Integer blocks that were run length encoded could produce the wrong
value when read back out because the deltas were not zig zag decoded
before scaling the final value. If the deltas were negative, as would
be seen in a counter that decrements by a constant value, the results
would be random with som negative and positive values.
Fixes#7391
This allows encoders to be re-used and maintained in a pool to
avoid allocating new ones on every compactions and write of an encoded
block. The pool used is not a sync.Pool to ensure that the encoders
will not be garbage collected.
This commit makes a number of performance improvements to
reduce allocations during query execution. Several objects
and buffers are now reused across the components to avoid
allocations.
Previously a simple `count(value)` query across 1M points
would require 26,000+ allocations. After the changes in
this commit that number has been reduced to 88.
This will help large integer counters type fields that increment by
small amounts over time. Instead of storing the larger raw value
in a compressed format, we store the difference from the prior value
in compressed format which allows the value to be stored using
fewer bits.
Will make it less error-prone to add new encodings int the future
since each encoder has it's set of constants. There are some placeholder
contants for uncompressed encodings which are not in all encoder currently.
Abirdcfly
Stuart Carnie
Mark Rushakoff
Jason Wilder
Ben Johnson
Paul Dix