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toast_internals.h File Reference
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Data Structures

struct  toast_compress_header
 

Macros

#define TOAST_COMPRESS_EXTSIZE(ptr)   (((toast_compress_header *) (ptr))->tcinfo & VARLENA_EXTSIZE_MASK)
 
#define TOAST_COMPRESS_METHOD(ptr)   (((toast_compress_header *) (ptr))->tcinfo >> VARLENA_EXTSIZE_BITS)
 
#define TOAST_COMPRESS_SET_SIZE_AND_COMPRESS_METHOD(ptr, len, cm_method)
 

Typedefs

typedef struct toast_compress_header toast_compress_header
 

Functions

Datum toast_compress_datum (Datum value, char cmethod)
 
Oid toast_get_valid_index (Oid toastoid, LOCKMODE lock)
 
void toast_delete_datum (Relation rel, Datum value, bool is_speculative)
 
Datum toast_save_datum (Relation rel, Datum value, struct varlena *oldexternal, int options)
 
int toast_open_indexes (Relation toastrel, LOCKMODE lock, Relation **toastidxs, int *num_indexes)
 
void toast_close_indexes (Relation *toastidxs, int num_indexes, LOCKMODE lock)
 
void init_toast_snapshot (Snapshot toast_snapshot)
 

Macro Definition Documentation

◆ TOAST_COMPRESS_EXTSIZE

#define TOAST_COMPRESS_EXTSIZE (   ptr)    (((toast_compress_header *) (ptr))->tcinfo & VARLENA_EXTSIZE_MASK)

Definition at line 34 of file toast_internals.h.

Referenced by toast_decompress_datum_slice().

◆ TOAST_COMPRESS_METHOD

#define TOAST_COMPRESS_METHOD (   ptr)    (((toast_compress_header *) (ptr))->tcinfo >> VARLENA_EXTSIZE_BITS)

Definition at line 36 of file toast_internals.h.

Referenced by toast_decompress_datum(), and toast_decompress_datum_slice().

◆ TOAST_COMPRESS_SET_SIZE_AND_COMPRESS_METHOD

#define TOAST_COMPRESS_SET_SIZE_AND_COMPRESS_METHOD (   ptr,
  len,
  cm_method 
)
Value:
do { \
Assert((len) > 0 && (len) <= VARLENA_EXTSIZE_MASK); \
Assert((cm_method) == TOAST_PGLZ_COMPRESSION_ID || \
(cm_method) == TOAST_LZ4_COMPRESSION_ID); \
((toast_compress_header *) (ptr))->tcinfo = \
(len) | ((uint32) (cm_method) << VARLENA_EXTSIZE_BITS); \
} while (0)
#define VARLENA_EXTSIZE_BITS
Definition: postgres.h:82
#define VARLENA_EXTSIZE_MASK
Definition: postgres.h:83
unsigned int uint32
Definition: c.h:441

Definition at line 39 of file toast_internals.h.

Referenced by toast_compress_datum().

Typedef Documentation

◆ toast_compress_header

Function Documentation

◆ init_toast_snapshot()

void init_toast_snapshot ( Snapshot  toast_snapshot)

Definition at line 639 of file toast_internals.c.

References elog, ERROR, GetOldestSnapshot(), InitToastSnapshot, SnapshotData::lsn, and SnapshotData::whenTaken.

Referenced by check_toasted_attribute(), heap_fetch_toast_slice(), and toast_delete_datum().

