RocksDB is cloned from github and version v4.9 (latest at the time of
this writing) is checked out.
RocksDB can only be compiled as C++11, which means that RocksDB and hence
storage_rocksdb can be built only if the GCC version is >= 4.7.
The actual storage implementation is quite straightforward.
- The key is a SHA512 of the entire query. That will be changed so that
the database/table name is stored in the beginning of the key unhashed
as that will cause cached items from the same table to be stored
together. Assumption is that if you access something from a particular
table, chances are you will access something else as well.
- When the SO is loaded, the initialization function will created a
subdirectory storage_rocksdb under the MaxScale cache directory.
- For each instance, the RocksDB cache is created into a directory
whose name is the same as the cache filter name in the configuration
file, under that directory.
- The storage API's get and put functions are then mapped directly on
top of RockDB's equivalent functions.
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