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1 : : /*-------------------------------------------------------------------------
2 : : *
3 : : * matview.c
4 : : * materialized view support
5 : : *
6 : : * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group
7 : : * Portions Copyright (c) 1994, Regents of the University of California
8 : : *
9 : : *
10 : : * IDENTIFICATION
11 : : * src/backend/commands/matview.c
12 : : *
13 : : *-------------------------------------------------------------------------
14 : : */
15 : : #include "postgres.h"
16 : :
17 : : #include "access/genam.h"
18 : : #include "access/heapam.h"
19 : : #include "access/htup_details.h"
20 : : #include "access/multixact.h"
21 : : #include "access/tableam.h"
22 : : #include "access/xact.h"
23 : : #include "catalog/indexing.h"
24 : : #include "catalog/namespace.h"
25 : : #include "catalog/pg_am.h"
26 : : #include "catalog/pg_opclass.h"
27 : : #include "commands/matview.h"
28 : : #include "commands/repack.h"
29 : : #include "commands/tablecmds.h"
30 : : #include "commands/tablespace.h"
31 : : #include "executor/executor.h"
32 : : #include "executor/spi.h"
33 : : #include "miscadmin.h"
34 : : #include "pgstat.h"
35 : : #include "rewrite/rewriteHandler.h"
36 : : #include "storage/lmgr.h"
37 : : #include "tcop/tcopprot.h"
38 : : #include "utils/builtins.h"
39 : : #include "utils/lsyscache.h"
40 : : #include "utils/rel.h"
41 : : #include "utils/snapmgr.h"
42 : : #include "utils/syscache.h"
43 : :
44 : :
45 : : typedef struct
46 : : {
47 : : DestReceiver pub; /* publicly-known function pointers */
48 : : Oid transientoid; /* OID of new heap into which to store */
49 : : /* These fields are filled by transientrel_startup: */
50 : : Relation transientrel; /* relation to write to */
51 : : CommandId output_cid; /* cmin to insert in output tuples */
52 : : uint32 ti_options; /* table_tuple_insert performance options */
53 : : BulkInsertState bistate; /* bulk insert state */
54 : : } DR_transientrel;
55 : :
56 : : static int matview_maintenance_depth = 0;
57 : :
58 : : static void transientrel_startup(DestReceiver *self, int operation, TupleDesc typeinfo);
59 : : static bool transientrel_receive(TupleTableSlot *slot, DestReceiver *self);
60 : : static void transientrel_shutdown(DestReceiver *self);
61 : : static void transientrel_destroy(DestReceiver *self);
62 : : static uint64 refresh_matview_datafill(DestReceiver *dest, Query *query,
63 : : const char *queryString, bool is_create);
64 : : static void refresh_by_match_merge(Oid matviewOid, Oid tempOid, Oid relowner,
65 : : int save_sec_context);
66 : : static void refresh_by_heap_swap(Oid matviewOid, Oid OIDNewHeap, char relpersistence);
67 : : static bool is_usable_unique_index(Relation indexRel);
68 : : static void OpenMatViewIncrementalMaintenance(void);
69 : : static void CloseMatViewIncrementalMaintenance(void);
70 : :
71 : : /*
72 : : * SetMatViewPopulatedState
73 : : * Mark a materialized view as populated, or not.
74 : : *
75 : : * NOTE: caller must be holding an appropriate lock on the relation.
76 : : */
77 : : void
78 : 385 : SetMatViewPopulatedState(Relation relation, bool newstate)
79 : : {
80 : : Relation pgrel;
81 : : HeapTuple tuple;
82 : :
83 : : Assert(relation->rd_rel->relkind == RELKIND_MATVIEW);
84 : :
85 : : /*
86 : : * Update relation's pg_class entry. Crucial side-effect: other backends
87 : : * (and this one too!) are sent SI message to make them rebuild relcache
88 : : * entries.
89 : : */
90 : 385 : pgrel = table_open(RelationRelationId, RowExclusiveLock);
91 : 385 : tuple = SearchSysCacheCopy1(RELOID,
92 : : ObjectIdGetDatum(RelationGetRelid(relation)));
93 [ - + ]: 385 : if (!HeapTupleIsValid(tuple))
94 [ # # ]: 0 : elog(ERROR, "cache lookup failed for relation %u",
95 : : RelationGetRelid(relation));
96 : :
97 : 385 : ((Form_pg_class) GETSTRUCT(tuple))->relispopulated = newstate;
98 : :
99 : 385 : CatalogTupleUpdate(pgrel, &tuple->t_self, tuple);
100 : :
101 : 385 : heap_freetuple(tuple);
102 : 385 : table_close(pgrel, RowExclusiveLock);
103 : :
104 : : /*
105 : : * Advance command counter to make the updated pg_class row locally
106 : : * visible.
107 : : */
108 : 385 : CommandCounterIncrement();
109 : 385 : }
110 : :
111 : : /*
112 : : * ExecRefreshMatView -- execute a REFRESH MATERIALIZED VIEW command
113 : : *
114 : : * If WITH NO DATA was specified, this is effectively like a TRUNCATE;
115 : : * otherwise it is like a TRUNCATE followed by an INSERT using the SELECT
116 : : * statement associated with the materialized view. The statement node's
117 : : * skipData field shows whether the clause was used.
118 : : */
119 : : ObjectAddress
120 : 174 : ExecRefreshMatView(RefreshMatViewStmt *stmt, const char *queryString,
121 : : QueryCompletion *qc)
122 : : {
123 : : Oid matviewOid;
124 : : LOCKMODE lockmode;
125 : :
126 : : /* Determine strength of lock needed. */
127 [ + + ]: 174 : lockmode = stmt->concurrent ? ExclusiveLock : AccessExclusiveLock;
128 : :
129 : : /*
130 : : * Get a lock until end of transaction.