640 {
641  Snapshot snapshot = GetOldestSnapshot();
642 
643  /*
644  * GetOldestSnapshot returns NULL if the session has no active snapshots.
645  * We can get that if, for example, a procedure fetches a toasted value
646  * into a local variable, commits, and then tries to detoast the value.
647  * Such coding is unsafe, because once we commit there is nothing to
648  * prevent the toast data from being deleted. Detoasting *must* happen in
649  * the same transaction that originally fetched the toast pointer. Hence,
650  * rather than trying to band-aid over the problem, throw an error. (This
651  * is not very much protection, because in many scenarios the procedure
652  * would have already created a new transaction snapshot, preventing us
653  * from detecting the problem. But it's better than nothing, and for sure
654  * we shouldn't expend code on masking the problem more.)
655  */
656  if (snapshot == NULL)
657  elog(ERROR, "cannot fetch toast data without an active snapshot");
658 
659  InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
660 }
XLogRecPtr lsn
Definition: snapshot.h:209
#define ERROR
Definition: elog.h:46
Snapshot GetOldestSnapshot(void)
Definition: snapmgr.c:357
#define elog(elevel,...)
Definition: elog.h:232
TimestampTz whenTaken
Definition: snapshot.h:208
#define InitToastSnapshot(snapshotdata, l, w)
Definition: snapmgr.h:90

◆ toast_close_indexes()

void toast_close_indexes ( Relation toastidxs,
int  num_indexes,
LOCKMODE  lock 
)

Definition at line 620 of file toast_internals.c.

References i, index_close(), and pfree().

Referenced by heap_fetch_toast_slice(), toast_delete_datum(), toast_get_valid_index(), toast_save_datum(), toastrel_valueid_exists(), and verify_heapam().

621 {
622  int i;
623 
624  /* Close relations and clean up things */
625  for (i = 0; i < num_indexes; i++)
626  index_close(toastidxs[i], lock);
627  pfree(toastidxs);
628 }
void pfree(void *pointer)
Definition: mcxt.c:1169
void index_close(Relation relation, LOCKMODE lockmode)
Definition: indexam.c:158
int i

◆ toast_compress_datum()

Datum toast_compress_datum ( Datum  value,
char  cmethod 
)

Definition at line 47 of file toast_internals.c.

References Assert, CompressionMethodIsValid, DatumGetPointer, default_toast_compression, elog, ERROR, lz4_compress_datum(), pfree(), pglz_compress_datum(), PointerGetDatum, TOAST_COMPRESS_SET_SIZE_AND_COMPRESS_METHOD, TOAST_INVALID_COMPRESSION_ID, TOAST_LZ4_COMPRESSION, TOAST_LZ4_COMPRESSION_ID, TOAST_PGLZ_COMPRESSION, TOAST_PGLZ_COMPRESSION_ID, VARATT_IS_COMPRESSED, VARATT_IS_EXTERNAL, VARSIZE, and VARSIZE_ANY_EXHDR.

Referenced by brin_form_tuple(), index_form_tuple(), and toast_tuple_try_compression().

48 {
49  struct varlena *tmp = NULL;
50  int32 valsize;
52 
55 
57 
58  /* If the compression method is not valid, use the current default */
59  if (!CompressionMethodIsValid(cmethod))
60  cmethod = default_toast_compression;
61 
62  /*
63  * Call appropriate compression routine for the compression method.
64  */
65  switch (cmethod)
66  {
68  tmp = pglz_compress_datum((const struct varlena *) value);
70  break;
72  tmp = lz4_compress_datum((const struct varlena *) value);
74  break;
75  default:
76  elog(ERROR, "invalid compression method %c", cmethod);
77  }
78 
79  if (tmp == NULL)
80  return PointerGetDatum(NULL);
81 
82  /*
83  * We recheck the actual size even if compression reports success, because
84  * it might be satisfied with having saved as little as one byte in the
85  * compressed data --- which could turn into a net loss once you consider
86  * header and alignment padding. Worst case, the compressed format might
87  * require three padding bytes (plus header, which is included in
88  * VARSIZE(tmp)), whereas the uncompressed format would take only one
89  * header byte and no padding if the value is short enough. So we insist
90  * on a savings of more than 2 bytes to ensure we have a gain.
91  */
92  if (VARSIZE(tmp) < valsize - 2)
93  {
94  /* successful compression */
97  return PointerGetDatum(tmp);
98  }
99  else
100  {
101  /* incompressible data */
102  pfree(tmp);
103  return PointerGetDatum(NULL);
104  }
105 }
#define VARATT_IS_COMPRESSED(PTR)
Definition: postgres.h:325
#define CompressionMethodIsValid(cm)
#define VARSIZE(PTR)
Definition: postgres.h:316
#define PointerGetDatum(X)
Definition: postgres.h:600
ToastCompressionId
signed int int32
Definition: c.h:429
#define VARATT_IS_EXTERNAL(PTR)
Definition: postgres.h:326
void pfree(void *pointer)
Definition: mcxt.c:1169
#define ERROR
Definition: elog.h:46
#define TOAST_LZ4_COMPRESSION
struct varlena * pglz_compress_datum(const struct varlena *value)
struct varlena * lz4_compress_datum(const struct varlena *value)
static struct @143 value
#define TOAST_COMPRESS_SET_SIZE_AND_COMPRESS_METHOD(ptr, len, cm_method)
#define Assert(condition)
Definition: c.h:804
#define TOAST_PGLZ_COMPRESSION
#define DatumGetPointer(X)
Definition: postgres.h:593
#define VARSIZE_ANY_EXHDR(PTR)
Definition: postgres.h:354
#define elog(elevel,...)
Definition: elog.h:232
Definition: c.h:621
int default_toast_compression

