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relation.c
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1 /*-------------------------------------------------------------------------
2  * relation.c
3  * PostgreSQL logical replication
4  *
5  * Copyright (c) 2016-2017, PostgreSQL Global Development Group
6  *
7  * IDENTIFICATION
8  * src/backend/replication/logical/relation.c
9  *
10  * NOTES
11  * This file contains helper functions for logical replication relation
12  * mapping cache.
13  *
14  *-------------------------------------------------------------------------
15  */
16 
17 #include "postgres.h"
18 
19 #include "access/heapam.h"
20 #include "access/sysattr.h"
21 #include "catalog/namespace.h"
23 #include "executor/executor.h"
24 #include "nodes/makefuncs.h"
27 #include "utils/builtins.h"
28 #include "utils/inval.h"
29 #include "utils/lsyscache.h"
30 #include "utils/memutils.h"
31 #include "utils/syscache.h"
32 
34 
35 static HTAB *LogicalRepRelMap = NULL;
36 static HTAB *LogicalRepTypMap = NULL;
37 
38 static void logicalrep_typmap_invalidate_cb(Datum arg, int cacheid,
39  uint32 hashvalue);
40 
41 /*
42  * Relcache invalidation callback for our relation map cache.
43  */
44 static void
46 {
47  LogicalRepRelMapEntry *entry;
48 
49  /* Just to be sure. */
50  if (LogicalRepRelMap == NULL)
51  return;
52 
53  if (reloid != InvalidOid)
54  {
56 
57  hash_seq_init(&status, LogicalRepRelMap);
58 
59  /* TODO, use inverse lookup hashtable? */
60  while ((entry = (LogicalRepRelMapEntry *) hash_seq_search(&status)) != NULL)
61  {
62  if (entry->localreloid == reloid)
63  {
64  entry->localreloid = InvalidOid;
65  hash_seq_term(&status);
66  break;
67  }
68  }
69  }
70  else
71  {
72  /* invalidate all cache entries */
74 
75  hash_seq_init(&status, LogicalRepRelMap);
76 
77  while ((entry = (LogicalRepRelMapEntry *) hash_seq_search(&status)) != NULL)
78  entry->localreloid = InvalidOid;
79  }
80 }
81 
82 /*
83  * Initialize the relation map cache.
84  */
85 static void
87 {
88  HASHCTL ctl;
89 
90  if (!LogicalRepRelMapContext)
91  LogicalRepRelMapContext =
93  "LogicalRepRelMapContext",
95 
96  /* Initialize the relation hash table. */
97  MemSet(&ctl, 0, sizeof(ctl));
98  ctl.keysize = sizeof(LogicalRepRelId);
99  ctl.entrysize = sizeof(LogicalRepRelMapEntry);
101 
102  LogicalRepRelMap = hash_create("logicalrep relation map cache", 128, &ctl,
104 
105  /* Initialize the type hash table. */
106  MemSet(&ctl, 0, sizeof(ctl));
107  ctl.keysize = sizeof(Oid);
108  ctl.entrysize = sizeof(LogicalRepTyp);
110 
111  /* This will usually be small. */
112  LogicalRepTypMap = hash_create("logicalrep type map cache", 2, &ctl,
114 
115  /* Watch for invalidation events. */
117  (Datum) 0);
119  (Datum) 0);
120 }
121 
122 /*
123  * Free the entry of a relation map cache.
124  */
125 static void
127 {
128  LogicalRepRelation *remoterel;
129 
130  remoterel = &entry->remoterel;
131 
132  pfree(remoterel->nspname);
133  pfree(remoterel->relname);
134 
135  if (remoterel->natts > 0)
136  {
137  int i;
138 
139  for (i = 0; i < remoterel->natts; i++)
140  pfree(remoterel->attnames[i]);
141 
142  pfree(remoterel->attnames);
143  pfree(remoterel->atttyps);
144  }
145  bms_free(remoterel->attkeys);
146 
147  if (entry->attrmap)
148  pfree(entry->attrmap);
149 }
150 
151 /*
152  * Add new entry or update existing entry in the relation map cache.
153  *
154  * Called when new relation mapping is sent by the publisher to update
155  * our expected view of incoming data from said publisher.
156  */
157 void
159 {
160  MemoryContext oldctx;
161  LogicalRepRelMapEntry *entry;
162  bool found;
163  int i;
164 
165  if (LogicalRepRelMap == NULL)
167 
168  /*
169  * HASH_ENTER returns the existing entry if present or creates a new one.
