Hanumath Rao Maduri created DRILL-6312:
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Summary: Enable pushing of cast expressions to the scanner for
better schema discovery.
Key: DRILL-6312
URL: https://issues.apache.org/jira/browse/DRILL-6312
Project: Apache Drill
Issue Type: Bug
Components: Execution - Relational Operators, Query Planning &
Optimization
Affects Versions: 1.13.0
Reporter: Hanumath Rao Maduri
Drill is a schema less engine which tries to infer the schema from disparate
sources at the read time. Currently the scanners infer the schema for each
batch depending upon the data for that column in the corresponding batch. This
solves many uses cases but can error out when the data is too different between
batches like int and array[int] etc... (There are other cases as well but just
to give one example).
There is also a mechanism to create a view by type casting the columns to
appropriate type. This solves issues in some cases but fails in many other
cases. This is due to the fact that cast expression is not being pushed down to
the scanner but staying at the project or filter etc operators up the query
plan.
This JIRA is to fix this by propagating the type information embedded in the
cast function to the scanners so that scanners can cast the incoming data
appropriately.
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