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1 : /*-------------------------------------------------------------------------
2 : *
3 : * htup_details.h
4 : * POSTGRES heap tuple header definitions.
5 : *
6 : *
7 : * Portions Copyright (c) 1996-2023, 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/transam.h"
19 : #include "access/tupdesc.h"
20 : #include "access/tupmacs.h"
21 : #include "storage/bufpage.h"
22 : #include "varatt.h"
23 :
24 : /*
25 : * MaxTupleAttributeNumber limits the number of (user) columns in a tuple.
26 : * The key limit on this value is that the size of the fixed overhead for
27 : * a tuple, plus the size of the null-values bitmap (at 1 bit per column),
28 : * plus MAXALIGN alignment, must fit into t_hoff which is uint8. On most
29 : * machines the upper limit without making t_hoff wider would be a little
30 : * over 1700. We use round numbers here and for MaxHeapAttributeNumber
31 : * so that alterations in HeapTupleHeaderData layout won't change the
32 : * supported max number of columns.
33 : */
34 : #define MaxTupleAttributeNumber 1664 /* 8 * 208 */
35 :
36 : /*
37 : * MaxHeapAttributeNumber limits the number of (user) columns in a table.
38 : * This should be somewhat less than MaxTupleAttributeNumber. It must be
39 : * at least one less, else we will fail to do UPDATEs on a maximal-width
40 : * table (because UPDATE has to form working tuples that include CTID).
41 : * In practice we want some additional daylight so that we can gracefully
42 : * support operations that add hidden "resjunk" columns, for example
43 : * SELECT * FROM wide_table ORDER BY foo, bar, baz.
44 : * In any case, depending on column data types you will likely be running
45 : * into the disk-block-based limit on overall tuple size if you have more
46 : * than a thousand or so columns. TOAST won't help.
47 : */
48 : #define MaxHeapAttributeNumber 1600 /* 8 * 200 */
49 :
50 : /*
51 : * Heap tuple header. To avoid wasting space, the fields should be
52 : * laid out in such a way as to avoid structure padding.
53 : *
54 : * Datums of composite types (row types) share the same general structure
55 : * as on-disk tuples, so that the same routines can be used to build and
56 : * examine them. However the requirements are slightly different: a Datum
57 : * does not need any transaction visibility information, and it does need
58 : * a length word and some embedded type information. We can achieve this
59 : * by overlaying the xmin/cmin/xmax/cmax/xvac fields of a heap tuple
60 : * with the fields needed in the Datum case. Typically, all tuples built
61 : * in-memory will be initialized with the Datum fields; but when a tuple is
62 : * about to be inserted in a table, the transaction fields will be filled,
63 : * overwriting the datum fields.
64 : *
65 : * The overall structure of a heap tuple looks like:
66 : * fixed fields (HeapTupleHeaderData struct)
67 : * nulls bitmap (if HEAP_HASNULL is set in t_infomask)
68 : * alignment padding (as needed to make user data MAXALIGN'd)
69 : * object ID (if HEAP_HASOID_OLD is set in t_infomask, not created
70 : * anymore)
71 : * user data fields
72 : *
73 : * We store five "virtual" fields Xmin, Cmin, Xmax, Cmax, and Xvac in three
74 : * physical fields. Xmin and Xmax are always really stored, but Cmin, Cmax
75 : * and Xvac share a field. This works because we know that Cmin and Cmax
76 : * are only interesting for the lifetime of the inserting and deleting
77 : * transaction respectively. If a tuple is inserted and deleted in the same
78 : * transaction, we store a "combo" command id that can be mapped to the real
79 : * cmin and cmax, but only by use of local state within the originating
80 : * backend. See combocid.c for more details. Meanwhile, Xvac is only set by
81 : * old-style VACUUM FULL, which does not have any command sub-structure and so
82 : * does not need either Cmin or Cmax. (This requires that old-style VACUUM
83 : * FULL never try to move a tuple whose Cmin or Cmax is still interesting,
84 : * ie, an insert-in-progress or delete-in-progress tuple.)
85 : *
86 : * A word about t_ctid: whenever a new tuple is stored on disk, its t_ctid
87 : * is initialized with its own TID (location). If the tuple is ever updated,
88 : * its t_ctid is changed to point to the replacement version of the tuple. Or
89 : * if the tuple is moved from one partition to another, due to an update of
90 : * the partition key, t_ctid is set to a special value to indicate that
91 : * (see ItemPointerSetMovedPartitions). Thus, a tuple is the latest version
92 : * of its row iff XMAX is invalid or
93 : * t_ctid points to itself (in which case, if XMAX is valid, the tuple is
94 : * either locked or deleted). One can follow the chain of t_ctid links
95 : * to find the newest version of the row, unless it was moved to a different
96 : * partition. Beware however that VACUUM might
97 : * erase the pointed-to (newer) tuple before erasing the pointing (older)
98 : * tuple. Hence, when following a t_ctid link, it is necessary to check
99 : * to see if the referenced slot is empty or contains an unrelated tuple.
100 : * Check that the referenced tuple has XMIN equal to the referencing tuple's
101 : * XMAX to verify that it is actually the descendant version and not an
102 : * unrelated tuple stored into a slot recently freed by VACUUM. If either
103 : * check fails, one may assume that there is no live descendant version.
