/*
* GetNewOid
* Generate a new OID that is unique within the given relation.
*
* Caller must have a suitable lock on the relation.
*
* Uniqueness is promised only if the relation has a unique index on OID.
* This is true for all system catalogs that have OIDs, but might not be
* true for user tables. Note that we are effectively assuming that the
* table has a relatively small number of entries (much less than 2^32)
* and there aren't very long runs of consecutive existing OIDs. Again,
* this is reasonable for system catalogs but less so for user tables.
*
* Since the OID is not immediately inserted into the table, there is a
* race condition here; but a problem could occur only if someone else
* managed to cycle through 2^32 OIDs and generate the same OID before we
* finish inserting our row. This seems unlikely to be a problem. Note
* that if we had to *commit* the row to end the race condition, the risk
* would be rather higher; therefore we use SnapshotDirty in the test,
* so that we will see uncommitted rows.
*/
Oid
GetNewOid(Relation relation)
{
Oid oidIndex;
/* If relation doesn't have OIDs at all, caller is confused */
Assert(relation->rd_rel->relhasoids);
/* In bootstrap mode, we don't have any indexes to use */
if (IsBootstrapProcessingMode())
return GetNewObjectId();
/* The relcache will cache the identity of the OID index for us */
oidIndex = RelationGetOidIndex(relation);
/* If no OID index, just hand back the next OID counter value */
if (!OidIsValid(oidIndex))
{
/*
* System catalogs that have OIDs should *always* have a unique OID
* index; we should only take this path for user tables. Give a
* warning if it looks like somebody forgot an index.
*/
if (IsSystemRelation(relation))
elog(WARNING, "generating possibly-non-unique OID for \"%s\"",
RelationGetRelationName(relation));
return GetNewObjectId();
}
/* Otherwise, use the index to find a nonconflicting OID */
return GetNewOidWithIndex(relation, oidIndex, ObjectIdAttributeNumber);
}
/*
* GetNewOid
* Generate a new OID that is unique within the given relation.
*
* Caller must have a suitable lock on the relation.
*
* Uniqueness is promised only if the relation has a unique index on OID.
* This is true for all system catalogs that have OIDs, but might not be
* true for user tables. Note that we are effectively assuming that the
* table has a relatively small number of entries (much less than 2^32)
* and there aren't very long runs of consecutive existing OIDs. Again,
* this is reasonable for system catalogs but less so for user tables.
*
* Since the OID is not immediately inserted into the table, there is a
* race condition here; but a problem could occur only if someone else
* managed to cycle through 2^32 OIDs and generate the same OID before we
* finish inserting our row. This seems unlikely to be a problem. Note
* that if we had to *commit* the row to end the race condition, the risk
* would be rather higher; therefore we use SnapshotDirty in the test,
* so that we will see uncommitted rows.
*/
Oid
GetNewOid(Relation relation)
{
Oid newOid;
Oid oidIndex;
Relation indexrel;
/* If relation doesn't have OIDs at all, caller is confused */
Assert(relation->rd_rel->relhasoids);
/* In bootstrap mode, we don't have any indexes to use */
if (IsBootstrapProcessingMode())
return GetNewObjectId();
/* The relcache will cache the identity of the OID index for us */
oidIndex = RelationGetOidIndex(relation);
/* If no OID index, just hand back the next OID counter value */
if (!OidIsValid(oidIndex))
{
Oid result;
/*
* System catalogs that have OIDs should *always* have a unique OID
* index; we should only take this path for user tables. Give a
* warning if it looks like somebody forgot an index.
