of line
571 * pointers to this anyway, to avoid excessive line-pointer bloat and not
572 * require increases in the size of work arrays.
573 */
574#define MaxHeapTuplesPerPage \
575 ((int) ((BLCKSZ - SizeOfPageHeaderData) / \
576 (MAXALIGN(SizeofHeapTupleHeader) + sizeof(ItemIdData))))
577
578/*
579 * MaxAttrSize is a somewhat arbitrary upper limit on the declared size of
580 * data fields of char(n) and similar types. It need not have anything
581 * directly to do with the *actual* upper limit of varlena values, which
582 * is currently 1Gb (see TOAST structures in postgres.h). I've set it
583 * at 10Mb which seems like a reasonable number --- tgl 8/6/00.
584 */
585#define MaxAttrSize (10 * 1024 * 1024)
586
587
588/*
589 * MinimalTuple is an alternative representation that is used for transient
590 * tuples inside the executor, in places where transaction status information
591 * is not required, the tuple rowtype is known, and shaving off a few bytes
592 * is worthwhile because we need to store many tuples. The representation
593 * is chosen so that tuple access routines can work with either full or
594 * minimal tuples via a HeapTupleData pointer structure. The access routines
595 * see no difference, except that they must not access the transaction status
596 * or t_ctid fields because those aren't there.
597 *
598 * For the most part, MinimalTuples should be accessed via TupleTableSlot
599 * routines. These routines will prevent access to the "system columns"
600 * and thereby prevent accidental use of the nonexistent fields.
601 *
602 * MinimalTupleData contains a length word, some padding, and fields matching
603 * HeapTupleHeaderData beginning with t_infomask2. The padding is chosen so
604 * that offsetof(t_infomask2) is the same modulo MAXIMUM_ALIGNOF in both
605 * structs. This makes data alignment rules equivalent in both cases.
606 *
607 * When a minimal tuple is accessed via a HeapTupleData pointer, t_data is
608 * set to point MINIMAL_TUPLE_OFFSET bytes before the actual start of the
609 * minimal tuple --- that is, where a full tuple matching the minimal tuple's
610 * data would start. This trick is what makes the structs seem equivalent.
611 *
612 * Note that t_hoff is computed the same as in a full tuple, hence it includes
613 * the MINIMAL_TUPLE_OFFSET distance. t_len does not include that, however.
614 *
615 * MINIMAL_TUPLE_DATA_OFFSET is the offset to the first useful (non-pad) data
616 * other than the length word. tuplesort.c and tuplestore.c use this to avoid
617 * writing the padding to disk.
618 */
619#define MINIMAL_TUPLE_OFFSET \
620 ((offsetof(HeapTupleHeaderData, t_infomask2) - sizeof(uint32)) / MAXIMUM_ALIGNOF * MAXIMUM_ALIGNOF)
621#define MINIMAL_TUPLE_PADDING \
622 ((offsetof(HeapTupleHeaderData, t_infomask2) - sizeof(uint32)) % MAXIMUM_ALIGNOF)
623#define MINIMAL_TUPLE_DATA_OFFSET \
624 offsetof(MinimalTupleData, t_infomask2)
625
626struct MinimalTupleData
627{
628 uint32 t_len; /* actual length of minimal tuple */
629
630 char mt_padding[MINIMAL_TUPLE_PADDING];
631
632 /* Fields below here must match HeapTupleHeaderData! */
633
634 uint16 t_infomask2; /* number of attributes + various flags */
635
636 uint16 t_infomask; /* various flag bits, see below */
637
638 uint8 t_hoff; /* sizeof header incl. bitmap, padding */
639
640 /* ^ - 23 bytes - ^ */
641
642 bits8 t_bits[FLEXIBLE_ARRAY_MEMBER]; /* bitmap of NULLs */
643
644 /* MORE DATA FOLLOWS AT END OF STRUCT */
645};
646
647/* typedef appears in htup.h */
648
649#define SizeofMinimalTupleHeader offsetof(MinimalTupleData, t_bits)
650
651
652/*
653 * GETSTRUCT - given a HeapTuple pointer, return address of the user data
654 */
655#define GETSTRUCT(TUP) ((char *) ((TUP)->t_data) + (TUP)->t_data->t_hoff)
656
657/*
658 * Accessor macros to be used with HeapTuple pointers.