104 : *
105 : * t_ctid is sometimes used to store a speculative insertion token, instead
106 : * of a real TID. A speculative token is set on a tuple that's being
107 : * inserted, until the inserter is sure that it wants to go ahead with the
108 : * insertion. Hence a token should only be seen on a tuple with an XMAX
109 : * that's still in-progress, or invalid/aborted. The token is replaced with
110 : * the tuple's real TID when the insertion is confirmed. One should never
111 : * see a speculative insertion token while following a chain of t_ctid links,
112 : * because they are not used on updates, only insertions.
113 : *
114 : * Following the fixed header fields, the nulls bitmap is stored (beginning
115 : * at t_bits). The bitmap is *not* stored if t_infomask shows that there
116 : * are no nulls in the tuple. If an OID field is present (as indicated by
117 : * t_infomask), then it is stored just before the user data, which begins at
118 : * the offset shown by t_hoff. Note that t_hoff must be a multiple of
119 : * MAXALIGN.
120 : */
121 :
122 : typedef struct HeapTupleFields
123 : {
124 : TransactionId t_xmin; /* inserting xact ID */
125 : TransactionId t_xmax; /* deleting or locking xact ID */
126 :
127 : union
128 : {
129 : CommandId t_cid; /* inserting or deleting command ID, or both */
130 : TransactionId t_xvac; /* old-style VACUUM FULL xact ID */
131 : } t_field3;
132 : } HeapTupleFields;
133 :
134 : typedef struct DatumTupleFields
135 : {
136 : int32 datum_len_; /* varlena header (do not touch directly!) */
137 :
138 : int32 datum_typmod; /* -1, or identifier of a record type */
139 :
140 : Oid datum_typeid; /* composite type OID, or RECORDOID */
141 :
142 : /*
143 : * datum_typeid cannot be a domain over composite, only plain composite,
144 : * even if the datum is meant as a value of a domain-over-composite type.
145 : * This is in line with the general principle that CoerceToDomain does not
146 : * change the physical representation of the base type value.
147 : *
148 : * Note: field ordering is chosen with thought that Oid might someday
149 : * widen to 64 bits.
150 : */
151 : } DatumTupleFields;
152 :
153 : struct HeapTupleHeaderData
154 : {
155 : union
156 : {
157 : HeapTupleFields t_heap;
158 : DatumTupleFields t_datum;
159 : } t_choice;
160 :
161 : ItemPointerData t_ctid; /* current TID of this or newer tuple (or a
162 : * speculative insertion token) */
163 :
164 : /* Fields below here must match MinimalTupleData! */
165 :
166 : #define FIELDNO_HEAPTUPLEHEADERDATA_INFOMASK2 2
167 : uint16 t_infomask2; /* number of attributes + various flags */
168 :
169 : #define FIELDNO_HEAPTUPLEHEADERDATA_INFOMASK 3
170 : uint16 t_infomask; /* various flag bits, see below */
171 :
172 : #define FIELDNO_HEAPTUPLEHEADERDATA_HOFF 4
173 : uint8 t_hoff; /* sizeof header incl. bitmap, padding */
174 :
175 : /* ^ - 23 bytes - ^ */
176 :
177 : #define FIELDNO_HEAPTUPLEHEADERDATA_BITS 5
178 : bits8 t_bits[FLEXIBLE_ARRAY_MEMBER]; /* bitmap of NULLs */
179 :
180 : /* MORE DATA FOLLOWS AT END OF STRUCT */
181 : };
182 :
183 : /* typedef appears in htup.h */
184 :
185 : #define SizeofHeapTupleHeader offsetof(HeapTupleHeaderData, t_bits)
186 :
187 : /*
188 : * information stored in t_infomask:
189 : */
190 : #define HEAP_HASNULL 0x0001 /* has null attribute(s) */
191 : #define HEAP_HASVARWIDTH 0x0002 /* has variable-width attribute(s) */
192 : #define HEAP_HASEXTERNAL 0x0004 /* has external stored attribute(s) */
193 : #define HEAP_HASOID_OLD 0x0008 /* has an object-id field */
194 : #define HEAP_XMAX_KEYSHR_LOCK 0x0010 /* xmax is a key-shared locker */
195 : #define HEAP_COMBOCID 0x0020 /* t_cid is a combo CID */
196 : #define HEAP_XMAX_EXCL_LOCK 0x0040 /* xmax is exclusive locker */
197 : #define HEAP_XMAX_LOCK_ONLY 0x0080 /* xmax, if valid, is only a locker */
198 :
199 : /* xmax is a shared locker */
200 : #define HEAP_XMAX_SHR_LOCK (HEAP_XMAX_EXCL_LOCK | HEAP_XMAX_KEYSHR_LOCK)
201 :
202 : #define HEAP_LOCK_MASK (HEAP_XMAX_SHR_LOCK | HEAP_XMAX_EXCL_LOCK | \
203 : HEAP_XMAX_KEYSHR_LOCK)
204 : #define HEAP_XMIN_COMMITTED 0x0100 /* t_xmin committed */
205 : #define HEAP_XMIN_INVALID 0x0200 /* t_xmin invalid/aborted */
206 : #define HEAP_XMIN_FROZEN (HEAP_XMIN_COMMITTED|HEAP_XMIN_INVALID)
207 : #define HEAP_XMAX_COMMITTED 0x0400 /* t_xmax committed */
208 : #define HEAP_XMAX_INVALID 0x0800 /* t_xmax invalid/aborted */
209 : #define HEAP_XMAX_IS_MULTI 0x1000 /* t_xmax is a MultiXactId */
210 : #define HEAP_UPDATED 0x2000 /* this is UPDATEd version of row */
211 : #define HEAP_MOVED_OFF 0x4000 /* moved to another place by pre-9.0
212 : * VACUUM FULL; kept for binary
213 : * upgrade support */
214 : #define HEAP_MOVED_IN 0x8000 /* moved from another place by pre-9.0
215 : * VACUUM FULL; kept for binary
216 : * upgrade support */
217 : #define HEAP_MOVED (HEAP_MOVED_OFF | HEAP_MOVED_IN)
218 :
219 : #define HEAP_XACT_MASK 0xFFF0 /* visibility-related bits */
220 :
221 : /*
222 : * A tuple is only locked (i.e. not updated by its Xmax) if the
223 : * HEAP_XMAX_LOCK_ONLY bit is set; or, for pg_upgrade's sake, if the Xmax is
224 : * not a multi and the EXCL_LOCK bit is set.
