A. Read – only Materialized Views
I. Overview
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Clients can query data at the local machine without having to remote machines Master Database. Helps reduce query time and reduce the load for the Master Database server.
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Clients only read the data on the local machine (Read - only Materialized Views) can not update, delete, ...
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Only can update, delete, ... data on the master machine with the user account has the ability (eg, SYS, SYSTEM, or the user is granted the right ...).
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Each table in the computer while updating the Master Database after 1 period (Do configuration), data change will automatically update to the machine Slave (Read - only Materialized Views
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1 read - only table snapshot: 1 copy table data from one or more other tables on the remote machine (master machine.), Along with the update logs.
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Ex: From a table on master:
SQL> CREATE SNAPSHOT obj_1 AS SELECT * FROM obj_1@orc1
SQL> CREATE SNAPSHOT sales.orders AS SELECT * FROM sales.orders@hq.acme.com o
WHERE EXISTS
( SELECT c_id FROM sales.customers@hq.acme.com c
WHERE o.c_id = c.c_id AND zip = 19555);
table user_snapshot_log MLOG$_name_of_table_replicated
database oracle replication

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