Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * heap_surgery.c
4 : * Functions to perform surgery on the damaged heap table.
5 : *
6 : * Copyright (c) 2020-2024, PostgreSQL Global Development Group
7 : *
8 : * IDENTIFICATION
9 : * contrib/pg_surgery/heap_surgery.c
10 : *
11 : *-------------------------------------------------------------------------
12 : */
13 : #include "postgres.h"
14 :
15 : #include "access/htup_details.h"
16 : #include "access/relation.h"
17 : #include "access/visibilitymap.h"
18 : #include "access/xloginsert.h"
19 : #include "catalog/pg_am_d.h"
20 : #include "miscadmin.h"
21 : #include "storage/bufmgr.h"
22 : #include "utils/acl.h"
23 : #include "utils/array.h"
24 : #include "utils/rel.h"
25 :
26 2 : PG_MODULE_MAGIC;
27 :
28 : /* Options to forcefully change the state of a heap tuple. */
29 : typedef enum HeapTupleForceOption
30 : {
31 : HEAP_FORCE_KILL,
32 : HEAP_FORCE_FREEZE,
33 : } HeapTupleForceOption;
34 :
35 4 : PG_FUNCTION_INFO_V1(heap_force_kill);
36 4 : PG_FUNCTION_INFO_V1(heap_force_freeze);
37 :
38 : static int32 tidcmp(const void *a, const void *b);
39 : static Datum heap_force_common(FunctionCallInfo fcinfo,
40 : HeapTupleForceOption heap_force_opt);
41 : static void sanity_check_tid_array(ArrayType *ta, int *ntids);
42 : static BlockNumber find_tids_one_page(ItemPointer tids, int ntids,
43 : OffsetNumber *next_start_ptr);
44 :
45 : /*-------------------------------------------------------------------------
46 : * heap_force_kill()
47 : *
48 : * Force kill the tuple(s) pointed to by the item pointer(s) stored in the
49 : * given TID array.
50 : *
51 : * Usage: SELECT heap_force_kill(regclass, tid[]);
52 : *-------------------------------------------------------------------------
53 : */
54 : Datum
55 18 : heap_force_kill(PG_FUNCTION_ARGS)
56 : {
57 18 : PG_RETURN_DATUM(heap_force_common(fcinfo, HEAP_FORCE_KILL));
58 : }
59 :
60 : /*-------------------------------------------------------------------------
61 : * heap_force_freeze()
62 : *
63 : * Force freeze the tuple(s) pointed to by the item pointer(s) stored in the
64 : * given TID array.
65 : *
66 : * Usage: SELECT heap_force_freeze(regclass, tid[]);
67 : *-------------------------------------------------------------------------
68 : */
69 : Datum
70 14 : heap_force_freeze(PG_FUNCTION_ARGS)
71 : {
72 14 : PG_RETURN_DATUM(heap_force_common(fcinfo, HEAP_FORCE_FREEZE));
73 : }
74 :
75 : /*-------------------------------------------------------------------------
76 : * heap_force_common()
77 : *
78 : * Common code for heap_force_kill and heap_force_freeze
79 : *-------------------------------------------------------------------------
80 : */
81 : static Datum
82 32 : heap_force_common(FunctionCallInfo fcinfo, HeapTupleForceOption heap_force_opt)
83 : {
84 32 : Oid relid = PG_GETARG_OID(0);
85 32 : ArrayType *ta = PG_GETARG_ARRAYTYPE_P_COPY(1);
86 : ItemPointer tids;
87 : int ntids,
88 : nblocks;
89 : Relation rel;
90 : OffsetNumber curr_start_ptr,
91 : next_start_ptr;
92 : bool include_this_tid[MaxHeapTuplesPerPage];
93 :
94 32 : if (RecoveryInProgress())
95 0 : ereport(ERROR,
96 : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
97 : errmsg("recovery is in progress"),
98 : errhint("Heap surgery functions cannot be executed during recovery.")));
99 :
100 : /* Check inputs. */
101 32 : sanity_check_tid_array(ta, &ntids);
102 :
103 28 : rel = relation_open(relid, RowExclusiveLock);
104 :
105 : /*
106 : * Check target relation.