225 : *
226 : * See also HeapTupleHeaderIsOnlyLocked, which also checks for a possible
227 : * aborted updater transaction.
228 : *
229 : * Beware of multiple evaluations of the argument.
230 : */
231 : #define HEAP_XMAX_IS_LOCKED_ONLY(infomask) \
232 : (((infomask) & HEAP_XMAX_LOCK_ONLY) || \
233 : (((infomask) & (HEAP_XMAX_IS_MULTI | HEAP_LOCK_MASK)) == HEAP_XMAX_EXCL_LOCK))
234 :
235 : /*
236 : * A tuple that has HEAP_XMAX_IS_MULTI and HEAP_XMAX_LOCK_ONLY but neither of
237 : * HEAP_XMAX_EXCL_LOCK and HEAP_XMAX_KEYSHR_LOCK must come from a tuple that was
238 : * share-locked in 9.2 or earlier and then pg_upgrade'd.
239 : *
240 : * In 9.2 and prior, HEAP_XMAX_IS_MULTI was only set when there were multiple
241 : * FOR SHARE lockers of that tuple. That set HEAP_XMAX_LOCK_ONLY (with a
242 : * different name back then) but neither of HEAP_XMAX_EXCL_LOCK and
243 : * HEAP_XMAX_KEYSHR_LOCK. That combination is no longer possible in 9.3 and
244 : * up, so if we see that combination we know for certain that the tuple was
245 : * locked in an earlier release; since all such lockers are gone (they cannot
246 : * survive through pg_upgrade), such tuples can safely be considered not
247 : * locked.
248 : *
249 : * We must not resolve such multixacts locally, because the result would be
250 : * bogus, regardless of where they stand with respect to the current valid
251 : * multixact range.
252 : */
253 : #define HEAP_LOCKED_UPGRADED(infomask) \
254 : ( \
255 : ((infomask) & HEAP_XMAX_IS_MULTI) != 0 && \
256 : ((infomask) & HEAP_XMAX_LOCK_ONLY) != 0 && \
257 : (((infomask) & (HEAP_XMAX_EXCL_LOCK | HEAP_XMAX_KEYSHR_LOCK)) == 0) \
258 : )
259 :
260 : /*
261 : * Use these to test whether a particular lock is applied to a tuple
262 : */
263 : #define HEAP_XMAX_IS_SHR_LOCKED(infomask) \
264 : (((infomask) & HEAP_LOCK_MASK) == HEAP_XMAX_SHR_LOCK)
265 : #define HEAP_XMAX_IS_EXCL_LOCKED(infomask) \
266 : (((infomask) & HEAP_LOCK_MASK) == HEAP_XMAX_EXCL_LOCK)
267 : #define HEAP_XMAX_IS_KEYSHR_LOCKED(infomask) \
268 : (((infomask) & HEAP_LOCK_MASK) == HEAP_XMAX_KEYSHR_LOCK)
269 :
270 : /* turn these all off when Xmax is to change */
271 : #define HEAP_XMAX_BITS (HEAP_XMAX_COMMITTED | HEAP_XMAX_INVALID | \
272 : HEAP_XMAX_IS_MULTI | HEAP_LOCK_MASK | HEAP_XMAX_LOCK_ONLY)
273 :
274 : /*
275 : * information stored in t_infomask2:
276 : */
277 : #define HEAP_NATTS_MASK 0x07FF /* 11 bits for number of attributes */
278 : /* bits 0x1800 are available */
279 : #define HEAP_KEYS_UPDATED 0x2000 /* tuple was updated and key cols
280 : * modified, or tuple deleted */
281 : #define HEAP_HOT_UPDATED 0x4000 /* tuple was HOT-updated */
282 : #define HEAP_ONLY_TUPLE 0x8000 /* this is heap-only tuple */
283 :
284 : #define HEAP2_XACT_MASK 0xE000 /* visibility-related bits */
285 :
286 : /*
287 : * HEAP_TUPLE_HAS_MATCH is a temporary flag used during hash joins. It is
288 : * only used in tuples that are in the hash table, and those don't need
289 : * any visibility information, so we can overlay it on a visibility flag
290 : * instead of using up a dedicated bit.