170  */
171  entry = hash_search(LogicalRepRelMap, (void *) &remoterel->remoteid,
172  HASH_ENTER, &found);
173 
174  if (found)
176 
177  memset(entry, 0, sizeof(LogicalRepRelMapEntry));
178 
179  /* Make cached copy of the data */
180  oldctx = MemoryContextSwitchTo(LogicalRepRelMapContext);
181  entry->remoterel.remoteid = remoterel->remoteid;
182  entry->remoterel.nspname = pstrdup(remoterel->nspname);
183  entry->remoterel.relname = pstrdup(remoterel->relname);
184  entry->remoterel.natts = remoterel->natts;
185  entry->remoterel.attnames = palloc(remoterel->natts * sizeof(char *));
186  entry->remoterel.atttyps = palloc(remoterel->natts * sizeof(Oid));
187  for (i = 0; i < remoterel->natts; i++)
188  {
189  entry->remoterel.attnames[i] = pstrdup(remoterel->attnames[i]);
190  entry->remoterel.atttyps[i] = remoterel->atttyps[i];
191  }
192  entry->remoterel.replident = remoterel->replident;
193  entry->remoterel.attkeys = bms_copy(remoterel->attkeys);
194  MemoryContextSwitchTo(oldctx);
195 }
196 
197 /*
198  * Find attribute index in TupleDesc struct by attribute name.
199  *
200  * Returns -1 if not found.
201  */
202 static int
203 logicalrep_rel_att_by_name(LogicalRepRelation *remoterel, const char *attname)
204 {
205  int i;
206 
207  for (i = 0; i < remoterel->natts; i++)
208  {
209  if (strcmp(remoterel->attnames[i], attname) == 0)
210  return i;
211  }
212 
213  return -1;
214 }
215 
216 /*
217  * Open the local relation associated with the remote one.
218  *
219  * Optionally rebuilds the Relcache mapping if it was invalidated
220  * by local DDL.
221  */
224 {
225  LogicalRepRelMapEntry *entry;
226  bool found;
227 
228  if (LogicalRepRelMap == NULL)
230 
231  /* Search for existing entry. */
232  entry = hash_search(LogicalRepRelMap, (void *) &remoteid,
233  HASH_FIND, &found);
234 
235  if (!found)
236  elog(ERROR, "no relation map entry for remote relation ID %u",
237  remoteid);
238 
239  /* Need to update the local cache? */
240  if (!OidIsValid(entry->localreloid))
241  {
242  Oid relid;
243  int i;
244  int found;
245  Bitmapset *idkey;
246  TupleDesc desc;
247  LogicalRepRelation *remoterel;
248  MemoryContext oldctx;
249 
250  remoterel = &entry->remoterel;
251 
252  /* Try to find and lock the relation by name. */
253  relid = RangeVarGetRelid(makeRangeVar(remoterel->nspname,
254  remoterel->relname, -1),
255  lockmode, true);
256  if (!OidIsValid(relid))
257  ereport(ERROR,
258  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
259  errmsg("logical replication target relation \"%s.%s\" does not exist",
260  remoterel->nspname, remoterel->relname)));
261  entry->localrel = heap_open(relid, NoLock);
262 
263  /* Check for supported relkind. */
264  CheckSubscriptionRelkind(entry->localrel->rd_rel->relkind,
265  remoterel->nspname, remoterel->relname);
266 
267  /*
268  * Build the mapping of local attribute numbers to remote attribute
269  * numbers and validate that we don't miss any replicated columns as
270  * that would result in potentially unwanted data loss.
271  */
272  desc = RelationGetDescr(entry->localrel);
273  oldctx = MemoryContextSwitchTo(LogicalRepRelMapContext);
274  entry->attrmap = palloc(desc->natts * sizeof(int));
275  MemoryContextSwitchTo(oldctx);
276 
277  found = 0;
278  for (i = 0; i < desc->natts; i++)
279  {
280  int attnum;
281  Form_pg_attribute attr = TupleDescAttr(desc, i);
282 
283  if (attr->attisdropped)
284  {
285  entry->attrmap[i] = -1;
286  continue;
287  }
288 
289  attnum = logicalrep_rel_att_by_name(remoterel,
290  NameStr(attr->attname));
291 
292  entry->attrmap[i] = attnum;
293  if (attnum >= 0)
294  found++;
295  }
296 
297  /* TODO, detail message with names of missing columns */
298  if (found < remoterel->natts)
299  ereport(ERROR,
300  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
301  errmsg("logical replication target relation \"%s.%s\" is missing "
302  "some replicated columns",
303  remoterel->nspname, remoterel->relname)));
304 
305  /*
306  * Check that replica identity matches. We allow for stricter replica
307  * identity (fewer columns) on subscriber as that will not stop us
308  * from finding unique tuple. IE, if publisher has identity
309  * (id,timestamp) and subscriber just (id) this will not be a problem,
310  * but in the opposite scenario it will.
311  *
312  * Don't throw any error here just mark the relation entry as not
313  * updatable, as replica identity is only for updates and deletes but
314  * inserts can be replicated even without it.
315  */
316  entry->updatable = true;
317  idkey = RelationGetIndexAttrBitmap(entry->localrel,
319  /* fallback to PK if no replica identity */
320  if (idkey == NULL)
321  {
322  idkey = RelationGetIndexAttrBitmap(entry->localrel,
324 
325  /*
326  * If no replica identity index and no PK, the published table
327  * must have replica identity FULL.
