/*
* Open pg_largeobject and its index, if not already done in current xact
*/
static void
open_lo_relation(void)
{
ResourceOwner currentOwner;
if (lo_heap_r && lo_index_r)
return; /* already open in current xact */
/* Arrange for the top xact to own these relation references */
currentOwner = CurrentResourceOwner;
PG_TRY();
{
CurrentResourceOwner = TopTransactionResourceOwner;
/* Use RowExclusiveLock since we might either read or write */
if (lo_heap_r == NULL)
lo_heap_r = heap_openr(LargeObjectRelationName, RowExclusiveLock);
if (lo_index_r == NULL)
lo_index_r = index_openr(LargeObjectLOidPNIndex);
}
PG_CATCH();
{
/* Ensure CurrentResourceOwner is restored on error */
CurrentResourceOwner = currentOwner;
PG_RE_THROW();
}
PG_END_TRY();
CurrentResourceOwner = currentOwner;
}
/*
* systable_beginscan --- set up for heap-or-index scan
*
* rel: catalog to scan, already opened and suitably locked
* indexRelname: name of index to conditionally use
* indexOK: if false, forces a heap scan (see notes below)
* snapshot: time qual to use (usually should be SnapshotNow)
* nkeys, key: scan keys
*
* The attribute numbers in the scan key should be set for the heap case.
* If we choose to index, we reset them to 1..n to reference the index
* columns. Note this means there must be one scankey qualification per
* index column! This is checked by the Asserts in the normal, index-using
* case, but won't be checked if the heapscan path is taken.
*
* The routine checks the normal cases for whether an indexscan is safe,
* but caller can make additional checks and pass indexOK=false if needed.
* In standard case indexOK can simply be constant TRUE.
*/
SysScanDesc
systable_beginscan(Relation heapRelation,
const char *indexRelname,
bool indexOK,
Snapshot snapshot,
int nkeys, ScanKey key)
{
SysScanDesc sysscan;
Relation irel;
if (indexOK && !IsIgnoringSystemIndexes())
{
/* We assume it's a system index, so index_openr is OK */
irel = index_openr(indexRelname);
if (ReindexIsProcessingIndex(RelationGetRelid(irel)))
{
/* oops, can't use index that's being rebuilt */
index_close(irel);
irel = NULL;
}
}
else
irel = NULL;
sysscan = (SysScanDesc) palloc(sizeof(SysScanDescData));
sysscan->heap_rel = heapRelation;
sysscan->irel = irel;
if (irel)
{
int i;
/*
* Change attribute numbers to be index column numbers.
*
* This code could be generalized to search for the index key numbers
* to substitute, but for now there's no need.
*/
for (i = 0; i < nkeys; i++)
{
Assert(key[i].sk_attno == irel->rd_index->indkey[i]);
key[i].sk_attno = i + 1;
}
sysscan->iscan = index_beginscan(heapRelation, irel, snapshot,
nkeys, key);
sysscan->scan = NULL;
}
else
{
sysscan->scan = heap_beginscan(heapRelation, snapshot, nkeys, key);
sysscan->iscan = NULL;
}
return sysscan;
}
/*
* InitCatCachePhase2 -- external interface for CatalogCacheInitializeCache
*
* The only reason to call this routine is to ensure that the relcache
* has created entries for all the catalogs and indexes referenced by
* catcaches. Therefore, open the index too. An exception is the indexes
* on pg_am, which we don't use (cf. IndexScanOK).
*/
void
InitCatCachePhase2(CatCache *cache)
{
if (cache->cc_tupdesc == NULL)
CatalogCacheInitializeCache(cache);
if (cache->id != AMOID &&
cache->id != AMNAME)
{
Relation idesc;
idesc = index_openr(cache->cc_indname);
index_close(idesc);
}
}
/*
* cluster
*
* Check that the relation is a relation in the appropriate user
* ACL. I will use the same security that limits users on the
* renamerel() function.
*
* Check that the index specified is appropriate for the task
* ( ie it's an index over this relation ). This is trickier.
