mirror of
https://github.com/postgres/postgres.git
synced 2025-10-15 05:46:52 +03:00
Split tuptoaster.c into three separate files.
detoast.c/h contain functions required to detoast a datum, partially or completely, plus a few other utility functions for examining the size of toasted datums. toast_internals.c/h contain functions that are used internally to the TOAST subsystem but which (mostly) do not need to be accessed from outside. heaptoast.c/h contains code that is intrinsically specific to the heap AM, either because it operates on HeapTuples or is based on the layout of a heap page. detoast.c and toast_internals.c are placed in src/backend/access/common rather than src/backend/access/heap. At present, both files still have dependencies on the heap, but that will be improved in a future commit. Patch by me, reviewed and tested by Prabhat Sabu, Thomas Munro, Andres Freund, and Álvaro Herrera. Discussion: http://postgr.es/m/CA+TgmoZv-=2iWM4jcw5ZhJeL18HF96+W1yJeYrnGMYdkFFnEpQ@mail.gmail.com
This commit is contained in:
Robert Haas
632
src/backend/access/common/toast_internals.c
Normal file
632
src/backend/access/common/toast_internals.c
Normal file
@@ -0,0 +1,632 @@
|
||||
/*-------------------------------------------------------------------------
|
||||
*
|
||||
* toast_internals.c
|
||||
* Functions for internal use by the TOAST system.
|
||||
*
|
||||
* Copyright (c) 2000-2019, PostgreSQL Global Development Group
|
||||
*
|
||||
* IDENTIFICATION
|
||||
* src/backend/access/common/toast_internals.c
|
||||
*
|
||||
*-------------------------------------------------------------------------
|
||||
*/
|
||||
|
||||
#include "postgres.h"
|
||||
|
||||
#include "access/detoast.h"
|
||||
#include "access/genam.h"
|
||||
#include "access/heapam.h"
|
||||
#include "access/heaptoast.h"
|
||||
#include "access/table.h"
|
||||
#include "access/toast_internals.h"
|
||||
#include "access/xact.h"
|
||||
#include "catalog/catalog.h"
|
||||
#include "common/pg_lzcompress.h"
|
||||
#include "miscadmin.h"
|
||||
#include "utils/fmgroids.h"
|
||||
#include "utils/rel.h"
|
||||
#include "utils/snapmgr.h"
|
||||
|
||||
static bool toastrel_valueid_exists(Relation toastrel, Oid valueid);
|
||||
static bool toastid_valueid_exists(Oid toastrelid, Oid valueid);
|
||||
|
||||
/* ----------
|
||||
* toast_compress_datum -
|
||||
*
|
||||
* Create a compressed version of a varlena datum
|
||||
*
|
||||
* If we fail (ie, compressed result is actually bigger than original)
|
||||
* then return NULL. We must not use compressed data if it'd expand
|
||||
* the tuple!
|
||||
*
|
||||
* We use VAR{SIZE,DATA}_ANY so we can handle short varlenas here without
|
||||
* copying them. But we can't handle external or compressed datums.
|
||||
* ----------
|
||||
*/
|
||||
Datum
|
||||
toast_compress_datum(Datum value)
|
||||
{
|
||||
struct varlena *tmp;
|
||||
int32 valsize = VARSIZE_ANY_EXHDR(DatumGetPointer(value));
|
||||
int32 len;
|
||||
|
||||
Assert(!VARATT_IS_EXTERNAL(DatumGetPointer(value)));
|
||||
Assert(!VARATT_IS_COMPRESSED(DatumGetPointer(value)));
|
||||
|
||||
/*
|
||||
* No point in wasting a palloc cycle if value size is out of the allowed
|
||||
* range for compression
|
||||
*/
|
||||
if (valsize < PGLZ_strategy_default->min_input_size ||
|
||||
valsize > PGLZ_strategy_default->max_input_size)
|
||||
return PointerGetDatum(NULL);
|
||||
|
||||
tmp = (struct varlena *) palloc(PGLZ_MAX_OUTPUT(valsize) +
|
||||
TOAST_COMPRESS_HDRSZ);
|
||||
|
||||
/*
|
||||
* We recheck the actual size even if pglz_compress() reports success,
|
||||
* because it might be satisfied with having saved as little as one byte
|
||||
* in the compressed data --- which could turn into a net loss once you
|
||||
* consider header and alignment padding. Worst case, the compressed
|
||||
* format might require three padding bytes (plus header, which is
|
||||
* included in VARSIZE(tmp)), whereas the uncompressed format would take
|
||||
* only one header byte and no padding if the value is short enough. So
|
||||
* we insist on a savings of more than 2 bytes to ensure we have a gain.
