tree 05659fc5cb210d27a869186a4897f73cf77b9ca8
parent a421d952efd85ec581131069a5b132934ee286d3
author Ryan Blue <blue@apache.org> 1468792760 -0700
committer Ryan Blue <blue@apache.org> 1468792760 -0700

PARQUET-651: Improve Avro's isElementType check.

The Avro implementation needs to check whether the read schema that is
passed by the user (or automatically converted from the file schema)
expects an extra 1-field layer to be returned, which matches the
previous behavior of Avro when reading a 3-level list. Before this
commit, the check was done by testing the structure of the expected list
element type against the repeated group's schema. If they matched, then
Avro assumed that the user expected an extra layer. However, for records
that happened to match (1-field records with a field named "element")
the check could be wrong and would cause exceptions later.

This commit updates the check to convert the file's element schema to
Avro and compare the compatibility of that schema with what was passed
by the user. This checks the entire tree from the element down and gets
the answer right based on the element and its children, not just the
field names on the element.

Author: Ryan Blue <blue@apache.org>

Closes #352 from rdblue/PARQUET-651-improve-is-element-type-check and squashes the following commits:

ad9c1ee [Ryan Blue] PARQUET-651: Undo accidental default setting change.
1efa248 [Ryan Blue] PARQUET-651: Improve Avro's isElementType check.