Summary:
Update branch name from master to main in docs/*
Pull Request resolved: https://github.com/facebook/rocksdb/pull/8743
Reviewed By: ltamasi
Differential Revision: D30712263
Pulled By: akankshamahajan15
fbshipit-source-id: a1a5e20d95210e792705030f98dd2b38ca542eb5
main
Akanksha Mahajan3 years agocommitted byFacebook GitHub Bot
@ -17,7 +17,7 @@ The first use-case of our spatial database was an experimental map renderer. As
The usual Mapnik workflow is to load the map data into a SQL-based database and then define map layers with SQL statements. To render a tile, Mapnik needs to execute a couple of SQL queries. The benefit of this approach is that you don't need to reload your database when you change your map style. You can just change your SQL query and Mapnik picks it up. In our model, we decided to precompute the features we need for each tile. We need to know the map style before we create the database. However, when rendering the map tile, we only fetch the features that we need to render.
We haven't open sourced the RocksDB Mapnik plugin or the database loading pipeline. However, the spatial indexing is available in RocksDB under a name [SpatialDB](https://github.com/facebook/rocksdb/blob/master/include/rocksdb/utilities/spatial_db.h). The API is focused on map rendering use-case, but we hope that it can also be used for other spatial-based applications.
We haven't open sourced the RocksDB Mapnik plugin or the database loading pipeline. However, the spatial indexing is available in RocksDB under a name [SpatialDB](https://github.com/facebook/rocksdb/blob/main/include/rocksdb/utilities/spatial_db.h). The API is focused on map rendering use-case, but we hope that it can also be used for other spatial-based applications.
Let's take a tour of the API. When you create a spatial database, you specify the spatial indexes that need to be built. Each spatial index is defined by a bounding box and granularity. For map rendering, we create a spatial index for each zoom levels. Higher zoom levels have more granularity.
The GetThreadList API is defined in [include/rocksdb/env.h](https://github.com/facebook/rocksdb/blob/master/include/rocksdb/env.h#L317-L318), which is an Env
The GetThreadList API is defined in [include/rocksdb/env.h](https://github.com/facebook/rocksdb/blob/main/include/rocksdb/env.h#L317-L318), which is an Env
function:
```c++
@ -151,7 +151,7 @@ that using the same Env.
The `GetThreadList()` API simply returns a vector of `ThreadStatus`, each describes
the current status of a thread. The `ThreadStatus` structure, defined in
[include/rocksdb/thread_status.h](https://github.com/facebook/rocksdb/blob/master/include/rocksdb/thread_status.h), contains the following information:
[include/rocksdb/thread_status.h](https://github.com/facebook/rocksdb/blob/main/include/rocksdb/thread_status.h), contains the following information:
### [](https://github.com/facebook/rocksdb/blob/master/HISTORY.md#public-api-change-1)Public API Change
### [](https://github.com/facebook/rocksdb/blob/main/HISTORY.md#public-api-change-1)Public API Change
* Allow preset compression dictionary for improved compression of block-based tables. This is supported for zlib, zstd, and lz4. The compression dictionary's size is configurable via CompressionOptions::max_dict_bytes.
* Delete deprecated classes for creating backups (BackupableDB) and restoring from backups (RestoreBackupableDB). Now, BackupEngine should be used for creating backups, and BackupEngineReadOnly should be used for restorations. For more details, see [https://github.com/facebook/rocksdb/wiki/How-to-backup-RocksDB%3F](https://github.com/facebook/rocksdb/wiki/How-to-backup-RocksDB%3F)
* Expose estimate of per-level compression ratio via DB property: "rocksdb.compression-ratio-at-levelN".
* Added EventListener::OnTableFileCreationStarted. EventListener::OnTableFileCreated will be called on failure case. User can check creation status via TableFileCreationInfo::status.
### [](https://github.com/facebook/rocksdb/blob/master/HISTORY.md#new-features-2)New Features
### [](https://github.com/facebook/rocksdb/blob/main/HISTORY.md#new-features-2)New Features
* Add ReadOptions::readahead_size. If non-zero, NewIterator will create a new table reader which performs reads of the given size.
### [](https://github.com/facebook/rocksdb/blob/master/HISTORY.md#public-api-change-2)Public API Change
### [](https://github.com/facebook/rocksdb/blob/main/HISTORY.md#public-api-change-2)Public API Change
* rename options compaction_measure_io_stats to report_bg_io_stats and include flush too.