◆ toast_delete_datum()

void toast_delete_datum ( Relation  rel,
Datum  value,
bool  is_speculative 
)

Definition at line 384 of file toast_internals.c.

References BTEqualStrategyNumber, DatumGetPointer, ForwardScanDirection, heap_abort_speculative(), init_toast_snapshot(), ObjectIdGetDatum, RowExclusiveLock, ScanKeyInit(), simple_heap_delete(), systable_beginscan_ordered(), systable_endscan_ordered(), systable_getnext_ordered(), HeapTupleData::t_self, table_close(), table_open(), toast_close_indexes(), toast_open_indexes(), varatt_external::va_toastrelid, varatt_external::va_valueid, VARATT_EXTERNAL_GET_POINTER, and VARATT_IS_EXTERNAL_ONDISK.

Referenced by toast_delete_external(), and toast_tuple_cleanup().

385 {
386  struct varlena *attr = (struct varlena *) DatumGetPointer(value);
387  struct varatt_external toast_pointer;
388  Relation toastrel;
389  Relation *toastidxs;
390  ScanKeyData toastkey;
391  SysScanDesc toastscan;
392  HeapTuple toasttup;
393  int num_indexes;
394  int validIndex;
395  SnapshotData SnapshotToast;
396 
397  if (!VARATT_IS_EXTERNAL_ONDISK(attr))
398  return;
399 
400  /* Must copy to access aligned fields */
401  VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
402 
403  /*
404  * Open the toast relation and its indexes
405  */
406  toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
407 
408  /* Fetch valid relation used for process */
409  validIndex = toast_open_indexes(toastrel,
411  &toastidxs,
412  &num_indexes);
413 
414  /*
415  * Setup a scan key to find chunks with matching va_valueid
416  */
417  ScanKeyInit(&toastkey,
418  (AttrNumber) 1,
419  BTEqualStrategyNumber, F_OIDEQ,
420  ObjectIdGetDatum(toast_pointer.va_valueid));
421 
422  /*
423  * Find all the chunks. (We don't actually care whether we see them in
424  * sequence or not, but since we've already locked the index we might as
425  * well use systable_beginscan_ordered.)
426  */
427  init_toast_snapshot(&SnapshotToast);
428  toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
429  &SnapshotToast, 1, &toastkey);
430  while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
431  {
432  /*
433  * Have a chunk, delete it
434  */
435  if (is_speculative)
436  heap_abort_speculative(toastrel, &toasttup->t_self);
437  else
438  simple_heap_delete(toastrel, &toasttup->t_self);
439  }
440 
441  /*
442  * End scan and close relations
443  */
444  systable_endscan_ordered(toastscan);
445  toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
446  table_close(toastrel, RowExclusiveLock);
447 }
#define VARATT_IS_EXTERNAL_ONDISK(PTR)
Definition: postgres.h:327
void heap_abort_speculative(Relation relation, ItemPointer tid)
Definition: heapam.c:5838
void table_close(Relation relation, LOCKMODE lockmode)
Definition: table.c:167
#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr)
Definition: detoast.h:22
void init_toast_snapshot(Snapshot toast_snapshot)
HeapTuple systable_getnext_ordered(SysScanDesc sysscan, ScanDirection direction)
Definition: genam.c:707
#define ObjectIdGetDatum(X)
Definition: postgres.h:551
ItemPointerData t_self
Definition: htup.h:65
#define RowExclusiveLock
Definition: lockdefs.h:38
void toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
int toast_open_indexes(Relation toastrel, LOCKMODE lock, Relation **toastidxs, int *num_indexes)
void systable_endscan_ordered(SysScanDesc sysscan)
Definition: genam.c:732
static struct @143 value
void simple_heap_delete(Relation relation, ItemPointer tid)
Definition: heapam.c:3107
#define DatumGetPointer(X)
Definition: postgres.h:593
SysScanDesc systable_beginscan_ordered(Relation heapRelation, Relation indexRelation, Snapshot snapshot, int nkeys, ScanKey key)
Definition: genam.c:642
void ScanKeyInit(ScanKey entry, AttrNumber attributeNumber, StrategyNumber strategy, RegProcedure procedure, Datum argument)
Definition: scankey.c:76
Definition: c.h:621
Relation table_open(Oid relationId, LOCKMODE lockmode)
Definition: table.c:39
int16 AttrNumber
Definition: attnum.h:21
#define BTEqualStrategyNumber
Definition: stratnum.h:31