291 : */
292 : #define HEAP_TUPLE_HAS_MATCH HEAP_ONLY_TUPLE /* tuple has a join match */
293 :
294 : /*
295 : * HeapTupleHeader accessor macros
296 : *
297 : * Note: beware of multiple evaluations of "tup" argument. But the Set
298 : * macros evaluate their other argument only once.
299 : */
300 :
301 : /*
302 : * HeapTupleHeaderGetRawXmin returns the "raw" xmin field, which is the xid
303 : * originally used to insert the tuple. However, the tuple might actually
304 : * be frozen (via HeapTupleHeaderSetXminFrozen) in which case the tuple's xmin
305 : * is visible to every snapshot. Prior to PostgreSQL 9.4, we actually changed
306 : * the xmin to FrozenTransactionId, and that value may still be encountered
307 : * on disk.
308 : */
309 : #define HeapTupleHeaderGetRawXmin(tup) \
310 : ( \
311 : (tup)->t_choice.t_heap.t_xmin \
312 : )
313 :
314 : #define HeapTupleHeaderGetXmin(tup) \
315 : ( \
316 : HeapTupleHeaderXminFrozen(tup) ? \
317 : FrozenTransactionId : HeapTupleHeaderGetRawXmin(tup) \
318 : )
319 :
320 : #define HeapTupleHeaderSetXmin(tup, xid) \
321 : ( \
322 : (tup)->t_choice.t_heap.t_xmin = (xid) \
323 : )
324 :
325 : #define HeapTupleHeaderXminCommitted(tup) \
326 : ( \
327 : ((tup)->t_infomask & HEAP_XMIN_COMMITTED) != 0 \
328 : )
329 :
330 : #define HeapTupleHeaderXminInvalid(tup) \
331 : ( \
332 : ((tup)->t_infomask & (HEAP_XMIN_COMMITTED|HEAP_XMIN_INVALID)) == \
333 : HEAP_XMIN_INVALID \
334 : )
335 :
336 : #define HeapTupleHeaderXminFrozen(tup) \
337 : ( \
338 : ((tup)->t_infomask & (HEAP_XMIN_FROZEN)) == HEAP_XMIN_FROZEN \
339 : )
340 :
341 : #define HeapTupleHeaderSetXminCommitted(tup) \
342 : ( \
343 : AssertMacro(!HeapTupleHeaderXminInvalid(tup)), \
344 : ((tup)->t_infomask |= HEAP_XMIN_COMMITTED) \
345 : )
346 :
347 : #define HeapTupleHeaderSetXminInvalid(tup) \
348 : ( \
349 : AssertMacro(!HeapTupleHeaderXminCommitted(tup)), \
350 : ((tup)->t_infomask |= HEAP_XMIN_INVALID) \
351 : )
352 :
353 : #define HeapTupleHeaderSetXminFrozen(tup) \
354 : ( \
355 : AssertMacro(!HeapTupleHeaderXminInvalid(tup)), \
356 : ((tup)->t_infomask |= HEAP_XMIN_FROZEN) \
357 : )
358 :
359 : /*
360 : * HeapTupleHeaderGetRawXmax gets you the raw Xmax field. To find out the Xid
361 : * that updated a tuple, you might need to resolve the MultiXactId if certain
362 : * bits are set. HeapTupleHeaderGetUpdateXid checks those bits and takes care
363 : * to resolve the MultiXactId if necessary. This might involve multixact I/O,
364 : * so it should only be used if absolutely necessary.
365 : */
366 : #define HeapTupleHeaderGetUpdateXid(tup) \
367 : ( \
368 : (!((tup)->t_infomask & HEAP_XMAX_INVALID) && \
369 : ((tup)->t_infomask & HEAP_XMAX_IS_MULTI) && \
370 : !((tup)->t_infomask & HEAP_XMAX_LOCK_ONLY)) ? \
371 : HeapTupleGetUpdateXid(tup) \
372 : : \
373 : HeapTupleHeaderGetRawXmax(tup) \
374 : )
375 :
376 : #define HeapTupleHeaderGetRawXmax(tup) \
377 : ( \
378 : (tup)->t_choice.t_heap.t_xmax \
379 : )
380 :
381 : #define HeapTupleHeaderSetXmax(tup, xid) \
382 : ( \
383 : (tup)->t_choice.t_heap.t_xmax = (xid) \
384 : )
385 :
386 : /*
387 : * HeapTupleHeaderGetRawCommandId will give you what's in the header whether
388 : * it is useful or not. Most code should use HeapTupleHeaderGetCmin or
389 : * HeapTupleHeaderGetCmax instead, but note that those Assert that you can
390 : * get a legitimate result, ie you are in the originating transaction!
