Notes

LevelDB is not a SQL Database

LevelDB stores keys, values and other arbitrary Byte arrays. Data is sorted by key. It supports batching write forward and backward iteration, and compression of the data via Google's Snappy compression library.



LevelDB is not a SQL database. It is not able to support SQL queries, unlike other NoSQL or dbm stores. It doesn't support indexes. Applications use LevelDB as a library since it doesn't provide a server or command-line interface.



MariaDB 10.0 includes an engine for storage that allows users to search LevelDB tables through MariaDB. [6]



LevelDB is based on the concepts from Google's Bigtable database system. The table implementation for the Bigtable database system was created in 2004. It is built on an entirely different Google code base that is different from the LevelDB code. The code base is based on a number Google code libraries that aren't open source. Therefore, it would be difficult to open the source code. Sanjay Ghemawat and Jeff Dean wanted to create an application similar to the Bigtable tablet stack. It would have minimal dependencies, be open sourced and compatible with Chrome's IndexedDB implementation. LevelDB was developed by them in the early 2011 with the same design and layout as the Bigtable tablet stack, but without sharing any of their code. [7]



Usage[edit]



LevelDB is the backend database of Google Chrome's IndexedDB. It is also one of the supported backends to Riak. [88 Bitcoin Core and go–ethereum also store blockchain metadata using the LevelDB Database. [9] Minecraft Bedrock Edition uses a modified version for chunk and entity data storage. 10. Autodesk AutoCAD 2016 also uses LevelDB.



Performance[edit]



Google has benchmarks that compare LevelDB's performance with SQLite or Kyoto Cabinet in different scenarios. 11 LevelDB outperforms both SQLite and Kyoto Cabinet in write operations and sequential-order read operations. LevelDB excels in batch writing, but is slower than SQLite when dealing with large numbers. The benchmarks that are currently available were revised following SQLite errors in configuration were discovered in the earlier version of the results. The new benchmarks[13] show LevelDB outperforms Berkeley DB. However the tests also reveal OpenLDAP LightningDB to be a lot faster (10x in some scenarios) for read operations (e.g. batch and synchronous write See the link above), and is almost equal throughout the test.



Please take note that the benchmarks mentioned above are from 2011 to 2014. They may not be historical in any way. SQLite, for example, became significantly more efficient. [14]



Bugs and reliability[edit]



LevelDB has a history of database corruption bugs. [15][16][17][18][19][20] A study from 2014 has found that, on older (non-checksummed) file systems, the database could become corrupted after a crash or power failure. [21]



Lightning Memory-Mapped Database rocksDB an open-source and free software portal


References[edit]



^ "Release 1.23". 23 February 2021. Retrieved 13 March 2021. "Google Research Scientists and Engineers": Jeffrey Dean. Google, Inc. ^ "Research Scientists and Engineers: Sanjay Ghemawat". Google, Inc. Google Open-Sources NoSQL Database Called LevelDB ReadWriteWeb. July 30 2011. The original article was published on August 16 the 16th of August, 2011. Retrieved July 30, 2011. ^ "Google Open Source Blog: LevelDB: A Fast Persistent Key-Value Store". Google, Inc. ^ LevelDB storage engine ^ Jeff Dean. "LevelDB mailing list: "Current Status of LevelDB"". ^ LevelDB. Docs.basho.com. Retrieved 2013-09-18. ^ Andreas M. Antonopoulos. "Chapter 7. The Blockchain". Retrieved 8 January 2015. ^ "Bedrock Edition level format". ^ "LevelDB Benchmarks". Google, Inc. Retrieved from the original on 2011-08-20. ^ "LevelDB Benchmark discussion". Database Microbenchmarks Retrieved 2014-08-09 from the Wayback Machine, Symas Corp., 2012-09. https://minecraft-server-list.xyz/ Retrieved 22 October 2016."Measuring the CPU utilization in SQLite". Repairing LevelDB Issues * google/leveldb GitHub Unrecoverable Chromium corruption Corruption following power loss. The problem is that it's corrupted in Ethereum All File Systems Are Not the Same: The Complexity of Crafting Crash Consistent Applications 2014. pp. 433-448. ISBN 9781931971164. External links[edit[edit



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