◆ toast_get_valid_index()

Oid toast_get_valid_index ( Oid  toastoid,
LOCKMODE  lock 
)

Definition at line 527 of file toast_internals.c.

References NoLock, RelationGetRelid, table_close(), table_open(), toast_close_indexes(), and toast_open_indexes().

Referenced by finish_heap_swap(), and swap_relation_files().

528 {
529  int num_indexes;
530  int validIndex;
531  Oid validIndexOid;
532  Relation *toastidxs;
533  Relation toastrel;
534 
535  /* Open the toast relation */
536  toastrel = table_open(toastoid, lock);
537 
538  /* Look for the valid index of the toast relation */
539  validIndex = toast_open_indexes(toastrel,
540  lock,
541  &toastidxs,
542  &num_indexes);
543  validIndexOid = RelationGetRelid(toastidxs[validIndex]);
544 
545  /* Close the toast relation and all its indexes */
546  toast_close_indexes(toastidxs, num_indexes, NoLock);
547  table_close(toastrel, NoLock);
548 
549  return validIndexOid;
550 }
void table_close(Relation relation, LOCKMODE lockmode)
Definition: table.c:167
unsigned int Oid
Definition: postgres_ext.h:31
#define NoLock
Definition: lockdefs.h:34
void toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
int toast_open_indexes(Relation toastrel, LOCKMODE lock, Relation **toastidxs, int *num_indexes)
Relation table_open(Oid relationId, LOCKMODE lockmode)
Definition: table.c:39
#define RelationGetRelid(relation)
Definition: rel.h:477

◆ toast_open_indexes()

int toast_open_indexes ( Relation  toastrel,
LOCKMODE  lock,
Relation **  toastidxs,
int *  num_indexes 
)

Definition at line 561 of file toast_internals.c.

References Assert, elog, ERROR, i, index_open(), lfirst_oid, list_free(), list_length(), NIL, palloc(), RelationData::rd_index, RelationGetIndexList(), and RelationGetRelid.

Referenced by heap_fetch_toast_slice(), toast_delete_datum(), toast_get_valid_index(), toast_save_datum(), toastrel_valueid_exists(), and verify_heapam().

