Topic : Snaphot

What is a potential reason for a Snapshot too old error message?


  • You did not refresh your snapshots in time.
  • An ITL entry in a data block has been reused.
  • Rollback segment extent sizes are too large.
  • Your online redo log files are not big enough to snap your largest transactions.

Answer :

An ITL entry in a data block has been reused.

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Explain Read-only replication and snapshots


Answer :

Read-only replication and snapshots.
Replication
Replication is the process of copying database into one or more databases to make a system distributed.
Changes made to one database are forwarded and applied to the databases at the rest of the locations.
Advantages of Replication:
- Provides user with fast; local access to shared data;
- Protects availability of applications
- Even if one site becomes unavailable; users can continue to query or even update the remaining locations.
Read-only snapshots are used for query only. Changes made to the primary database are replicated to the snapshot by the Mobile Client.
Snapshot
- A snapshot is a full set or a subset of rows of a table or view at a point in time.
- A snapshot is created by executing a SQL query against a base table.
- Snapshots are either read-only or updateable.
- They vary in complexity.

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