How to Remove A Table From Cache In Oracle?

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To remove a table from cache in Oracle, you can use the following steps:

  1. Open SQL*Plus or any other SQL editor.
  2. Connect to your Oracle database using a privileged user account.
  3. Execute the following command to flush the cache for the specific table: ALTER TABLE table_name STORAGE (BUFFER_POOL DEFAULT);


By executing this command, you are removing the table from the cache and moving it back to the default buffer pool. This will help to free up memory resources and improve the overall performance of your database.


How can I flush cache for a specific table in Oracle?

To flush the cache for a specific table in Oracle, you can use the following command:


ALTER TABLE <table_name> DEALLOCATE UNUSED;


This command will deallocate any unused space in the cache for the specified table, effectively flushing the cache for that specific table.


How can I verify if a table is cached in Oracle database?

There are a few methods you can use to verify if a table is cached in an Oracle database:

  1. Check the V$CACHE_OBJECTS view: You can query the V$CACHE_OBJECTS view to see if the table is listed as a cached object. The view provides information about the objects that are currently cached in the buffer cache.
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SELECT * FROM V$CACHE_OBJECTS WHERE OBJECT_NAME = 'your_table_name';


  1. Check the DBA_TABLES view: You can also check the DBA_TABLES view to see if the table has the CACHE parameter set to YES. This indicates that the table is set to be cached in the buffer cache.
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SELECT * FROM DBA_TABLES WHERE TABLE_NAME = 'your_table_name' AND CACHE = 'Y';


  1. Check the buffer cache usage: You can use the following query to check the buffer cache usage and see if the table is currently in the cache:
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SELECT * FROM V$BUFFER_POOL_STATISTICS WHERE NAME = 'DEFAULT' AND TYPE = 'data' AND COUNTER > 0;


If the table is in the buffer cache, it will have a non-zero value in the COUNTER column.


By using these methods, you can verify if a table is cached in an Oracle database.


What are the risks of removing a table from cache in Oracle?

  1. Increased load on the database server: When a table is removed from cache, queries that were previously serviced from the cache will now have to be processed by the database server. This can lead to increased load on the server, potentially causing performance degradation for other queries and applications.
  2. Increased latency: Since queries that were previously served from cache will now have to be processed by the server, there may be an increase in query response times. This can impact the overall performance of the database and the applications relying on it.
  3. Increased I/O operations: When a table is removed from cache, the database will have to fetch the data from disk every time a query is executed. This can lead to an increase in I/O operations, potentially slowing down the performance of the database.
  4. Decreased scalability: Removing a table from cache can limit the scalability of the database, as it may not be able to handle as many queries and transactions as before. This can impact the ability of the database to support growing data volumes and increasing user loads.
  5. Data inconsistency: Removing a table from cache can lead to data inconsistency, as queries may return outdated or stale data if the cache is not properly managed. This can result in incorrect query results and potential data corruption issues.


How to avoid caching for a particular table in Oracle?

To avoid caching for a particular table in Oracle, you can use the following steps:

  1. Disable the caching for the specific table by using the NOCACHE option when creating or altering the table. This will prevent the table from being cached in the buffer cache:
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CREATE TABLE table_name (column1 datatype, column2 datatype, ...) NOCACHE;


  1. You can also use the CACHE clause with the table creation or alteration command to explicitly enable caching, in case it has been disabled. If you want to avoid caching, make sure to omit the CACHE keyword:
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CREATE TABLE table_name (column1 datatype, column2 datatype, ...) CACHE;


  1. You can also set the cache property for the table to NOCACHE using the ALTER TABLE command:
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ALTER TABLE table_name NOCACHE;


By following these steps, you can ensure that a particular table is not cached in Oracle, avoiding potential performance issues or stale data problems.

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