565 {
566  int i = 0;
567  int res = 0;
568  bool found = false;
569  List *indexlist;
570  ListCell *lc;
571 
572  /* Get index list of the toast relation */
573  indexlist = RelationGetIndexList(toastrel);
574  Assert(indexlist != NIL);
575 
576  *num_indexes = list_length(indexlist);
577 
578  /* Open all the index relations */
579  *toastidxs = (Relation *) palloc(*num_indexes * sizeof(Relation));
580  foreach(lc, indexlist)
581  (*toastidxs)[i++] = index_open(lfirst_oid(lc), lock);
582 
583  /* Fetch the first valid index in list */
584  for (i = 0; i < *num_indexes; i++)
585  {
586  Relation toastidx = (*toastidxs)[i];
587 
588  if (toastidx->rd_index->indisvalid)
589  {
590  res = i;
591  found = true;
592  break;
593  }
594  }
595 
596  /*
597  * Free index list, not necessary anymore as relations are opened and a
598  * valid index has been found.
599  */
600  list_free(indexlist);
601 
602  /*
603  * The toast relation should have one valid index, so something is going
604  * wrong if there is nothing.
605  */
606  if (!found)
607  elog(ERROR, "no valid index found for toast relation with Oid %u",
608  RelationGetRelid(toastrel));
609 
610  return res;
611 }
#define NIL
Definition: pg_list.h:65
Form_pg_index rd_index
Definition: rel.h:187
#define ERROR
Definition: elog.h:46
#define Assert(condition)
Definition: c.h:804
static int list_length(const List *l)
Definition: pg_list.h:149
List * RelationGetIndexList(Relation relation)
Definition: relcache.c:4573
void * palloc(Size size)
Definition: mcxt.c:1062
void list_free(List *list)
Definition: list.c:1391
#define elog(elevel,...)
Definition: elog.h:232
int i
Definition: pg_list.h:50
#define RelationGetRelid(relation)
Definition: rel.h:477
Relation index_open(Oid relationId, LOCKMODE lockmode)
Definition: indexam.c:132
#define lfirst_oid(lc)
Definition: pg_list.h:171

◆ toast_save_datum()

Datum toast_save_datum ( Relation  rel,
Datum  value,
struct varlena oldexternal,
int  options 
)

Definition at line 120 of file toast_internals.c.

References Assert, CHECK_FOR_INTERRUPTS, DatumGetPointer, GetCurrentCommandId(), GetNewOidWithIndex(), heap_form_tuple(), heap_freetuple(), heap_insert(), i, index_insert(), Int32GetDatum, InvalidOid, Min, ObjectIdGetDatum, OidIsValid, palloc(), PointerGetDatum, RelationData::rd_att, RelationData::rd_index, RelationData::rd_rel, RelationData::rd_toastoid, RelationGetRelid, RowExclusiveLock, SET_VARSIZE, SET_VARTAG_EXTERNAL, HeapTupleData::t_self, table_close(), table_open(), toast_close_indexes(), TOAST_MAX_CHUNK_SIZE, toast_open_indexes(), TOAST_POINTER_SIZE, toastid_valueid_exists(), toastrel_valueid_exists(), UNIQUE_CHECK_NO, UNIQUE_CHECK_YES, varatt_external::va_extinfo, varatt_external::va_rawsize, varatt_external::va_toastrelid, varatt_external::va_valueid, VARATT_EXTERNAL_GET_POINTER, VARATT_EXTERNAL_IS_COMPRESSED, VARATT_EXTERNAL_SET_SIZE_AND_COMPRESS_METHOD, VARATT_IS_COMPRESSED, VARATT_IS_EXTERNAL, VARATT_IS_EXTERNAL_ONDISK, VARATT_IS_SHORT, VARDATA, VARDATA_COMPRESSED_GET_COMPRESS_METHOD, VARDATA_COMPRESSED_GET_EXTSIZE, VARDATA_EXTERNAL, VARDATA_SHORT, VARHDRSZ, VARHDRSZ_SHORT, VARSIZE, VARSIZE_SHORT, and VARTAG_ONDISK.

Referenced by toast_tuple_externalize().

