CS655-HessahAlsaaran-DBonS3

To optimize it using data locality 41 42 7 102913

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Unformatted text preview: ed to all replicas but in the same order. 33 34 Data Organization and Queries Consistency Model Ê༌  Simple relational data model with flexible schemas. Ê༌  Per- record timeline consistency Ê༌  Tables are horizontally partitioned in tablets, and distributed to many servers. Ê༌  Updates to a record are applied to all the record’s replicas in the same order. New generation Ê༌  All replicas move forward in time. New version Ê༌  PNUTS query language only supports single tables (limitation). Ê༌  Read and write of single records or small group of records. Ê༌  Predicates can be used for evaluating scans at the servers. Ê༌  Multiget operation: get records from one or more tables, using a set of primary keys and predicates. 35 Ê༌  Implementation: Ê༌  Assign a master replica for each record. Ê༌  All updates to a record are forwarded to the master replica of this record. Ê༌  The master assignment is adaptive to load change. Ê༌  The replica that receives most of the write requests becomes the master. 36 Diagram from page 1279 of (Cooper et al., 2008) 6 10/29/13 System Architecture API Calls à༎ Different Consistency Levels Ê༌  Write Ê༌  Returns the version number of the record Assignment and interval mapping Customers have different (*) but share (*) Updates are written Cached Record location? Ê༌  Read- any Ê༌...
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