659 */
660
661#define HeapTupleHasNulls(tuple) \
662 (((tuple)->t_data->t_infomask & HEAP_HASNULL) != 0)
663
664#define HeapTupleNoNulls(tuple) \
665 (!((tuple)->t_data->t_infomask & HEAP_HASNULL))
666
667#define HeapTupleHasVarWidth(tuple) \
668 (((tuple)->t_data->t_infomask & HEAP_HASVARWIDTH) != 0)
669
670#define HeapTupleAllFixed(tuple) \
671 (!((tuple)->t_data->t_infomask & HEAP_HASVARWIDTH))
672
673#define HeapTupleHasExternal(tuple) \
674 (((tuple)->t_data->t_infomask & HEAP_HASEXTERNAL) != 0)
675
676#define HeapTupleIsHotUpdated(tuple) \
677 HeapTupleHeaderIsHotUpdated((tuple)->t_data)
678
679#define HeapTupleSetHotUpdated(tuple) \
680 HeapTupleHeaderSetHotUpdated((tuple)->t_data)
681
682#define HeapTupleClearHotUpdated(tuple) \
683 HeapTupleHeaderClearHotUpdated((tuple)->t_data)
684
685#define HeapTupleIsHeapOnly(tuple) \
686 HeapTupleHeaderIsHeapOnly((tuple)->t_data)
687
688#define HeapTupleSetHeapOnly(tuple) \
689 HeapTupleHeaderSetHeapOnly((tuple)->t_data)
690
691#define HeapTupleClearHeapOnly(tuple) \
692 HeapTupleHeaderClearHeapOnly((tuple)->t_data)
693
694
695/* ----------------
696 * fastgetattr
697 *
698 * Fetch a user attribute's value as a Datum (might be either a
699 * value, or a pointer into the data area of the tuple).
700 *
701 * This must not be used when a system attribute might be requested.
702 * Furthermore, the passed attnum MUST be valid. Use heap_getattr()
703 * instead, if in doubt.
704 *
705 * This gets called many times, so we macro the cacheable and NULL
706 * lookups, and call nocachegetattr() for the rest.
707 * ----------------
708 */
709
710#if !defined(DISABLE_COMPLEX_MACRO)
711
712#define fastgetattr(tup, attnum, tupleDesc, isnull) \
713( \
714 AssertMacro((attnum) > 0), \
715 (*(isnull) = false), \
716 HeapTupleNoNulls(tup) ? \
717 ( \
718 TupleDescAttr((tupleDesc), (attnum)-1)->attcacheoff >= 0 ? \
719 ( \
720 fetchatt(TupleDescAttr((tupleDesc), (attnum)-1), \
721 (char *) (tup)->t_data + (tup)->t_data->t_hoff + \
722 TupleDescAttr((tupleDesc), (attnum)-1)->attcacheoff)\
723 ) \
724 : \
725 nocachegetattr((tup), (attnum), (tupleDesc)) \
726 ) \
727 : \
728 ( \
729 att_isnull((attnum)-1, (tup)->t_data->t_bits) ? \
730 ( \
731 (*(isnull) = true), \
732 (Datum)NULL \
733 ) \
734 : \
735 ( \
736 nocachegetattr((tup), (attnum), (tupleDesc)) \
737 ) \
738 ) \
739)
740#else /* defined(DISABLE_COMPLEX_MACRO) */
741
742extern Datum fastgetattr(HeapTuple tup, int attnum, TupleDesc tupleDesc,
743 bool *isnull);
744#endif /* defined(DISABLE_COMPLEX_MACRO) */
745
746
747/* ----------------
748 * heap_getattr
749 *
750 * Extract an attribute of a heap tuple and return it as a Datum.
