How to pre - load all database rows into cache

Question

Hi All,
The below is my cache configuration, I would like to know how to load all the database rows/specified number of rows into the cache.
<?xml version="1.0"?>
<!DOCTYPE cache-config SYSTEM "cache-config.dtd">
<cache-config>
<caching-scheme-mapping>
<cache-mapping>
<cache-name>TableEmp</cache-name>
<scheme-name>distributed-hibernate</scheme-name>
<init-params>
<init-param>
<param-name>entityname</param-name>
<param-value>com.tangosol.examples.explore.Emp</param-value>
</init-param>
</init-params>
</cache-mapping>
</caching-scheme-mapping>
<caching-schemes>
<distributed-scheme>
<scheme-name>distributed-hibernate</scheme-name>
<backing-map-scheme>
<read-write-backing-map-scheme>
<internal-cache-scheme>
<local-scheme></local-scheme>
</internal-cache-scheme>
<cachestore-scheme>
<class-scheme>
<class-name>
com.tangosol.coherence.hibernate.HibernateCacheStore
</class-name>
<init-params>
<init-param>
<param-type>java.lang.String</param-type>
<param-value>{entityname}</param-value>
</init-param>
</init-params>
</class-scheme>
</cachestore-scheme>
</read-write-backing-map-scheme>
</backing-map-scheme>
</distributed-scheme>
</caching-schemes>
</cache-config>
Please kindly provide a solution.
Regards
S

Answer 1

Hi Rich,
Imagine I have just downloaded coherence, I have run a server with the default config. From what you said to S coherence can pull the data from database itself WITHOUT me having to push it to coherence? If so can you please explain how this done, or point me at a guide?You might start with [Read-Through Caching|http://coherence.oracle.com/display/COH34UG/Read-Through%2C+Write-Through%2C+Write-Behind+and+Refresh-Ahead+Caching#Read-Through%2CWrite-Through%2CWrite-BehindandRefresh-AheadCaching-ReadThroughCache] to understand how Coherence can pull data. It is the implementation of a CacheLoader that enables the Coherence cache to pull the data.
The cache configuration that S provided specifies a read-write-backing-map-scheme indicating that HibernateCacheStore class should be used by Coherence and is similar to the configuration discussed at [Using Hibernate as a CacheStore for Coherence|http://wiki.tangosol.com/display/COH34UG/Using+Hibernate+as+a+CacheStore+for+Coherence]. In responding to the original question, I was assuming that the data source being queried to be loaded into the cache is the same as the data source fronted by the Hibernate configuration.
Secondly with the respects to the answer to my question. If I don't care about versioning ... do I need a EvolvablePortableObject? If you really don't want to version your serialized representations, you can implement the PortableObject interface instead but the additional cost of implementing EvolvablePortableObject is small and the potential benefit is great.
So my question is, can coherence pull the data from the database using a preload request and serialize into a pof format without me having to push the data to coherence via a separate app? And if so could you please explain how? Or direct me at some documentation?You do not need to push data to Coherence via a separate app. Coherence can pull the data from the database. Coherence can also preload the cache using an EntryProcessor. You can configure Coherence to use POF and will need to implement POF serialization methods for your cache objects.
The [Partitioned cache with a serializer|http://coherence.oracle.com/display/COH34UG/Sample+Cache+Configurations#SampleCacheConfigurations-Partitionedcacheofadatabase] example and the links it provides should provide sufficient documentation for configuring and using POF.
Whether you decide to use the HibernateCacheStore, the TopLinkCacheStore or implement your own CacheStore or CacheLoader class to access your data in your database is your decision. You should be able to find sufficient documentation and examples to help you decide how you would like to use Coherence at the [Coherence Knowledge Base|http://wiki.tangosol.com/display/COH/Oracle+Coherence+Knowledge+Base+Home]. I would recommend starting with the [User Guide|http://wiki.tangosol.com/display/COH34UG/Coherence+3.4+Home] if you would like to get a better grasp of the overall architecture.
Regards,
Harv