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1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * rewriteheap.c
4 : : * Support functions to rewrite tables.
5 : : *
6 : : * These functions provide a facility to completely rewrite a heap, while
7 : : * preserving visibility information and update chains.
8 : : *
9 : : * INTERFACE
10 : : *
11 : : * The caller is responsible for creating the new heap, all catalog
12 : : * changes, supplying the tuples to be written to the new heap, and
13 : : * rebuilding indexes. The caller must hold AccessExclusiveLock on the
14 : : * target table, because we assume no one else is writing into it.
15 : : *
16 : : * To use the facility:
17 : : *
18 : : * begin_heap_rewrite
19 : : * while (fetch next tuple)
20 : : * {
21 : : * if (tuple is dead)
22 : : * rewrite_heap_dead_tuple
23 : : * else
24 : : * {
25 : : * // do any transformations here if required
26 : : * rewrite_heap_tuple
27 : : * }
28 : : * }
29 : : * end_heap_rewrite
30 : : *
31 : : * The contents of the new relation shouldn't be relied on until after
32 : : * end_heap_rewrite is called.
33 : : *
34 : : *
35 : : * IMPLEMENTATION
36 : : *
37 : : * This would be a fairly trivial affair, except that we need to maintain
38 : : * the ctid chains that link versions of an updated tuple together.
39 : : * Since the newly stored tuples will have tids different from the original
40 : : * ones, if we just copied t_ctid fields to the new table the links would
41 : : * be wrong. When we are required to copy a (presumably recently-dead or
42 : : * delete-in-progress) tuple whose ctid doesn't point to itself, we have
43 : : * to substitute the correct ctid instead.
44 : : *
45 : : * For each ctid reference from A -> B, we might encounter either A first
46 : : * or B first. (Note that a tuple in the middle of a chain is both A and B
47 : : * of different pairs.)
48 : : *
49 : : * If we encounter A first, we'll store the tuple in the unresolved_tups
50 : : * hash table. When we later encounter B, we remove A from the hash table,
51 : : * fix the ctid to point to the new location of B, and insert both A and B
52 : : * to the new heap.
53 : : *
54 : : * If we encounter B first, we can insert B to the new heap right away.
55 : : * We then add an entry to the old_new_tid_map hash table showing B's
56 : : * original tid (in the old heap) and new tid (in the new heap).
57 : : * When we later encounter A, we get the new location of B from the table,
58 : : * and can write A immediately with the correct ctid.
59 : : *
60 : : * Entries in the hash tables can be removed as soon as the later tuple
61 : : * is encountered. That helps to keep the memory usage down. At the end,
62 : : * both tables are usually empty; we should have encountered both A and B
63 : : * of each pair. However, it's possible for A to be RECENTLY_DEAD and B
64 : : * entirely DEAD according to HeapTupleSatisfiesVacuum, because the test
65 : : * for deadness using OldestXmin is not exact. In such a case we might
66 : : * encounter B first, and skip it, and find A later. Then A would be added
67 : : * to unresolved_tups, and stay there until end of the rewrite. Since
68 : : * this case is very unusual, we don't worry about the memory usage.
69 : : *
70 : : * Using in-memory hash tables means that we use some memory for each live
71 : : * update chain in the table, from the time we find one end of the
72 : : * reference until we find the other end. That shouldn't be a problem in
73 : : * practice, but if you do something like an UPDATE without a where-clause
74 : : * on a large table, and then run CLUSTER in the same transaction, you
75 : : * could run out of memory. It doesn't seem worthwhile to add support for
76 : : * spill-to-disk, as there shouldn't be that many RECENTLY_DEAD tuples in a
77 : : * table under normal circumstances. Furthermore, in the typical scenario
78 : : * of CLUSTERing on an unchanging key column, we'll see all the versions
79 : : * of a given tuple together anyway, and so the peak memory usage is only
80 : : * proportional to the number of RECENTLY_DEAD versions of a single row, not
81 : : * in the whole table. Note that if we do fail halfway through a CLUSTER,
82 : : * the old table is still valid, so failure is not catastrophic.
83 : : *
84 : : * We can't use the normal heap_insert function to insert into the new
85 : : * heap, because heap_insert overwrites the visibility information.
86 : : * We use a special-purpose raw_heap_insert function instead, which
87 : : * is optimized for bulk inserting a lot of tuples, knowing that we have
88 : : * exclusive access to the heap. raw_heap_insert builds new pages in
89 : : * local storage. When a page is full, or at the end of the process,
90 : : * we insert it to WAL as a single record and then write it to disk with
91 : : * the bulk smgr writer. Note, however, that any data sent to the new
92 : : * heap's TOAST table will go through the normal bufmgr.
93 : : *
94 : : *
95 : : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
96 : : * Portions Copyright (c) 1994-5, Regents of the University of California
97 : : *
98 : : * IDENTIFICATION
99 : : * src/backend/access/heap/rewriteheap.c
100 : : *
101 : : *-------------------------------------------------------------------------
102 : : */
103 : : #include "postgres.h"
104 : :
105 : : #include <unistd.h>
106 : :
107 : : #include "access/heapam.h"
108 : : #include "access/heapam_xlog.h"
109 : : #include "access/heaptoast.h"
110 : : #include "access/rewriteheap.h"
111 : : #include "access/transam.h"
112 : : #include "access/xact.h"
113 : : #include "access/xloginsert.h"
114 : : #include "common/file_utils.h"
115 : : #include "lib/ilist.h"
116 : : #include "miscadmin.h"
117 : : #include "pgstat.h"
118 : : #include "replication/slot.h"
119 : : #include "storage/bufmgr.h"
120 : : #include "storage/bulk_write.h"
121 : : #include "storage/fd.h"
122 : : #include "storage/procarray.h"
123 : : #include "utils/memutils.h"
124 : : #include "utils/rel.h"
125 : : #include "utils/wait_event.h"
126 : :
127 : : /*
128 : : * State associated with a rewrite operation. This is opaque to the user
129 : : * of the rewrite facility.
130 : : */
131 : : typedef struct RewriteStateData
132 : : {
133 : : Relation rs_old_rel; /* source heap */
134 : : Relation rs_new_rel; /* destination heap */
135 : : BulkWriteState *rs_bulkstate; /* writer for the destination */
136 : : BulkWriteBuffer rs_buffer; /* page currently being built */
137 : : BlockNumber rs_blockno; /* block where page will go */
138 : : bool rs_logical_rewrite; /* do we need to do logical rewriting */
139 : : TransactionId rs_oldest_xmin; /* oldest xmin used by caller to determine
140 : : * tuple visibility */
141 : : TransactionId rs_freeze_xid; /* Xid that will be used as freeze cutoff
142 : : * point */
143 : : TransactionId rs_logical_xmin; /* Xid that will be used as cutoff point
144 : : * for logical rewrites */
145 : : MultiXactId rs_cutoff_multi; /* MultiXactId that will be used as cutoff
146 : : * point for multixacts */
147 : : MemoryContext rs_cxt; /* for hash tables and entries and tuples in
148 : : * them */
149 : : XLogRecPtr rs_begin_lsn; /* XLogInsertLsn when starting the rewrite */
150 : : HTAB *rs_unresolved_tups; /* unmatched A tuples */
151 : : HTAB *rs_old_new_tid_map; /* unmatched B tuples */
152 : : HTAB *rs_logical_mappings; /* logical remapping files */
153 : : uint32 rs_num_rewrite_mappings; /* # in memory mappings */
154 : : } RewriteStateData;
155 : :
156 : : /*
157 : : * The lookup keys for the hash tables are tuple TID and xmin (we must check
158 : : * both to avoid false matches from dead tuples). Beware that there is
159 : : * probably some padding space in this struct; it must be zeroed out for
160 : : * correct hashtable operation.