751 * This works for either system or user attributes. The given attnum
752 * is properly range-checked.
753 *
754 * If the field in question has a NULL value, we return a zero Datum
755 * and set *isnull == true. Otherwise, we set *isnull == false.
756 *
757 * <tup> is the pointer to the heap tuple. <attnum> is the attribute
758 * number of the column (field) caller wants. <tupleDesc> is a
759 * pointer to the structure describing the row and all its fields.
760 * ----------------
761 */
762#define heap_getattr(tup, attnum, tupleDesc, isnull) \
763 ( \
764 ((attnum) > 0) ? \
765 ( \
766 ((attnum) > (int) HeapTupleHeaderGetNatts((tup)->t_data)) ? \
767 getmissingattr((tupleDesc), (attnum), (isnull)) \
768 : \
769 fastgetattr((tup), (attnum), (tupleDesc), (isnull)) \
770 ) \
771 : \
772 heap_getsysattr((tup), (attnum), (tupleDesc), (isnull)) \
773 )
774
775
776/* prototypes for functions in common/heaptuple.c */
777extern Size heap_compute_data_size(TupleDesc tupleDesc,
778 Datum *values, bool *isnull);
779extern void heap_fill_tuple(TupleDesc tupleDesc,
780 Datum *values, bool *isnull,
781 char *data, Size data_size,
782 uint16 *infomask, bits8 *bit);
783extern bool heap_attisnull(HeapTuple tup, int attnum, TupleDesc tupleDesc);
784extern Datum nocachegetattr(HeapTuple tup, int attnum,
785 TupleDesc att);
786extern Datum heap_getsysattr(HeapTuple tup, int attnum, TupleDesc tupleDesc,
787 bool *isnull);
788extern Datum getmissingattr(TupleDesc tupleDesc,
789 int attnum, bool *isnull);
790extern HeapTuple heap_copytuple(HeapTuple tuple);
791extern void heap_copytuple_with_tuple(HeapTuple src, HeapTuple dest);
792extern Datum heap_copy_tuple_as_datum(HeapTuple tuple, TupleDesc tupleDesc);
793extern HeapTuple heap_form_tuple(TupleDesc tupleDescriptor,
794 Datum *values, bool *isnull);
795extern HeapTuple heap_modify_tuple(HeapTuple tuple,
796 TupleDesc tupleDesc,
797 Datum *replValues,
798 bool *replIsnull,
799 bool *doReplace);
800extern HeapTuple heap_modify_tuple_by_cols(HeapTuple tuple,
801 TupleDesc tupleDesc,
802 int nCols,
803 int *replCols,
804 Datum *replValues,
805 bool *replIsnull);
806extern void heap_deform_tuple(HeapTuple tuple, TupleDesc tupleDesc,
807 Datum *values, bool *isnull);
808extern void heap_freetuple(HeapTuple htup);
809extern MinimalTuple heap_form_minimal_tuple(TupleDesc tupleDescriptor,
810 Datum *values, bool *isnull);
811extern void heap_free_minimal_tuple(MinimalTuple mtup);
812extern MinimalTuple heap_copy_minimal_tuple(MinimalTuple mtup);
813extern HeapTuple heap_tuple_from_minimal_tuple(MinimalTuple mtup);
814extern MinimalTuple minimal_tuple_from_heap_tuple(HeapTuple htup);
815extern size_t varsize_any(void *p);
816extern HeapTuple heap_expand_tuple(HeapTuple sourceTuple, TupleDesc tupleDesc);
817extern MinimalTuple minimal_expand_tuple(HeapTuple sourceTuple, TupleDesc tupleDesc);
818
819#endif /* HTUP_DETAILS_H */
820