Better filter application in queries accessing multiple catalog views

Detail name	Value
Changelog Number	7754
Type	Improvement
Status	Resolved
Fix Versions	Exasol 6.1.3
Resolution Date	2019-04-12

Background
To improve the performance of catalog queries, propagated filters on catalog tables are evaluated early.

For technical reasons early filter application is only possible for catalog tables that are not referenced more than monce in a given single query. Thus multiple occurrences of the same catalog table even with strong filters will result in bad performance.

As different catalog views may use the same catalog table using multiple catalog views in one query may also result in bad performance.

Problem
Some logically different catalog views (for example EXA_DBA_OBJECTS and EXA_DBA_OBJECT_SIZES) access the same catalog table increasing the chance of bad catalog query performance.

Improvement
More catalog tables have been added so that every logical group of catalog views like EXA_DBA_OBJECTS, EXA_ALL_OBJECTS and EXA_USER_OBJECTS accesses its own catalog table.