161 : : */
162 : : typedef struct
163 : : {
164 : : TransactionId xmin; /* tuple xmin */
165 : : ItemPointerData tid; /* tuple location in old heap */
166 : : } TidHashKey;
167 : :
168 : : /*
169 : : * Entry structures for the hash tables
170 : : */
171 : : typedef struct
172 : : {
173 : : TidHashKey key; /* expected xmin/old location of B tuple */
174 : : ItemPointerData old_tid; /* A's location in the old heap */
175 : : HeapTuple tuple; /* A's tuple contents */
176 : : } UnresolvedTupData;
177 : :
178 : : typedef UnresolvedTupData *UnresolvedTup;
179 : :
180 : : typedef struct
181 : : {
182 : : TidHashKey key; /* actual xmin/old location of B tuple */
183 : : ItemPointerData new_tid; /* where we put it in the new heap */
184 : : } OldToNewMappingData;
185 : :
186 : : typedef OldToNewMappingData *OldToNewMapping;
187 : :
188 : : /*
189 : : * In-Memory data for an xid that might need logical remapping entries
190 : : * to be logged.
191 : : */
192 : : typedef struct RewriteMappingFile
193 : : {
194 : : TransactionId xid; /* xid that might need to see the row */
195 : : int vfd; /* fd of mappings file */
196 : : off_t off; /* how far have we written yet */
197 : : dclist_head mappings; /* list of in-memory mappings */
198 : : char path[MAXPGPATH]; /* path, for error messages */
199 : : } RewriteMappingFile;
200 : :
201 : : /*
202 : : * A single In-Memory logical rewrite mapping, hanging off
203 : : * RewriteMappingFile->mappings.
204 : : */
205 : : typedef struct RewriteMappingDataEntry
206 : : {
207 : : LogicalRewriteMappingData map; /* map between old and new location of the
208 : : * tuple */
209 : : dlist_node node;
210 : : } RewriteMappingDataEntry;
211 : :
212 : :
213 : : /* prototypes for internal functions */
214 : : static void raw_heap_insert(RewriteState state, HeapTuple tup);
215 : :
216 : : /* internal logical remapping prototypes */
217 : : static void logical_begin_heap_rewrite(RewriteState state);
218 : : static void logical_rewrite_heap_tuple(RewriteState state, ItemPointerData old_tid, HeapTuple new_tuple);
219 : : static void logical_end_heap_rewrite(RewriteState state);
220 : :
221 : :
222 : : /*
223 : : * Begin a rewrite of a table
224 : : *
225 : : * old_heap old, locked heap relation tuples will be read from
226 : : * new_heap new, locked heap relation to insert tuples to
227 : : * oldest_xmin xid used by the caller to determine which tuples are dead
228 : : * freeze_xid xid before which tuples will be frozen
229 : : * cutoff_multi multixact before which multis will be removed
230 : : *
231 : : * Returns an opaque RewriteState, allocated in current memory context,
232 : : * to be used in subsequent calls to the other functions.
233 : : */
234 : : RewriteState
235 : 399 : begin_heap_rewrite(Relation old_heap, Relation new_heap, TransactionId oldest_xmin,
236 : : TransactionId freeze_xid, MultiXactId cutoff_multi)
237 : : {
238 : : RewriteState state;
239 : : MemoryContext rw_cxt;
240 : : MemoryContext old_cxt;
241 : : HASHCTL hash_ctl;
242 : :
243 : : /*
244 : : * To ease cleanup, make a separate context that will contain the
245 : : * RewriteState struct itself plus all subsidiary data.
246 : : */
247 : 399 : rw_cxt = AllocSetContextCreate(CurrentMemoryContext,
248 : : "Table rewrite",
249 : : ALLOCSET_DEFAULT_SIZES);
250 : 399 : old_cxt = MemoryContextSwitchTo(rw_cxt);
251 : :
252 : : /* Create and fill in the state struct */
253 : 399 : state = palloc0_object(RewriteStateData);
254 : :
255 : 399 : state->rs_old_rel = old_heap;
256 : 399 : state->rs_new_rel = new_heap;
257 : 399 : state->rs_buffer = NULL;
258 : : /* new_heap needn't be empty, just locked */
259 : 399 : state->rs_blockno = RelationGetNumberOfBlocks(new_heap);
260 : 399 : state->rs_oldest_xmin = oldest_xmin;
261 : 399 : state->rs_freeze_xid = freeze_xid;
262 : 399 : state->rs_cutoff_multi = cutoff_multi;
263 : 399 : state->rs_cxt = rw_cxt;
264 : 399 : state->rs_bulkstate = smgr_bulk_start_rel(new_heap, MAIN_FORKNUM);
265 : :
266 : : /* Initialize hash tables used to track update chains */
267 : 399 : hash_ctl.keysize = sizeof(TidHashKey);
268 : 399 : hash_ctl.entrysize = sizeof(UnresolvedTupData);
269 : 399 : hash_ctl.hcxt = state->rs_cxt;
270 : :
271 : 399 : state->rs_unresolved_tups =
272 : 399 : hash_create("Rewrite / Unresolved ctids",
273 : : 128, /* arbitrary initial size */
274 : : &hash_ctl,
275 : : HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
276 : :
277 : 399 : hash_ctl.entrysize = sizeof(OldToNewMappingData);
278 : :
279 : 399 : state->rs_old_new_tid_map =
280 : 399 : hash_create("Rewrite / Old to new tid map",
281 : : 128, /* arbitrary initial size */
282 : : &hash_ctl,
283 : : HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
284 : :
285 : 399 : MemoryContextSwitchTo(old_cxt);
286 : :
287 : 399 : logical_begin_heap_rewrite(state);
288 : :
289 : 399 : return state;
290 : : }
291 : :
292 : : /*
293 : : * End a rewrite.
294 : : *
295 : : * state and any other resources are freed.
296 : : */
297 : : void
298 : 399 : end_heap_rewrite(RewriteState state)
299 : : {
300 : : HASH_SEQ_STATUS seq_status;
301 : : UnresolvedTup unresolved;
302 : :
303 : : /*
304 : : * Write any remaining tuples in the UnresolvedTups table. If we have any
305 : : * left, they should in fact be dead, but let's err on the safe side.
306 : : */
307 : 399 : hash_seq_init(&seq_status, state->rs_unresolved_tups);
308 : :
309 [ - + ]: 399 : while ((unresolved = hash_seq_search(&seq_status)) != NULL)
310 : : {
311 : 0 : ItemPointerSetInvalid(&unresolved->tuple->t_data->t_ctid);
312 : 0 : raw_heap_insert(state, unresolved->tuple);
313 : : }
314 : :
315 : : /* Write the last page, if any */
316 [ + + ]: 399 : if (state->rs_buffer)
317 : : {
318 : 272 : smgr_bulk_write(state->rs_bulkstate, state->rs_blockno, state->rs_buffer, true);
319 : 272 : state->rs_buffer = NULL;
320 : : }
321 : :
322 : 399 : smgr_bulk_finish(state->rs_bulkstate);
323 : :
324 : 399 : logical_end_heap_rewrite(state);
325 : :
326 : : /* Deleting the context frees everything */
327 : 399 : MemoryContextDelete(state->rs_cxt);
328 : 399 : }
329 : :
330 : : /*
331 : : * Add a tuple to the new heap.
