String Data
-----------
Created by modifying Impala's HdfsAvroTableWriter(removed).

These files' schemas have a single nullable string column 's'.

negative_string_len.avro: contains two values, but the second value has a negative length.

invalid_union.avro: contains three values, all of which have an invalid union value (4,
which decodes to 2). Also has a single extra byte at the end (0x0a), which will be
interpreted as a malformed data block.

truncated_string.avro: contains one value, which is missing the last byte.

Float Data
----------
Created by modifying Impala's HdfsAvroTableWriter(removed).

These files' schemas have a single nullable float column 'c1'.

truncated_float.avro: contains two float values. The second is missing the last byte.

Bad Schema
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Created by editing the schema of a valid Avro file with vim.

invalid_decimal_schema.avro: two columns, name STRING and value DECIMAL(5,7).
  The DECIMAL value is invalid.