|
||||
*/
|
||||
len = pglz_compress(VARDATA_ANY(DatumGetPointer(value)),
|
||||
valsize,
|
||||
TOAST_COMPRESS_RAWDATA(tmp),
|
||||
PGLZ_strategy_default);
|
||||
if (len >= 0 &&
|
||||
len + TOAST_COMPRESS_HDRSZ < valsize - 2)
|
||||
{
|
||||
TOAST_COMPRESS_SET_RAWSIZE(tmp, valsize);
|
||||
SET_VARSIZE_COMPRESSED(tmp, len + TOAST_COMPRESS_HDRSZ);
|
||||
/* successful compression */
|
||||
return PointerGetDatum(tmp);
|
||||
}
|
||||
else
|
||||
{
|
||||
/* incompressible data */
|
||||
pfree(tmp);
|
||||
return PointerGetDatum(NULL);
|
||||
}
|
||||
}
|
||||
|
||||
/* ----------
|
||||
* toast_save_datum -
|
||||
*
|
||||
* Save one single datum into the secondary relation and return
|
||||
* a Datum reference for it.
|
||||
*
|
||||
* rel: the main relation we're working with (not the toast rel!)
|
||||
* value: datum to be pushed to toast storage
|
||||
* oldexternal: if not NULL, toast pointer previously representing the datum
|
||||
* options: options to be passed to heap_insert() for toast rows
|
||||
* ----------
|
||||
*/
|
||||
Datum
|
||||
toast_save_datum(Relation rel, Datum value,
|
||||
struct varlena *oldexternal, int options)
|
||||
{
|
||||
Relation toastrel;
|
||||
Relation *toastidxs;
|
||||
HeapTuple toasttup;
|
||||
TupleDesc toasttupDesc;
|
||||
Datum t_values[3];
|
||||
bool t_isnull[3];
|
||||
CommandId mycid = GetCurrentCommandId(true);
|
||||
struct varlena *result;
|
||||
struct varatt_external toast_pointer;
|
||||
union
|
||||
{
|
||||
struct varlena hdr;
|
||||
/* this is to make the union big enough for a chunk: */
|
||||
char data[TOAST_MAX_CHUNK_SIZE + VARHDRSZ];
|
||||
/* ensure union is aligned well enough: */
|
||||
int32 align_it;
|
||||
} chunk_data;
|
||||
int32 chunk_size;
|
||||
int32 chunk_seq = 0;
|
||||
char *data_p;
|
||||
int32 data_todo;
|
||||
Pointer dval = DatumGetPointer(value);
|
||||
int num_indexes;
|
||||
int validIndex;
|
||||
|
||||
Assert(!VARATT_IS_EXTERNAL(value));
|
||||
|
||||
/*
|
||||
* Open the toast relation and its indexes. We can use the index to check
|
||||
* uniqueness of the OID we assign to the toasted item, even though it has
|
||||
* additional columns besides OID.
|
||||
*/
|
||||
toastrel = table_open(rel->rd_rel->reltoastrelid, RowExclusiveLock);
|
||||
toasttupDesc = toastrel->rd_att;
|
||||
|
||||
/* Open all the toast indexes and look for the valid one */
|
||||
validIndex = toast_open_indexes(toastrel,
|
||||
RowExclusiveLock,
|
||||
&toastidxs,
|
||||
&num_indexes);
|
||||
|
||||
/*
|
||||
* Get the data pointer and length, and compute va_rawsize and va_extsize.
