Progressive Query Optimization for Federated Queries

Federated queries are regular relational queries accessing data on one or more remote relational or non-relational data sources, possibly combining them with tables stored in the federated DBMS server. Their execution is typically divided between the federated server and the remote data sources. Outdated and incomplete statistics have a bigger impact on federated DBMS than on regular DBMS, as maintenance of federated statistics is unequally more complicated and expensive than the maintenance of the local statistics; consequently bad performance commonly occurs for federated queries due to the selection of a suboptimal query plan. To solve this problem we propose a progressive optimization technique for federated queries called POP/FED by extending the state of the art for progressive reoptimization for local source queries, POP [4]. POP/FED uses (a) an opportunistic, but risk controlled reoptimization technique for federated DBMS, (b) a technique for multiple reoptimizations during fe...

• Type: Conference
• Year: 2006
• Where: EDBT
• Authors: Stephan Ewen, Holger Kache, Volker Markl, Vijayshankar Raman
• Keywords: Database, EDBT 2006, Federated Dbms, Federated Queries, Federated Query Processing