107 : */
108 28 : if (!RELKIND_HAS_TABLE_AM(rel->rd_rel->relkind))
109 4 : ereport(ERROR,
110 : (errcode(ERRCODE_WRONG_OBJECT_TYPE),
111 : errmsg("cannot operate on relation \"%s\"",
112 : RelationGetRelationName(rel)),
113 : errdetail_relkind_not_supported(rel->rd_rel->relkind)));
114 :
115 24 : if (rel->rd_rel->relam != HEAP_TABLE_AM_OID)
116 0 : ereport(ERROR,
117 : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
118 : errmsg("only heap AM is supported")));
119 :
120 : /* Must be owner of the table or superuser. */
121 24 : if (!object_ownercheck(RelationRelationId, RelationGetRelid(rel), GetUserId()))
122 0 : aclcheck_error(ACLCHECK_NOT_OWNER,
123 0 : get_relkind_objtype(rel->rd_rel->relkind),
124 0 : RelationGetRelationName(rel));
125 :
126 24 : tids = ((ItemPointer) ARR_DATA_PTR(ta));
127 :
128 : /*
129 : * If there is more than one TID in the array, sort them so that we can
130 : * easily fetch all the TIDs belonging to one particular page from the
131 : * array.
132 : */
133 24 : if (ntids > 1)
134 4 : qsort(tids, ntids, sizeof(ItemPointerData), tidcmp);
135 :
136 24 : curr_start_ptr = next_start_ptr = 0;
137 24 : nblocks = RelationGetNumberOfBlocks(rel);
138 :
139 : /*
140 : * Loop, performing the necessary actions for each block.
141 : */
142 48 : while (next_start_ptr != ntids)
143 : {
144 : Buffer buf;
145 24 : Buffer vmbuf = InvalidBuffer;
146 : Page page;
147 : BlockNumber blkno;
148 : OffsetNumber curoff;
149 : OffsetNumber maxoffset;
150 : int i;
151 24 : bool did_modify_page = false;
152 24 : bool did_modify_vm = false;
153 :
154 24 : CHECK_FOR_INTERRUPTS();
155 :
156 : /*
157 : * Find all the TIDs belonging to one particular page starting from
158 : * next_start_ptr and process them one by one.
159 : */
160 24 : blkno = find_tids_one_page(tids, ntids, &next_start_ptr);
161 :
162 : /* Check whether the block number is valid. */
163 24 : if (blkno >= nblocks)
164 : {
165 : /* Update the current_start_ptr before moving to the next page. */
166 2 : curr_start_ptr = next_start_ptr;
167 :
168 2 : ereport(NOTICE,
169 : (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
170 : errmsg("skipping block %u for relation \"%s\" because the block number is out of range",
171 : blkno, RelationGetRelationName(rel))));
172 2 : continue;
173 : }
174 :
175 22 : buf = ReadBuffer(rel, blkno);
176 22 : LockBufferForCleanup(buf);
177 :
178 22 : page = BufferGetPage(buf);
179 :
180 22 : maxoffset = PageGetMaxOffsetNumber(page);
181 :
182 : /*
183 : * Figure out which TIDs we are going to process and which ones we are
184 : * going to skip.