|
||||
*
|
||||
* va_rawsize is the size of the equivalent fully uncompressed datum, so
|
||||
* we have to adjust for short headers.
|
||||
*
|
||||
* va_extsize is the actual size of the data payload in the toast records.
|
||||
*/
|
||||
if (VARATT_IS_SHORT(dval))
|
||||
{
|
||||
data_p = VARDATA_SHORT(dval);
|
||||
data_todo = VARSIZE_SHORT(dval) - VARHDRSZ_SHORT;
|
||||
toast_pointer.va_rawsize = data_todo + VARHDRSZ; /* as if not short */
|
||||
toast_pointer.va_extsize = data_todo;
|
||||
}
|
||||
else if (VARATT_IS_COMPRESSED(dval))
|
||||
{
|
||||
data_p = VARDATA(dval);
|
||||
data_todo = VARSIZE(dval) - VARHDRSZ;
|
||||
/* rawsize in a compressed datum is just the size of the payload */
|
||||
toast_pointer.va_rawsize = VARRAWSIZE_4B_C(dval) + VARHDRSZ;
|
||||
toast_pointer.va_extsize = data_todo;
|
||||
/* Assert that the numbers look like it's compressed */
|
||||
Assert(VARATT_EXTERNAL_IS_COMPRESSED(toast_pointer));
|
||||
}
|
||||
else
|
||||
{
|
||||
data_p = VARDATA(dval);
|
||||
data_todo = VARSIZE(dval) - VARHDRSZ;
|
||||
toast_pointer.va_rawsize = VARSIZE(dval);
|
||||
toast_pointer.va_extsize = data_todo;
|
||||
}
|
||||
|
||||
/*
|
||||
* Insert the correct table OID into the result TOAST pointer.
|
||||
*
|
||||
* Normally this is the actual OID of the target toast table, but during
|
||||
* table-rewriting operations such as CLUSTER, we have to insert the OID
|
||||
* of the table's real permanent toast table instead. rd_toastoid is set
|
||||
* if we have to substitute such an OID.
|
||||
*/
|
||||
if (OidIsValid(rel->rd_toastoid))
|
||||
toast_pointer.va_toastrelid = rel->rd_toastoid;
|
||||
else
|
||||
toast_pointer.va_toastrelid = RelationGetRelid(toastrel);
|
||||
|
||||
/*
|
||||
* Choose an OID to use as the value ID for this toast value.
|
||||
*
|
||||
* Normally we just choose an unused OID within the toast table. But
|
||||
* during table-rewriting operations where we are preserving an existing
|
||||
* toast table OID, we want to preserve toast value OIDs too. So, if
|
||||
* rd_toastoid is set and we had a prior external value from that same
|
||||
* toast table, re-use its value ID. If we didn't have a prior external
|
||||
* value (which is a corner case, but possible if the table's attstorage
|
||||
* options have been changed), we have to pick a value ID that doesn't
|
||||
* conflict with either new or existing toast value OIDs.
|
||||
*/
|
||||
if (!OidIsValid(rel->rd_toastoid))
|
||||
{
|
||||
/* normal case: just choose an unused OID */
|
||||
toast_pointer.va_valueid =
|
||||
GetNewOidWithIndex(toastrel,
|
||||
RelationGetRelid(toastidxs[validIndex]),
|
||||
(AttrNumber) 1);
|
||||
}
|
||||
else
|
||||
{
|
||||
/* rewrite case: check to see if value was in old toast table */
|
||||
toast_pointer.va_valueid = InvalidOid;
|
||||
if (oldexternal != NULL)
|
||||
{
|
||||
struct varatt_external old_toast_pointer;
|
||||
|
||||
Assert(VARATT_IS_EXTERNAL_ONDISK(oldexternal));
|
||||
/* Must copy to access aligned fields */
|
||||
VARATT_EXTERNAL_GET_POINTER(old_toast_pointer, oldexternal);
|
||||
if (old_toast_pointer.va_toastrelid == rel->rd_toastoid)
|
||||
{
|
||||
/* This value came from the old toast table; reuse its OID */
|
||||
toast_pointer.va_valueid = old_toast_pointer.va_valueid;
|
||||
|
||||
/*
|
||||
* There is a corner case here: the table rewrite might have
|
||||
* to copy both live and recently-dead versions of a row, and
|
||||
* those versions could easily reference the same toast value.