131 : : */
132 : 174 : matviewOid = RangeVarGetRelidExtended(stmt->relation,
133 : : lockmode, 0,
134 : : RangeVarCallbackMaintainsTable,
135 : : NULL);
136 : :
137 : 296 : return RefreshMatViewByOid(matviewOid, false, stmt->skipData,
138 : 170 : stmt->concurrent, queryString, qc);
139 : : }
140 : :
141 : : /*
142 : : * RefreshMatViewByOid -- refresh materialized view by OID
143 : : *
144 : : * This refreshes the materialized view by creating a new table and swapping
145 : : * the relfilenumbers of the new table and the old materialized view, so the OID
146 : : * of the original materialized view is preserved. Thus we do not lose GRANT
147 : : * nor references to this materialized view.
148 : : *
149 : : * If skipData is true, this is effectively like a TRUNCATE; otherwise it is
150 : : * like a TRUNCATE followed by an INSERT using the SELECT statement associated
151 : : * with the materialized view.
152 : : *
153 : : * Indexes are rebuilt too, via REINDEX. Since we are effectively bulk-loading
154 : : * the new heap, it's better to create the indexes afterwards than to fill them
155 : : * incrementally while we load.
156 : : *
157 : : * The matview's "populated" state is changed based on whether the contents
158 : : * reflect the result set of the materialized view's query.
159 : : *
160 : : * This is also used to populate the materialized view created by CREATE
161 : : * MATERIALIZED VIEW command.
162 : : */
163 : : ObjectAddress
164 : 389 : RefreshMatViewByOid(Oid matviewOid, bool is_create, bool skipData,
165 : : bool concurrent, const char *queryString,
166 : : QueryCompletion *qc)
167 : : {
168 : : Relation matviewRel;
169 : : RewriteRule *rule;
170 : : List *actions;
171 : : Query *dataQuery;
172 : : Oid tableSpace;
173 : : Oid relowner;
174 : : Oid OIDNewHeap;
175 : 389 : uint64 processed = 0;
176 : : char relpersistence;
177 : : Oid save_userid;
178 : : int save_sec_context;
179 : : int save_nestlevel;
180 : : ObjectAddress address;
181 : :
182 : 389 : matviewRel = table_open(matviewOid, NoLock);
183 : 389 : relowner = matviewRel->rd_rel->relowner;
184 : :
185 : : /*
186 : : * Switch to the owner's userid, so that any functions are run as that
187 : : * user. Also lock down security-restricted operations and arrange to
188 : : * make GUC variable changes local to this command.
189 : : */
190 : 389 : GetUserIdAndSecContext(&save_userid, &save_sec_context);
191 : 389 : SetUserIdAndSecContext(relowner,
192 : : save_sec_context | SECURITY_RESTRICTED_OPERATION);
193 : 389 : save_nestlevel = NewGUCNestLevel();
194 : 389 : RestrictSearchPath();
195 : :
196 : : /* Make sure it is a materialized view. */
197 [ - + ]: 389 : if (matviewRel->rd_rel->relkind != RELKIND_MATVIEW)
198 [ # # ]: 0 : ereport(ERROR,
199 : : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
200 : : errmsg("\"%s\" is not a materialized view",
201 : : RelationGetRelationName(matviewRel))));
202 : :
203 : : /* Check that CONCURRENTLY is not specified if not populated. */
204 [ + + - + ]: 389 : if (concurrent && !RelationIsPopulated(matviewRel))
205 [ # # ]: 0 : ereport(ERROR,
206 : : (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
207 : : errmsg("CONCURRENTLY cannot be used when the materialized view is not populated")));
208 : :
209 : : /* Check that conflicting options have not been specified. */
210 [ + + + + ]: 389 : if (concurrent && skipData)
211 [ + - ]: 4 : ereport(ERROR,
212 : : (errcode(ERRCODE_SYNTAX_ERROR),
213 : : errmsg("%s options %s and %s cannot be used together",
214 : : "REFRESH", "CONCURRENTLY", "WITH NO DATA")));
215 : :
216 : : /*
217 : : * Check that everything is correct for a refresh. Problems at this point
218 : : * are internal errors, so elog is sufficient.
219 : : */
220 [ + - ]: 385 : if (matviewRel->rd_rel->relhasrules == false ||
221 [ - + ]: 385 : matviewRel->rd_rules->numLocks < 1)
222 [ # # ]: 0 : elog(ERROR,
223 : : "materialized view \"%s\" is missing rewrite information",
224 : : RelationGetRelationName(matviewRel));
225 : :
226 [ - + ]: 385 : if (matviewRel->rd_rules->numLocks > 1)
227 [ # # ]: 0 : elog(ERROR,
228 : : "materialized view \"%s\" has too many rules",
229 : : RelationGetRelationName(matviewRel));
230 : :
231 : 385 : rule = matviewRel->rd_rules->rules[0];
232 [ + - - + ]: 385 : if (rule->event != CMD_SELECT || !(rule->isInstead))
233 [ # # ]: 0 : elog(ERROR,
234 : : "the rule for materialized view \"%s\" is not a SELECT INSTEAD OF rule",
235 : : RelationGetRelationName(matviewRel));
236 : :
237 : 385 : actions = rule->actions;
238 [ - + ]: 385 : if (list_length(actions) != 1)
239 [ # # ]: 0 : elog(ERROR,
240 : : "the rule for materialized view \"%s\" is not a single action",
241 : : RelationGetRelationName(matviewRel));
242 : :
243 : : /*
244 : : * Check that there is a unique index with no WHERE clause on one or more
245 : : * columns of the materialized view if CONCURRENTLY is specified.
