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toasting.c
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1 /*-------------------------------------------------------------------------
2  *
3  * toasting.c
4  * This file contains routines to support creation of toast tables
5  *
6  *
7  * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
8  * Portions Copyright (c) 1994, Regents of the University of California
9  *
10  * IDENTIFICATION
11  * src/backend/catalog/toasting.c
12  *
13  *-------------------------------------------------------------------------
14  */
15 #include "postgres.h"
16 
17 #include "access/heapam.h"
19 #include "access/xact.h"
20 #include "catalog/binary_upgrade.h"
21 #include "catalog/catalog.h"
22 #include "catalog/dependency.h"
23 #include "catalog/heap.h"
24 #include "catalog/index.h"
25 #include "catalog/namespace.h"
26 #include "catalog/pg_am.h"
27 #include "catalog/pg_namespace.h"
28 #include "catalog/pg_opclass.h"
29 #include "catalog/pg_type.h"
30 #include "catalog/toasting.h"
31 #include "miscadmin.h"
32 #include "nodes/makefuncs.h"
33 #include "storage/lock.h"
34 #include "utils/builtins.h"
35 #include "utils/rel.h"
36 #include "utils/syscache.h"
37 
38 static void CheckAndCreateToastTable(Oid relOid, Datum reloptions,
39  LOCKMODE lockmode, bool check);
40 static bool create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
41  Datum reloptions, LOCKMODE lockmode, bool check);
42 static bool needs_toast_table(Relation rel);
43 
44 
45 /*
46  * CreateToastTable variants
47  * If the table needs a toast table, and doesn't already have one,
48  * then create a toast table for it.
49  *
50  * reloptions for the toast table can be passed, too. Pass (Datum) 0
51  * for default reloptions.
52  *
53  * We expect the caller to have verified that the relation is a table and have
54  * already done any necessary permission checks. Callers expect this function
55  * to end with CommandCounterIncrement if it makes any changes.
56  */
57 void
58 AlterTableCreateToastTable(Oid relOid, Datum reloptions, LOCKMODE lockmode)
59 {
60  CheckAndCreateToastTable(relOid, reloptions, lockmode, true);
61 }
62 
63 void
64 NewHeapCreateToastTable(Oid relOid, Datum reloptions, LOCKMODE lockmode)
65 {
66  CheckAndCreateToastTable(relOid, reloptions, lockmode, false);
67 }
68 
69 void
71 {
72  CheckAndCreateToastTable(relOid, reloptions, AccessExclusiveLock, false);
73 }
74 
75 static void
76 CheckAndCreateToastTable(Oid relOid, Datum reloptions, LOCKMODE lockmode, bool check)
77 {
78  Relation rel;
79 
80  rel = table_open(relOid, lockmode);
81 
82  /* create_toast_table does all the work */
83  (void) create_toast_table(rel, InvalidOid, InvalidOid, reloptions, lockmode, check);
84 
85  table_close(rel, NoLock);
86 }
87 
88 /*
89  * Create a toast table during bootstrap
90  *
91  * Here we need to prespecify the OIDs of the toast table and its index
92  */
93 void
94 BootstrapToastTable(char *relName, Oid toastOid, Oid toastIndexOid)
95 {
96  Relation rel;
97 
98  rel = table_openrv(makeRangeVar(NULL, relName, -1), AccessExclusiveLock);
99 
100  if (rel->rd_rel->relkind != RELKIND_RELATION &&
101  rel->rd_rel->relkind != RELKIND_MATVIEW)
102  elog(ERROR, "\"%s\" is not a table or materialized view",
103  relName);
104 
105  /* create_toast_table does all the work */
106  if (!create_toast_table(rel, toastOid, toastIndexOid, (Datum) 0,
107  AccessExclusiveLock, false))
108  elog(ERROR, "\"%s\" does not require a toast table",
109  relName);
110 
111  table_close(rel, NoLock);
112 }
113 
114 
115 /*
116  * create_toast_table --- internal workhorse
117  *
118  * rel is already opened and locked
119  * toastOid and toastIndexOid are normally InvalidOid, but during
120  * bootstrap they can be nonzero to specify hand-assigned OIDs
121  */
122 static bool
123 create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
124  Datum reloptions, LOCKMODE lockmode, bool check)
125 {
126  Oid relOid = RelationGetRelid(rel);
127  HeapTuple reltup;
128  TupleDesc tupdesc;
129  bool shared_relation;
130  bool mapped_relation;
131  Relation toast_rel;
132  Relation class_rel;
133  Oid toast_relid;
134  Oid namespaceid;
135  char toast_relname[NAMEDATALEN];
136  char toast_idxname[NAMEDATALEN];
137  IndexInfo *indexInfo;
138  Oid collationObjectId[2];
139  Oid classObjectId[2];
140  int16 coloptions[2];
141  ObjectAddress baseobject,
142  toastobject;
143 
144  /*
145  * Is it already toasted?
