Sushil Mohanty created LENS-714:
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Summary: Replace dimension tables with subquery in Columnar
Rewriter
Key: LENS-714
URL: https://issues.apache.org/jira/browse/LENS-714
Project: Apache Lens
Issue Type: Improvement
Reporter: Sushil Mohanty
Assignee: Sushil Mohanty
In order to optimise the JDBC sql queries, we can skip directly joining with
the dimension tables. Instead we can create a subquery with only required
column for a table used in the query. For eg. If column id and name are queried
from table dim1 the query can be rewritten as
... inner join (select id,name from dim1) as d1 instead of ...inner join dim1
as d1.
For dimension tables with descent size this helps in improving performance to a
great extent. Planning to add this in ColumnarRewriter so that columnar DBs can
leverage this.
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