246 : : */
247 [ + + ]: 385 : if (concurrent)
248 : : {
249 : 49 : List *indexoidlist = RelationGetIndexList(matviewRel);
250 : : ListCell *indexoidscan;
251 : 49 : bool hasUniqueIndex = false;
252 : :
253 : : Assert(!is_create);
254 : :
255 [ + - + + : 57 : foreach(indexoidscan, indexoidlist)
+ + ]
256 : : {
257 : 53 : Oid indexoid = lfirst_oid(indexoidscan);
258 : : Relation indexRel;
259 : :
260 : 53 : indexRel = index_open(indexoid, AccessShareLock);
261 : 53 : hasUniqueIndex = is_usable_unique_index(indexRel);
262 : 53 : index_close(indexRel, AccessShareLock);
263 [ + + ]: 53 : if (hasUniqueIndex)
264 : 45 : break;
265 : : }
266 : :
267 : 49 : list_free(indexoidlist);
268 : :
269 [ + + ]: 49 : if (!hasUniqueIndex)
270 [ + - ]: 4 : ereport(ERROR,
271 : : (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
272 : : errmsg("cannot refresh materialized view \"%s\" concurrently",
273 : : quote_qualified_identifier(get_namespace_name(RelationGetNamespace(matviewRel)),
274 : : RelationGetRelationName(matviewRel))),
275 : : errhint("Create a unique index with no WHERE clause on one or more columns of the materialized view.")));
276 : : }
277 : :
278 : : /*
279 : : * The stored query was rewritten at the time of the MV definition, but
280 : : * has not been scribbled on by the planner.
281 : : */
282 : 381 : dataQuery = linitial_node(Query, actions);
283 : :
284 : : /*
285 : : * Check for active uses of the relation in the current transaction, such
286 : : * as open scans.
287 : : *
288 : : * NB: We count on this to protect us against problems with refreshing the
289 : : * data using TABLE_INSERT_FROZEN.
290 : : */
291 [ + + ]: 381 : CheckTableNotInUse(matviewRel,
292 : : is_create ? "CREATE MATERIALIZED VIEW" :
293 : : "REFRESH MATERIALIZED VIEW");
294 : :
295 : : /*
296 : : * Tentatively mark the matview as populated or not (this will roll back
297 : : * if we fail later).
298 : : */
299 : 381 : SetMatViewPopulatedState(matviewRel, !skipData);
300 : :
301 : : /* Concurrent refresh builds new data in temp tablespace, and does diff. */
302 [ + + ]: 381 : if (concurrent)
303 : : {
304 : 45 : tableSpace = GetDefaultTablespace(RELPERSISTENCE_TEMP, false);
305 : 45 : relpersistence = RELPERSISTENCE_TEMP;
306 : : }
307 : : else
308 : : {
309 : 336 : tableSpace = matviewRel->rd_rel->reltablespace;
310 : 336 : relpersistence = matviewRel->rd_rel->relpersistence;
311 : : }
312 : :
313 : : /*
314 : : * Create the transient table that will receive the regenerated data. Lock
315 : : * it against access by any other process until commit (by which time it
316 : : * will be gone).
317 : : */
318 : 762 : OIDNewHeap = make_new_heap(matviewOid, tableSpace,
319 : 381 : matviewRel->rd_rel->relam,
320 : : relpersistence, ExclusiveLock);
321 : : Assert(CheckRelationOidLockedByMe(OIDNewHeap, AccessExclusiveLock, false));
322 : :
323 : : /* Generate the data, if wanted. */
324 [ + - ]: 381 : if (!skipData)
325 : : {
326 : : DestReceiver *dest;
327 : :
328 : 381 : dest = CreateTransientRelDestReceiver(OIDNewHeap);
329 : 381 : processed = refresh_matview_datafill(dest, dataQuery, queryString,
330 : : is_create);
331 : : }
332 : :
333 : : /* Make the matview match the newly generated data. */
334 [ + + ]: 353 : if (concurrent)
335 : : {
336 : 45 : int old_depth = matview_maintenance_depth;
337 : :
338 [ + + ]: 45 : PG_TRY();
339 : : {
340 : 45 : refresh_by_match_merge(matviewOid, OIDNewHeap, relowner,
341 : : save_sec_context);
342 : : }
343 : 8 : PG_CATCH();
344 : : {
345 : 8 : matview_maintenance_depth = old_depth;
346 : 8 : PG_RE_THROW();
347 : : }
348 [ - + ]: 37 : PG_END_TRY();
349 : : Assert(matview_maintenance_depth == old_depth);
350 : : }
351 : : else
352 : : {
353 : 308 : refresh_by_heap_swap(matviewOid, OIDNewHeap, relpersistence);
354 : :
355 : : /*
356 : : * Inform cumulative stats system about our activity: basically, we
357 : : * truncated the matview and inserted some new data. (The concurrent
358 : : * code path above doesn't need to worry about this because the
359 : : * inserts and deletes it issues get counted by lower-level code.)
360 : : */
361 : 304 : pgstat_count_truncate(matviewRel);
362 [ + - ]: 304 : if (!skipData)
363 : 304 : pgstat_count_heap_insert(matviewRel, processed);
364 : : }
365 : :
366 : 341 : table_close(matviewRel, NoLock);
367 : :
368 : : /* Roll back any GUC changes */
369 : 341 : AtEOXact_GUC(false, save_nestlevel);
370 : :
371 : : /* Restore userid and security context */
372 : 341 : SetUserIdAndSecContext(save_userid, save_sec_context);
373 : :
374 : 341 : ObjectAddressSet(address, RelationRelationId, matviewOid);
375 : :
376 : : /*
377 : : * Save the rowcount so that pg_stat_statements can track the total number
378 : : * of rows processed by REFRESH MATERIALIZED VIEW command. Note that we
379 : : * still don't display the rowcount in the command completion tag output,
380 : : * i.e., the display_rowcount flag of CMDTAG_REFRESH_MATERIALIZED_VIEW
381 : : * command tag is left false in cmdtaglist.h. Otherwise, the change of
382 : : * completion tag output might break applications using it.