|
||||
* When we copy the second or later version of such a row,
|
||||
* reusing the OID will mean we select an OID that's already
|
||||
* in the new toast table. Check for that, and if so, just
|
||||
* fall through without writing the data again.
|
||||
*
|
||||
* While annoying and ugly-looking, this is a good thing
|
||||
* because it ensures that we wind up with only one copy of
|
||||
* the toast value when there is only one copy in the old
|
||||
* toast table. Before we detected this case, we'd have made
|
||||
* multiple copies, wasting space; and what's worse, the
|
||||
* copies belonging to already-deleted heap tuples would not
|
||||
* be reclaimed by VACUUM.
|
||||
*/
|
||||
if (toastrel_valueid_exists(toastrel,
|
||||
toast_pointer.va_valueid))
|
||||
{
|
||||
/* Match, so short-circuit the data storage loop below */
|
||||
data_todo = 0;
|
||||
}
|
||||
}
|
||||
}
|
||||
if (toast_pointer.va_valueid == InvalidOid)
|
||||
{
|
||||
/*
|
||||
* new value; must choose an OID that doesn't conflict in either
|
||||
* old or new toast table
|
||||
*/
|
||||
do
|
||||
{
|
||||
toast_pointer.va_valueid =
|
||||
GetNewOidWithIndex(toastrel,
|
||||
RelationGetRelid(toastidxs[validIndex]),
|
||||
(AttrNumber) 1);
|
||||
} while (toastid_valueid_exists(rel->rd_toastoid,
|
||||
toast_pointer.va_valueid));
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Initialize constant parts of the tuple data
|
||||
*/
|
||||
t_values[0] = ObjectIdGetDatum(toast_pointer.va_valueid);
|
||||
t_values[2] = PointerGetDatum(&chunk_data);
|
||||
t_isnull[0] = false;
|
||||
t_isnull[1] = false;
|
||||
t_isnull[2] = false;
|
||||
|
||||
/*
|
||||
* Split up the item into chunks
|
||||
*/
|
||||
while (data_todo > 0)
|
||||
{
|
||||
int i;
|
||||
|
||||
CHECK_FOR_INTERRUPTS();
|
||||
|
||||
/*
|
||||
* Calculate the size of this chunk
|
||||
*/
|
||||
chunk_size = Min(TOAST_MAX_CHUNK_SIZE, data_todo);
|
||||
|
||||
/*
|
||||
* Build a tuple and store it
|
||||
*/
|
||||
t_values[1] = Int32GetDatum(chunk_seq++);
|
||||
SET_VARSIZE(&chunk_data, chunk_size + VARHDRSZ);
|
||||
memcpy(VARDATA(&chunk_data), data_p, chunk_size);
|
||||
toasttup = heap_form_tuple(toasttupDesc, t_values, t_isnull);
|
||||
|
||||
heap_insert(toastrel, toasttup, mycid, options, NULL);
|
||||
|
||||
/*
|
||||
* Create the index entry. We cheat a little here by not using
|
||||
* FormIndexDatum: this relies on the knowledge that the index columns
|
||||
* are the same as the initial columns of the table for all the
|
||||
* indexes. We also cheat by not providing an IndexInfo: this is okay
|
||||
* for now because btree doesn't need one, but we might have to be
|
||||
* more honest someday.
|
||||
*
|
||||
* Note also that there had better not be any user-created index on
|
||||
* the TOAST table, since we don't bother to update anything else.