332 : : *
333 : : * Visibility information is copied from the original tuple, except that
334 : : * we "freeze" very-old tuples. Note that since we scribble on new_tuple,
335 : : * it had better be temp storage not a pointer to the original tuple.
336 : : *
337 : : * state opaque state as returned by begin_heap_rewrite
338 : : * old_tuple original tuple in the old heap
339 : : * new_tuple new, rewritten tuple to be inserted to new heap
340 : : */
341 : : void
342 : 470610 : rewrite_heap_tuple(RewriteState state,
343 : : HeapTuple old_tuple, HeapTuple new_tuple)
344 : : {
345 : : MemoryContext old_cxt;
346 : : ItemPointerData old_tid;
347 : : TidHashKey hashkey;
348 : : bool found;
349 : : bool free_new;
350 : :
351 : 470610 : old_cxt = MemoryContextSwitchTo(state->rs_cxt);
352 : :
353 : : /*
354 : : * Copy the original tuple's visibility information into new_tuple.
355 : : *
356 : : * XXX we might later need to copy some t_infomask2 bits, too? Right now,
357 : : * we intentionally clear the HOT status bits.
358 : : */
359 : 470610 : memcpy(&new_tuple->t_data->t_choice.t_heap,
360 : 470610 : &old_tuple->t_data->t_choice.t_heap,
361 : : sizeof(HeapTupleFields));
362 : :
363 : 470610 : new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
364 : 470610 : new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
365 : 470610 : new_tuple->t_data->t_infomask |=
366 : 470610 : old_tuple->t_data->t_infomask & HEAP_XACT_MASK;
367 : :
368 : : /*
369 : : * While we have our hands on the tuple, we may as well freeze any
370 : : * eligible xmin or xmax, so that future VACUUM effort can be saved.
371 : : */
372 : 470610 : heap_freeze_tuple(new_tuple->t_data,
373 : 470610 : state->rs_old_rel->rd_rel->relfrozenxid,
374 : 470610 : state->rs_old_rel->rd_rel->relminmxid,
375 : : state->rs_freeze_xid,
376 : : state->rs_cutoff_multi);
377 : :
378 : : /*
379 : : * Invalid ctid means that ctid should point to the tuple itself. We'll
380 : : * override it later if the tuple is part of an update chain.
381 : : */
382 : 470610 : ItemPointerSetInvalid(&new_tuple->t_data->t_ctid);
383 : :
384 : : /*
385 : : * If the tuple has been updated, check the old-to-new mapping hash table.
386 : : *
387 : : * Note that this check relies on the HeapTupleSatisfiesVacuum() in
388 : : * heapam_relation_copy_for_cluster() to have set hint bits.
389 : : */
390 [ + + + - ]: 495800 : if (!((old_tuple->t_data->t_infomask & HEAP_XMAX_INVALID) ||
391 : 25190 : HeapTupleHeaderIsOnlyLocked(old_tuple->t_data)) &&
392 [ + - ]: 25190 : !HeapTupleHeaderIndicatesMovedPartitions(old_tuple->t_data) &&
393 [ + + ]: 25190 : !(ItemPointerEquals(&(old_tuple->t_self),
394 : 25190 : &(old_tuple->t_data->t_ctid))))
395 : : {
396 : : OldToNewMapping mapping;
397 : :
398 : 438 : memset(&hashkey, 0, sizeof(hashkey));
399 : 438 : hashkey.xmin = HeapTupleHeaderGetUpdateXid(old_tuple->t_data);
400 : 438 : hashkey.tid = old_tuple->t_data->t_ctid;
401 : :
402 : : mapping = (OldToNewMapping)
403 : 438 : hash_search(state->rs_old_new_tid_map, &hashkey,
404 : : HASH_FIND, NULL);
405 : :
406 [ + + ]: 438 : if (mapping != NULL)
407 : : {
408 : : /*
409 : : * We've already copied the tuple that t_ctid points to, so we can
410 : : * set the ctid of this tuple to point to the new location, and
411 : : * insert it right away.
412 : : */
413 : 254 : new_tuple->t_data->t_ctid = mapping->new_tid;
414 : :
415 : : /* We don't need the mapping entry anymore */
416 : 254 : hash_search(state->rs_old_new_tid_map, &hashkey,
417 : : HASH_REMOVE, &found);
418 : : Assert(found);
419 : : }
420 : : else
421 : : {
422 : : /*
423 : : * We haven't seen the tuple t_ctid points to yet. Stash this
424 : : * tuple into unresolved_tups to be written later.
425 : : */
426 : : UnresolvedTup unresolved;
427 : :
428 : 184 : unresolved = hash_search(state->rs_unresolved_tups, &hashkey,
429 : : HASH_ENTER, &found);
430 : : Assert(!found);
431 : :
432 : 184 : unresolved->old_tid = old_tuple->t_self;
433 : 184 : unresolved->tuple = heap_copytuple(new_tuple);
434 : :
435 : : /*
436 : : * We can't do anything more now, since we don't know where the
437 : : * tuple will be written.
438 : : */
439 : 184 : MemoryContextSwitchTo(old_cxt);
440 : 184 : return;
441 : : }
442 : : }
443 : :
444 : : /*
445 : : * Now we will write the tuple, and then check to see if it is the B tuple
446 : : * in any new or known pair. When we resolve a known pair, we will be
447 : : * able to write that pair's A tuple, and then we have to check if it
448 : : * resolves some other pair. Hence, we need a loop here.
449 : : */
450 : 470426 : old_tid = old_tuple->t_self;
451 : 470426 : free_new = false;
452 : :
453 : : for (;;)
454 : 184 : {
455 : : ItemPointerData new_tid;
456 : :
457 : : /* Insert the tuple and find out where it's put in new_heap */
458 : 470610 : raw_heap_insert(state, new_tuple);
459 : 470610 : new_tid = new_tuple->t_self;
460 : :
461 : 470610 : logical_rewrite_heap_tuple(state, old_tid, new_tuple);
462 : :
463 : : /*
464 : : * If the tuple is the updated version of a row, and the prior version
465 : : * wouldn't be DEAD yet, then we need to either resolve the prior
466 : : * version (if it's waiting in rs_unresolved_tups), or make an entry
467 : : * in rs_old_new_tid_map (so we can resolve it when we do see it). The
468 : : * previous tuple's xmax would equal this one's xmin, so it's
469 : : * RECENTLY_DEAD if and only if the xmin is not before OldestXmin.
470 : : */
471 [ + + ]: 470610 : if ((new_tuple->t_data->t_infomask & HEAP_UPDATED) &&
472 [ + + ]: 10839 : !TransactionIdPrecedes(HeapTupleHeaderGetXmin(new_tuple->t_data),
473 : : state->rs_oldest_xmin))
474 : : {
475 : : /*
476 : : * Okay, this is B in an update pair. See if we've seen A.
477 : : */
478 : : UnresolvedTup unresolved;
479 : :
480 : 438 : memset(&hashkey, 0, sizeof(hashkey));
481 : 438 : hashkey.xmin = HeapTupleHeaderGetXmin(new_tuple->t_data);
482 : 438 : hashkey.tid = old_tid;
483 : :
484 : 438 : unresolved = hash_search(state->rs_unresolved_tups, &hashkey,
485 : : HASH_FIND, NULL);
486 : :
487 [ + + ]: 438 : if (unresolved != NULL)
488 : : {
489 : : /*
490 : : * We have seen and memorized the previous tuple already. Now
491 : : * that we know where we inserted the tuple its t_ctid points
492 : : * to, fix its t_ctid and insert it to the new heap.
