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1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * htup_details.h
4 : : * POSTGRES heap tuple header definitions.
5 : : *
6 : : *
7 : : * Portions Copyright (c) 1996-2024, 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 : : const Datum *values, const bool *isnull);
700 : : extern void heap_fill_tuple(TupleDesc tupleDesc,
701 : : const Datum *values, const 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 : : const Datum *values, const bool *isnull);
716 : : extern HeapTuple heap_modify_tuple(HeapTuple tuple,
717 : : TupleDesc tupleDesc,
718 : : const Datum *replValues,
719 : : const bool *replIsnull,
720 : : const bool *doReplace);
721 : : extern HeapTuple heap_modify_tuple_by_cols(HeapTuple tuple,
722 : : TupleDesc tupleDesc,
723 : : int nCols,
724 : : const int *replCols,
725 : : const Datum *replValues,
726 : : const 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 : : const Datum *values, const 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
752 alvherre@alvh.no-ip. 754 :CBC 126699860 : fastgetattr(HeapTuple tup, int attnum, TupleDesc tupleDesc, bool *isnull)
755 : : {
739 peter@eisentraut.org 756 [ - + ]: 126699860 : Assert(attnum > 0);
757 : :
752 alvherre@alvh.no-ip. 758 : 126699860 : *isnull = false;
759 [ + + ]: 126699860 : if (HeapTupleNoNulls(tup))
760 : : {
761 : : Form_pg_attribute att;
762 : :
763 : 55199875 : att = TupleDescAttr(tupleDesc, attnum - 1);
764 [ + + ]: 55199875 : if (att->attcacheoff >= 0)
765 : 33844234 : return fetchatt(att, (char *) tup->t_data + tup->t_data->t_hoff +
766 : : att->attcacheoff);
767 : : else
768 : 21355641 : return nocachegetattr(tup, attnum, tupleDesc);
769 : : }
770 : : else
771 : : {
772 [ + + ]: 71499985 : if (att_isnull(attnum - 1, tup->t_data->t_bits))
773 : : {
774 : 8392627 : *isnull = true;
775 : 8392627 : return (Datum) NULL;
776 : : }
777 : : else
778 : 63107358 : return nocachegetattr(tup, attnum, tupleDesc);
779 : : }
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
797 : 118643842 : heap_getattr(HeapTuple tup, int attnum, TupleDesc tupleDesc, bool *isnull)
798 : : {
799 [ + - ]: 118643842 : if (attnum > 0)
800 : : {
801 [ + + ]: 118643842 : if (attnum > (int) HeapTupleHeaderGetNatts(tup->t_data))
802 : 166 : return getmissingattr(tupleDesc, attnum, isnull);
803 : : else
804 : 118643676 : return fastgetattr(tup, attnum, tupleDesc, isnull);
805 : : }
806 : : else
752 alvherre@alvh.no-ip. 807 :UBC 0 : return heap_getsysattr(tup, attnum, tupleDesc, isnull);
808 : : }
809 : : #endif /* FRONTEND */
810 : :
811 : : #endif /* HTUP_DETAILS_H */
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