328  */
329  if (idkey == NULL && remoterel->replident != REPLICA_IDENTITY_FULL)
330  entry->updatable = false;
331  }
332 
333  i = -1;
334  while ((i = bms_next_member(idkey, i)) >= 0)
335  {
336  int attnum = i + FirstLowInvalidHeapAttributeNumber;
337 
338  if (!AttrNumberIsForUserDefinedAttr(attnum))
339  ereport(ERROR,
340  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
341  errmsg("logical replication target relation \"%s.%s\" uses "
342  "system columns in REPLICA IDENTITY index",
343  remoterel->nspname, remoterel->relname)));
344 
345  attnum = AttrNumberGetAttrOffset(attnum);
346 
347  if (!bms_is_member(entry->attrmap[attnum], remoterel->attkeys))
348  {
349  entry->updatable = false;
350  break;
351  }
352  }
353 
354  entry->localreloid = relid;
355  }
356  else
357  entry->localrel = heap_open(entry->localreloid, lockmode);
358 
359  if (entry->state != SUBREL_STATE_READY)
361  entry->localreloid,
362  &entry->statelsn,
363  true);
364 
365  return entry;
366 }
367 
368 /*
369  * Close the previously opened logical relation.
370  */
371 void
373 {
374  heap_close(rel->localrel, lockmode);
375  rel->localrel = NULL;
376 }
377 
378 
379 /*
380  * Type cache invalidation callback for our type map cache.
381  */
382 static void
384 {
386  LogicalRepTyp *entry;
387 
388  /* Just to be sure. */
389  if (LogicalRepTypMap == NULL)
390  return;
391 
392  /* invalidate all cache entries */
393  hash_seq_init(&status, LogicalRepTypMap);
394 
395  while ((entry = (LogicalRepTyp *) hash_seq_search(&status)) != NULL)
396  entry->typoid = InvalidOid;
397 }
398 
399 /*
400  * Free the type map cache entry data.
401  */
402 static void
404 {
405  pfree(entry->nspname);
406  pfree(entry->typname);
407 
408  entry->typoid = InvalidOid;
409 }
410 
411 /*
412  * Add new entry or update existing entry in the type map cache.
413  */
414 void
416 {
417  MemoryContext oldctx;
418  LogicalRepTyp *entry;
419  bool found;
420 
421  if (LogicalRepTypMap == NULL)
423 
424  /*
425  * HASH_ENTER returns the existing entry if present or creates a new one.
426  */
427  entry = hash_search(LogicalRepTypMap, (void *) &remotetyp->remoteid,
428  HASH_ENTER, &found);
429 
430  if (found)
432 
433  /* Make cached copy of the data */
434  entry->remoteid = remotetyp->remoteid;
435  oldctx = MemoryContextSwitchTo(LogicalRepRelMapContext);
436  entry->nspname = pstrdup(remotetyp->nspname);
437  entry->typname = pstrdup(remotetyp->typname);
438  MemoryContextSwitchTo(oldctx);
439  entry->typoid = InvalidOid;
440 }
441 
442 /*
443  * Fetch type info from the cache.
444  */
445 Oid
447 {
448  LogicalRepTyp *entry;
449  bool found;
450  Oid nspoid;
451 
452  /* Internal types are mapped directly. */
453  if (remoteid < FirstNormalObjectId)
454  {
455  if (!get_typisdefined(remoteid))
456  ereport(ERROR,
457  (errmsg("built-in type %u not found", remoteid),
458  errhint("This can be caused by having a publisher with a higher PostgreSQL major version than the subscriber.")));
459  return remoteid;
460  }
461 
462  if (LogicalRepTypMap == NULL)
464 
465  /* Try finding the mapping. */
466  entry = hash_search(LogicalRepTypMap, (void *) &remoteid,
467  HASH_FIND, &found);
468 
469  if (!found)
470  elog(ERROR, "no type map entry for remote type %u",
471  remoteid);
472 
473  /* Found and mapped, return the oid. */
474  if (OidIsValid(entry->typoid))
475  return entry->typoid;
476 
477  /* Otherwise, try to map to local type. */
478  nspoid = LookupExplicitNamespace(entry->nspname, true);
479  if (OidIsValid(nspoid))
481  PointerGetDatum(entry->typname),
482  ObjectIdGetDatum(nspoid));
483  else
484  entry->typoid = InvalidOid;
485 
486  if (!OidIsValid(entry->typoid))
487  ereport(ERROR,
488  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
489  errmsg("data type \"%s.%s\" required for logical replication does not exist",
490  entry->nspname, entry->typname)));
491 
492  return entry->typoid;
493 }
Subscription * MySubscription
Definition: worker.c:112
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Definition: relation.c:126
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Definition: rel.h:114
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Definition: relation.c:36
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Definition: relation.c:45
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struct LogicalRepRelMapEntry LogicalRepRelMapEntry
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