The locations in the GFS of tablets are recorded as database entries in multiple special tablets, which are called "META1" tablets. When Table size threaten to grow beyond a specified limit, the tablets may be compressed using the algorithm BMDiff and the Zippy compression algorithm publicly known and open-sourced as Snappy, which is a less space-optimal variation of LZ77 but more efficient in terms of computing time. A bigtable is somewhat like a mapreduce worker pool in that thousands to hundreds of thousands of tablet shards may be served by hundreds to thousands of BigTable servers. Tables are split into multiple tablets – segments of the table are split at certain row keys so that each tablet is a few hundred megabytes or a few gigabytes in size. Another function of the timestamp is to allow for both versioning and garbage collection of expired data. Each cell of a bigtable can have zero or more timestamped versions of the data. The page column can have several timestamped versions describing different copies of the web page timestamped by when they were fetched. For example, Google's copy of the web can be stored in a bigtable where the row key is a domain-reversed URL, and columns describe various properties of a web page, with one particular column holding the page itself. Bigtable is designed to scale into the petabyte range across "hundreds or thousands of machines, and to make it easy to add more machines the system and automatically start taking advantage of those resources without any reconfiguration". : 1 It is built on Colossus ( Google File System), Chubby Lock Service, SSTable (log-structured storage like LevelDB) and a few other Google technologies. It is not a relational database and can be better defined as a sparse, distributed multi-dimensional sorted map. It maps two arbitrary string values (row key and column key) and timestamp (hence three-dimensional mapping) into an associated arbitrary byte array. Design īigtable is one of the prototypical examples of a wide-column store. On January 27, 2022, Google announced a number of updates to Bigtable, including automated scalability. Īs of January 2022, Bigtable manages over 10 Exabytes of data and serves more than 5 billion requests per second. On May 6, 2015, a public version of Bigtable was made available as a part of Google Cloud under the name Cloud Bigtable. Īpache HBase and Cassandra are some of the best known open source projects that were modeled after Bigtable. Google F1 was built using Spanner to replace an implementation based on MySQL. Google's Spanner RDBMS is layered on an implementation of Bigtable with a Paxos group for two-phase commits to each table. Google's reasons for developing its own database include scalability and better control of performance characteristics. It is now used by a number of Google applications, such as Google Analytics, web indexing, MapReduce, which is often used for generating and modifying data stored in Bigtable, Google Maps, Google Books search, "My Search History", Google Earth,, Google Code hosting, YouTube, and Gmail. Bigtable is a fully managed wide-column and key-value NoSQL database service for large analytical and operational workloads as part of the Google Cloud portfolio.īigtable development began in 2004.
0 Comments
Leave a Reply. |