122 {
123  Relation toastrel;
124  Relation *toastidxs;
125  HeapTuple toasttup;
126  TupleDesc toasttupDesc;
127  Datum t_values[3];
128  bool t_isnull[3];
129  CommandId mycid = GetCurrentCommandId(true);
130  struct varlena *result;
131  struct varatt_external toast_pointer;
132  union
133  {
134  struct varlena hdr;
135  /* this is to make the union big enough for a chunk: */
136  char data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
137  /* ensure union is aligned well enough: */
138  int32 align_it;
139  } chunk_data;
140  int32 chunk_size;
141  int32 chunk_seq = 0;
142  char *data_p;
143  int32 data_todo;
144  Pointer dval = DatumGetPointer(value);
145  int num_indexes;
146  int validIndex;
147 
149 
150  /*
151  * Open the toast relation and its indexes. We can use the index to check
152  * uniqueness of the OID we assign to the toasted item, even though it has
153  * additional columns besides OID.
154  */
155  toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
156  toasttupDesc = toastrel->rd_att;
157 
158  /* Open all the toast indexes and look for the valid one */
159  validIndex = toast_open_indexes(toastrel,
161  &toastidxs,
162  &num_indexes);
163 
164  /*
165  * Get the data pointer and length, and compute va_rawsize and va_extinfo.
166  *
167  * va_rawsize is the size of the equivalent fully uncompressed datum, so
168  * we have to adjust for short headers.
169  *
170  * va_extinfo stored the actual size of the data payload in the toast
171  * records and the compression method in first 2 bits if data is
172  * compressed.
173  */
174  if (VARATT_IS_SHORT(dval))
175  {
176  data_p = VARDATA_SHORT(dval);
177  data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT;
178  toast_pointer.va_rawsize = data_todo + VARHDRSZ; /* as if not short */
179  toast_pointer.va_extinfo = data_todo;
180  }
181  else if (VARATT_IS_COMPRESSED(dval))
182  {
183  data_p = VARDATA(dval);
184  data_todo = VARSIZE(dval) - VARHDRSZ;
185  /* rawsize in a compressed datum is just the size of the payload */
186  toast_pointer.va_rawsize = VARDATA_COMPRESSED_GET_EXTSIZE(dval) + VARHDRSZ;
187 
188  /* set external size and compression method */
189  VARATT_EXTERNAL_SET_SIZE_AND_COMPRESS_METHOD(toast_pointer, data_todo,
191  /* Assert that the numbers look like it's compressed */
192  Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
193  }
194  else
195  {
196  data_p = VARDATA(dval);
197  data_todo = VARSIZE(dval) - VARHDRSZ;
198  toast_pointer.va_rawsize = VARSIZE(dval);
199  toast_pointer.va_extinfo = data_todo;
200  }
201 
202  /*
203  * Insert the correct table OID into the result TOAST pointer.
204  *
205  * Normally this is the actual OID of the target toast table, but during
206  * table-rewriting operations such as CLUSTER, we have to insert the OID
207  * of the table's real permanent toast table instead. rd_toastoid is set
208  * if we have to substitute such an OID.
209  */
210  if (OidIsValid(rel->rd_toastoid))
211  toast_pointer.va_toastrelid = rel->rd_toastoid;
212  else
213  toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
214 
215  /*
216  * Choose an OID to use as the value ID for this toast value.
217  *
218  * Normally we just choose an unused OID within the toast table. But
219  * during table-rewriting operations where we are preserving an existing
220  * toast table OID, we want to preserve toast value OIDs too. So, if
221  * rd_toastoid is set and we had a prior external value from that same
222  * toast table, re-use its value ID. If we didn't have a prior external
223  * value (which is a corner case, but possible if the table's attstorage
224  * options have been changed), we have to pick a value ID that doesn't
225  * conflict with either new or existing toast value OIDs.
226  */
227  if (!OidIsValid(rel->rd_toastoid))
228  {
229  /* normal case: just choose an unused OID */
230  toast_pointer.va_valueid =
231  GetNewOidWithIndex(toastrel,
