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https://issues.apache.org/jira/browse/DERBY-7073?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17074846#comment-17074846
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Richard N. Hillegas commented on DERBY-7073:
--------------------------------------------
I am not familiar with the capabilities of PolarDB
(https://dbdb.io/db/polardb). It sounds as though it runs on top of a
distributed file system. Derby's crash-recovery logic assumes that the data
files (tables and indexes) are located on a single disk. Derby lets you put the
recovery logs on a separate disk. You should be able to replace either of these
disks with something like a RAID cluster in order to push much of the recovery
problem into the hardware layer.
I don't understand your proposal about harnessing multiple Derby nodes into a
single, logical storage layer.
You are on the right track to use a subprotocol in order to swap out the
default file system with something fancier. As an example of how to do this,
look at how in-memory databases (the memory subprotocol) were implemented.
Hope this helps,
-Rick
> Can we override the underlying storage to implement a distributed Derby using
> Derby's subsubprotocol mechanism
> --------------------------------------------------------------------------------------------------------------
>
> Key: DERBY-7073
> URL: https://issues.apache.org/jira/browse/DERBY-7073
> Project: Derby
> Issue Type: Task
> Reporter: liaochuntao
> Priority: Trivial
>
> /**
> * derby.subSubProtocol.xxx
> *<p>
> *
> * A new subsubprotocol can be defined by specifying the class that handles
> storage for the
> * subsubprotocol by implementing the
> * org.apache.derby.io.StorageFactory StorageFactory or
> * org.apache.derby.io.WritableStorageFactory WritableStorageFactory
> interface. This
> * is done using a property named db2j.subsubprotocol.<i>xxx</i> where
> <i>xxx</i> is the subsubprotocol name.
> * Subsubprotocol names are case sensitive and must be at least 3 characters
> in length.
> *<p>
> *
> * For instance:
> *<br>
> * derby.subSubProtocol.mem=com.mycompany.MemStore
> *<br>
> * defines the "mem" subsubprotocol with class com.mycompany.MemStore as its
> StorageFactory implementation.
> * A database implemented using this subsubprotocol can be opened with the
> URL "jdbc:derby:mem:myDatabase".
> *<p>
> *
> * Subsubprotocols "directory", "classpath", "jar", "http", and "https" are
> built in and may not be overridden.
> */
>
> Can we take advantage of this capability to implement a distributed
> contribution storage, with Derby acting as the computing layer and multiple
> Derby nodes contributing a storage layer, and realize Ploar DB similar to ali
> cloud, namely a distributed Derby
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