Auto distribute metrics evenly among buckets

• Auto distribute metrics evenly among buckets to improve query performance;
• More checks for invalid data to prevent data corruption;

Compatible with OpenTSDB 2.2

TickTockDB is now compatible with OpenTSDB 2.2, as far as Grafana is concerned. You can now create variables for your Grafana dashboards. We will have a demo Grafana dashboard, with variables, in our latest version of the docker image.

Support special values NaN and Inf

• Support special values NaN and Inf
• Fix bugs in level 2 rollup

Support OpenTSDB 2.x filters and formatted time in query

• Support formatted time in query;
• Support OpenTSDB 2.x filters;
• Fixed an issue where TickTockDB won't restart due to failure to restore from WAL;
• Fixed an issue where TickTockDB crashes in compressor v4;
• More parallelism to improve performance;

Added compressor v4

1. Added compressor v4 that will take advantage of special cases, such as strictly linear patterns.
2. Fixed timestamp resolution issues (see Examples in wiki).
3. Enable adaptive page count to optimize disk usages according to workload.

[Beta] [NOT BACKWARDS COMPATIBLE] Query optimizations

Warning: This release is NOT backwards compatible with previous releases. If you need to migrate existing data, please see this wiki page for instructions.

This release contains query optimizations. It makes querying data for a long period of time faster.

[Beta] Fix inspect tool OOM issue

The inspect tool runs out-of-memory under certain conditions.

[Beta] Bug fixes in Json parser; memory leak

1. Json parser not able to handle boolean values;
2. Memory leak when writing data with _field tags;

[Beta] Query and compaction optimization

Improved query and compaction efficiency. Reduced compaction time and its resource usage.

[Beta] Bug fixes.

1. Bug fixes:

• When TickTockDB runs out of memory, return HTTP 503 instead of return empty/partial results;
• If TickTockDB's timestamp are stored at seconds resolution, but downsample interval is specified in milliseconds, TickTockDB will round the millisecond interval to seconds;
• On 32-bit OS, virtual memory size is reduced to support large query range;
• No need to specify http.request.format anymore. Write requests in json, Opentsdb put, and InfluxDB line formats are supported by default;
• Memory Leaks.

2. Support 'top5' aggregator;
3. Support OpenTSDB's 'explicit_tags'