kvdb-rocksdb 0.7.0

kvdb implementation backed by RocksDB
Documentation
# Changelog

The format is based on [Keep a Changelog].

[Keep a Changelog]: http://keepachangelog.com/en/1.0.0/

## [Unreleased]

## [0.7.0] - 2020-03-16
- Updated dependencies. [#361]https://github.com/paritytech/parity-common/pull/361

## [0.6.0] - 2020-02-28
- License changed from GPL3 to dual MIT/Apache2. [#342]https://github.com/paritytech/parity-common/pull/342
- Added `get_statistics` method and `enable_statistics` config parameter. [#347]https://github.com/paritytech/parity-common/pull/347

## [0.5.0] - 2019-02-05
- Bump parking_lot to 0.10. [#332]https://github.com/paritytech/parity-common/pull/332

## [0.4.2] - 2019-02-04
### Fixes
- Fixed `iter_from_prefix` being slow. [#326]https://github.com/paritytech/parity-common/pull/326

## [0.4.1] - 2019-01-06
- Updated features and feature dependencies. [#307]https://github.com/paritytech/parity-common/pull/307

## [0.4.0] - 2019-01-03
- Add I/O statistics for RocksDB. [#294]https://github.com/paritytech/parity-common/pull/294
- Support querying memory footprint via `MallocSizeOf` trait. [#292]https://github.com/paritytech/parity-common/pull/292

## [0.3.0] - 2019-12-19
- Use `get_pinned` API to save one allocation for each call to `get()`. [#274]https://github.com/paritytech/parity-common/pull/274
- Rename `drop_column` to `remove_last_column`. [#274]https://github.com/paritytech/parity-common/pull/274
- Rename `get_cf` to `cf`. [#274]https://github.com/paritytech/parity-common/pull/274
- Default column support removed from the API. [#278]https://github.com/paritytech/parity-common/pull/278
  - Column argument type changed from `Option<u32>` to `u32`
  - Migration
    - Column index `None` -> unsupported, `Some(0)` -> `0`, `Some(1)` -> `1`, etc.
    - Database must be opened with at least one column and existing DBs has to be opened with a number of columns increased by 1 to avoid having to migrate the data, e.g. before: `Some(9)`, after: `10`.
  - `DatabaseConfig::default()` defaults to 1 column
  - `Database::with_columns` still accepts `u32`, but panics if `0` is provided
  - `Database::open` panics if configuration with 0 columns is provided
- Add `num_keys(col)` to get an estimate of the number of keys in a column. [#285]https://github.com/paritytech/parity-common/pull/285
- Remove `ElasticArray` and use the new `DBValue` (alias for `Vec<u8>`) and `DBKey` types from `kvdb`. [#282]https://github.com/paritytech/parity-common/pull/282

## [0.2.0] - 2019-11-28
- Switched away from using [parity-rocksdb]https://crates.io/crates/parity-rocksdb in favour of upstream [rust-rocksdb]https://crates.io/crates/rocksdb. [#257]https://github.com/paritytech/parity-common/pull/257
- Revamped configuration handling, allowing per-column memory budgeting. [#256]https://github.com/paritytech/parity-common/pull/256
### Dependencies
- rust-rocksdb v0.13

## [0.1.6] - 2019-10-24
- Updated to 2018 edition idioms. [#237]https://github.com/paritytech/parity-common/pull/237
### Dependencies
- Updated dependencies. [#239]https://github.com/paritytech/parity-common/pull/239