232  RelationGetRelid(toastidxs[validIndex]),
233  (AttrNumber) 1);
234  }
235  else
236  {
237  /* rewrite case: check to see if value was in old toast table */
238  toast_pointer.va_valueid = InvalidOid;
239  if (oldexternal != NULL)
240  {
241  struct varatt_external old_toast_pointer;
242 
243  Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
244  /* Must copy to access aligned fields */
245  VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
246  if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
247  {
248  /* This value came from the old toast table; reuse its OID */
249  toast_pointer.va_valueid = old_toast_pointer.va_valueid;
250 
251  /*
252  * There is a corner case here: the table rewrite might have
253  * to copy both live and recently-dead versions of a row, and
254  * those versions could easily reference the same toast value.
255  * When we copy the second or later version of such a row,
256  * reusing the OID will mean we select an OID that's already
257  * in the new toast table. Check for that, and if so, just
258  * fall through without writing the data again.
259  *
260  * While annoying and ugly-looking, this is a good thing
261  * because it ensures that we wind up with only one copy of
262  * the toast value when there is only one copy in the old
263  * toast table. Before we detected this case, we'd have made
264  * multiple copies, wasting space; and what's worse, the
265  * copies belonging to already-deleted heap tuples would not
266  * be reclaimed by VACUUM.
267  */
268  if (toastrel_valueid_exists(toastrel,
269  toast_pointer.va_valueid))
270  {
271  /* Match, so short-circuit the data storage loop below */
272  data_todo = 0;
273  }
274  }
275  }
276  if (toast_pointer.va_valueid == InvalidOid)
277  {
278  /*
279  * new value; must choose an OID that doesn't conflict in either
280  * old or new toast table
281  */
282  do
283  {
284  toast_pointer.va_valueid =
285  GetNewOidWithIndex(toastrel,
286  RelationGetRelid(toastidxs[validIndex]),
287  (AttrNumber) 1);
288  } while (toastid_valueid_exists(rel->rd_toastoid,
289  toast_pointer.va_valueid));
290  }
291  }
292 
293  /*
294  * Initialize constant parts of the tuple data
295  */
296  t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
297  t_values[2] = PointerGetDatum(&chunk_data);
298  t_isnull[0] = false;
299  t_isnull[1] = false;
300  t_isnull[2] = false;
301 
302  /*
303  * Split up the item into chunks
304  */
305  while (data_todo > 0)
306  {
307  int i;
308 
310 
311  /*
312  * Calculate the size of this chunk
313  */
314  chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
315 
316  /*
317  * Build a tuple and store it
318  */
319  t_values[1] = Int32GetDatum(chunk_seq++);
320  SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
321  memcpy(VARDATA(&chunk_data), data_p, chunk_size);
322  toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
323 
324  heap_insert(toastrel, toasttup, mycid, options, NULL);
325 
326  /*
327  * Create the index entry. We cheat a little here by not using
328  * FormIndexDatum: this relies on the knowledge that the index columns
329  * are the same as the initial columns of the table for all the
330  * indexes. We also cheat by not providing an IndexInfo: this is okay
331  * for now because btree doesn't need one, but we might have to be
332  * more honest someday.
333  *
334  * Note also that there had better not be any user-created index on
335  * the TOAST table, since we don't bother to update anything else.
336  */
337  for (i = 0; i < num_indexes; i++)
338  {
339  /* Only index relations marked as ready can be updated */
340  if (toastidxs[i]->rd_index->indisready)
341  index_insert(toastidxs[i], t_values, t_isnull,
342  &(toasttup->t_self),
343  toastrel,
344  toastidxs[i]->rd_index->indisunique ?
346  false, NULL);
347  }
348 
349  /*
350  * Free memory
351  */
352  heap_freetuple(toasttup);
353 
354  /*
355  * Move on to next chunk
356  */
