Notes

LevelDB is not A SQL Database

LevelDB stores keys and values in any byte arrays, and data is sorted by key. It supports batching, forward and reverse iteration as well as compression of data via Google's Snappy compression tool.



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



MariaDB 10.0 comes with a storage engine which allows users to access LevelDB tables through MariaDB. [6]



LevelDB is based on concepts of Google's Bigtable database system. The table implementation for the Bigtable system was developed in about 2004 and is based on an entirely different Google internal code base that is different from the LevelDB code. This code base is dependent on a number Google code libraries that aren't open sourced. This is why it would have been difficult to open source the code. Jeff Dean and Sanjay Ghemawat wanted to create an alternative to the Bigtable tablet stack that had minimal dependencies and would be suitable for open source, and also suitable for use with Chrome for the IndexedDB implementation. They started writing LevelDB beginning in the early part of 2011, using the same general design as the Bigtable tablet stack, but not sharing any of the code. [7]



Usage[edit]



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



Performance[edit]



Google has provided benchmarks that compare LevelDB's performance against SQLite and Kyoto Cabinet in different scenarios. 11 LevelDB is superior to both SQLite and Kyoto Cabinet in sequential-order read and write operations. LevelDB also excels at batch writes, but is slower than SQLite when dealing with large amounts of data. After SQLite configuration issues were discovered in an earlier versionof the software, the current benchmarks were updated. [12] New benchmarks[13reveal that LevelDB also outperforms Berkeley DB however, these tests also demonstrate that OpenLDAP LightningDB is much faster (~10 times in certain situations) in read operations and certain types of write (e.g. batch and synchronous write, see the link above) and is also nearly equal in the rest of the test.



Please note that all the above benchmarks are from 2011 until 2014, and could only have historical significance as SQLite for instance, became significantly more efficient. [14]



Bugs and reliability[edit]



LevelDB has been known to have 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 is a free and open-source software portal


References[edit]



^ "Release 1.23". 23 February 2021 Retrieved 13 March 2021. Then, you can go to "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. Archived from the original 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. Minecraft "LevelDB mailing list: "Current Status of LevelDB"". ^ LevelDB. Docs.basho.com. Retrieved on 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 on 2014-08-09 through the Wayback Machine, Symas Corp., 2012-09. Retrieved 22 October 2016. "Measuring the CPU utilization in SQLite". ^ Repairing LevelDB ^ Issues * google/leveldb * GitHub Unrecoverable corruption in Chromium ^ Corruption in syncthing ^ Corruption after power loss Corruption in Ethereum All File Systems Are Not All Equal: A Study of the difficulty of crafting crash-proof applications. 2014. pp. 433-448. ISBN 9781931971164. External links[edit]



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