146  */
147  if (rel->rd_rel->reltoastrelid != InvalidOid)
148  return false;
149 
150  /*
151  * Check to see whether the table actually needs a TOAST table.
152  */
153  if (!IsBinaryUpgrade)
154  {
155  /* Normal mode, normal check */
156  if (!needs_toast_table(rel))
157  return false;
158  }
159  else
160  {
161  /*
162  * In binary-upgrade mode, create a TOAST table if and only if
163  * pg_upgrade told us to (ie, a TOAST table OID has been provided).
164  *
165  * This indicates that the old cluster had a TOAST table for the
166  * current table. We must create a TOAST table to receive the old
167  * TOAST file, even if the table seems not to need one.
168  *
169  * Contrariwise, if the old cluster did not have a TOAST table, we
170  * should be able to get along without one even if the new version's
171  * needs_toast_table rules suggest we should have one. There is a lot
172  * of daylight between where we will create a TOAST table and where
173  * one is really necessary to avoid failures, so small cross-version
174  * differences in the when-to-create heuristic shouldn't be a problem.
175  * If we tried to create a TOAST table anyway, we would have the
176  * problem that it might take up an OID that will conflict with some
177  * old-cluster table we haven't seen yet.
178  */
180  return false;
181  }
182 
183  /*
184  * If requested check lockmode is sufficient. This is a cross check in
185  * case of errors or conflicting decisions in earlier code.
186  */
187  if (check && lockmode != AccessExclusiveLock)
188  elog(ERROR, "AccessExclusiveLock required to add toast table.");
189 
190  /*
191  * Create the toast table and its index
192  */
193  snprintf(toast_relname, sizeof(toast_relname),
194  "pg_toast_%u", relOid);
195  snprintf(toast_idxname, sizeof(toast_idxname),
196  "pg_toast_%u_index", relOid);
197 
198  /* this is pretty painful... need a tuple descriptor */
199  tupdesc = CreateTemplateTupleDesc(3);
200  TupleDescInitEntry(tupdesc, (AttrNumber) 1,
201  "chunk_id",
202  OIDOID,
203  -1, 0);
204  TupleDescInitEntry(tupdesc, (AttrNumber) 2,
205  "chunk_seq",
206  INT4OID,
207  -1, 0);
208  TupleDescInitEntry(tupdesc, (AttrNumber) 3,
209  "chunk_data",
210  BYTEAOID,
211  -1, 0);
212 
213  /*
214  * Ensure that the toast table doesn't itself get toasted, or we'll be
215  * toast :-(. This is essential for chunk_data because type bytea is
216  * toastable; hit the other two just to be sure.
