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ASF GitHub Bot commented on DRILL-4826: --------------------------------------- Github user asfgit closed the pull request at: https://github.com/apache/drill/pull/592 > Query against INFORMATION_SCHEMA.TABLES degrades as the number of views > increases > --------------------------------------------------------------------------------- > > Key: DRILL-4826 > URL: https://issues.apache.org/jira/browse/DRILL-4826 > Project: Apache Drill > Issue Type: Bug > Reporter: Parth Chandra > Assignee: Padma Penumarthy > > Queries against INFORMATION_SCHEMA.TABLES and INFORMATION_SCHEMA.VIEWS slow > down as the number of views increases. > BI tools like Tableau issue a query like the following at connection time: > {code} > select TABLE_CATALOG, TABLE_SCHEMA, TABLE_NAME, TABLE_TYPE from > INFORMATION_SCHEMA.`TABLES` WHERE TABLE_CATALOG LIKE 'DRILL' ESCAPE '\' AND > TABLE_SCHEMA <> 'sys' AND TABLE_SCHEMA <> 'INFORMATION_SCHEMA'ORDER BY > TABLE_TYPE, TABLE_CATALOG, TABLE_SCHEMA, TABLE_NAME > {code} > The time to query the information schema tables degrades as the number of > views increases. On a test system: > || Views || Time(secs) || > |500 | 6 | > |1000 | 19 | > |1500 | 33 | > This can result in a single connection taking more than a minute to establish. > The problem occurs because we read the view file for every view and this > appears to take most of the time. > Querying information_schema.tables does not, in fact, need to open the view > file at all, it merely needs to get a listing of the view files. Eliminating > the view file read will speed up the query tremendously. -- This message was sent by Atlassian JIRA (v6.3.4#6332)