*/
if (IsSystemRelation(relation))
elog(WARNING, "generating possibly-non-unique OID for \"%s\"",
RelationGetRelationName(relation));
result= GetNewObjectId();
if (IsSystemNamespace(RelationGetNamespace(relation)))
{
if (Gp_role == GP_ROLE_EXECUTE)
{
elog(DEBUG1,"Allocating Oid %u on relid %u %s in EXECUTE mode",result,relation->rd_id,RelationGetRelationName(relation));
}
if (Gp_role == GP_ROLE_DISPATCH)
{
elog(DEBUG5,"Allocating Oid %u on relid %u %s in DISPATCH mode",result,relation->rd_id,RelationGetRelationName(relation));
}
}
return result;
}
/* Otherwise, use the index to find a nonconflicting OID */
indexrel = index_open(oidIndex, AccessShareLock);
newOid = GetNewOidWithIndex(relation, indexrel);
index_close(indexrel, AccessShareLock);
return newOid;
}
/*
* GetNewOid
* Generate a new OID that is unique within the given relation.
*
* Caller must have a suitable lock on the relation.
*
* Uniqueness is promised only if the relation has a unique index on OID.
* This is true for all system catalogs that have OIDs, but might not be
* true for user tables. Note that we are effectively assuming that the
* table has a relatively small number of entries (much less than 2^32)
* and there aren't very long runs of consecutive existing OIDs. Again,
* this is reasonable for system catalogs but less so for user tables.
*
* Since the OID is not immediately inserted into the table, there is a
* race condition here; but a problem could occur only if someone else
* managed to cycle through 2^32 OIDs and generate the same OID before we
* finish inserting our row. This seems unlikely to be a problem. Note
* that if we had to *commit* the row to end the race condition, the risk
* would be rather higher; therefore we use SnapshotDirty in the test,
* so that we will see uncommitted rows.
*/
Oid
GetNewOid(Relation relation)
{
Oid newOid;
Oid oidIndex;
Relation indexrel;
/* If relation doesn't have OIDs at all, caller is confused */
Assert(relation->rd_rel->relhasoids);
/* In bootstrap mode, we don't have any indexes to use */
if (IsBootstrapProcessingMode())
return GetNewObjectId();
/* The relcache will cache the identity of the OID index for us */
oidIndex = RelationGetOidIndex(relation);
/* If no OID index, just hand back the next OID counter value */
if (!OidIsValid(oidIndex))
{
/*
* System catalogs that have OIDs should *always* have a unique OID
* index; we should only take this path for user tables. Give a
* warning if it looks like somebody forgot an index.
*/
if (IsSystemRelation(relation))
elog(WARNING, "generating possibly-non-unique OID for \"%s\"",
RelationGetRelationName(relation));
return GetNewObjectId();
}
/* Otherwise, use the index to find a nonconflicting OID */
indexrel = index_open(oidIndex, AccessShareLock);
do {
newOid = GetNewOidWithIndex(relation, indexrel);
} while(!IsOidAcceptable(newOid));
index_close(indexrel, AccessShareLock);
/*
* Most catalog objects need to have the same OID in the master and all
* segments. When creating a new object, the master should allocate the
* OID and tell the segments to use the same, so segments should have no
* need to ever allocate OIDs on their own. Therefore, give a WARNING if
* GetNewOid() is called in a segment. (There are a few exceptions, see
* RelationNeedsSynchronizedOIDs()).