217  */
218  TupleDescAttr(tupdesc, 0)->attstorage = TYPSTORAGE_PLAIN;
219  TupleDescAttr(tupdesc, 1)->attstorage = TYPSTORAGE_PLAIN;
220  TupleDescAttr(tupdesc, 2)->attstorage = TYPSTORAGE_PLAIN;
221 
222  /* Toast field should not be compressed */
223  TupleDescAttr(tupdesc, 0)->attcompression = InvalidCompressionMethod;
224  TupleDescAttr(tupdesc, 1)->attcompression = InvalidCompressionMethod;
225  TupleDescAttr(tupdesc, 2)->attcompression = InvalidCompressionMethod;
226 
227  /*
228  * Toast tables for regular relations go in pg_toast; those for temp
229  * relations go into the per-backend temp-toast-table namespace.
230  */
231  if (isTempOrTempToastNamespace(rel->rd_rel->relnamespace))
232  namespaceid = GetTempToastNamespace();
233  else
234  namespaceid = PG_TOAST_NAMESPACE;
235 
236  /* Toast table is shared if and only if its parent is. */
237  shared_relation = rel->rd_rel->relisshared;
238 
239  /* It's mapped if and only if its parent is, too */
240  mapped_relation = RelationIsMapped(rel);
241 
242  toast_relid = heap_create_with_catalog(toast_relname,
243  namespaceid,
244  rel->rd_rel->reltablespace,
245  toastOid,
246  InvalidOid,
247  InvalidOid,
248  rel->rd_rel->relowner,
250  tupdesc,
251  NIL,
252  RELKIND_TOASTVALUE,
253  rel->rd_rel->relpersistence,
254  shared_relation,
255  mapped_relation,
257  reloptions,
258  false,
259  true,
260  true,
261  InvalidOid,
262  NULL);
263  Assert(toast_relid != InvalidOid);
264 
265  /* make the toast relation visible, else table_open will fail */
267 
268  /* ShareLock is not really needed here, but take it anyway */
269  toast_rel = table_open(toast_relid, ShareLock);
270 
271  /*
272  * Create unique index on chunk_id, chunk_seq.
273  *
274  * NOTE: the normal TOAST access routines could actually function with a
275  * single-column index on chunk_id only. However, the slice access
276  * routines use both columns for faster access to an individual chunk. In
277  * addition, we want it to be unique as a check against the possibility of
278  * duplicate TOAST chunk OIDs. The index might also be a little more
279  * efficient this way, since btree isn't all that happy with large numbers
280  * of equal keys.
281  */
282 
283  indexInfo = makeNode(IndexInfo);
284  indexInfo->ii_NumIndexAttrs = 2;
285  indexInfo->ii_NumIndexKeyAttrs = 2;
286  indexInfo->ii_IndexAttrNumbers[0] = 1;
287  indexInfo->ii_IndexAttrNumbers[1] = 2;
288  indexInfo->ii_Expressions = NIL;
289  indexInfo->ii_ExpressionsState = NIL;
290  indexInfo->ii_Predicate = NIL;
291  indexInfo->ii_PredicateState = NULL;
292  indexInfo->ii_ExclusionOps = NULL;
293  indexInfo->ii_ExclusionProcs = NULL;
294  indexInfo->ii_ExclusionStrats = NULL;
295  indexInfo->ii_OpclassOptions = NULL;
296  indexInfo->ii_Unique = true;
297  indexInfo->ii_ReadyForInserts = true;
298  indexInfo->ii_Concurrent = false;
299  indexInfo->ii_BrokenHotChain = false;
300  indexInfo->ii_ParallelWorkers = 0;
301  indexInfo->ii_Am = BTREE_AM_OID;
302  indexInfo->ii_AmCache = NULL;
303  indexInfo->ii_Context = CurrentMemoryContext;
304 
305  collationObjectId[0] = InvalidOid;
306  collationObjectId[1] = InvalidOid;
307 
308  classObjectId[0] = OID_BTREE_OPS_OID;
309  classObjectId[1] = INT4_BTREE_OPS_OID;
310 
311  coloptions[0] = 0;
312  coloptions[1] = 0;
313 
314  index_create(toast_rel, toast_idxname, toastIndexOid, InvalidOid,
316  indexInfo,
317  list_make2("chunk_id", "chunk_seq"),
318  BTREE_AM_OID,
319  rel->rd_rel->reltablespace,
320  collationObjectId, classObjectId, coloptions, (Datum) 0,
321  INDEX_CREATE_IS_PRIMARY, 0, true, true, NULL);
322 
323  table_close(toast_rel, NoLock);
324 
325  /*
326  * Store the toast table's OID in the parent relation's pg_class row
327  */
