Sharding with LOBs

2.6 Sharding with LOBs

LOBs can be used in a sharded environment. This section discusses the interfaces to support LOBs in sharded tables.

The following interfaces are supported:

Query and DML statements
- Cross shard queries involving LOBs are supported.
- DML statements involving more than one shard are not supported. This behavior is similar to scalar columns.
- DML statements involving a single shard are supported from coordinator.
- Locator selected from a shard can be passed as bind value to the same shard.
OCILob
All non-BFILE related OCILob APIs in a sharding environment are supported, with some restrictions.

On the coordinator, the OCI_ATTR_LOB_REMOTE attribute of a LOB descriptor returns TRUE if the LOB was obtained from a sharded table.

Restrictions: For APIs that take two locators as input, OCILobAppend, OCILobCompare for example, both of the locators should be obtained from the same shard. If locators are from different shards an error is given.
DBMS_LOB

All non-BFILE related DBMS_LOB APIs in a sharding environment are supported, with some restrictions. On the coordinator, DBMS_LOB.isremote returns TRUE if the LOB was obtained from a sharded table.

Restrictions: For APIs that take two locators as input, DBMS_LOB.append and DBMS_LOB.compare for example, both of the locators should be obtained from the same shard. If the locators are from different shards an error given.