|
||||
*/
|
||||
for (i = 0; i < num_indexes; i++)
|
||||
{
|
||||
/* Only index relations marked as ready can be updated */
|
||||
if (toastidxs[i]->rd_index->indisready)
|
||||
index_insert(toastidxs[i], t_values, t_isnull,
|
||||
&(toasttup->t_self),
|
||||
toastrel,
|
||||
toastidxs[i]->rd_index->indisunique ?
|
||||
UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
|
||||
NULL);
|
||||
}
|
||||
|
||||
/*
|
||||
* Free memory
|
||||
*/
|
||||
heap_freetuple(toasttup);
|
||||
|
||||
/*
|
||||
* Move on to next chunk
|
||||
*/
|
||||
data_todo -= chunk_size;
|
||||
data_p += chunk_size;
|
||||
}
|
||||
|
||||
/*
|
||||
* Done - close toast relation and its indexes
|
||||
*/
|
||||
toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
|
||||
table_close(toastrel, RowExclusiveLock);
|
||||
|
||||
/*
|
||||
* Create the TOAST pointer value that we'll return
|
||||
*/
|
||||
result = (struct varlena *) palloc(TOAST_POINTER_SIZE);
|
||||
SET_VARTAG_EXTERNAL(result, VARTAG_ONDISK);
|
||||
memcpy(VARDATA_EXTERNAL(result), &toast_pointer, sizeof(toast_pointer));
|
||||
|
||||
return PointerGetDatum(result);
|
||||
}
|
||||
|
||||
/* ----------
|
||||
* toast_delete_datum -
|
||||
*
|
||||
* Delete a single external stored value.
|
||||
* ----------
|
||||
*/
|
||||
void
|
||||
toast_delete_datum(Relation rel, Datum value, bool is_speculative)
|
||||
{
|
||||
struct varlena *attr = (struct varlena *) DatumGetPointer(value);
|
||||
struct varatt_external toast_pointer;
|
||||
Relation toastrel;
|
||||
Relation *toastidxs;
|
||||
ScanKeyData toastkey;
|
||||
SysScanDesc toastscan;
|
||||
HeapTuple toasttup;
|
||||
int num_indexes;
|
||||
int validIndex;
|
||||
SnapshotData SnapshotToast;
|
||||
|
||||
if (!VARATT_IS_EXTERNAL_ONDISK(attr))
|
||||
return;
|
||||
|
||||
/* Must copy to access aligned fields */
|
||||
VARATT_EXTERNAL_GET_POINTER(toast_pointer, attr);
|
||||
|
||||
/*
|
||||
* Open the toast relation and its indexes
|
||||
*/
|
||||
toastrel = table_open(toast_pointer.va_toastrelid, RowExclusiveLock);
|
||||
|
||||
/* Fetch valid relation used for process */
|
||||
validIndex = toast_open_indexes(toastrel,
|
||||
RowExclusiveLock,
|
||||
&toastidxs,
|
||||
&num_indexes);
|
||||
|
||||
/*
|
||||
* Setup a scan key to find chunks with matching va_valueid
|
||||
*/
|
||||
ScanKeyInit(&toastkey,
|
||||
(AttrNumber) 1,
|
||||
BTEqualStrategyNumber, F_OIDEQ,
|
||||
ObjectIdGetDatum(toast_pointer.va_valueid));
|
||||
|
||||
/*
|
||||
* Find all the chunks. (We don't actually care whether we see them in
|
||||
* sequence or not, but since we've already locked the index we might as
|
||||
* well use systable_beginscan_ordered.)
