A distributed database is a network of databases managed by multiple database servers that appears to a user as single logical database.
Two-phase commit is mechanism that guarantees a distributed transaction either commits on all involved nodes or rolls back on all involved nodes to maintain data consistency
Snapshots and SNAPSHOT LOGs
Snapshots are read-only copies of a master table located on a remote node which is periodically refreshed to reflect changes made to the master table.
A snapshot log is a table in the master database that is associated with the master table. ORACLE uses a snapshot log to track the rows that have been updated
- Replication of data in distributed environment. - Using snapshots to replicate data. - Using remote procedure calls.
Snapshot is an object used to dynamically replicate data between distribute database at specified time intervals. In ver 7.0 they are read only.
- A simple snapshot is based on a query that does not contains GROUP BY clauses, CONNECT BY clauses, JOINs, sub-query or snashot of operations.
Updating or Inserting records in remote database through database triggers. It may fail if remote database is having any problem.
COMPLETE - Tables are completely regenerated using the snapshots query and the master tables every time the snapshot referenced.FAST - If simple snapshot
