/*
* Reset a sequence to its initial value.
*
* The change is made transactionally, so that on failure of the current
* transaction, the sequence will be restored to its previous state.
* We do that by creating a whole new___ relfilenode for the sequence; so this
* works much like the rewriting forms of ALTER TABLE.
*
* Caller is assumed to have acquired AccessExclusiveLock on the sequence,
* which must not be released until end of transaction. Caller is also
* responsible for permissions checking.
*/
void
ResetSequence(Oid seq_relid)
{
Relation seq_rel;
SeqTable elm;
Form_pg_sequence seq;
Buffer buf;
HeapTupleData seqtuple;
HeapTuple tuple;
/*
* Read the old sequence. This does a bit more work than really
* necessary, but it's simple, and we do want to double-check that it's
* indeed a sequence.
*/
init_sequence(seq_relid, &elm, &seq_rel);
(void) read_seq_tuple(elm, seq_rel, &buf, &seqtuple);
/*
* Copy the existing sequence tuple.
*/
tuple = heap_copytuple(&seqtuple);
/* Now we're done with the old page */
UnlockReleaseBuffer(buf);
/*
* Modify the copied tuple to execute the restart (compare the RESTART
* action in AlterSequence)
*/
seq = (Form_pg_sequence) GETSTRUCT(tuple);
seq->last_value = seq->start_value;
seq->is_called = false;
seq->log_cnt = 0;
/*
* Create a new___ storage file for the sequence. We want to keep the
* sequence's relfrozenxid at 0, since it won't contain any unfrozen XIDs.
* Same with relminmxid, since a sequence will never contain multixacts.
*/
RelationSetNewRelfilenode(seq_rel, seq_rel->rd_rel->relpersistence,
InvalidTransactionId, InvalidMultiXactId);
/*
* Insert the modified tuple into the new___ storage file.
*/
fill_seq_with_data(seq_rel, tuple);
/* Clear local cache so that we don't think we have cached numbers */
/* Note that we do not change the currval() state */
elm->cached = elm->last;
relation_close(seq_rel, NoLock);
}
static void
_bt_mergebuild(Spooler *self, BTSpool *btspool)
{
Relation heapRel = self->relinfo->ri_RelationDesc;
BTWriteState wstate;
BTReader reader;
bool merge;
Assert(btspool->index->rd_index->indisvalid);
tuplesort_performsort(btspool->sortstate);
wstate.index = btspool->index;
/*
* We need to log index creation in WAL iff WAL archiving is enabled AND
* it's not a temp index.
*/
wstate.btws_use_wal = self->use_wal &&
XLogArchivingActive() && !RELATION_IS_LOCAL(wstate.index);
/* reserve the metapage */
wstate.btws_pages_alloced = BTREE_METAPAGE + 1;
wstate.btws_pages_written = 0;
wstate.btws_zeropage = NULL; /* until needed */
/*
* Flush dirty buffers so that we will read the index files directly
* in order to get pre-existing data. We must acquire AccessExclusiveLock
* for the target table for calling FlushRelationBuffer().
*/
LockRelation(wstate.index, AccessExclusiveLock);
FlushRelationBuffers(wstate.index);
BULKLOAD_PROFILE(&prof_flush);
merge = BTReaderInit(&reader, wstate.index);
elog(DEBUG1, "pg_bulkload: build \"%s\" %s merge (%s wal)",
RelationGetRelationName(wstate.index),
merge ? "with" : "without",
wstate.btws_use_wal ? "with" : "without");
/* Assign a new file node. */
RelationSetNewRelfilenode(wstate.index, InvalidTransactionId);
if (merge || (btspool->isunique && self->max_dup_errors > 0))
{
/* Merge two streams into the new file node that we assigned. */
BULKLOAD_PROFILE_PUSH();
_bt_mergeload(self, &wstate, btspool, &reader, heapRel);
BULKLOAD_PROFILE_POP();
BULKLOAD_PROFILE(&prof_merge);
}
else
{
/* Fast path for newly created index. */
_bt_load(&wstate, btspool, NULL);
BULKLOAD_PROFILE(&prof_index);
}
BTReaderTerm(&reader);
}