391 : */
392 : #define HeapTupleHeaderGetRawCommandId(tup) \
393 : ( \
394 : (tup)->t_choice.t_heap.t_field3.t_cid \
395 : )
396 :
397 : /* SetCmin is reasonably simple since we never need a combo CID */
398 : #define HeapTupleHeaderSetCmin(tup, cid) \
399 : do { \
400 : Assert(!((tup)->t_infomask & HEAP_MOVED)); \
401 : (tup)->t_choice.t_heap.t_field3.t_cid = (cid); \
402 : (tup)->t_infomask &= ~HEAP_COMBOCID; \
403 : } while (0)
404 :
405 : /* SetCmax must be used after HeapTupleHeaderAdjustCmax; see combocid.c */
406 : #define HeapTupleHeaderSetCmax(tup, cid, iscombo) \
407 : do { \
408 : Assert(!((tup)->t_infomask & HEAP_MOVED)); \
409 : (tup)->t_choice.t_heap.t_field3.t_cid = (cid); \
410 : if (iscombo) \
411 : (tup)->t_infomask |= HEAP_COMBOCID; \
412 : else \
413 : (tup)->t_infomask &= ~HEAP_COMBOCID; \
414 : } while (0)
415 :
416 : #define HeapTupleHeaderGetXvac(tup) \
417 : ( \
418 : ((tup)->t_infomask & HEAP_MOVED) ? \
419 : (tup)->t_choice.t_heap.t_field3.t_xvac \
420 : : \
421 : InvalidTransactionId \
422 : )
423 :
424 : #define HeapTupleHeaderSetXvac(tup, xid) \
425 : do { \
426 : Assert((tup)->t_infomask & HEAP_MOVED); \
427 : (tup)->t_choice.t_heap.t_field3.t_xvac = (xid); \
428 : } while (0)
429 :
430 : StaticAssertDecl(MaxOffsetNumber < SpecTokenOffsetNumber,
431 : "invalid speculative token constant");
432 :
433 : #define HeapTupleHeaderIsSpeculative(tup) \
434 : ( \
435 : (ItemPointerGetOffsetNumberNoCheck(&(tup)->t_ctid) == SpecTokenOffsetNumber) \
436 : )
437 :
438 : #define HeapTupleHeaderGetSpeculativeToken(tup) \
439 : ( \
440 : AssertMacro(HeapTupleHeaderIsSpeculative(tup)), \
441 : ItemPointerGetBlockNumber(&(tup)->t_ctid) \
442 : )
443 :
444 : #define HeapTupleHeaderSetSpeculativeToken(tup, token) \
445 : ( \
446 : ItemPointerSet(&(tup)->t_ctid, token, SpecTokenOffsetNumber) \
447 : )
448 :
449 : #define HeapTupleHeaderIndicatesMovedPartitions(tup) \
450 : ItemPointerIndicatesMovedPartitions(&(tup)->t_ctid)
451 :
452 : #define HeapTupleHeaderSetMovedPartitions(tup) \
453 : ItemPointerSetMovedPartitions(&(tup)->t_ctid)
454 :
455 : #define HeapTupleHeaderGetDatumLength(tup) \
456 : VARSIZE(tup)
457 :
458 : #define HeapTupleHeaderSetDatumLength(tup, len) \
459 : SET_VARSIZE(tup, len)
460 :
461 : #define HeapTupleHeaderGetTypeId(tup) \
462 : ( \
463 : (tup)->t_choice.t_datum.datum_typeid \
464 : )
465 :
466 : #define HeapTupleHeaderSetTypeId(tup, typeid) \
467 : ( \
468 : (tup)->t_choice.t_datum.datum_typeid = (typeid) \
469 : )
470 :
471 : #define HeapTupleHeaderGetTypMod(tup) \
472 : ( \
473 : (tup)->t_choice.t_datum.datum_typmod \
474 : )
475 :
476 : #define HeapTupleHeaderSetTypMod(tup, typmod) \
477 : ( \
478 : (tup)->t_choice.t_datum.datum_typmod = (typmod) \
479 : )
480 :
481 : /*
482 : * Note that we stop considering a tuple HOT-updated as soon as it is known
483 : * aborted or the would-be updating transaction is known aborted. For best
484 : * efficiency, check tuple visibility before using this macro, so that the
485 : * INVALID bits will be as up to date as possible.