383 : : *
384 : : * When called from CREATE MATERIALIZED VIEW command, the rowcount is
385 : : * displayed with the command tag CMDTAG_SELECT.
386 : : */
387 [ + + ]: 341 : if (qc)
388 [ + + ]: 335 : SetQueryCompletion(qc,
389 : : is_create ? CMDTAG_SELECT : CMDTAG_REFRESH_MATERIALIZED_VIEW,
390 : : processed);
391 : :
392 : 341 : return address;
393 : : }
394 : :
395 : : /*
396 : : * refresh_matview_datafill
397 : : *
398 : : * Execute the given query, sending result rows to "dest" (which will
399 : : * insert them into the target matview).
400 : : *
401 : : * Returns number of rows inserted.
402 : : */
403 : : static uint64
404 : 381 : refresh_matview_datafill(DestReceiver *dest, Query *query,
405 : : const char *queryString, bool is_create)
406 : : {
407 : : List *rewritten;
408 : : PlannedStmt *plan;
409 : : QueryDesc *queryDesc;
410 : : Query *copied_query;
411 : : uint64 processed;
412 : :
413 : : /* Lock and rewrite, using a copy to preserve the original query. */
414 : 381 : copied_query = copyObject(query);
415 : 381 : AcquireRewriteLocks(copied_query, true, false);
416 : 381 : rewritten = QueryRewrite(copied_query);
417 : :
418 : : /* SELECT should never rewrite to more or less than one SELECT query */
419 [ - + ]: 381 : if (list_length(rewritten) != 1)
420 [ # # # # ]: 0 : elog(ERROR, "unexpected rewrite result for %s",
421 : : is_create ? "CREATE MATERIALIZED VIEW " : "REFRESH MATERIALIZED VIEW");
422 : 381 : query = (Query *) linitial(rewritten);
423 : :
424 : : /* Check for user-requested abort. */
425 [ - + ]: 381 : CHECK_FOR_INTERRUPTS();
426 : :
427 : : /* Plan the query which will generate data for the refresh. */
428 : 381 : plan = pg_plan_query(query, queryString, CURSOR_OPT_PARALLEL_OK, NULL, NULL);
429 : :
430 : : /*
431 : : * Use a snapshot with an updated command ID to ensure this query sees
432 : : * results of any previously executed queries. (This could only matter if
433 : : * the planner executed an allegedly-stable function that changed the
434 : : * database contents, but let's do it anyway to be safe.)
435 : : */
436 : 373 : PushCopiedSnapshot(GetActiveSnapshot());
437 : 373 : UpdateActiveSnapshotCommandId();
438 : :
439 : : /* Create a QueryDesc, redirecting output to our tuple receiver */
440 : 373 : queryDesc = CreateQueryDesc(plan, queryString,
441 : : GetActiveSnapshot(), InvalidSnapshot,
442 : : dest, NULL, NULL, 0);
443 : :
444 : : /* call ExecutorStart to prepare the plan for execution */
445 : 373 : ExecutorStart(queryDesc, 0);
446 : :
447 : : /* run the plan */
448 : 373 : ExecutorRun(queryDesc, ForwardScanDirection, 0);
449 : :
450 : 353 : processed = queryDesc->estate->es_processed;
451 : :
452 : : /* and clean up */
453 : 353 : ExecutorFinish(queryDesc);
454 : 353 : ExecutorEnd(queryDesc);
455 : :
456 : 353 : FreeQueryDesc(queryDesc);
457 : :
458 : 353 : PopActiveSnapshot();
459 : :
460 : 353 : return processed;
461 : : }
462 : :
463 : : DestReceiver *
464 : 381 : CreateTransientRelDestReceiver(Oid transientoid)
465 : : {
466 : 381 : DR_transientrel *self = palloc0_object(DR_transientrel);
467 : :
468 : 381 : self->pub.receiveSlot = transientrel_receive;
469 : 381 : self->pub.rStartup = transientrel_startup;
470 : 381 : self->pub.rShutdown = transientrel_shutdown;
471 : 381 : self->pub.rDestroy = transientrel_destroy;
472 : 381 : self->pub.mydest = DestTransientRel;
473 : 381 : self->transientoid = transientoid;
474 : :
475 : 381 : return (DestReceiver *) self;
476 : : }
477 : :
478 : : /*
479 : : * transientrel_startup --- executor startup
480 : : */
481 : : static void
482 : 373 : transientrel_startup(DestReceiver *self, int operation, TupleDesc typeinfo)
483 : : {
484 : 373 : DR_transientrel *myState = (DR_transientrel *) self;
485 : : Relation transientrel;
486 : :
487 : 373 : transientrel = table_open(myState->transientoid, NoLock);
488 : :
489 : : /*
490 : : * Fill private fields of myState for use by later routines
491 : : */
492 : 373 : myState->transientrel = transientrel;
493 : 373 : myState->output_cid = GetCurrentCommandId(true);
494 : 373 : myState->ti_options = TABLE_INSERT_SKIP_FSM | TABLE_INSERT_FROZEN;
495 : 373 : myState->bistate = GetBulkInsertState();
496 : :
497 : : /*
498 : : * Valid smgr_targblock implies something already wrote to the relation.
