Distributed DBMS - CS712 Power Point Slides Lecture 35

inter site transfers ship whole entire relation

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Unformatted text preview: ons decisions • Optimizes local processing Optimizes time & communication time. time • Optimizer, based on Optimizer, stats of DB and size of iterm results, decides about about –Join Ordering –Join Algo (nested/mergeJoin) –Access path (indexed/seq.). • Inter-site transfers – Ship-whole • Entire relation transferred • Stored in a temp relation • In case of merge-join approach, tuples can be processed as they arrive – Fetch-as-needed • nExternal relation is sequentially scanned • Join attribute value is sent to other relation • Relevant tuples scanned at other site and sent to first site. • Inter-site tran...
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