* Change some default options. Now default options will optimize for server-workloads. Also enable slowdown and full stop triggers for pending compaction bytes. These changes may cause sub-optimal performance or significant increase of resource usage. To avoid these risks, users can open existing RocksDB with options extracted from RocksDB option files. See [https://github.com/facebook/rocksdb/wiki/RocksDB-Options-File](https://github.com/facebook/rocksdb/wiki/RocksDB-Options-File) for how to use RocksDB option files. Or you can call Options.OldDefaults() to recover old defaults. DEFAULT_OPTIONS_HISTORY.md will track change history of default options.
### [](https://github.com/facebook/rocksdb/blob/master/HISTORY.md#public-api-changes-1)Public API Changes
### [](https://github.com/facebook/rocksdb/blob/main/HISTORY.md#public-api-changes-1)Public API Changes
* Change default of BlockBasedTableOptions.format_version to 2. It means default DB created by 4.6 or up cannot be opened by RocksDB version 3.9 or earlier
* Added strict_capacity_limit option to NewLRUCache. If the flag is set to true, insert to cache will fail if no enough capacity can be free. Signature of Cache::Insert() is updated accordingly.
* Tickers [NUMBER_DB_NEXT, NUMBER_DB_PREV, NUMBER_DB_NEXT_FOUND, NUMBER_DB_PREV_FOUND, ITER_BYTES_READ] are not updated immediately. The are updated when the Iterator is deleted.
* Add monotonically increasing counter (DB property "rocksdb.current-super-version-number") that increments upon any change to the LSM tree.
### [](https://github.com/facebook/rocksdb/blob/master/HISTORY.md#new-features-3)New Features
### [](https://github.com/facebook/rocksdb/blob/main/HISTORY.md#new-features-3)New Features
* Add CompactionPri::kMinOverlappingRatio, a compaction picking mode friendly to write amplification.
* Deprecate Iterator::IsKeyPinned() and replace it with Iterator::GetProperty() with prop_name="rocksdb.iterator.is.key.pinned"
You can also [initialize the internal buffer](https://github.com/facebook/rocksdb/blob/9e583711144f580390ce21a49a8ceacca338fcd5/include/rocksdb/db.h#L314) of PinnableSlice by passing your own string in the constructor. [simple_example.cc](https://github.com/facebook/rocksdb/blob/master/examples/simple_example.cc) demonstrates that with more examples.
You can also [initialize the internal buffer](https://github.com/facebook/rocksdb/blob/9e583711144f580390ce21a49a8ceacca338fcd5/include/rocksdb/db.h#L314) of PinnableSlice by passing your own string in the constructor. [simple_example.cc](https://github.com/facebook/rocksdb/blob/main/examples/simple_example.cc) demonstrates that with more examples.
The initial RocksDB support for the secondary cache has been merged into the master branch, and will be available in the 6.21 release. This includes providing a way for the user to configure a secondary cache when instantiating RocksDB’s LRU cache (volatile block cache), spilling blocks evicted from the LRU cache to the flash cache, promoting a block read from the SecondaryCache to the LRU cache, update tools such as cache_bench and db_bench to specify a flash cache. The relevant PRs are [#8271](https://github.com/facebook/rocksdb/pull/8271), [#8191](https://github.com/facebook/rocksdb/pull/8191), and [#8312](https://github.com/facebook/rocksdb/pull/8312).
The initial RocksDB support for the secondary cache has been merged into the main branch, and will be available in the 6.21 release. This includes providing a way for the user to configure a secondary cache when instantiating RocksDB’s LRU cache (volatile block cache), spilling blocks evicted from the LRU cache to the flash cache, promoting a block read from the SecondaryCache to the LRU cache, update tools such as cache_bench and db_bench to specify a flash cache. The relevant PRs are [#8271](https://github.com/facebook/rocksdb/pull/8271), [#8191](https://github.com/facebook/rocksdb/pull/8191), and [#8312](https://github.com/facebook/rocksdb/pull/8312).
We prototyped an end-to-end solution, with the above PRs as well as a Cachelib based implementation of the SecondaryCache. We ran a mixgraph benchmark to simulate a realistic read/write workload. The results showed a 15% gain with the local flash cache over no local cache, and a ~25-30% reduction in network reads with a corresponding decrease in cache misses.
Akanksha Mahajan
3 years ago
committed by