328  class_rel = table_open(RelationRelationId, RowExclusiveLock);
329 
330  reltup = SearchSysCacheCopy1(RELOID, ObjectIdGetDatum(relOid));
331  if (!HeapTupleIsValid(reltup))
332  elog(ERROR, "cache lookup failed for relation %u", relOid);
333 
334  ((Form_pg_class) GETSTRUCT(reltup))->reltoastrelid = toast_relid;
335 
337  {
338  /* normal case, use a transactional update */
339  CatalogTupleUpdate(class_rel, &reltup->t_self, reltup);
340  }
341  else
342  {
343  /* While bootstrapping, we cannot UPDATE, so overwrite in-place */
344  heap_inplace_update(class_rel, reltup);
345  }
346 
347  heap_freetuple(reltup);
348 
349  table_close(class_rel, RowExclusiveLock);
350 
351  /*
352  * Register dependency from the toast table to the main, so that the toast
353  * table will be deleted if the main is. Skip this in bootstrap mode.
354  */
356  {
357  baseobject.classId = RelationRelationId;
358  baseobject.objectId = relOid;
359  baseobject.objectSubId = 0;
360  toastobject.classId = RelationRelationId;
361  toastobject.objectId = toast_relid;
362  toastobject.objectSubId = 0;
363 
364  recordDependencyOn(&toastobject, &baseobject, DEPENDENCY_INTERNAL);
365  }
366 
367  /*
368  * Make changes visible
369  */
371 
372  return true;
373 }
374 
375 /*
376  * Check to see whether the table needs a TOAST table.
377  */
378 static bool
380 {
381  /*
382  * No need to create a TOAST table for partitioned tables.
383  */
384  if (rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE)
385  return false;
386 
387  /*
388  * We cannot allow toasting a shared relation after initdb (because
389  * there's no way to mark it toasted in other databases' pg_class).
390  */
391  if (rel->rd_rel->relisshared && !IsBootstrapProcessingMode())
392  return false;
393 
394  /*
395  * Ignore attempts to create toast tables on catalog tables after initdb.
396  * Which catalogs get toast tables is explicitly chosen in catalog/pg_*.h.
397  * (We could get here via some ALTER TABLE command if the catalog doesn't
398  * have a toast table.)
399  */
401  return false;
402 
403  /* Otherwise, let the AM decide. */
405 }
#define list_make2(x1, x2)
Definition: pg_list.h:208
signed short int16
Definition: c.h:428
#define NIL
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void table_close(Relation relation, LOCKMODE lockmode)
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#define GETSTRUCT(TUP)
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List * ii_Predicate
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void AlterTableCreateToastTable(Oid relOid, Datum reloptions, LOCKMODE lockmode)
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int LOCKMODE
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Oid binary_upgrade_next_toast_pg_class_oid
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Oid index_create(Relation heapRelation, const char *indexRelationName, Oid indexRelationId, Oid parentIndexRelid, Oid parentConstraintId, Oid relFileNode, IndexInfo *indexInfo, List *indexColNames, Oid accessMethodObjectId, Oid tableSpaceId, Oid *collationObjectId, Oid *classObjectId, int16 *coloptions, Datum reloptions, bits16 flags, bits16 constr_flags, bool allow_system_table_mods, bool is_internal, Oid *constraintId)
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Definition: toasting.c:123
void BootstrapToastTable(char *relName, Oid toastOid, Oid toastIndexOid)
Definition: toasting.c:94
#define NAMEDATALEN
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static void CheckAndCreateToastTable(Oid relOid, Datum reloptions, LOCKMODE lockmode, bool check)
Definition: toasting.c:76
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#define ERROR
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