499 : : * This may be harmless, but this function hasn't planned for it.
500 : : */
501 : : Assert(RelationGetTargetBlock(transientrel) == InvalidBlockNumber);
502 : 373 : }
503 : :
504 : : /*
505 : : * transientrel_receive --- receive one tuple
506 : : */
507 : : static bool
508 : 2574 : transientrel_receive(TupleTableSlot *slot, DestReceiver *self)
509 : : {
510 : 2574 : DR_transientrel *myState = (DR_transientrel *) self;
511 : :
512 : : /*
513 : : * Note that the input slot might not be of the type of the target
514 : : * relation. That's supported by table_tuple_insert(), but slightly less
515 : : * efficient than inserting with the right slot - but the alternative
516 : : * would be to copy into a slot of the right type, which would not be
517 : : * cheap either. This also doesn't allow accessing per-AM data (say a
518 : : * tuple's xmin), but since we don't do that here...
519 : : */
520 : :
521 : 2574 : table_tuple_insert(myState->transientrel,
522 : : slot,
523 : : myState->output_cid,
524 : : myState->ti_options,
525 : 2574 : myState->bistate);
526 : :
527 : : /* We know this is a newly created relation, so there are no indexes */
528 : :
529 : 2574 : return true;
530 : : }
531 : :
532 : : /*
533 : : * transientrel_shutdown --- executor end
534 : : */
535 : : static void
536 : 353 : transientrel_shutdown(DestReceiver *self)
537 : : {
538 : 353 : DR_transientrel *myState = (DR_transientrel *) self;
539 : :
540 : 353 : FreeBulkInsertState(myState->bistate);
541 : :
542 : 353 : table_finish_bulk_insert(myState->transientrel, myState->ti_options);
543 : :
544 : : /* close transientrel, but keep lock until commit */
545 : 353 : table_close(myState->transientrel, NoLock);
546 : 353 : myState->transientrel = NULL;
547 : 353 : }
548 : :
549 : : /*
550 : : * transientrel_destroy --- release DestReceiver object
551 : : */
552 : : static void
553 : 0 : transientrel_destroy(DestReceiver *self)
554 : : {
555 : 0 : pfree(self);
556 : 0 : }
557 : :
558 : : /*
559 : : * refresh_by_match_merge
560 : : *
561 : : * Refresh a materialized view with transactional semantics, while allowing
562 : : * concurrent reads.
563 : : *
564 : : * This is called after a new version of the data has been created in a
565 : : * temporary table. It performs a full outer join against the old version of
566 : : * the data, producing "diff" results. This join cannot work if there are any
567 : : * duplicated rows in either the old or new versions, in the sense that every
568 : : * column would compare as equal between the two rows. It does work correctly
569 : : * in the face of rows which have at least one NULL value, with all non-NULL
570 : : * columns equal. The behavior of NULLs on equality tests and on UNIQUE
571 : : * indexes turns out to be quite convenient here; the tests we need to make
572 : : * are consistent with default behavior. If there is at least one UNIQUE
573 : : * index on the materialized view, we have exactly the guarantee we need.
574 : : *
575 : : * The temporary table used to hold the diff results contains just the TID of
576 : : * the old record (if matched) and the ROW from the new table as a single
577 : : * column of complex record type (if matched).
578 : : *
579 : : * Once we have the diff table, we perform set-based DELETE and INSERT
580 : : * operations against the materialized view, and discard both temporary
581 : : * tables.
582 : : *
583 : : * Everything from the generation of the new data to applying the differences
584 : : * takes place under cover of an ExclusiveLock, since it seems as though we
585 : : * would want to prohibit not only concurrent REFRESH operations, but also
586 : : * incremental maintenance. It also doesn't seem reasonable or safe to allow
587 : : * SELECT FOR UPDATE or SELECT FOR SHARE on rows being updated or deleted by
588 : : * this command.
589 : : */
590 : : static void
591 : 45 : refresh_by_match_merge(Oid matviewOid, Oid tempOid, Oid relowner,
592 : : int save_sec_context)
593 : : {
594 : : StringInfoData querybuf;
595 : : Relation matviewRel;
596 : : Relation tempRel;
597 : : char *matviewname;
598 : : char *tempname;
599 : : char *diffname;
600 : : char *temprelname;
601 : : char *diffrelname;
602 : : char *nsp;
603 : : TupleDesc tupdesc;
604 : : bool foundUniqueIndex;
605 : : List *indexoidlist;
606 : : ListCell *indexoidscan;
607 : : int16 relnatts;
608 : : Oid *opUsedForQual;
609 : :
610 : 45 : initStringInfo(&querybuf);
611 : 45 : matviewRel = table_open(matviewOid, NoLock);
612 : 45 : matviewname = quote_qualified_identifier(get_namespace_name(RelationGetNamespace(matviewRel)),
613 : 45 : RelationGetRelationName(matviewRel));
614 : 45 : tempRel = table_open(tempOid, NoLock);
615 : :
616 : : /*
617 : : * Build qualified names of the temporary table and the diff table. The
618 : : * only difference between them is the "_2" suffix on the diff table name.