|
||||
*/
|
||||
init_toast_snapshot(&SnapshotToast);
|
||||
toastscan = systable_beginscan_ordered(toastrel, toastidxs[validIndex],
|
||||
&SnapshotToast, 1, &toastkey);
|
||||
while ((toasttup = systable_getnext_ordered(toastscan, ForwardScanDirection)) != NULL)
|
||||
{
|
||||
/*
|
||||
* Have a chunk, delete it
|
||||
*/
|
||||
if (is_speculative)
|
||||
heap_abort_speculative(toastrel, &toasttup->t_self);
|
||||
else
|
||||
simple_heap_delete(toastrel, &toasttup->t_self);
|
||||
}
|
||||
|
||||
/*
|
||||
* End scan and close relations
|
||||
*/
|
||||
systable_endscan_ordered(toastscan);
|
||||
toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
|
||||
table_close(toastrel, RowExclusiveLock);
|
||||
}
|
||||
|
||||
/* ----------
|
||||
* toastrel_valueid_exists -
|
||||
*
|
||||
* Test whether a toast value with the given ID exists in the toast relation.
|
||||
* For safety, we consider a value to exist if there are either live or dead
|
||||
* toast rows with that ID; see notes for GetNewOidWithIndex().
|
||||
* ----------
|
||||
*/
|
||||
static bool
|
||||
toastrel_valueid_exists(Relation toastrel, Oid valueid)
|
||||
{
|
||||
bool result = false;
|
||||
ScanKeyData toastkey;
|
||||
SysScanDesc toastscan;
|
||||
int num_indexes;
|
||||
int validIndex;
|
||||
Relation *toastidxs;
|
||||
|
||||
/* Fetch a valid index relation */
|
||||
validIndex = toast_open_indexes(toastrel,
|
||||
RowExclusiveLock,
|
||||
&toastidxs,
|
||||
&num_indexes);
|
||||
|
||||
/*
|
||||
* Setup a scan key to find chunks with matching va_valueid
|
||||
*/
|
||||
ScanKeyInit(&toastkey,
|
||||
(AttrNumber) 1,
|
||||
BTEqualStrategyNumber, F_OIDEQ,
|
||||
ObjectIdGetDatum(valueid));
|
||||
|
||||
/*
|
||||
* Is there any such chunk?
|
||||
*/
|
||||
toastscan = systable_beginscan(toastrel,
|
||||
RelationGetRelid(toastidxs[validIndex]),
|
||||
true, SnapshotAny, 1, &toastkey);
|
||||
|
||||
if (systable_getnext(toastscan) != NULL)
|
||||
result = true;
|
||||
|
||||
systable_endscan(toastscan);
|
||||
|
||||
/* Clean up */
|
||||
toast_close_indexes(toastidxs, num_indexes, RowExclusiveLock);
|
||||
|
||||
return result;
|
||||
}
|
||||
|
||||
/* ----------
|
||||
* toastid_valueid_exists -
|
||||
*
|
||||
* As above, but work from toast rel's OID not an open relation
|
||||
* ----------
|
||||
*/
|
||||
static bool
|
||||
toastid_valueid_exists(Oid toastrelid, Oid valueid)
|
||||
{
|
||||
bool result;
|
||||
Relation toastrel;
|
||||
|
||||
toastrel = table_open(toastrelid, AccessShareLock);
|
||||
|
||||
result = toastrel_valueid_exists(toastrel, valueid);
|
||||
|
||||
table_close(toastrel, AccessShareLock);
|
||||
|
||||
return result;
|
||||
}
|
||||
|
||||
/* ----------
|
||||
* toast_get_valid_index
|
||||
*
|
||||
* Get OID of valid index associated to given toast relation. A toast
|
||||
* relation can have only one valid index at the same time.
|
||||
*/
|
||||
Oid
|
||||
toast_get_valid_index(Oid toastoid, LOCKMODE lock)
|
||||
{
|
||||
int num_indexes;
|
||||
int validIndex;
|
||||
Oid validIndexOid;
|
||||
Relation *toastidxs;
|
||||
Relation toastrel;
|
||||
|
||||
/* Open the toast relation */
|
||||
toastrel = table_open(toastoid, lock);
|
||||
|
||||
/* Look for the valid index of the toast relation */
|
||||
validIndex = toast_open_indexes(toastrel,
|
||||
lock,
|
||||
&toastidxs,
|
||||
&num_indexes);
|
||||
validIndexOid = RelationGetRelid(toastidxs[validIndex]);
|
||||
|
||||
/* Close the toast relation and all its indexes */
|
||||
toast_close_indexes(toastidxs, num_indexes, lock);
|
||||
table_close(toastrel, lock);
|
||||
|
||||
return validIndexOid;
|
||||
}
|
||||
|
||||
/* ----------
|
||||
* toast_open_indexes
|
||||
*
|
||||
* Get an array of the indexes associated to the given toast relation
|
||||
* and return as well the position of the valid index used by the toast
|
||||
* relation in this array. It is the responsibility of the caller of this
|
||||
* function to close the indexes as well as free them.
