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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 
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 = logicalrep_rel_att_by_name(remoterel,
281  NameStr(desc->attrs[i]->attname));
282 
283  entry->attrmap[i] = attnum;
284  if (attnum >= 0)
285  found++;
286  }
287 
288  /* TODO, detail message with names of missing columns */
289  if (found < remoterel->natts)
290  ereport(ERROR,
291  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
292  errmsg("logical replication target relation \"%s.%s\" is missing "
293  "some replicated columns",
294  remoterel->nspname, remoterel->relname)));
295 
296  /*
297  * Check that replica identity matches. We allow for stricter replica
298  * identity (fewer columns) on subscriber as that will not stop us
299  * from finding unique tuple. IE, if publisher has identity
300  * (id,timestamp) and subscriber just (id) this will not be a problem,
301  * but in the opposite scenario it will.
302  *
303  * Don't throw any error here just mark the relation entry as not
304  * updatable, as replica identity is only for updates and deletes but
305  * inserts can be replicated even without it.
306  */
307  entry->updatable = true;
308  idkey = RelationGetIndexAttrBitmap(entry->localrel,
310  /* fallback to PK if no replica identity */
311  if (idkey == NULL)
312  {
313  idkey = RelationGetIndexAttrBitmap(entry->localrel,
315 
316  /*
317  * If no replica identity index and no PK, the published table
318  * must have replica identity FULL.
319  */
320  if (idkey == NULL && remoterel->replident != REPLICA_IDENTITY_FULL)
321  entry->updatable = false;
322  }
323 
324  i = -1;
325  while ((i = bms_next_member(idkey, i)) >= 0)
326  {
327  int attnum = i + FirstLowInvalidHeapAttributeNumber;
328 
329  if (!AttrNumberIsForUserDefinedAttr(attnum))
330  ereport(ERROR,
331  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
332  errmsg("logical replication target relation \"%s.%s\" uses "
333  "system columns in REPLICA IDENTITY index",
334  remoterel->nspname, remoterel->relname)));
335 
336  attnum = AttrNumberGetAttrOffset(attnum);
337 
338  if (!bms_is_member(entry->attrmap[attnum], remoterel->attkeys))
339  {
340  entry->updatable = false;
341  break;
342  }
343  }
344 
345  entry->localreloid = relid;
346  }
347  else
348  entry->localrel = heap_open(entry->localreloid, lockmode);
349 
350  if (entry->state != SUBREL_STATE_READY)
352  entry->localreloid,
353  &entry->statelsn,
354  true);
355 
356  return entry;
357 }
358 
359 /*
360  * Close the previously opened logical relation.
361  */
362 void
364 {
365  heap_close(rel->localrel, lockmode);
366  rel->localrel = NULL;
367 }
368 
369 
370 /*
371  * Type cache invalidation callback for our type map cache.
372  */
373 static void
375 {
377  LogicalRepTyp *entry;
378 
379  /* Just to be sure. */
380  if (LogicalRepTypMap == NULL)
381  return;
382 
383  /* invalidate all cache entries */
384  hash_seq_init(&status, LogicalRepTypMap);
385 
386  while ((entry = (LogicalRepTyp *) hash_seq_search(&status)) != NULL)
387  entry->typoid = InvalidOid;
388 }
389 
390 /*
391  * Free the type map cache entry data.
392  */
393 static void
395 {
396  pfree(entry->nspname);
397  pfree(entry->typname);
398 
399  entry->typoid = InvalidOid;
400 }
401 
402 /*
403  * Add new entry or update existing entry in the type map cache.
404  */
405 void
407 {
408  MemoryContext oldctx;
409  LogicalRepTyp *entry;
410  bool found;
411 
412  if (LogicalRepTypMap == NULL)
414 
415  /*
416  * HASH_ENTER returns the existing entry if present or creates a new one.
417  */
418  entry = hash_search(LogicalRepTypMap, (void *) &remotetyp->remoteid,
419  HASH_ENTER, &found);
420 
421  if (found)
423 
424  /* Make cached copy of the data */
425  entry->remoteid = remotetyp->remoteid;
426  oldctx = MemoryContextSwitchTo(LogicalRepRelMapContext);
427  entry->nspname = pstrdup(remotetyp->nspname);
428  entry->typname = pstrdup(remotetyp->typname);
429  MemoryContextSwitchTo(oldctx);
430  entry->typoid = InvalidOid;
431 }
432 
433 /*
434  * Fetch type info from the cache.
435  */
436 Oid
438 {
439  LogicalRepTyp *entry;
440  bool found;
441  Oid nspoid;
442 
443  /* Internal types are mapped directly. */
444  if (remoteid < FirstNormalObjectId)
445  {
446  if (!get_typisdefined(remoteid))
447  ereport(ERROR,
448  (errmsg("builtin type %u not found", remoteid),
449  errhint("This can be caused by having publisher with "
450  "higher major version than subscriber")));
451  return remoteid;
452  }
453 
454  if (LogicalRepTypMap == NULL)
456 
457  /* Try finding the mapping. */
458  entry = hash_search(LogicalRepTypMap, (void *) &remoteid,
459  HASH_FIND, &found);
460 
461  if (!found)
462  elog(ERROR, "no type map entry for remote type %u",
463  remoteid);
464 
465  /* Found and mapped, return the oid. */
466  if (OidIsValid(entry->typoid))
467  return entry->typoid;
468 
469  /* Otherwise, try to map to local type. */
470  nspoid = LookupExplicitNamespace(entry->nspname, true);
471  if (OidIsValid(nspoid))
473  PointerGetDatum(entry->typname),
474  ObjectIdGetDatum(nspoid));
475  else
476  entry->typoid = InvalidOid;
477 
478  if (!OidIsValid(entry->typoid))
479  ereport(ERROR,
480  (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
481  errmsg("data type \"%s.%s\" required for logical replication does not exist",
482  entry->nspname, entry->typname)));
483 
484  return entry->typoid;
485 }
Subscription * MySubscription
Definition: worker.c:109
static void logicalrep_relmap_free_entry(LogicalRepRelMapEntry *entry)
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:158
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Definition: relation.c:203
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Definition: relation.c:45
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Definition: relation.c:223
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struct LogicalRepRelMapEntry LogicalRepRelMapEntry
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