486 : */
487 : #define HeapTupleHeaderIsHotUpdated(tup) \
488 : ( \
489 : ((tup)->t_infomask2 & HEAP_HOT_UPDATED) != 0 && \
490 : ((tup)->t_infomask & HEAP_XMAX_INVALID) == 0 && \
491 : !HeapTupleHeaderXminInvalid(tup) \
492 : )
493 :
494 : #define HeapTupleHeaderSetHotUpdated(tup) \
495 : ( \
496 : (tup)->t_infomask2 |= HEAP_HOT_UPDATED \
497 : )
498 :
499 : #define HeapTupleHeaderClearHotUpdated(tup) \
500 : ( \
501 : (tup)->t_infomask2 &= ~HEAP_HOT_UPDATED \
502 : )
503 :
504 : #define HeapTupleHeaderIsHeapOnly(tup) \
505 : ( \
506 : ((tup)->t_infomask2 & HEAP_ONLY_TUPLE) != 0 \
507 : )
508 :
509 : #define HeapTupleHeaderSetHeapOnly(tup) \
510 : ( \
511 : (tup)->t_infomask2 |= HEAP_ONLY_TUPLE \
512 : )
513 :
514 : #define HeapTupleHeaderClearHeapOnly(tup) \
515 : ( \
516 : (tup)->t_infomask2 &= ~HEAP_ONLY_TUPLE \
517 : )
518 :
519 : #define HeapTupleHeaderHasMatch(tup) \
520 : ( \
521 : ((tup)->t_infomask2 & HEAP_TUPLE_HAS_MATCH) != 0 \
522 : )
523 :
524 : #define HeapTupleHeaderSetMatch(tup) \
525 : ( \
526 : (tup)->t_infomask2 |= HEAP_TUPLE_HAS_MATCH \
527 : )
528 :
529 : #define HeapTupleHeaderClearMatch(tup) \
530 : ( \
531 : (tup)->t_infomask2 &= ~HEAP_TUPLE_HAS_MATCH \
532 : )
533 :
534 : #define HeapTupleHeaderGetNatts(tup) \
535 : ((tup)->t_infomask2 & HEAP_NATTS_MASK)
536 :
537 : #define HeapTupleHeaderSetNatts(tup, natts) \
538 : ( \
539 : (tup)->t_infomask2 = ((tup)->t_infomask2 & ~HEAP_NATTS_MASK) | (natts) \
540 : )
541 :
542 : #define HeapTupleHeaderHasExternal(tup) \
543 : (((tup)->t_infomask & HEAP_HASEXTERNAL) != 0)
544 :
545 :
546 : /*
547 : * BITMAPLEN(NATTS) -
548 : * Computes size of null bitmap given number of data columns.
549 : */
550 : #define BITMAPLEN(NATTS) (((int)(NATTS) + 7) / 8)
551 :
552 : /*
553 : * MaxHeapTupleSize is the maximum allowed size of a heap tuple, including
554 : * header and MAXALIGN alignment padding. Basically it's BLCKSZ minus the
555 : * other stuff that has to be on a disk page. Since heap pages use no
556 : * "special space", there's no deduction for that.
557 : *
558 : * NOTE: we allow for the ItemId that must point to the tuple, ensuring that
559 : * an otherwise-empty page can indeed hold a tuple of this size. Because
560 : * ItemIds and tuples have different alignment requirements, don't assume that
561 : * you can, say, fit 2 tuples of size MaxHeapTupleSize/2 on the same page.
562 : */
563 : #define MaxHeapTupleSize (BLCKSZ - MAXALIGN(SizeOfPageHeaderData + sizeof(ItemIdData)))
564 : #define MinHeapTupleSize MAXALIGN(SizeofHeapTupleHeader)
565 :
566 : /*
567 : * MaxHeapTuplesPerPage is an upper bound on the number of tuples that can
568 : * fit on one heap page. (Note that indexes could have more, because they
569 : * use a smaller tuple header.) We arrive at the divisor because each tuple
570 : * must be maxaligned, and it must have an associated line pointer.
571 : *
572 : * Note: with HOT, there could theoretically be more line pointers (not actual
573 : * tuples) than this on a heap page. However we constrain the number of line
574 : * pointers to this anyway, to avoid excessive line-pointer bloat and not
575 : * require increases in the size of work arrays.
576 : */
577 : #define MaxHeapTuplesPerPage \
578 : ((int) ((BLCKSZ - SizeOfPageHeaderData) / \
579 : (MAXALIGN(SizeofHeapTupleHeader) + sizeof(ItemIdData))))
580 :
581 : /*
582 : * MaxAttrSize is a somewhat arbitrary upper limit on the declared size of
583 : * data fields of char(n) and similar types. It need not have anything
584 : * directly to do with the *actual* upper limit of varlena values, which
585 : * is currently 1Gb (see TOAST structures in postgres.h). I've set it
586 : * at 10Mb which seems like a reasonable number --- tgl 8/6/00.
587 : */
588 : #define MaxAttrSize (10 * 1024 * 1024)
589 :
590 :
591 : /*
592 : * MinimalTuple is an alternative representation that is used for transient
593 : * tuples inside the executor, in places where transaction status information
594 : * is not required, the tuple rowtype is known, and shaving off a few bytes
595 : * is worthwhile because we need to store many tuples. The representation
596 : * is chosen so that tuple access routines can work with either full or
597 : * minimal tuples via a HeapTupleData pointer structure. The access routines
598 : * see no difference, except that they must not access the transaction status
599 : * or t_ctid fields because those aren't there.
600 : *
601 : * For the most part, MinimalTuples should be accessed via TupleTableSlot
602 : * routines. These routines will prevent access to the "system columns"
603 : * and thereby prevent accidental use of the nonexistent fields.
604 : *
605 : * MinimalTupleData contains a length word, some padding, and fields matching
606 : * HeapTupleHeaderData beginning with t_infomask2. The padding is chosen so
607 : * that offsetof(t_infomask2) is the same modulo MAXIMUM_ALIGNOF in both
608 : * structs. This makes data alignment rules equivalent in both cases.
609 : *
610 : * When a minimal tuple is accessed via a HeapTupleData pointer, t_data is
611 : * set to point MINIMAL_TUPLE_OFFSET bytes before the actual start of the
612 : * minimal tuple --- that is, where a full tuple matching the minimal tuple's
613 : * data would start. This trick is what makes the structs seem equivalent.
