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1.
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How can we reduce the network traffic? |
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- Replication of data in distributed environment.
- Using snapshots to replicate data.
- Using remote procedure calls.
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2.
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What is snapshots? |
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Snapshot is an object used to dynamically replicate data
between distribute database at specified time intervals.
In ver 7.0 they are read only.
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3.
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What are the various type of snapshots? |
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Simple and Complex.
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4.
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Differentiate simple and complex, snapshots? |
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- A simple snapshot is based on a query that does not
contains GROUP BY clauses, CONNECT BY
clauses, Joins, sub-query or snapshot of operations.
- A complex snapshots contain at least any one of the
above.
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5.
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What dynamic data replication? |
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Updating or Inserting records in remote database through
database triggers. It may fail if remote database is
having any problem. |
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6.
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How can you Enforce Referential Integrity in snapshots? |
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Time the references to occur when master tables are not
in use.
Perform the reference the manually immediately locking
the master tables.
We can join tables in snapshots by creating a complex
snapshots that will based on the master tables.
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7.
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What are the options available to refresh snapshots? |
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COMPLETE - Tables are completely regenerated using the
snapshot's query and the master tables every time the
snapshot referenced.
FAST - If simple snapshot used then a snapshot log can
be used to send the changes to the snapshot
tables.
FORCE - Default value. If possible it performs a FAST
refresh; Otherwise it will perform a complete refresh.
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8.
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What is snapshot log? |
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It is a table that maintains a record of modifications
to the master table in a snapshot. It is stored in the
same database as master table and is only available for
simple snapshots. It should be created before creating
snapshots.
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9.
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When will the data in the snapshot log be used? |
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We must be able to create a after row trigger on table
(i.e., it should be not be already available)
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10. |
After giving table privileges. |
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We cannot specify snapshot log name because oracle uses
the name of the master table in the name of the database
objects that support its snapshot log.
The master table name should be less than or equal to 23
characters.
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11. |
What are the benefits of distributed options in
databases? |
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Database on other servers can be updated and those
transactions can be grouped together with others in a
logical unit.
Database uses a two phase commit.
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