619 : : */
620 : 45 : nsp = get_namespace_name(RelationGetNamespace(tempRel));
621 : 45 : temprelname = RelationGetRelationName(tempRel);
622 : 45 : diffrelname = psprintf("%s_2", temprelname);
623 : :
624 : 45 : tempname = quote_qualified_identifier(nsp, temprelname);
625 : 45 : diffname = quote_qualified_identifier(nsp, diffrelname);
626 : :
627 : 45 : relnatts = RelationGetNumberOfAttributes(matviewRel);
628 : :
629 : : /* Open SPI context. */
630 : 45 : SPI_connect();
631 : :
632 : : /* Analyze the temp table with the new contents. */
633 : 45 : appendStringInfo(&querybuf, "ANALYZE %s", tempname);
634 [ - + ]: 45 : if (SPI_exec(querybuf.data, 0) != SPI_OK_UTILITY)
635 [ # # ]: 0 : elog(ERROR, "SPI_exec failed: %s", querybuf.data);
636 : :
637 : : /*
638 : : * We need to ensure that there are not duplicate rows without NULLs in
639 : : * the new data set before we can count on the "diff" results. Check for
640 : : * that in a way that allows showing the first duplicated row found. Even
641 : : * after we pass this test, a unique index on the materialized view may
642 : : * find a duplicate key problem.
643 : : *
644 : : * Note: here and below, we use "tablename.*::tablerowtype" as a hack to
645 : : * keep ".*" from being expanded into multiple columns in a SELECT list.
646 : : * Compare ruleutils.c's get_variable().
647 : : */
648 : 45 : resetStringInfo(&querybuf);
649 : 45 : appendStringInfo(&querybuf,
650 : : "SELECT newdata.*::%s FROM %s newdata "
651 : : "WHERE newdata.* IS NOT NULL AND EXISTS "
652 : : "(SELECT 1 FROM %s newdata2 WHERE newdata2.* IS NOT NULL "
653 : : "AND newdata2.* OPERATOR(pg_catalog.*=) newdata.* "
654 : : "AND newdata2.ctid OPERATOR(pg_catalog.<>) "
655 : : "newdata.ctid)",
656 : : tempname, tempname, tempname);
657 [ - + ]: 45 : if (SPI_execute(querybuf.data, false, 1) != SPI_OK_SELECT)
658 [ # # ]: 0 : elog(ERROR, "SPI_exec failed: %s", querybuf.data);
659 [ + + ]: 45 : if (SPI_processed > 0)
660 : : {
661 : : /*
662 : : * Note that this ereport() is returning data to the user. Generally,
663 : : * we would want to make sure that the user has been granted access to
664 : : * this data. However, REFRESH MAT VIEW is only able to be run by the
665 : : * owner of the mat view (or a superuser) and therefore there is no
666 : : * need to check for access to data in the mat view.
667 : : */
668 [ + - ]: 4 : ereport(ERROR,
669 : : (errcode(ERRCODE_CARDINALITY_VIOLATION),
670 : : errmsg("new data for materialized view \"%s\" contains duplicate rows without any null columns",
671 : : RelationGetRelationName(matviewRel)),
672 : : errdetail("Row: %s",
673 : : SPI_getvalue(SPI_tuptable->vals[0], SPI_tuptable->tupdesc, 1))));
674 : : }
675 : :
676 : : /*
677 : : * Create the temporary "diff" table.
678 : : *
679 : : * Temporarily switch out of the SECURITY_RESTRICTED_OPERATION context,
680 : : * because you cannot create temp tables in SRO context. For extra
681 : : * paranoia, add the composite type column only after switching back to
682 : : * SRO context.
683 : : */
684 : 41 : SetUserIdAndSecContext(relowner,
685 : : save_sec_context | SECURITY_LOCAL_USERID_CHANGE);
686 : 41 : resetStringInfo(&querybuf);
687 : 41 : appendStringInfo(&querybuf,
688 : : "CREATE TEMP TABLE %s (tid pg_catalog.tid)",
689 : : diffname);
690 [ - + ]: 41 : if (SPI_exec(querybuf.data, 0) != SPI_OK_UTILITY)
691 [ # # ]: 0 : elog(ERROR, "SPI_exec failed: %s", querybuf.data);
692 : 41 : SetUserIdAndSecContext(relowner,
693 : : save_sec_context | SECURITY_RESTRICTED_OPERATION);
694 : 41 : resetStringInfo(&querybuf);
695 : 41 : appendStringInfo(&querybuf,
696 : : "ALTER TABLE %s ADD COLUMN newdata %s",
697 : : diffname, tempname);
698 [ - + ]: 41 : if (SPI_exec(querybuf.data, 0) != SPI_OK_UTILITY)
699 [ # # ]: 0 : elog(ERROR, "SPI_exec failed: %s", querybuf.data);
700 : :
701 : : /* Start building the query for populating the diff table. */
702 : 41 : resetStringInfo(&querybuf);
703 : 41 : appendStringInfo(&querybuf,
704 : : "INSERT INTO %s "
705 : : "SELECT mv.ctid AS tid, newdata.*::%s AS newdata "
706 : : "FROM %s mv FULL JOIN %s newdata ON (",
707 : : diffname, tempname, matviewname, tempname);
708 : :
709 : : /*
710 : : * Get the list of index OIDs for the table from the relcache, and look up
711 : : * each one in the pg_index syscache. We will test for equality on all
712 : : * columns present in all unique indexes which only reference columns and
713 : : * include all rows.