493 : : */
494 [ + + ]: 184 : if (free_new)
495 : 49 : heap_freetuple(new_tuple);
496 : 184 : new_tuple = unresolved->tuple;
497 : 184 : free_new = true;
498 : 184 : old_tid = unresolved->old_tid;
499 : 184 : new_tuple->t_data->t_ctid = new_tid;
500 : :
501 : : /*
502 : : * We don't need the hash entry anymore, but don't free its
503 : : * tuple just yet.
504 : : */
505 : 184 : hash_search(state->rs_unresolved_tups, &hashkey,
506 : : HASH_REMOVE, &found);
507 : : Assert(found);
508 : :
509 : : /* loop back to insert the previous tuple in the chain */
510 : 184 : continue;
511 : : }
512 : : else
513 : : {
514 : : /*
515 : : * Remember the new tid of this tuple. We'll use it to set the
516 : : * ctid when we find the previous tuple in the chain.
517 : : */
518 : : OldToNewMapping mapping;
519 : :
520 : 254 : mapping = hash_search(state->rs_old_new_tid_map, &hashkey,
521 : : HASH_ENTER, &found);
522 : : Assert(!found);
523 : :
524 : 254 : mapping->new_tid = new_tid;
525 : : }
526 : : }
527 : :
528 : : /* Done with this (chain of) tuples, for now */
529 [ + + ]: 470426 : if (free_new)
530 : 135 : heap_freetuple(new_tuple);
531 : 470426 : break;
532 : : }
533 : :
534 : 470426 : MemoryContextSwitchTo(old_cxt);
535 : : }
536 : :
537 : : /*
538 : : * Register a dead tuple with an ongoing rewrite. Dead tuples are not
539 : : * copied to the new table, but we still make note of them so that we
540 : : * can release some resources earlier.
541 : : *
542 : : * Returns true if a tuple was removed from the unresolved_tups table.
543 : : * This indicates that that tuple, previously thought to be "recently dead",
544 : : * is now known really dead and won't be written to the output.
545 : : */
546 : : bool
547 : 21372 : rewrite_heap_dead_tuple(RewriteState state, HeapTuple old_tuple)
548 : : {
549 : : /*
550 : : * If we have already seen an earlier tuple in the update chain that
551 : : * points to this tuple, let's forget about that earlier tuple. It's in
552 : : * fact dead as well, our simple xmax < OldestXmin test in
553 : : * HeapTupleSatisfiesVacuum just wasn't enough to detect it. It happens
554 : : * when xmin of a tuple is greater than xmax, which sounds
555 : : * counter-intuitive but is perfectly valid.
556 : : *
557 : : * We don't bother to try to detect the situation the other way round,
558 : : * when we encounter the dead tuple first and then the recently dead one
559 : : * that points to it. If that happens, we'll have some unmatched entries
560 : : * in the UnresolvedTups hash table at the end. That can happen anyway,
561 : : * because a vacuum might have removed the dead tuple in the chain before
562 : : * us.
563 : : */
564 : : UnresolvedTup unresolved;
565 : : TidHashKey hashkey;
566 : : bool found;
567 : :
568 : 21372 : memset(&hashkey, 0, sizeof(hashkey));
569 : 21372 : hashkey.xmin = HeapTupleHeaderGetXmin(old_tuple->t_data);
570 : 21372 : hashkey.tid = old_tuple->t_self;
571 : :
572 : 21372 : unresolved = hash_search(state->rs_unresolved_tups, &hashkey,
573 : : HASH_FIND, NULL);
574 : :
575 [ - + ]: 21372 : if (unresolved != NULL)
576 : : {
577 : : /* Need to free the contained tuple as well as the hashtable entry */
578 : 0 : heap_freetuple(unresolved->tuple);
579 : 0 : hash_search(state->rs_unresolved_tups, &hashkey,
580 : : HASH_REMOVE, &found);
581 : : Assert(found);
582 : 0 : return true;
583 : : }
584 : :
585 : 21372 : return false;
586 : : }
587 : :
588 : : /*
589 : : * Insert a tuple to the new relation. This has to track heap_insert
590 : : * and its subsidiary functions!
591 : : *
592 : : * t_self of the tuple is set to the new TID of the tuple. If t_ctid of the
593 : : * tuple is invalid on entry, it's replaced with the new TID as well (in
594 : : * the inserted data only, not in the caller's copy).
595 : : */
596 : : static void
597 : 470610 : raw_heap_insert(RewriteState state, HeapTuple tup)
598 : : {
599 : : Page page;
600 : : Size pageFreeSpace,
601 : : saveFreeSpace;
602 : : Size len;
603 : : OffsetNumber newoff;
604 : : HeapTuple heaptup;
605 : :
606 : : /*
607 : : * If the new tuple is too big for storage or contains already toasted
608 : : * out-of-line attributes from some other relation, invoke the toaster.
609 : : *
610 : : * Note: below this point, heaptup is the data we actually intend to store
611 : : * into the relation; tup is the caller's original untoasted data.
612 : : */
613 [ - + ]: 470610 : if (state->rs_new_rel->rd_rel->relkind == RELKIND_TOASTVALUE)
614 : : {
615 : : /* toast table entries should never be recursively toasted */
616 : : Assert(!HeapTupleHasExternal(tup));
617 : 0 : heaptup = tup;
618 : : }
619 [ + + + + ]: 470610 : else if (HeapTupleHasExternal(tup) || tup->t_len > TOAST_TUPLE_THRESHOLD)
620 : 399 : {
621 : 399 : uint32 options = HEAP_INSERT_SKIP_FSM;
622 : :
623 : : /*
624 : : * While rewriting the heap for REPACK, make sure data for the TOAST
625 : : * table are not logically decoded. The main heap is WAL-logged as
626 : : * XLOG FPI records, which are not logically decoded.
627 : : */
628 : 399 : options |= HEAP_INSERT_NO_LOGICAL;
629 : :
630 : 399 : heaptup = heap_toast_insert_or_update(state->rs_new_rel, tup, NULL,
631 : : options);
632 : : }
633 : : else
634 : 470211 : heaptup = tup;
635 : :
636 : 470610 : len = MAXALIGN(heaptup->t_len); /* be conservative */
637 : :
638 : : /*
639 : : * If we're gonna fail for oversize tuple, do it right away
640 : : */
641 [ - + ]: 470610 : if (len > MaxHeapTupleSize)
642 [ # # ]: 0 : ereport(ERROR,
643 : : (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
644 : : errmsg("row is too big: size %zu, maximum size %zu",
645 : : len, MaxHeapTupleSize)));
646 : :
647 : : /* Compute desired extra freespace due to fillfactor option */
648 [ + + ]: 470610 : saveFreeSpace = RelationGetTargetPageFreeSpace(state->rs_new_rel,
649 : : HEAP_DEFAULT_FILLFACTOR);
650 : :
651 : : /* Now we can check to see if there's enough free space already. */
652 : 470610 : page = (Page) state->rs_buffer;
653 [ + + ]: 470610 : if (page)
654 : : {
655 : 470338 : pageFreeSpace = PageGetHeapFreeSpace(page);
656 : :
657 [ + + ]: 470338 : if (len + saveFreeSpace > pageFreeSpace)
658 : : {
659 : : /*
660 : : * Doesn't fit, so write out the existing page. It always
661 : : * contains a tuple. Hence, unlike RelationGetBufferForTuple(),
662 : : * enforce saveFreeSpace unconditionally.
