[ https://issues.apache.org/jira/browse/HIVE-28259?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
ASF GitHub Bot updated HIVE-28259: ---------------------------------- Labels: pull-request-available (was: ) > Common table expression detection and rewrites using CBO > -------------------------------------------------------- > > Key: HIVE-28259 > URL: https://issues.apache.org/jira/browse/HIVE-28259 > Project: Hive > Issue Type: New Feature > Components: CBO > Reporter: Stamatis Zampetakis > Assignee: Stamatis Zampetakis > Priority: Major > Labels: pull-request-available > > Hive already provides the means to detect and exploit CTEs via the > {{SharedWorkOptimizer}}. The {{SharedWorkOptimizer}} relies on a series of > heuristic transformations of the physical plan ({{Operator}} DAG) that apply > towards the end of the planning process. The optimizer is quite powerful and > offers various properties ({{hive.optimize.shared.work*}}) through which its > behavior can be fine tuned by users but has also a few drawbacks: > * not cost-based > * limited customization > * complex implementation > This ticket aims to leverage CBO for detecting and exploiting common table > expressions (CTE) in queries in an attempt to alleviate some of the > shortcomings of the {{SharedWorkOptimizer}} and open the road for more > powerful transformations. > The initial work focuses on establishing the general design and the main APIs > for CBO based CTE transformations. > The main idea is to model CTEs as materialized views (MVs) and rely on > existing MV rewrite logic to incorporate them in the plan in a cost-based > fashion as a new CBO planning phase. -- This message was sent by Atlassian Jira (v8.20.10#820010)