Notes

LevelDB is not a SQL Database

LevelDB stores keys and values in arbitrary bytes arrays, and data is sorted according to key. It supports batching, forward and reverse iteration and compression of data using Google's Snappy compression tool.



LevelDB is not an SQL database. It does not support SQL queries, unlike other NoSQL or dbm stores. It is not able to support indexes. Applications use LevelDB as a library because it does not offer a server or command-line interface.



MariaDB 10.0 comes with an engine for storage that lets users search LevelDB tables directly from MariaDB. [6]



LevelDB is based on concepts from Google's Bigtable database system. The table implementation for the Bigtable system was developed starting around 2004 and is built on an entirely different Google internal code base that is different from the LevelDB code. The code base is based on a number of Google code libraries that aren't open-sourced, therefore directly open-sourcing the code would have been difficult. Sanjay Ghemawat and Jeff Dean wanted to create a system that was comparable to the Bigtable tablet stack. It would have minimal dependencies, be openly sourced and compatible with Chrome's IndexedDB implementation. LevelDB was written by them in the beginning of 2011 with the same design and layout as the Bigtable tablet stack but without sharing any of their code. [7]



Usage[edit]



LevelDB is used as the backend database of Google Chrome's IndexedDB and is one of the backends that are supported for Riak. [88 Bitcoin Core and go–ethereum also store blockchain metadata with a LevelDB Database. [9] Minecraft Bedrock Edition uses a modified version to store chunks 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 excels in batch writes but is slower than SQLite when it comes to large numbers. After SQLite configuration issues were discovered in an earlier version, the current benchmarks were updated. The latest benchmarks[13] demonstrate that LevelDB outperforms Berkeley DB. However the tests also show OpenLDAP LightningDB to be much faster (10x in some scenarios) for read operations (e.g. batch and synchronous writes (see the link above) and is nearly equal throughout the test.



Please take note that the benchmarks mentioned above are from the year 2011 through 2014. They are not historical in any way. SQLite, for example, 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 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. Archived from the original on August 16, 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 on 2013-09-18. ^ Andreas M. Antonopoulos. "Chapter 7. The Blockchain Retrieved 8 January 2015. ^ "Bedrock Edition level format". ^ "LevelDB Benchmarks". Premiumebooks.Net Google, Inc. Retrieved from the original on 2008-08-20. ^ "LevelDB Benchmark discussion". ^ Database Microbenchmarks Retrieved on 2014-08-09 through the Wayback Machine, Symas Corp., 2012-09. Retrieved 22 October 2016. "Measuring CPU Usage 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 created equal: The Complexity of Crafting Crash-Consistent Applications. 2014. pp. 433-448. ISBN 9781931971164. External links[editISBN 9781931971164. External links[edit



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