185 : */
186 22 : memset(include_this_tid, 0, sizeof(include_this_tid));
187 48 : for (i = curr_start_ptr; i < next_start_ptr; i++)
188 : {
189 26 : OffsetNumber offno = ItemPointerGetOffsetNumberNoCheck(&tids[i]);
190 : ItemId itemid;
191 :
192 : /* Check whether the offset number is valid. */
193 26 : if (offno == InvalidOffsetNumber || offno > maxoffset)
194 : {
195 4 : ereport(NOTICE,
196 : errmsg("skipping tid (%u, %u) for relation \"%s\" because the item number is out of range",
197 : blkno, offno, RelationGetRelationName(rel)));
198 4 : continue;
199 : }
200 :
201 22 : itemid = PageGetItemId(page, offno);
202 :
203 : /* Only accept an item ID that is used. */
204 22 : if (ItemIdIsRedirected(itemid))
205 : {
206 2 : ereport(NOTICE,
207 : errmsg("skipping tid (%u, %u) for relation \"%s\" because it redirects to item %u",
208 : blkno, offno, RelationGetRelationName(rel),
209 : ItemIdGetRedirect(itemid)));
210 2 : continue;
211 : }
212 20 : else if (ItemIdIsDead(itemid))
213 : {
214 4 : ereport(NOTICE,
215 : (errmsg("skipping tid (%u, %u) for relation \"%s\" because it is marked dead",
216 : blkno, offno, RelationGetRelationName(rel))));
217 4 : continue;
218 : }
219 16 : else if (!ItemIdIsUsed(itemid))
220 : {
221 2 : ereport(NOTICE,
222 : (errmsg("skipping tid (%u, %u) for relation \"%s\" because it is marked unused",
223 : blkno, offno, RelationGetRelationName(rel))));
224 2 : continue;
225 : }
226 :
227 : /* Mark it for processing. */
228 : Assert(offno < MaxHeapTuplesPerPage);
229 14 : include_this_tid[offno] = true;
230 : }
231 :
232 : /*
233 : * Before entering the critical section, pin the visibility map page
234 : * if it appears to be necessary.
235 : */
236 22 : if (heap_force_opt == HEAP_FORCE_KILL && PageIsAllVisible(page))
237 6 : visibilitymap_pin(rel, blkno, &vmbuf);
238 :
239 : /* No ereport(ERROR) from here until all the changes are logged. */
240 22 : START_CRIT_SECTION();
241 :
242 110 : for (curoff = FirstOffsetNumber; curoff <= maxoffset;
243 88 : curoff = OffsetNumberNext(curoff))
244 : {
245 : ItemId itemid;
246 :
247 88 : if (!include_this_tid[curoff])
248 74 : continue;
249 :
250 14 : itemid = PageGetItemId(page, curoff);
251 : Assert(ItemIdIsNormal(itemid));
252 :
253 14 : did_modify_page = true;
254 :
255 14 : if (heap_force_opt == HEAP_FORCE_KILL)
256 : {
257 6 : ItemIdSetDead(itemid);
258 :
259 : /*
260 : * If the page is marked all-visible, we must clear
261 : * PD_ALL_VISIBLE flag on the page header and an all-visible
262 : * bit on the visibility map corresponding to the page.
263 : */
264 6 : if (PageIsAllVisible(page))
265 : {
266 2 : PageClearAllVisible(page);
267 2 : visibilitymap_clear(rel, blkno, vmbuf,
268 : VISIBILITYMAP_VALID_BITS);
269 2 : did_modify_vm = true;
270 : }
271 : }
272 : else
273 : {
274 : HeapTupleHeader htup;
275 :
276 : Assert(heap_force_opt == HEAP_FORCE_FREEZE);
277 :
278 8 : htup = (HeapTupleHeader) PageGetItem(page, itemid);
279 :
280 : /*
281 : * Reset all visibility-related fields of the tuple. This
282 : * logic should mimic heap_execute_freeze_tuple(), but we
283 : * choose to reset xmin and ctid just to be sure that no
284 : * potentially-garbled data is left behind.
285 : */
286 8 : ItemPointerSet(&htup->t_ctid, blkno, curoff);
287 8 : HeapTupleHeaderSetXmin(htup, FrozenTransactionId);
288 8 : HeapTupleHeaderSetXmax(htup, InvalidTransactionId);
289 8 : if (htup->t_infomask & HEAP_MOVED)
290 : {
291 0 : if (htup->t_infomask & HEAP_MOVED_OFF)
292 0 : HeapTupleHeaderSetXvac(htup, InvalidTransactionId);
293 : else
294 0 : HeapTupleHeaderSetXvac(htup, FrozenTransactionId);
295 : }
296 :
297 : /*
298 : * Clear all the visibility-related bits of this tuple and
299 : * mark it as frozen. Also, get rid of HOT_UPDATED and
300 : * KEYS_UPDATES bits.