357  data_todo -= chunk_size;
358  data_p += chunk_size;
359  }
360 
361  /*
362  * Done - close toast relation and its indexes
363  */
364  toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
365  table_close(toastrel, RowExclusiveLock);
366 
367  /*
368  * Create the TOAST pointer value that we'll return
369  */
370  result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
372  memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
373 
374  return PointerGetDatum(result);
375 }
void heap_insert(Relation relation, HeapTuple tup, CommandId cid, int options, BulkInsertState bistate)
Definition: heapam.c:2060
uint32 CommandId
Definition: c.h:601
Oid GetNewOidWithIndex(Relation relation, Oid indexId, AttrNumber oidcolumn)
Definition: catalog.c:381
#define VARATT_IS_EXTERNAL_ONDISK(PTR)
Definition: postgres.h:327
#define VARATT_IS_COMPRESSED(PTR)
Definition: postgres.h:325
void table_close(Relation relation, LOCKMODE lockmode)
Definition: table.c:167
#define VARDATA(PTR)
Definition: postgres.h:315
#define TOAST_MAX_CHUNK_SIZE
Definition: heaptoast.h:84
#define VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer)
Definition: postgres.h:391
#define VARHDRSZ_SHORT
Definition: postgres.h:292
#define VARSIZE(PTR)
Definition: postgres.h:316
#define VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr)
Definition: detoast.h:22
#define PointerGetDatum(X)
Definition: postgres.h:600
#define VARHDRSZ
Definition: c.h:627
#define Min(x, y)
Definition: c.h:986
HeapTuple heap_form_tuple(TupleDesc tupleDescriptor, Datum *values, bool *isnull)
Definition: heaptuple.c:1020
#define VARDATA_COMPRESSED_GET_EXTSIZE(PTR)
Definition: postgres.h:365
Form_pg_class rd_rel
Definition: rel.h:109
void heap_freetuple(HeapTuple htup)
Definition: heaptuple.c:1338
#define OidIsValid(objectId)
Definition: c.h:710
#define VARDATA_EXTERNAL(PTR)
Definition: postgres.h:323
signed int int32
Definition: c.h:429
#define VARATT_IS_EXTERNAL(PTR)
Definition: postgres.h:326
Form_pg_index rd_index
Definition: rel.h:187
char * Pointer
Definition: c.h:418
#define ObjectIdGetDatum(X)
Definition: postgres.h:551
#define VARATT_IS_SHORT(PTR)
Definition: postgres.h:339
static bool toastid_valueid_exists(Oid toastrelid, Oid valueid)
ItemPointerData t_self
Definition: htup.h:65
#define SET_VARTAG_EXTERNAL(PTR, tag)
Definition: postgres.h:346
Oid rd_toastoid
Definition: rel.h:246
#define RowExclusiveLock
Definition: lockdefs.h:38
void toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
#define TOAST_POINTER_SIZE
Definition: detoast.h:31
#define VARSIZE_SHORT(PTR)
Definition: postgres.h:318
int toast_open_indexes(Relation toastrel, LOCKMODE lock, Relation **toastidxs, int *num_indexes)
uintptr_t Datum
Definition: postgres.h:411
TupleDesc rd_att
Definition: rel.h:110
#define InvalidOid
Definition: postgres_ext.h:36
static struct @143 value
#define Assert(condition)
Definition: c.h:804
#define VARDATA_COMPRESSED_GET_COMPRESS_METHOD(PTR)
Definition: postgres.h:367
#define DatumGetPointer(X)
Definition: postgres.h:593
#define VARDATA_SHORT(PTR)
Definition: postgres.h:319
#define Int32GetDatum(X)
Definition: postgres.h:523
void * palloc(Size size)
Definition: mcxt.c:1062
int i
#define VARATT_EXTERNAL_SET_SIZE_AND_COMPRESS_METHOD(toast_pointer, len, cm)
Definition: postgres.h:376
Definition: c.h:621
#define CHECK_FOR_INTERRUPTS()
Definition: miscadmin.h:120
#define SET_VARSIZE(PTR, len)
Definition: postgres.h:342
CommandId GetCurrentCommandId(bool used)
Definition: xact.c:761
bool index_insert(Relation indexRelation, Datum *values, bool *isnull, ItemPointer heap_t_ctid, Relation heapRelation, IndexUniqueCheck checkUnique, bool indexUnchanged, IndexInfo *indexInfo)
Definition: indexam.c:176
static bool toastrel_valueid_exists(Relation toastrel, Oid valueid)
Relation table_open(Oid relationId, LOCKMODE lockmode)
Definition: table.c:39
int16 AttrNumber
Definition: attnum.h:21
#define RelationGetRelid(relation)
Definition: rel.h:477