Notes

LevelDB is not an SQL Database

LevelDB stores keys, values, and arbitrary bytes. Data is sorted according to key. All about minecraft It supports batching forward and reverse iteration, as well as compression of data using Google's Snappy compression tool.



LevelDB is not an SQL database. Similar to other NoSQL and dbm stores, it does not have a relational model for data and it does not support SQL queries. It doesn't support indexes. Applications utilize LevelDB as a library, as it does not provide an interface for command-line or server.



MariaDB 10.0 comes with an engine for storage that allows users to access LevelDB tables directly from MariaDB. [6]



LevelDB is based on ideas of Google's Bigtable data base system. The table implementation for the Bigtable system was developed starting in the year 2004 and is based on an entirely different Google internal code base than the LevelDB code. This code base relies on a variety of Google code libraries that aren't open sourced, so directly open sourcing that code would have been difficult. Sanjay Ghemawat and Jeff Dean wanted to create a system that was similar to the Bigtable tablet stack. It would have only a few dependencies, be open sourced and compatible with Google's IndexedDB implementation. LevelDB was written by them in the early 2011 with similar design to 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 backends that are supported to Riak. Furthermore, Bitcoin Core and go-ethereum store blockchain metadata in a LevelDB database. 9 Minecraft Bedrock Edition uses a modified version of the database for chunk and entity data storage. [10] Autodesk AutoCAD 2016 also uses LevelDB.



Performance[edit]



Google has provided benchmarks comparing LevelDB's performance to SQLite and Kyoto Cabinet in different scenarios. 11 LevelDB is superior to both SQLite & Kyoto Cabinet in sequential-order read and write operations. LevelDB excels in batch write but is slower than SQLite when it comes to large numbers. After SQLite configuration errors were found in an earlier versionof the software, the benchmarks of the current version were revised. The new benchmarks[13] show LevelDB outperforms Berkeley DB. However the tests also reveal OpenLDAP LightningDB to be much faster (10x in certain scenarios) for read operations (e.g. batch and synchronous writes See the link above) and is also nearly equal throughout the test.



Please note that the benchmarks above are from the year 2011 through 2014. They are not historical in any way. SQLite, for example has significantly improved its efficiency. [14]



Bugs and reliability[editBugs 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]



Free and open-source software portal Lightning Memory-Mapped Database RocksDB


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. Retrieved 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". Google, Inc. Archived from the original on 2011-08-20. ^ "LevelDB Benchmark discussion". Database Microbenchmarks Archived 2014-08-10 at the Wayback Machine Symas Corp. 2012-09. Retrieved 22 October 2016 "Measuring and Reducing CPU Usage in SQLite". Repairing LevelDB Problems google/leveldb GitHub Unrecoverable Chromium corruption, corruption due to power loss. Corrupted in Ethereum All File System Are Not the Same: The Challenge of Creating Crash Consistent Applications 2014. pp. 433-448. ISBN 9781931971164. External links[editISBN 9781931971164. External links[edit



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