*/
if (Gp_role == GP_ROLE_EXECUTE && RelationNeedsSynchronizedOIDs(relation))
elog(PANIC, "allocated OID %u for relation \"%s\" in segment",
newOid, RelationGetRelationName(relation));
return newOid;
}
bool
CheckNewRelFileNodeIsOk(Oid newOid, Oid reltablespace, bool relisshared,
Relation pg_class)
{
RelFileNode rnode;
char *rpath;
int fd;
bool collides;
if (pg_class)
{
Oid oidIndex;
Relation indexrel;
IndexScanDesc scan;
ScanKeyData key;
Assert(!IsBootstrapProcessingMode());
Assert(pg_class->rd_rel->relhasoids);
/* The relcache will cache the identity of the OID index for us */
oidIndex = RelationGetOidIndex(pg_class);
Assert(OidIsValid(oidIndex));
indexrel = index_open(oidIndex, AccessShareLock);
ScanKeyInit(&key,
(AttrNumber) 1,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(newOid));
scan = index_beginscan(pg_class, indexrel, SnapshotDirty, 1, &key);
collides = HeapTupleIsValid(index_getnext(scan, ForwardScanDirection));
index_endscan(scan);
index_close(indexrel, AccessShareLock);
if (collides)
elog(ERROR, "relfilenode %d already in use in \"pg_class\"",
newOid);
}
/* This should match RelationInitPhysicalAddr */
rnode.spcNode = reltablespace ? reltablespace : MyDatabaseTableSpace;
rnode.dbNode = relisshared ? InvalidOid : MyDatabaseId;
rnode.relNode = newOid;
/* Check for existing file of same name */
rpath = relpath(rnode);
fd = BasicOpenFile(rpath, O_RDONLY | PG_BINARY, 0);
if (fd >= 0)
{
/* definite collision */
gp_retry_close(fd);
collides = true;
}
else
collides = false;
pfree(rpath);
if (collides && !relisshared)
elog(ERROR, "oid %d already in use", newOid);
while(GetNewObjectId() < newOid);
return !collides;
}
/*
* GetNewSequenceRelationOid
* Get a sequence relation Oid and verify it is valid against
* the pg_class relation by doing an index lookup. The caller
* should have a suitable lock on pg_class.
*/
Oid
GetNewSequenceRelationOid(Relation relation)
{
Oid newOid;
Oid oidIndex;
Relation indexrel;
SnapshotData SnapshotDirty;
IndexScanDesc scan;
ScanKeyData key;
bool collides;
RelFileNode rnode;
char *rpath;
int fd;
/* This should match RelationInitPhysicalAddr */
rnode.spcNode = relation->rd_rel->reltablespace ? relation->rd_rel->reltablespace : MyDatabaseTableSpace;
rnode.dbNode = relation->rd_rel->relisshared ? InvalidOid : MyDatabaseId;
/* We should only be using pg_class */
Assert(RelationGetRelid(relation) == RelationRelationId);
/* The relcache will cache the identity of the OID index for us */
oidIndex = RelationGetOidIndex(relation);
/* Otherwise, use the index to find a nonconflicting OID */
indexrel = index_open(oidIndex, AccessShareLock);
InitDirtySnapshot(SnapshotDirty);
/* Generate new sequence relation OIDs until we find one not in the table */
do
{
CHECK_FOR_INTERRUPTS();
newOid = GetNewSequenceRelationObjectId();
ScanKeyInit(&key,
(AttrNumber) 1,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(newOid));
/* see notes above about using SnapshotDirty */
scan = index_beginscan(relation, indexrel,
&SnapshotDirty, 1, &key);
collides = HeapTupleIsValid(index_getnext(scan, ForwardScanDirection));
index_endscan(scan);
if (!collides)
{
/* Check for existing file of same name */
rpath = relpath(rnode);
fd = BasicOpenFile(rpath, O_RDONLY | PG_BINARY, 0);
if (fd >= 0)
{
/* definite collision */
gp_retry_close(fd);
collides = true;
}
else
{
/*
* Here we have a little bit of a dilemma: if errno is something
* other than ENOENT, should we declare a collision and loop? In
* particular one might think this advisable for, say, EPERM.
* However there really shouldn't be any unreadable files in a
* tablespace directory, and if the EPERM is actually complaining
* that we can't read the directory itself, we'd be in an infinite
* loop. In practice it seems best to go ahead regardless of the
* errno. If there is a colliding file we will get an smgr
* failure when we attempt to create the new relation file.
*/
collides = false;
}
}
/*
* Also check that the OID hasn't been pre-assigned for a different
* relation.
*
* We're a bit sloppy between OIDs and relfilenodes here; it would be
* OK to use a value that's been reserved for use as a type or
* relation OID here, as long as the relfilenode is free. But there's
* no harm in skipping over those too, so we don't bother to
* distinguish them.
*/
if (!collides && !IsOidAcceptable(newOid))
collides = true;
} while (collides);
index_close(indexrel, AccessShareLock);
return newOid;
}
