The last improvement of memory usage introduced a performance
regression. The ingestion performance dropped by 50%-80%, because
for every inserted entry the Tags were created inefficient.
This reduces the size of the old generation by 100MB (300MB down to
200MB). Unfortunately the total JVM size didn't change and is still
512MB.
Doc stores the path as byte array instead of Path.
Before we could only group by a single field. But it is acutally
very useful to group by multiple fields. For example to see the
graph for a small set of methods grouped by host and project.
Store values in sequences of variable length. Instead of using 8 bytes
per entry we are now using between 2 and 20 bytes. But we are also able
to store every non-negative long value.