714 : : */
715 : 41 : tupdesc = matviewRel->rd_att;
716 : 41 : opUsedForQual = palloc0_array(Oid, relnatts);
717 : 41 : foundUniqueIndex = false;
718 : :
719 : 41 : indexoidlist = RelationGetIndexList(matviewRel);
720 : :
721 [ + + + + : 86 : foreach(indexoidscan, indexoidlist)
+ + ]
722 : : {
723 : 45 : Oid indexoid = lfirst_oid(indexoidscan);
724 : : Relation indexRel;
725 : :
726 : 45 : indexRel = index_open(indexoid, RowExclusiveLock);
727 [ + - ]: 45 : if (is_usable_unique_index(indexRel))
728 : : {
729 : 45 : Form_pg_index indexStruct = indexRel->rd_index;
730 : 45 : int indnkeyatts = indexStruct->indnkeyatts;
731 : : oidvector *indclass;
732 : : Datum indclassDatum;
733 : : int i;
734 : :
735 : : /* Must get indclass the hard way. */
736 : 45 : indclassDatum = SysCacheGetAttrNotNull(INDEXRELID,
737 : 45 : indexRel->rd_indextuple,
738 : : Anum_pg_index_indclass);
739 : 45 : indclass = (oidvector *) DatumGetPointer(indclassDatum);
740 : :
741 : : /* Add quals for all columns from this index. */
742 [ + + ]: 98 : for (i = 0; i < indnkeyatts; i++)
743 : : {
744 : 53 : int attnum = indexStruct->indkey.values[i];
745 : 53 : Oid opclass = indclass->values[i];
746 : 53 : Form_pg_attribute attr = TupleDescAttr(tupdesc, attnum - 1);
747 : 53 : Oid attrtype = attr->atttypid;
748 : : HeapTuple cla_ht;
749 : : Form_pg_opclass cla_tup;
750 : : Oid opfamily;
751 : : Oid opcintype;
752 : : Oid op;
753 : : const char *leftop;
754 : : const char *rightop;
755 : :
756 : : /*
757 : : * Identify the equality operator associated with this index
758 : : * column. First we need to look up the column's opclass.
759 : : */
760 : 53 : cla_ht = SearchSysCache1(CLAOID, ObjectIdGetDatum(opclass));
761 [ - + ]: 53 : if (!HeapTupleIsValid(cla_ht))
762 [ # # ]: 0 : elog(ERROR, "cache lookup failed for opclass %u", opclass);
763 : 53 : cla_tup = (Form_pg_opclass) GETSTRUCT(cla_ht);
764 : 53 : opfamily = cla_tup->opcfamily;
765 : 53 : opcintype = cla_tup->opcintype;
766 : 53 : ReleaseSysCache(cla_ht);
767 : :
768 : 53 : op = get_opfamily_member_for_cmptype(opfamily, opcintype, opcintype, COMPARE_EQ);
769 [ - + ]: 53 : if (!OidIsValid(op))
770 [ # # ]: 0 : elog(ERROR, "missing equality operator for (%u,%u) in opfamily %u",
771 : : opcintype, opcintype, opfamily);
772 : :
773 : : /*
774 : : * If we find the same column with the same equality semantics
775 : : * in more than one index, we only need to emit the equality
776 : : * clause once.
777 : : *
778 : : * Since we only remember the last equality operator, this
779 : : * code could be fooled into emitting duplicate clauses given
780 : : * multiple indexes with several different opclasses ... but
781 : : * that's so unlikely it doesn't seem worth spending extra
782 : : * code to avoid.
783 : : */
784 [ - + ]: 53 : if (opUsedForQual[attnum - 1] == op)
785 : 0 : continue;
786 : 53 : opUsedForQual[attnum - 1] = op;
787 : :
788 : : /*
789 : : * Actually add the qual, ANDed with any others.
790 : : */
791 [ + + ]: 53 : if (foundUniqueIndex)
792 : 16 : appendStringInfoString(&querybuf, " AND ");
793 : :
794 : 53 : leftop = quote_qualified_identifier("newdata",
795 : 53 : NameStr(attr->attname));
796 : 53 : rightop = quote_qualified_identifier("mv",
797 : 53 : NameStr(attr->attname));
798 : :
799 : 53 : generate_operator_clause(&querybuf,
800 : : leftop, attrtype,
801 : : op,
802 : : rightop, attrtype);
803 : :
804 : 53 : foundUniqueIndex = true;
805 : : }
806 : : }
807 : :
808 : : /* Keep the locks, since we're about to run DML which needs them. */
809 : 45 : index_close(indexRel, NoLock);
810 : : }
811 : :
812 : 41 : list_free(indexoidlist);
813 : :
814 : : /*
815 : : * There must be at least one usable unique index on the matview.
816 : : *
817 : : * ExecRefreshMatView() checks that after taking the exclusive lock on the
818 : : * matview. So at least one unique index is guaranteed to exist here
819 : : * because the lock is still being held. (One known exception is if a
820 : : * function called as part of refreshing the matview drops the index.
821 : : * That's a pretty silly thing to do.)
822 : : */
823 [ + + ]: 41 : if (!foundUniqueIndex)
824 [ + - ]: 4 : ereport(ERROR,
825 : : errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
826 : : errmsg("could not find suitable unique index on materialized view \"%s\"",
827 : : RelationGetRelationName(matviewRel)));
828 : :
829 : 37 : appendStringInfoString(&querybuf,
830 : : " AND newdata.* OPERATOR(pg_catalog.*=) mv.*) "
831 : : "WHERE newdata.* IS NULL OR mv.* IS NULL "
832 : : "ORDER BY tid");
833 : :
834 : : /* Populate the temporary "diff" table. */
835 [ - + ]: 37 : if (SPI_exec(querybuf.data, 0) != SPI_OK_INSERT)
836 [ # # ]: 0 : elog(ERROR, "SPI_exec failed: %s", querybuf.data);
837 : :
838 : : /*
839 : : * We have no further use for data from the "full-data" temp table, but we
840 : : * must keep it around because its type is referenced from the diff table.