663 : : */
664 : 6605 : smgr_bulk_write(state->rs_bulkstate, state->rs_blockno, state->rs_buffer, true);
665 : 6605 : state->rs_buffer = NULL;
666 : 6605 : page = NULL;
667 : 6605 : state->rs_blockno++;
668 : : }
669 : : }
670 : :
671 [ + + ]: 470610 : if (!page)
672 : : {
673 : : /* Initialize a new empty page */
674 : 6877 : state->rs_buffer = smgr_bulk_get_buf(state->rs_bulkstate);
675 : 6877 : page = (Page) state->rs_buffer;
676 : 6877 : PageInit(page, BLCKSZ, 0);
677 : : }
678 : :
679 : : /* And now we can insert the tuple into the page */
680 : 470610 : newoff = PageAddItem(page, heaptup->t_data, heaptup->t_len, InvalidOffsetNumber, false, true);
681 [ - + ]: 470610 : if (newoff == InvalidOffsetNumber)
682 [ # # ]: 0 : elog(ERROR, "failed to add tuple");
683 : :
684 : : /* Update caller's t_self to the actual position where it was stored */
685 : 470610 : ItemPointerSet(&(tup->t_self), state->rs_blockno, newoff);
686 : :
687 : : /*
688 : : * Insert the correct position into CTID of the stored tuple, too, if the
689 : : * caller didn't supply a valid CTID.
690 : : */
691 [ + + ]: 470610 : if (!ItemPointerIsValid(&tup->t_data->t_ctid))
692 : : {
693 : : ItemId newitemid;
694 : : HeapTupleHeader onpage_tup;
695 : :
696 : 470172 : newitemid = PageGetItemId(page, newoff);
697 : 470172 : onpage_tup = (HeapTupleHeader) PageGetItem(page, newitemid);
698 : :
699 : 470172 : onpage_tup->t_ctid = tup->t_self;
700 : : }
701 : :
702 : : /* If heaptup is a private copy, release it. */
703 [ + + ]: 470610 : if (heaptup != tup)
704 : 399 : heap_freetuple(heaptup);
705 : 470610 : }
706 : :
707 : : /* ------------------------------------------------------------------------
708 : : * Logical rewrite support
709 : : *
710 : : * When doing logical decoding - which relies on using cmin/cmax of catalog
711 : : * tuples, via xl_heap_new_cid records - heap rewrites have to log enough
712 : : * information to allow the decoding backend to update its internal mapping
713 : : * of (relfilelocator,ctid) => (cmin, cmax) to be correct for the rewritten heap.
714 : : *
715 : : * For that, every time we find a tuple that's been modified in a catalog
716 : : * relation within the xmin horizon of any decoding slot, we log a mapping
717 : : * from the old to the new location.
718 : : *
719 : : * To deal with rewrites that abort the filename of a mapping file contains
720 : : * the xid of the transaction performing the rewrite, which then can be
721 : : * checked before being read in.
722 : : *
723 : : * For efficiency we don't immediately spill every single map mapping for a
724 : : * row to disk but only do so in batches when we've collected several of them
725 : : * in memory or when end_heap_rewrite() has been called.
726 : : *
727 : : * Crash-Safety: This module diverts from the usual patterns of doing WAL
728 : : * since it cannot rely on checkpoint flushing out all buffers and thus
729 : : * waiting for exclusive locks on buffers. Usually the XLogInsert() covering
730 : : * buffer modifications is performed while the buffer(s) that are being
731 : : * modified are exclusively locked guaranteeing that both the WAL record and
732 : : * the modified heap are on either side of the checkpoint. But since the
733 : : * mapping files we log aren't in shared_buffers that interlock doesn't work.
734 : : *
735 : : * Instead we simply write the mapping files out to disk, *before* the
736 : : * XLogInsert() is performed. That guarantees that either the XLogInsert() is
737 : : * inserted after the checkpoint's redo pointer or that the checkpoint (via
738 : : * CheckPointLogicalRewriteHeap()) has flushed the (partial) mapping file to
739 : : * disk. That leaves the tail end that has not yet been flushed open to
740 : : * corruption, which is solved by including the current offset in the
741 : : * xl_heap_rewrite_mapping records and truncating the mapping file to it
742 : : * during replay. Every time a rewrite is finished all generated mapping files
743 : : * are synced to disk.
744 : : *
745 : : * Note that if we were only concerned about crash safety we wouldn't have to
746 : : * deal with WAL logging at all - an fsync() at the end of a rewrite would be
747 : : * sufficient for crash safety. Any mapping that hasn't been safely flushed to
748 : : * disk has to be by an aborted (explicitly or via a crash) transaction and is
749 : : * ignored by virtue of the xid in its name being subject to a
750 : : * TransactionDidCommit() check. But we want to support having standbys via
751 : : * physical replication, both for availability and to do logical decoding
752 : : * there.
753 : : * ------------------------------------------------------------------------
754 : : */
755 : :
756 : : /*
757 : : * Do preparations for logging logical mappings during a rewrite if
758 : : * necessary. If we detect that we don't need to log anything we'll prevent
759 : : * any further action by the various logical rewrite functions.
760 : : */
761 : : static void
762 : 399 : logical_begin_heap_rewrite(RewriteState state)
763 : : {
764 : : HASHCTL hash_ctl;
765 : : TransactionId logical_xmin;
766 : :
767 : : /*
768 : : * We only need to persist these mappings if the rewritten table can be
769 : : * accessed during logical decoding, if not, we can skip doing any
770 : : * additional work.
771 : : */
772 : 399 : state->rs_logical_rewrite =
773 [ + + - + : 399 : RelationIsAccessibleInLogicalDecoding(state->rs_old_rel);
+ - - + -
- - - + +
- + - - -
- - - ]
774 : :
775 [ + + ]: 399 : if (!state->rs_logical_rewrite)
776 : 379 : return;
777 : :
778 : 22 : ProcArrayGetReplicationSlotXmin(NULL, &logical_xmin);
779 : :
780 : : /*
781 : : * If there are no logical slots in progress we don't need to do anything,
782 : : * there cannot be any remappings for relevant rows yet. The relation's
783 : : * lock protects us against races.
784 : : */
785 [ + + ]: 22 : if (logical_xmin == InvalidTransactionId)
786 : : {
787 : 2 : state->rs_logical_rewrite = false;
788 : 2 : return;
789 : : }
790 : :
791 : 20 : state->rs_logical_xmin = logical_xmin;
792 : 20 : state->rs_begin_lsn = GetXLogInsertRecPtr();
793 : 20 : state->rs_num_rewrite_mappings = 0;
794 : :
795 : 20 : hash_ctl.keysize = sizeof(TransactionId);
796 : 20 : hash_ctl.entrysize = sizeof(RewriteMappingFile);
797 : 20 : hash_ctl.hcxt = state->rs_cxt;
798 : :
799 : 20 : state->rs_logical_mappings =
800 : 20 : hash_create("Logical rewrite mapping",
801 : : 128, /* arbitrary initial size */
802 : : &hash_ctl,
803 : : HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
804 : : }
805 : :
806 : : /*
807 : : * Flush all logical in-memory mappings to disk, but don't fsync them yet.
