Unexpected /*+MAKEDEP*/ behavior in JDV
Issue
- In an effort to combine data in the right order, using
/*+MAKEDEP*/query hints to increase the performance in comparison to the default behavior. - Costing calculation issues identified by TEIID-4320
- When determining if a dependent join should be used we'll rule out too many scenarios based upon requiring additional ndv info - when that can be determined from cardinality alone. Also we are inappropriately assuming key usage in predicate costing - as it does not consider the node which may not represent a single table.
Environment
- Red Hat JBoss Data Virtualization 6.2.6 and earlier.
server.logentries similar to
LOW Relational Planner parent join has no equa-join predicates - Rejecting dependent join Join(groups=...
LOW Relational Planner parent join has no equa-join predicates - Rejecting dependent join Access(groups=...
- use of
/*+ MAKEDEP */as defined in FROM Clause Hints
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