614 : *
615 : * Note that t_hoff is computed the same as in a full tuple, hence it includes
616 : * the MINIMAL_TUPLE_OFFSET distance. t_len does not include that, however.
617 : *
618 : * MINIMAL_TUPLE_DATA_OFFSET is the offset to the first useful (non-pad) data
619 : * other than the length word. tuplesort.c and tuplestore.c use this to avoid
620 : * writing the padding to disk.
621 : */
622 : #define MINIMAL_TUPLE_OFFSET \
623 : ((offsetof(HeapTupleHeaderData, t_infomask2) - sizeof(uint32)) / MAXIMUM_ALIGNOF * MAXIMUM_ALIGNOF)
624 : #define MINIMAL_TUPLE_PADDING \
625 : ((offsetof(HeapTupleHeaderData, t_infomask2) - sizeof(uint32)) % MAXIMUM_ALIGNOF)
626 : #define MINIMAL_TUPLE_DATA_OFFSET \
627 : offsetof(MinimalTupleData, t_infomask2)
628 :
629 : struct MinimalTupleData
630 : {
631 : uint32 t_len; /* actual length of minimal tuple */
632 :
633 : char mt_padding[MINIMAL_TUPLE_PADDING];
634 :
635 : /* Fields below here must match HeapTupleHeaderData! */
636 :
637 : uint16 t_infomask2; /* number of attributes + various flags */
638 :
639 : uint16 t_infomask; /* various flag bits, see below */
640 :
641 : uint8 t_hoff; /* sizeof header incl. bitmap, padding */
642 :
643 : /* ^ - 23 bytes - ^ */
644 :
645 : bits8 t_bits[FLEXIBLE_ARRAY_MEMBER]; /* bitmap of NULLs */
646 :
647 : /* MORE DATA FOLLOWS AT END OF STRUCT */
648 : };
649 :
650 : /* typedef appears in htup.h */
651 :
652 : #define SizeofMinimalTupleHeader offsetof(MinimalTupleData, t_bits)
653 :
654 :
655 : /*
656 : * GETSTRUCT - given a HeapTuple pointer, return address of the user data
657 : */
658 : #define GETSTRUCT(TUP) ((char *) ((TUP)->t_data) + (TUP)->t_data->t_hoff)
659 :
660 : /*
661 : * Accessor macros to be used with HeapTuple pointers.
662 : */
663 :
664 : #define HeapTupleHasNulls(tuple) \
665 : (((tuple)->t_data->t_infomask & HEAP_HASNULL) != 0)
666 :
667 : #define HeapTupleNoNulls(tuple) \
668 : (!((tuple)->t_data->t_infomask & HEAP_HASNULL))
669 :
670 : #define HeapTupleHasVarWidth(tuple) \
671 : (((tuple)->t_data->t_infomask & HEAP_HASVARWIDTH) != 0)
672 :
673 : #define HeapTupleAllFixed(tuple) \
674 : (!((tuple)->t_data->t_infomask & HEAP_HASVARWIDTH))
675 :
676 : #define HeapTupleHasExternal(tuple) \
677 : (((tuple)->t_data->t_infomask & HEAP_HASEXTERNAL) != 0)
678 :
679 : #define HeapTupleIsHotUpdated(tuple) \
680 : HeapTupleHeaderIsHotUpdated((tuple)->t_data)
681 :
682 : #define HeapTupleSetHotUpdated(tuple) \
683 : HeapTupleHeaderSetHotUpdated((tuple)->t_data)
684 :
685 : #define HeapTupleClearHotUpdated(tuple) \
686 : HeapTupleHeaderClearHotUpdated((tuple)->t_data)
687 :
688 : #define HeapTupleIsHeapOnly(tuple) \
689 : HeapTupleHeaderIsHeapOnly((tuple)->t_data)
690 :
691 : #define HeapTupleSetHeapOnly(tuple) \
692 : HeapTupleHeaderSetHeapOnly((tuple)->t_data)
693 :
694 : #define HeapTupleClearHeapOnly(tuple) \
695 : HeapTupleHeaderClearHeapOnly((tuple)->t_data)
696 :
697 : /* prototypes for functions in common/heaptuple.c */
698 : extern Size heap_compute_data_size(TupleDesc tupleDesc,
699 : Datum *values, bool *isnull);
700 : extern void heap_fill_tuple(TupleDesc tupleDesc,
701 : Datum *values, bool *isnull,
702 : char *data, Size data_size,
703 : uint16 *infomask, bits8 *bit);
704 : extern bool heap_attisnull(HeapTuple tup, int attnum, TupleDesc tupleDesc);
705 : extern Datum nocachegetattr(HeapTuple tup, int attnum,
706 : TupleDesc tupleDesc);
707 : extern Datum heap_getsysattr(HeapTuple tup, int attnum, TupleDesc tupleDesc,
708 : bool *isnull);
709 : extern Datum getmissingattr(TupleDesc tupleDesc,
710 : int attnum, bool *isnull);
711 : extern HeapTuple heap_copytuple(HeapTuple tuple);
712 : extern void heap_copytuple_with_tuple(HeapTuple src, HeapTuple dest);
713 : extern Datum heap_copy_tuple_as_datum(HeapTuple tuple, TupleDesc tupleDesc);
714 : extern HeapTuple heap_form_tuple(TupleDesc tupleDescriptor,
715 : Datum *values, bool *isnull);
716 : extern HeapTuple heap_modify_tuple(HeapTuple tuple,
717 : TupleDesc tupleDesc,