808 : : */
809 : : static void
810 : 9 : logical_heap_rewrite_flush_mappings(RewriteState state)
811 : : {
812 : : HASH_SEQ_STATUS seq_status;
813 : : RewriteMappingFile *src;
814 : : dlist_mutable_iter iter;
815 : :
816 : : Assert(state->rs_logical_rewrite);
817 : :
818 : : /* no logical rewrite in progress, no need to iterate over mappings */
819 [ - + ]: 9 : if (state->rs_num_rewrite_mappings == 0)
820 : 0 : return;
821 : :
822 [ - + ]: 9 : elog(DEBUG1, "flushing %u logical rewrite mapping entries",
823 : : state->rs_num_rewrite_mappings);
824 : :
825 : 9 : hash_seq_init(&seq_status, state->rs_logical_mappings);
826 [ + + ]: 99 : while ((src = (RewriteMappingFile *) hash_seq_search(&seq_status)) != NULL)
827 : : {
828 : : char *waldata;
829 : : char *waldata_start;
830 : : xl_heap_rewrite_mapping xlrec;
831 : : Oid dboid;
832 : : uint32 len;
833 : : int written;
834 : 90 : uint32 num_mappings = dclist_count(&src->mappings);
835 : :
836 : : /* this file hasn't got any new mappings */
837 [ - + ]: 90 : if (num_mappings == 0)
838 : 0 : continue;
839 : :
840 [ - + ]: 90 : if (state->rs_old_rel->rd_rel->relisshared)
841 : 0 : dboid = InvalidOid;
842 : : else
843 : 90 : dboid = MyDatabaseId;
844 : :
845 : 90 : xlrec.num_mappings = num_mappings;
846 : 90 : xlrec.mapped_rel = RelationGetRelid(state->rs_old_rel);
847 : 90 : xlrec.mapped_xid = src->xid;
848 : 90 : xlrec.mapped_db = dboid;
849 : 90 : xlrec.offset = src->off;
850 : 90 : xlrec.start_lsn = state->rs_begin_lsn;
851 : :
852 : : /* write all mappings consecutively */
853 : 90 : len = num_mappings * sizeof(LogicalRewriteMappingData);
854 : 90 : waldata_start = waldata = palloc(len);
855 : :
856 : : /*
857 : : * collect data we need to write out, but don't modify ondisk data yet
858 : : */
859 [ + - + + ]: 813 : dclist_foreach_modify(iter, &src->mappings)
860 : : {
861 : : RewriteMappingDataEntry *pmap;
862 : :
863 : 723 : pmap = dclist_container(RewriteMappingDataEntry, node, iter.cur);
864 : :
865 : 723 : memcpy(waldata, &pmap->map, sizeof(pmap->map));
866 : 723 : waldata += sizeof(pmap->map);
867 : :
868 : : /* remove from the list and free */
869 : 723 : dclist_delete_from(&src->mappings, &pmap->node);
870 : 723 : pfree(pmap);
871 : :
872 : : /* update bookkeeping */
873 : 723 : state->rs_num_rewrite_mappings--;
874 : : }
875 : :
876 : : Assert(dclist_count(&src->mappings) == 0);
877 : : Assert(waldata == waldata_start + len);
878 : :
879 : : /*
880 : : * Note that we deviate from the usual WAL coding practices here,
881 : : * check the above "Logical rewrite support" comment for reasoning.
882 : : */
883 : 90 : written = FileWrite(src->vfd, waldata_start, len, src->off,
884 : : WAIT_EVENT_LOGICAL_REWRITE_WRITE);
885 [ - + ]: 90 : if (written != len)
886 [ # # ]: 0 : ereport(ERROR,
887 : : (errcode_for_file_access(),
888 : : errmsg("could not write to file \"%s\", wrote %d of %d: %m", src->path,
889 : : written, len)));
890 : 90 : src->off += len;
891 : :
892 : 90 : XLogBeginInsert();
893 : 90 : XLogRegisterData(&xlrec, sizeof(xlrec));
894 : 90 : XLogRegisterData(waldata_start, len);
895 : :
896 : : /* write xlog record */
897 : 90 : XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_REWRITE);
898 : :
899 : 90 : pfree(waldata_start);
900 : : }
901 : : Assert(state->rs_num_rewrite_mappings == 0);
902 : : }
903 : :
904 : : /*
905 : : * Logical remapping part of end_heap_rewrite().
906 : : */
907 : : static void
908 : 399 : logical_end_heap_rewrite(RewriteState state)
909 : : {
910 : : HASH_SEQ_STATUS seq_status;
911 : : RewriteMappingFile *src;
912 : :
913 : : /* done, no logical rewrite in progress */
914 [ + + ]: 399 : if (!state->rs_logical_rewrite)
915 : 379 : return;
916 : :
917 : : /* writeout remaining in-memory entries */
918 [ + + ]: 20 : if (state->rs_num_rewrite_mappings > 0)
919 : 9 : logical_heap_rewrite_flush_mappings(state);
920 : :
921 : : /* Iterate over all mappings we have written and fsync the files. */
922 : 20 : hash_seq_init(&seq_status, state->rs_logical_mappings);
923 [ + + ]: 110 : while ((src = (RewriteMappingFile *) hash_seq_search(&seq_status)) != NULL)
924 : : {
925 [ - + ]: 90 : if (FileSync(src->vfd, WAIT_EVENT_LOGICAL_REWRITE_SYNC) != 0)
926 [ # # ]: 0 : ereport(data_sync_elevel(ERROR),
927 : : (errcode_for_file_access(),
928 : : errmsg("could not fsync file \"%s\": %m", src->path)));
929 : 90 : FileClose(src->vfd);
930 : : }
931 : : /* memory context cleanup will deal with the rest */
932 : : }
933 : :
934 : : /*
935 : : * Log a single (old->new) mapping for 'xid'.
936 : : */
937 : : static void
938 : 723 : logical_rewrite_log_mapping(RewriteState state, TransactionId xid,
939 : : LogicalRewriteMappingData *map)
940 : : {
941 : : RewriteMappingFile *src;
942 : : RewriteMappingDataEntry *pmap;
943 : : Oid relid;
944 : : bool found;
945 : :
946 : 723 : relid = RelationGetRelid(state->rs_old_rel);
947 : :
948 : : /* look for existing mappings for this 'mapped' xid */
949 : 723 : src = hash_search(state->rs_logical_mappings, &xid,
950 : : HASH_ENTER, &found);
951 : :
952 : : /*
953 : : * We haven't yet had the need to map anything for this xid, create
954 : : * per-xid data structures.
