/*
* Map a relation's (tablespace, filenode) to a relation's oid and cache the
* result.
*
* Returns InvalidOid if no relation matching the criteria could be found.
*/
Oid
RelidByRelfilenode(Oid reltablespace, Oid relfilenode)
{
RelfilenodeMapKey key;
RelfilenodeMapEntry *entry;
bool found;
SysScanDesc scandesc;
Relation relation;
HeapTuple ntp;
ScanKeyData skey[2];
if (RelfilenodeMapHash == NULL)
InitializeRelfilenodeMap();
/* pg_class will show 0 when the value is actually MyDatabaseTableSpace */
if (reltablespace == MyDatabaseTableSpace)
reltablespace = 0;
MemSet(&key, 0, sizeof(key));
key.reltablespace = reltablespace;
key.relfilenode = relfilenode;
/*
* Check cache and enter entry if nothing could be found. Even if no target
* relation can be found later on we store the negative match and return a
* InvalidOid from cache. That's not really necessary for performance since
* querying invalid values isn't supposed to be a frequent thing, but the
* implementation is simpler this way.
*/
entry = hash_search(RelfilenodeMapHash, (void *) &key, HASH_ENTER, &found);
if (found)
return entry->relid;
/* ok, no previous cache entry, do it the hard way */
/* check shared tables */
if (reltablespace == GLOBALTABLESPACE_OID)
{
entry->relid = RelationMapFilenodeToOid(relfilenode, true);
return entry->relid;
}
/* check plain relations by looking in pg_class */
relation = heap_open(RelationRelationId, AccessShareLock);
/* copy scankey to local copy, it will be modified during the scan */
memcpy(skey, relfilenode_skey, sizeof(skey));
/* set scan arguments */
skey[0].sk_argument = ObjectIdGetDatum(reltablespace);
skey[1].sk_argument = ObjectIdGetDatum(relfilenode);
scandesc = systable_beginscan(relation,
ClassTblspcRelfilenodeIndexId,
true,
NULL,
2,
skey);
found = false;
while (HeapTupleIsValid(ntp = systable_getnext(scandesc)))
{
bool isnull PG_USED_FOR_ASSERTS_ONLY;
if (found)
elog(ERROR,
"unexpected duplicate for tablespace %u, relfilenode %u",
reltablespace, relfilenode);
found = true;
#ifdef USE_ASSERT_CHECKING
if (assert_enabled)
{
Oid check;
check = fastgetattr(ntp, Anum_pg_class_reltablespace,
RelationGetDescr(relation),
&isnull);
Assert(!isnull && check == reltablespace);
check = fastgetattr(ntp, Anum_pg_class_relfilenode,
RelationGetDescr(relation),
&isnull);
Assert(!isnull && check == relfilenode);
}
#endif
entry->relid = HeapTupleGetOid(ntp);
}
systable_endscan(scandesc);
heap_close(relation, AccessShareLock);
/* check for tables that are mapped but not shared */
if (!found)
entry->relid = RelationMapFilenodeToOid(relfilenode, false);
return entry->relid;
}
/*
* Map a relation's (tablespace, filenode) to a relation's oid and cache the
* result.
*
* Returns InvalidOid if no relation matching the criteria could be found.
*/
Oid
RelidByRelfilenode(Oid reltablespace, Oid relfilenode)
{
RelfilenodeMapKey key;
RelfilenodeMapEntry *entry;
bool found;
SysScanDesc scandesc;
Relation relation;
HeapTuple ntp;
ScanKeyData skey[2];
Oid relid;
if (RelfilenodeMapHash == NULL)
InitializeRelfilenodeMap();
/* pg_class will show 0 when the value is actually MyDatabaseTableSpace */
if (reltablespace == MyDatabaseTableSpace)
reltablespace = 0;
MemSet(&key, 0, sizeof(key));
key.reltablespace = reltablespace;
key.relfilenode = relfilenode;
/*
* Check cache and return entry if one is found. Even if no target
* relation can be found later on we store the negative match and return a
* InvalidOid from cache. That's not really necessary for performance
* since querying invalid values isn't supposed to be a frequent thing,
* but it's basically free.
*/
entry = hash_search(RelfilenodeMapHash, (void *) &key, HASH_FIND, &found);
if (found)
return entry->relid;
/* ok, no previous cache entry, do it the hard way */
/* initialize empty/negative cache entry before doing the actual lookups */
relid = InvalidOid;
if (reltablespace == GLOBALTABLESPACE_OID)
{
/*
* Ok, shared table, check relmapper.
*/
relid = RelationMapFilenodeToOid(relfilenode, true);
}
else
{
/*
* Not a shared table, could either be a plain relation or a
* non-shared, nailed one, like e.g. pg_class.
*/
/* check for plain relations by looking in pg_class */
relation = heap_open(RelationRelationId, AccessShareLock);
/* copy scankey to local copy, it will be modified during the scan */
memcpy(skey, relfilenode_skey, sizeof(skey));
/* set scan arguments */
skey[0].sk_argument = ObjectIdGetDatum(reltablespace);
skey[1].sk_argument = ObjectIdGetDatum(relfilenode);
scandesc = systable_beginscan(relation,
ClassTblspcRelfilenodeIndexId,
true,
NULL,
2,
skey);
found = false;
while (HeapTupleIsValid(ntp = systable_getnext(scandesc)))
{
if (found)
elog(ERROR,
"unexpected duplicate for tablespace %u, relfilenode %u",
reltablespace, relfilenode);
found = true;
#ifdef USE_ASSERT_CHECKING
if (assert_enabled)
{
bool isnull;
Oid check;
check = fastgetattr(ntp, Anum_pg_class_reltablespace,
RelationGetDescr(relation),
&isnull);
Assert(!isnull && check == reltablespace);
check = fastgetattr(ntp, Anum_pg_class_relfilenode,
RelationGetDescr(relation),
&isnull);
Assert(!isnull && check == relfilenode);
}
#endif
relid = HeapTupleGetOid(ntp);
}
systable_endscan(scandesc);
heap_close(relation, AccessShareLock);
/* check for tables that are mapped but not shared */
if (!found)
relid = RelationMapFilenodeToOid(relfilenode, false);
}
/*
* Only enter entry into cache now, our opening of pg_class could have
* caused cache invalidations to be executed which would have deleted a
* new entry if we had entered it above.
*/
entry = hash_search(RelfilenodeMapHash, (void *) &key, HASH_ENTER, &found);
if (found)
elog(ERROR, "corrupted hashtable");
entry->relid = relid;
return relid;
}
