It's relatively tightly coupled with relational databases (like MySQL or PostgreSQL), so, having a NoSQL database (like Couchbase, MongoDB, Cassandra, etc) as the main store engine is not very easy.

//
// Questions left to address:
// * Might at some point need a way for callers to provide their own Env.
// * Maybe add TF_TensorShape that encapsulates dimension info.
//
// Design decisions made:
// * Backing store for tensor memory has an associated deallocation
//   function.  This deallocation function will point to client code
//   for tensors populated by the client.  So the client can do things
//   like shadowing a numpy array.

			endpoint := clnt.EndpointURL().String()
			if errInt, ok := opts.checkReadyErr.Load(endpoint); !ok {
				err = checkRemoteEndpoint(ctx, clnt.EndpointURL())
				opts.checkReadyErr.Store(endpoint, err)
			} else {
				if errInt == nil {
					err = nil
				} else {
					err, _ = errInt.(error)
				}
			}
			switch err.(type) {
			case BucketRemoteIdenticalToSource:

     * We will still use the readXxxWireFormat return values to
     * indicate how many bytes(note: readParameterWordsWireFormat
     * returns bytes read and not the number of words(but the
     * wordCount member DOES store the number of words)) we
     * actually read. Incedentally this is important to the
     * AndXServerMessageBlock class that needs to potentially
     * read in another smb's parameter words and bytes based on

			select {
			case <-ctx.Done():
				// Nobody wants it.
			case resCh <- results:
			}
		}
	}()
	return func() (metaCacheEntriesSorted, error) {
		select {
		case <-ctx.Done():
			done.Store(true)
			return metaCacheEntriesSorted{}, ctx.Err()
		case r := <-resultsDone:
			return r, resErr
		}
	}
}

// readOldGNUSparseMap reads the sparse map from the old GNU sparse format.
// The sparse map is stored in the tar header if it's small enough.
// If it's larger than four entries, then one or more extension headers are used
// to store the rest of the sparse map.
//
// The Header.Size does not reflect the size of any extended headers used.
// Thus, this function will read from the raw io.Reader to fetch extra headers.

     */
    protected static final String CREATE_TIME = "createTime";

    /**
     * Document type.
     */
    protected static final String _DOC = "_doc";

    /**
     * Fields that store timestamps.
     */
    protected static final String[] timestampFields = { LAST_MODIFIED, CREATE_TIME };

    /**
     * Hash function for generating IDs.
     */

            } catch (PluginVersionResolutionException e) {
                throw new PluginManagerException(plugin, e.getMessage(), e);
            }
        }

        // TODO: store plugin version

        // resolve plugin artifacts
        List<Artifact> artifacts;
        PluginArtifactsCache.Key cacheKey = pluginArtifactsCache.createKey(plugin, null, repositories, session);

	ANDW	$0x6006000060060, R27, R5                        // ERROR "cannot use REGTMP as source"
	STP	(R3, R4), 0x1234567(R27)                         // ERROR "REGTMP used in large offset store"
	LDP	0x1234567(R27), (R3, R4)                         // ERROR "REGTMP used in large offset load"
	STP	(R26, R27), 700(R2)                              // ERROR "cannot use REGTMP as source"

   */

  private transient Map<K, Collection<V>> map;
  private transient int totalSize;

  /**
   * Creates a new multimap that uses the provided map.
   *
   * @param map place to store the mapping from each key to its corresponding values
   * @throws IllegalArgumentException if {@code map} is not empty
   */
  protected AbstractMapBasedMultimap(Map<K, Collection<V>> map) {
    checkArgument(map.isEmpty());