718 : Datum *replValues,
719 : bool *replIsnull,
720 : bool *doReplace);
721 : extern HeapTuple heap_modify_tuple_by_cols(HeapTuple tuple,
722 : TupleDesc tupleDesc,
723 : int nCols,
724 : int *replCols,
725 : Datum *replValues,
726 : bool *replIsnull);
727 : extern void heap_deform_tuple(HeapTuple tuple, TupleDesc tupleDesc,
728 : Datum *values, bool *isnull);
729 : extern void heap_freetuple(HeapTuple htup);
730 : extern MinimalTuple heap_form_minimal_tuple(TupleDesc tupleDescriptor,
731 : Datum *values, bool *isnull);
732 : extern void heap_free_minimal_tuple(MinimalTuple mtup);
733 : extern MinimalTuple heap_copy_minimal_tuple(MinimalTuple mtup);
734 : extern HeapTuple heap_tuple_from_minimal_tuple(MinimalTuple mtup);
735 : extern MinimalTuple minimal_tuple_from_heap_tuple(HeapTuple htup);
736 : extern size_t varsize_any(void *p);
737 : extern HeapTuple heap_expand_tuple(HeapTuple sourceTuple, TupleDesc tupleDesc);
738 : extern MinimalTuple minimal_expand_tuple(HeapTuple sourceTuple, TupleDesc tupleDesc);
739 :
740 : #ifndef FRONTEND
741 : /*
742 : * fastgetattr
743 : * Fetch a user attribute's value as a Datum (might be either a
744 : * value, or a pointer into the data area of the tuple).
745 : *
746 : * This must not be used when a system attribute might be requested.
747 : * Furthermore, the passed attnum MUST be valid. Use heap_getattr()
748 : * instead, if in doubt.
749 : *
750 : * This gets called many times, so we macro the cacheable and NULL
751 : * lookups, and call nocachegetattr() for the rest.
752 : */
753 : static inline Datum
381 alvherre 754 GIC 323349305 : fastgetattr(HeapTuple tup, int attnum, TupleDesc tupleDesc, bool *isnull)
755 : {
368 peter 756 323349305 : Assert(attnum > 0);
757 :
381 alvherre 758 CBC 323349305 : *isnull = false;
381 alvherre 759 GIC 323349305 : if (HeapTupleNoNulls(tup))
381 alvherre 760 ECB : {
761 : Form_pg_attribute att;
762 :
381 alvherre 763 CBC 70908228 : att = TupleDescAttr(tupleDesc, attnum - 1);
381 alvherre 764 GIC 70908228 : if (att->attcacheoff >= 0)
765 54233012 : return fetchatt(att, (char *) tup->t_data + tup->t_data->t_hoff +
766 : att->attcacheoff);
381 alvherre 767 ECB : else
381 alvherre 768 CBC 16675216 : return nocachegetattr(tup, attnum, tupleDesc);
381 alvherre 769 ECB : }
770 : else
771 : {
381 alvherre 772 CBC 252441077 : if (att_isnull(attnum - 1, tup->t_data->t_bits))
773 : {
381 alvherre 774 GIC 27407451 : *isnull = true;
775 27407451 : return (Datum) NULL;
381 alvherre 776 ECB : }
777 : else
381 alvherre 778 CBC 225033626 : return nocachegetattr(tup, attnum, tupleDesc);
381 alvherre 779 ECB : }
780 : }
781 :
782 : /*
783 : * heap_getattr
784 : * Extract an attribute of a heap tuple and return it as a Datum.
785 : * This works for either system or user attributes. The given attnum
786 : * is properly range-checked.
787 : *
788 : * If the field in question has a NULL value, we return a zero Datum
789 : * and set *isnull == true. Otherwise, we set *isnull == false.
790 : *
791 : * <tup> is the pointer to the heap tuple. <attnum> is the attribute
792 : * number of the column (field) caller wants. <tupleDesc> is a
793 : * pointer to the structure describing the row and all its fields.
794 : *
795 : */
796 : static inline Datum
381 alvherre 797 GIC 309374357 : heap_getattr(HeapTuple tup, int attnum, TupleDesc tupleDesc, bool *isnull)
798 : {
799 309374357 : if (attnum > 0)
800 : {
381 alvherre 801 CBC 309374357 : if (attnum > (int) HeapTupleHeaderGetNatts(tup->t_data))
381 alvherre 802 GIC 166 : return getmissingattr(tupleDesc, attnum, isnull);
381 alvherre 803 ECB : else
381 alvherre 804 GIC 309374191 : return fastgetattr(tup, attnum, tupleDesc, isnull);
381 alvherre 805 ECB : }
806 : else
381 alvherre 807 UIC 0 : return heap_getsysattr(tup, attnum, tupleDesc, isnull);
381 alvherre 808 ECB : }
809 : #endif /* FRONTEND */
810 :
2118 tgl 811 EUB : #endif /* HTUP_DETAILS_H */
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