*
* Create a list of all the other indicies on this relation. Because
* the cluster will wreck all the tids, I'll need to destroy bogus
* indicies. The user will have to re-create them. Not nice, but
* I'm not a nice guy. The alternative is to try some kind of post
* destroy re-build. This may be possible. I'll check out what the
* index create functiond want in the way of paramaters. On the other
* hand, re-creating n indicies may blow out the space.
*
* Create new (temporary) relations for the base heap and the new
* index.
*
* Exclusively lock the relations.
*
* Create new clustered index and base heap relation.
*
*/
void
cluster(char oldrelname[], char oldindexname[])
{
Oid OIDOldHeap, OIDOldIndex, OIDNewHeap;
Relation OldHeap, OldIndex;
Relation NewHeap;
char *NewIndexName;
char *szNewHeapName;
/*
*
* I'm going to force all checking back into the commands.c function.
*
* Get the list if indicies for this relation. If the index we want
* is among them, do not add it to the 'kill' list, as it will be
* handled by the 'clean up' code which commits this transaction.
*
* I'm not using the SysCache, because this will happen but
* once, and the slow way is the sure way in this case.
*
*/
/*
* Like vacuum, cluster spans transactions, so I'm going to handle it in
* the same way.
*/
/* matches the StartTransaction in PostgresMain() */
OldHeap = heap_openr(oldrelname);
if (!RelationIsValid(OldHeap)) {
elog(WARN, "cluster: unknown relation: \"%-.*s\"",
NAMEDATALEN, oldrelname);
}
OIDOldHeap = OldHeap->rd_id; /* Get OID for the index scan */
OldIndex=index_openr(oldindexname);/* Open old index relation */
if (!RelationIsValid(OldIndex)) {
elog(WARN, "cluster: unknown index: \"%-.*s\"",
NAMEDATALEN, oldindexname);
}
OIDOldIndex = OldIndex->rd_id; /* OID for the index scan */
heap_close(OldHeap);
index_close(OldIndex);
/*
* I need to build the copies of the heap and the index. The Commit()
* between here is *very* bogus. If someone is appending stuff, they will
* get the lock after being blocked and add rows which won't be present in
* the new table. Bleagh! I'd be best to try and ensure that no-one's
* in the tables for the entire duration of this process with a pg_vlock.
*/
NewHeap = copy_heap(OIDOldHeap);
OIDNewHeap = NewHeap->rd_id;
szNewHeapName = pstrdup(NewHeap->rd_rel->relname.data);
/* Need to do this to make the new heap visible. */
CommandCounterIncrement();
rebuildheap(OIDNewHeap, OIDOldHeap, OIDOldIndex);
/* Need to do this to make the new heap visible. */
CommandCounterIncrement();
/* can't be found in the SysCache. */
copy_index(OIDOldIndex, OIDNewHeap); /* No contention with the old */
/*
* make this really happen. Flush all the buffers.
*/
CommitTransactionCommand();
StartTransactionCommand();
/*
* Questionable bit here. Because the renamerel destroys all trace of the
* pre-existing relation, I'm going to Destroy old, and then rename new
* to old. If this fails, it fails, and you lose your old. Tough - say
* I. Have good backups!
*/
/*
Here lies the bogosity. The RelationNameGetRelation returns a bad
list of TupleDescriptors. Damn. Can't work out why this is.
*/
heap_destroy(oldrelname); /* AAAAAAAAGH!! */
CommandCounterIncrement();
/*
* The Commit flushes all palloced memory, so I have to grab the
* New stuff again. This is annoying, but oh heck!
*/
/*
renamerel(szNewHeapName.data, oldrelname);
TypeRename(&szNewHeapName, &szOldRelName);
sprintf(NewIndexName.data, "temp_%x", OIDOldIndex);
renamerel(NewIndexName.data, szOldIndexName.data);
*/
NewIndexName = palloc(NAMEDATALEN+1); /* XXX */
sprintf(NewIndexName, "temp_%x", OIDOldIndex);
renamerel(NewIndexName, oldindexname);
}