|
||||
*/
|
||||
int
|
||||
toast_open_indexes(Relation toastrel,
|
||||
LOCKMODE lock,
|
||||
Relation **toastidxs,
|
||||
int *num_indexes)
|
||||
{
|
||||
int i = 0;
|
||||
int res = 0;
|
||||
bool found = false;
|
||||
List *indexlist;
|
||||
ListCell *lc;
|
||||
|
||||
/* Get index list of the toast relation */
|
||||
indexlist = RelationGetIndexList(toastrel);
|
||||
Assert(indexlist != NIL);
|
||||
|
||||
*num_indexes = list_length(indexlist);
|
||||
|
||||
/* Open all the index relations */
|
||||
*toastidxs = (Relation *) palloc(*num_indexes * sizeof(Relation));
|
||||
foreach(lc, indexlist)
|
||||
(*toastidxs)[i++] = index_open(lfirst_oid(lc), lock);
|
||||
|
||||
/* Fetch the first valid index in list */
|
||||
for (i = 0; i < *num_indexes; i++)
|
||||
{
|
||||
Relation toastidx = (*toastidxs)[i];
|
||||
|
||||
if (toastidx->rd_index->indisvalid)
|
||||
{
|
||||
res = i;
|
||||
found = true;
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Free index list, not necessary anymore as relations are opened and a
|
||||
* valid index has been found.
|
||||
*/
|
||||
list_free(indexlist);
|
||||
|
||||
/*
|
||||
* The toast relation should have one valid index, so something is going
|
||||
* wrong if there is nothing.
|
||||
*/
|
||||
if (!found)
|
||||
elog(ERROR, "no valid index found for toast relation with Oid %u",
|
||||
RelationGetRelid(toastrel));
|
||||
|
||||
return res;
|
||||
}
|
||||
|
||||
/* ----------
|
||||
* toast_close_indexes
|
||||
*
|
||||
* Close an array of indexes for a toast relation and free it. This should
|
||||
* be called for a set of indexes opened previously with toast_open_indexes.
|
||||
*/
|
||||
void
|
||||
toast_close_indexes(Relation *toastidxs, int num_indexes, LOCKMODE lock)
|
||||
{
|
||||
int i;
|
||||
|
||||
/* Close relations and clean up things */
|
||||
for (i = 0; i < num_indexes; i++)
|
||||
index_close(toastidxs[i], lock);
|
||||
pfree(toastidxs);
|
||||
}
|
||||
|
||||
/* ----------
|
||||
* init_toast_snapshot
|
||||
*
|
||||
* Initialize an appropriate TOAST snapshot. We must use an MVCC snapshot
|
||||
* to initialize the TOAST snapshot; since we don't know which one to use,
|
||||
* just use the oldest one. This is safe: at worst, we will get a "snapshot
|
||||
* too old" error that might have been avoided otherwise.
|
||||
*/
|
||||
void
|
||||
init_toast_snapshot(Snapshot toast_snapshot)
|
||||
{
|
||||
Snapshot snapshot = GetOldestSnapshot();
|
||||
|
||||
if (snapshot == NULL)
|
||||
elog(ERROR, "no known snapshots");
|
||||
|
||||
InitToastSnapshot(*toast_snapshot, snapshot->lsn, snapshot->whenTaken);
|
||||
}
|
||||
Reference in New Issue
Block a user