841 : : */
842 : :
843 : : /* Analyze the diff table. */
844 : 37 : resetStringInfo(&querybuf);
845 : 37 : appendStringInfo(&querybuf, "ANALYZE %s", diffname);
846 [ - + ]: 37 : if (SPI_exec(querybuf.data, 0) != SPI_OK_UTILITY)
847 [ # # ]: 0 : elog(ERROR, "SPI_exec failed: %s", querybuf.data);
848 : :
849 : 37 : OpenMatViewIncrementalMaintenance();
850 : :
851 : : /* Deletes must come before inserts; do them first. */
852 : 37 : resetStringInfo(&querybuf);
853 : 37 : appendStringInfo(&querybuf,
854 : : "DELETE FROM %s mv WHERE ctid OPERATOR(pg_catalog.=) ANY "
855 : : "(SELECT diff.tid FROM %s diff "
856 : : "WHERE diff.tid IS NOT NULL "
857 : : "AND diff.newdata IS NULL)",
858 : : matviewname, diffname);
859 [ - + ]: 37 : if (SPI_exec(querybuf.data, 0) != SPI_OK_DELETE)
860 [ # # ]: 0 : elog(ERROR, "SPI_exec failed: %s", querybuf.data);
861 : :
862 : : /* Inserts go last. */
863 : 37 : resetStringInfo(&querybuf);
864 : 37 : appendStringInfo(&querybuf,
865 : : "INSERT INTO %s SELECT (diff.newdata).* "
866 : : "FROM %s diff WHERE tid IS NULL",
867 : : matviewname, diffname);
868 [ - + ]: 37 : if (SPI_exec(querybuf.data, 0) != SPI_OK_INSERT)
869 [ # # ]: 0 : elog(ERROR, "SPI_exec failed: %s", querybuf.data);
870 : :
871 : : /* We're done maintaining the materialized view. */
872 : 37 : CloseMatViewIncrementalMaintenance();
873 : 37 : table_close(tempRel, NoLock);
874 : 37 : table_close(matviewRel, NoLock);
875 : :
876 : : /* Clean up temp tables. */
877 : 37 : resetStringInfo(&querybuf);
878 : 37 : appendStringInfo(&querybuf, "DROP TABLE %s, %s", diffname, tempname);
879 [ - + ]: 37 : if (SPI_exec(querybuf.data, 0) != SPI_OK_UTILITY)
880 [ # # ]: 0 : elog(ERROR, "SPI_exec failed: %s", querybuf.data);
881 : :
882 : : /* Close SPI context. */
883 [ - + ]: 37 : if (SPI_finish() != SPI_OK_FINISH)
884 [ # # ]: 0 : elog(ERROR, "SPI_finish failed");
885 : 37 : }
886 : :
887 : : /*
888 : : * Swap the physical files of the target and transient tables, then rebuild
889 : : * the target's indexes and throw away the transient table. Security context
890 : : * swapping is handled by the called function, so it is not needed here.
891 : : */
892 : : static void
893 : 308 : refresh_by_heap_swap(Oid matviewOid, Oid OIDNewHeap, char relpersistence)
894 : : {
895 : 308 : finish_heap_swap(matviewOid, OIDNewHeap, false, false, true, true,
896 : : true, /* reindex */
897 : : RecentXmin, ReadNextMultiXactId(), relpersistence);
898 : 304 : }
899 : :
900 : : /*
901 : : * Check whether specified index is usable for match merge.
902 : : */
903 : : static bool
904 : 98 : is_usable_unique_index(Relation indexRel)
905 : : {
906 : 98 : Form_pg_index indexStruct = indexRel->rd_index;
907 : :
908 : : /*
909 : : * Must be unique, valid, immediate, non-partial, and be defined over
910 : : * plain user columns (not expressions).
911 : : */
912 [ + - ]: 98 : if (indexStruct->indisunique &&
913 [ + - ]: 98 : indexStruct->indimmediate &&
914 [ + - + + ]: 196 : indexStruct->indisvalid &&
915 : 98 : RelationGetIndexPredicate(indexRel) == NIL &&
916 [ + - ]: 94 : indexStruct->indnatts > 0)
917 : : {
918 : : /*
919 : : * The point of groveling through the index columns individually is to
920 : : * reject both index expressions and system columns. Currently,
921 : : * matviews couldn't have OID columns so there's no way to create an
922 : : * index on a system column; but maybe someday that wouldn't be true,
923 : : * so let's be safe.
924 : : */
925 : 94 : int numatts = indexStruct->indnatts;
926 : : int i;
927 : :
928 [ + + ]: 200 : for (i = 0; i < numatts; i++)
929 : : {
930 : 110 : int attnum = indexStruct->indkey.values[i];
931 : :
932 [ + + ]: 110 : if (attnum <= 0)
933 : 4 : return false;
934 : : }
935 : 90 : return true;
936 : : }
937 : 4 : return false;
938 : : }
939 : :
940 : :
941 : : /*
942 : : * This should be used to test whether the backend is in a context where it is
943 : : * OK to allow DML statements to modify materialized views. We only want to
944 : : * allow that for internal code driven by the materialized view definition,
945 : : * not for arbitrary user-supplied code.
946 : : *
947 : : * While the function names reflect the fact that their main intended use is
948 : : * incremental maintenance of materialized views (in response to changes to
949 : : * the data in referenced relations), they are initially used to allow REFRESH
950 : : * without blocking concurrent reads.
951 : : */
952 : : bool
953 : 74 : MatViewIncrementalMaintenanceIsEnabled(void)
954 : : {
955 : 74 : return matview_maintenance_depth > 0;
956 : : }
957 : :
958 : : static void
959 : 37 : OpenMatViewIncrementalMaintenance(void)
960 : : {
961 : 37 : matview_maintenance_depth++;
962 : 37 : }
963 : :
964 : : static void
965 : 37 : CloseMatViewIncrementalMaintenance(void)
966 : : {
967 : 37 : matview_maintenance_depth--;
968 : : Assert(matview_maintenance_depth >= 0);
969 : 37 : }
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