301 : */
302 8 : htup->t_infomask &= ~HEAP_XACT_MASK;
303 8 : htup->t_infomask |= (HEAP_XMIN_FROZEN | HEAP_XMAX_INVALID);
304 8 : htup->t_infomask2 &= ~HEAP_HOT_UPDATED;
305 8 : htup->t_infomask2 &= ~HEAP_KEYS_UPDATED;
306 : }
307 : }
308 :
309 : /*
310 : * If the page was modified, only then, we mark the buffer dirty or do
311 : * the WAL logging.
312 : */
313 22 : if (did_modify_page)
314 : {
315 : /* Mark buffer dirty before we write WAL. */
316 12 : MarkBufferDirty(buf);
317 :
318 : /* XLOG stuff */
319 12 : if (RelationNeedsWAL(rel))
320 4 : log_newpage_buffer(buf, true);
321 : }
322 :
323 : /* WAL log the VM page if it was modified. */
324 22 : if (did_modify_vm && RelationNeedsWAL(rel))
325 0 : log_newpage_buffer(vmbuf, false);
326 :
327 22 : END_CRIT_SECTION();
328 :
329 22 : UnlockReleaseBuffer(buf);
330 :
331 22 : if (vmbuf != InvalidBuffer)
332 6 : ReleaseBuffer(vmbuf);
333 :
334 : /* Update the current_start_ptr before moving to the next page. */
335 22 : curr_start_ptr = next_start_ptr;
336 : }
337 :
338 24 : relation_close(rel, RowExclusiveLock);
339 :
340 24 : pfree(ta);
341 :
342 24 : PG_RETURN_VOID();
343 : }
344 :
345 : /*-------------------------------------------------------------------------
346 : * tidcmp()
347 : *
348 : * Compare two item pointers, return -1, 0, or +1.
349 : *
350 : * See ItemPointerCompare for details.
351 : * ------------------------------------------------------------------------
352 : */
353 : static int32
354 6 : tidcmp(const void *a, const void *b)
355 : {
356 6 : ItemPointer iptr1 = ((const ItemPointer) a);
357 6 : ItemPointer iptr2 = ((const ItemPointer) b);
358 :
359 6 : return ItemPointerCompare(iptr1, iptr2);
360 : }
361 :
362 : /*-------------------------------------------------------------------------
363 : * sanity_check_tid_array()
364 : *
365 : * Perform sanity checks on the given tid array, and set *ntids to the
366 : * number of items in the array.
367 : * ------------------------------------------------------------------------
368 : */
369 : static void
370 32 : sanity_check_tid_array(ArrayType *ta, int *ntids)
371 : {
372 32 : if (ARR_HASNULL(ta) && array_contains_nulls(ta))
373 2 : ereport(ERROR,
374 : (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
375 : errmsg("array must not contain nulls")));
376 :
377 30 : if (ARR_NDIM(ta) > 1)
378 2 : ereport(ERROR,
379 : (errcode(ERRCODE_DATA_EXCEPTION),
380 : errmsg("argument must be empty or one-dimensional array")));
381 :
382 28 : *ntids = ArrayGetNItems(ARR_NDIM(ta), ARR_DIMS(ta));
383 28 : }
384 :
385 : /*-------------------------------------------------------------------------
386 : * find_tids_one_page()
387 : *
388 : * Find all the tids residing in the same page as tids[next_start_ptr], and
389 : * update next_start_ptr so that it points to the first tid in the next page.
390 : *
391 : * NOTE: The input tids[] array must be sorted.
392 : * ------------------------------------------------------------------------
393 : */
394 : static BlockNumber
395 24 : find_tids_one_page(ItemPointer tids, int ntids, OffsetNumber *next_start_ptr)
396 : {
397 : int i;
398 : BlockNumber prev_blkno,
399 : blkno;
400 :
401 24 : prev_blkno = blkno = InvalidBlockNumber;
402 :
403 52 : for (i = *next_start_ptr; i < ntids; i++)
404 : {
405 30 : ItemPointerData tid = tids[i];
406 :
407 30 : blkno = ItemPointerGetBlockNumberNoCheck(&tid);
408 :
409 30 : if (i == *next_start_ptr)
410 24 : prev_blkno = blkno;
411 :
412 30 : if (prev_blkno != blkno)
413 2 : break;
414 : }
415 :
416 24 : *next_start_ptr = i;
417 24 : return prev_blkno;
418 : }
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