955 : : */
956 [ + + ]: 723 : if (!found)
957 : : {
958 : : char path[MAXPGPATH];
959 : : Oid dboid;
960 : :
961 [ - + ]: 90 : if (state->rs_old_rel->rd_rel->relisshared)
962 : 0 : dboid = InvalidOid;
963 : : else
964 : 90 : dboid = MyDatabaseId;
965 : :
966 : 90 : snprintf(path, MAXPGPATH,
967 : : "%s/" LOGICAL_REWRITE_FORMAT,
968 : : PG_LOGICAL_MAPPINGS_DIR, dboid, relid,
969 : 90 : LSN_FORMAT_ARGS(state->rs_begin_lsn),
970 : : xid, GetCurrentTransactionId());
971 : :
972 : 90 : dclist_init(&src->mappings);
973 : 90 : src->off = 0;
974 : 90 : memcpy(src->path, path, sizeof(path));
975 : 90 : src->vfd = PathNameOpenFile(path,
976 : : O_CREAT | O_EXCL | O_WRONLY | PG_BINARY);
977 [ - + ]: 90 : if (src->vfd < 0)
978 [ # # ]: 0 : ereport(ERROR,
979 : : (errcode_for_file_access(),
980 : : errmsg("could not create file \"%s\": %m", path)));
981 : : }
982 : :
983 : 723 : pmap = MemoryContextAlloc(state->rs_cxt,
984 : : sizeof(RewriteMappingDataEntry));
985 : 723 : memcpy(&pmap->map, map, sizeof(LogicalRewriteMappingData));
986 : 723 : dclist_push_tail(&src->mappings, &pmap->node);
987 : 723 : state->rs_num_rewrite_mappings++;
988 : :
989 : : /*
990 : : * Write out buffer every time we've too many in-memory entries across all
991 : : * mapping files.
992 : : */
993 [ - + ]: 723 : if (state->rs_num_rewrite_mappings >= 1000 /* arbitrary number */ )
994 : 0 : logical_heap_rewrite_flush_mappings(state);
995 : 723 : }
996 : :
997 : : /*
998 : : * Perform logical remapping for a tuple that's mapped from old_tid to
999 : : * new_tuple->t_self by rewrite_heap_tuple() if necessary for the tuple.
1000 : : */
1001 : : static void
1002 : 470610 : logical_rewrite_heap_tuple(RewriteState state, ItemPointerData old_tid,
1003 : : HeapTuple new_tuple)
1004 : : {
1005 : 470610 : ItemPointerData new_tid = new_tuple->t_self;
1006 : 470610 : TransactionId cutoff = state->rs_logical_xmin;
1007 : : TransactionId xmin;
1008 : : TransactionId xmax;
1009 : 470610 : bool do_log_xmin = false;
1010 : 470610 : bool do_log_xmax = false;
1011 : : LogicalRewriteMappingData map;
1012 : :
1013 : : /* no logical rewrite in progress, we don't need to log anything */
1014 [ + + ]: 470610 : if (!state->rs_logical_rewrite)
1015 : 469902 : return;
1016 : :
1017 : 27133 : xmin = HeapTupleHeaderGetXmin(new_tuple->t_data);
1018 : : /* use *GetUpdateXid to correctly deal with multixacts */
1019 : 27133 : xmax = HeapTupleHeaderGetUpdateXid(new_tuple->t_data);
1020 : :
1021 : : /*
1022 : : * Log the mapping iff the tuple has been created recently.
1023 : : */
1024 [ + + + - ]: 27133 : if (TransactionIdIsNormal(xmin) && !TransactionIdPrecedes(xmin, cutoff))
1025 : 535 : do_log_xmin = true;
1026 : :
1027 [ + + ]: 27133 : if (!TransactionIdIsNormal(xmax))
1028 : : {
1029 : : /*
1030 : : * no xmax is set, can't have any permanent ones, so this check is
1031 : : * sufficient
1032 : : */
1033 : : }
1034 [ + - ]: 501 : else if (HEAP_XMAX_IS_LOCKED_ONLY(new_tuple->t_data->t_infomask))
1035 : : {
1036 : : /* only locked, we don't care */
1037 : : }
1038 [ + - ]: 501 : else if (!TransactionIdPrecedes(xmax, cutoff))
1039 : : {
1040 : : /* tuple has been deleted recently, log */
1041 : 501 : do_log_xmax = true;
1042 : : }
1043 : :
1044 : : /* if neither needs to be logged, we're done */
1045 [ + + + + ]: 27133 : if (!do_log_xmin && !do_log_xmax)
1046 : 26425 : return;
1047 : :
1048 : : /* fill out mapping information */
1049 : 708 : map.old_locator = state->rs_old_rel->rd_locator;
1050 : 708 : map.old_tid = old_tid;
1051 : 708 : map.new_locator = state->rs_new_rel->rd_locator;
1052 : 708 : map.new_tid = new_tid;
1053 : :
1054 : : /* ---
1055 : : * Now persist the mapping for the individual xids that are affected. We
1056 : : * need to log for both xmin and xmax if they aren't the same transaction
1057 : : * since the mapping files are per "affected" xid.
1058 : : * We don't muster all that much effort detecting whether xmin and xmax
1059 : : * are actually the same transaction, we just check whether the xid is the
1060 : : * same disregarding subtransactions. Logging too much is relatively
1061 : : * harmless and we could never do the check fully since subtransaction
1062 : : * data is thrown away during restarts.
1063 : : * ---
1064 : : */
1065 [ + + ]: 708 : if (do_log_xmin)
1066 : 535 : logical_rewrite_log_mapping(state, xmin, &map);
1067 : : /* separately log mapping for xmax unless it'd be redundant */
1068 [ + + + + ]: 708 : if (do_log_xmax && !TransactionIdEquals(xmin, xmax))
1069 : 188 : logical_rewrite_log_mapping(state, xmax, &map);
1070 : : }
1071 : :
1072 : : /*
1073 : : * Replay XLOG_HEAP2_REWRITE records
1074 : : */
1075 : : void
1076 : 0 : heap_xlog_logical_rewrite(XLogReaderState *r)
1077 : : {
1078 : : char path[MAXPGPATH];
1079 : : int fd;
1080 : : xl_heap_rewrite_mapping *xlrec;
1081 : : uint32 len;
1082 : : char *data;
1083 : :
1084 : 0 : xlrec = (xl_heap_rewrite_mapping *) XLogRecGetData(r);
1085 : :
1086 : 0 : snprintf(path, MAXPGPATH,
1087 : : "%s/" LOGICAL_REWRITE_FORMAT,
1088 : : PG_LOGICAL_MAPPINGS_DIR, xlrec->mapped_db, xlrec->mapped_rel,
1089 : 0 : LSN_FORMAT_ARGS(xlrec->start_lsn),
1090 : 0 : xlrec->mapped_xid, XLogRecGetXid(r));
1091 : :
1092 : 0 : fd = OpenTransientFile(path,
1093 : : O_CREAT | O_WRONLY | PG_BINARY);
1094 [ # # ]: 0 : if (fd < 0)
1095 [ # # ]: 0 : ereport(ERROR,
1096 : : (errcode_for_file_access(),
1097 : : errmsg("could not create file \"%s\": %m", path)));
1098 : :
1099 : : /*
1100 : : * Truncate all data that's not guaranteed to have been safely fsynced (by
1101 : : * previous record or by the last checkpoint).
1102 : : */
1103 : 0 : pgstat_report_wait_start(WAIT_EVENT_LOGICAL_REWRITE_TRUNCATE);
1104 [ # # ]: 0 : if (ftruncate(fd, xlrec->offset) != 0)
1105 [ # # ]: 0 : ereport(ERROR,
1106 : : (errcode_for_file_access(),
1107 : : errmsg("could not truncate file \"%s\" to %u: %m",
1108 : : path, (uint32) xlrec->offset)));
1109 : 0 : pgstat_report_wait_end();
1110 : :
1111 : 0 : data = XLogRecGetData(r) + sizeof(*xlrec);
1112 : :
1113 : 0 : len = xlrec->num_mappings * sizeof(LogicalRewriteMappingData);
1114 : :
1115 : : /* write out tail end of mapping file (again) */
1116 : 0 : errno = 0;
1117 : 0 : pgstat_report_wait_start(WAIT_EVENT_LOGICAL_REWRITE_MAPPING_WRITE);
1118 [ # # ]: 0 : if (pg_pwrite(fd, data, len, xlrec->offset) != len)
1119 : : {
1120 : : /* if write didn't set errno, assume problem is no disk space */
1121 [ # # ]: 0 : if (errno == 0)
1122 : 0 : errno = ENOSPC;
1123 [ # # ]: 0 : ereport(ERROR,
1124 : : (errcode_for_file_access(),
1125 : : errmsg("could not write to file \"%s\": %m", path)));
1126 : : }
1127 : 0 : pgstat_report_wait_end();
1128 : :
1129 : : /*
1130 : : * Now fsync all previously written data. We could improve things and only
1131 : : * do this for the last write to a file, but the required bookkeeping
1132 : : * doesn't seem worth the trouble.
1133 : : */
1134 : 0 : pgstat_report_wait_start(WAIT_EVENT_LOGICAL_REWRITE_MAPPING_SYNC);
1135 [ # # ]: 0 : if (pg_fsync(fd) != 0)
1136 [ # # ]: 0 : ereport(data_sync_elevel(ERROR),
1137 : : (errcode_for_file_access(),
1138 : : errmsg("could not fsync file \"%s\": %m", path)));
1139 : 0 : pgstat_report_wait_end();
1140 : :
1141 [ # # ]: 0 : if (CloseTransientFile(fd) != 0)
1142 [ # # ]: 0 : ereport(ERROR,
1143 : : (errcode_for_file_access(),
1144 : : errmsg("could not close file \"%s\": %m", path)));
1145 : 0 : }
1146 : :
1147 : : /* ---
1148 : : * Perform a checkpoint for logical rewrite mappings
1149 : : *
1150 : : * This serves two tasks:
1151 : : * 1) Remove all mappings not needed anymore based on the logical restart LSN
1152 : : * 2) Flush all remaining mappings to disk, so that replay after a checkpoint
1153 : : * only has to deal with the parts of a mapping that have been written out
1154 : : * after the checkpoint started.
1155 : : * ---
1156 : : */
1157 : : void
1158 : 1944 : CheckPointLogicalRewriteHeap(void)
1159 : : {
1160 : : XLogRecPtr cutoff;
1161 : : XLogRecPtr redo;
1162 : : DIR *mappings_dir;
1163 : : struct dirent *mapping_de;
1164 : : char path[MAXPGPATH + sizeof(PG_LOGICAL_MAPPINGS_DIR)];
1165 : :
1166 : : /*
1167 : : * We start of with a minimum of the last redo pointer. No new decoding
1168 : : * slot will start before that, so that's a safe upper bound for removal.
1169 : : */
1170 : 1944 : redo = GetRedoRecPtr();
1171 : :
1172 : : /* now check for the restart ptrs from existing slots */
1173 : 1944 : cutoff = ReplicationSlotsComputeLogicalRestartLSN();
1174 : :
1175 : : /* don't start earlier than the restart lsn */
1176 [ + + + + ]: 1944 : if (XLogRecPtrIsValid(cutoff) && redo < cutoff)
1177 : 1 : cutoff = redo;
1178 : :
1179 : 1944 : mappings_dir = AllocateDir(PG_LOGICAL_MAPPINGS_DIR);
1180 [ + + ]: 6012 : while ((mapping_de = ReadDir(mappings_dir, PG_LOGICAL_MAPPINGS_DIR)) != NULL)
1181 : : {
1182 : : Oid dboid;
1183 : : Oid relid;
1184 : : XLogRecPtr lsn;
1185 : : TransactionId rewrite_xid;
1186 : : TransactionId create_xid;
1187 : : uint32 hi,
1188 : : lo;
1189 : : PGFileType de_type;
1190 : :
1191 [ + + ]: 4068 : if (strcmp(mapping_de->d_name, ".") == 0 ||
1192 [ + + ]: 2124 : strcmp(mapping_de->d_name, "..") == 0)
1193 : 3888 : continue;
1194 : :
1195 : 180 : snprintf(path, sizeof(path), "%s/%s", PG_LOGICAL_MAPPINGS_DIR, mapping_de->d_name);
1196 : 180 : de_type = get_dirent_type(path, mapping_de, false, DEBUG1);
1197 : :
1198 [ + - - + ]: 180 : if (de_type != PGFILETYPE_ERROR && de_type != PGFILETYPE_REG)
1199 : 0 : continue;
1200 : :
1201 : : /* Skip over files that cannot be ours. */
1202 [ - + ]: 180 : if (strncmp(mapping_de->d_name, "map-", 4) != 0)
1203 : 0 : continue;
1204 : :
1205 [ - + ]: 180 : if (sscanf(mapping_de->d_name, LOGICAL_REWRITE_FORMAT,
1206 : : &dboid, &relid, &hi, &lo, &rewrite_xid, &create_xid) != 6)
1207 [ # # ]: 0 : elog(ERROR, "could not parse filename \"%s\"", mapping_de->d_name);
1208 : :
1209 : 180 : lsn = ((uint64) hi) << 32 | lo;
1210 : :
1211 [ + + - + ]: 180 : if (lsn < cutoff || !XLogRecPtrIsValid(cutoff))
1212 : : {
1213 [ - + ]: 90 : elog(DEBUG1, "removing logical rewrite file \"%s\"", path);
1214 [ - + ]: 90 : if (unlink(path) < 0)
1215 [ # # ]: 0 : ereport(ERROR,
1216 : : (errcode_for_file_access(),
1217 : : errmsg("could not remove file \"%s\": %m", path)));
1218 : : }
1219 : : else
1220 : : {
1221 : : /* on some operating systems fsyncing a file requires O_RDWR */
1222 : 90 : int fd = OpenTransientFile(path, O_RDWR | PG_BINARY);
1223 : :
1224 : : /*
1225 : : * The file cannot vanish due to concurrency since this function
1226 : : * is the only one removing logical mappings and only one
1227 : : * checkpoint can be in progress at a time.
1228 : : */
1229 [ - + ]: 90 : if (fd < 0)
1230 [ # # ]: 0 : ereport(ERROR,
1231 : : (errcode_for_file_access(),
1232 : : errmsg("could not open file \"%s\": %m", path)));
1233 : :
1234 : : /*
1235 : : * We could try to avoid fsyncing files that either haven't
1236 : : * changed or have only been created since the checkpoint's start,
1237 : : * but it's currently not deemed worth the effort.
1238 : : */
1239 : 90 : pgstat_report_wait_start(WAIT_EVENT_LOGICAL_REWRITE_CHECKPOINT_SYNC);
1240 [ - + ]: 90 : if (pg_fsync(fd) != 0)
1241 [ # # ]: 0 : ereport(data_sync_elevel(ERROR),
1242 : : (errcode_for_file_access(),
1243 : : errmsg("could not fsync file \"%s\": %m", path)));
1244 : 90 : pgstat_report_wait_end();
1245 : :
1246 [ - + ]: 90 : if (CloseTransientFile(fd) != 0)
1247 [ # # ]: 0 : ereport(ERROR,
1248 : : (errcode_for_file_access(),
1249 : : errmsg("could not close file \"%s\": %m", path)));
1250 : : }
1251 : : }
1252 : 1944 : FreeDir(mappings_dir);
1253 : :
1254 : : /* persist directory entries to disk */
1255 : 1944 : fsync_fname(PG_LOGICAL_MAPPINGS_DIR, true);
1256 : 1944 : }
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