[jira] [Created] (HIVE-9692) Allocate only parquet selected columns in HiveStructConverter class

["Sergio Peña (JIRA)" <ji...@apache.org>]

Sergio Peña created HIVE-9692:
---------------------------------

             Summary: Allocate only parquet selected columns in HiveStructConverter class
                 Key: HIVE-9692
                 URL: https://issues.apache.org/jira/browse/HIVE-9692
             Project: Hive
          Issue Type: Sub-task
            Reporter: Sergio Peña
            Assignee: Sergio Peña


HiveStructConverter class is where Hive converts parquet objects to hive writable objects that will be later parsed by object inspectors. This class is allocating enough writable objects as number of columns of the file schema.

{noformat}
ublic HiveStructConverter(final GroupType requestedSchema, final GroupType tableSchema, Map<String, String> metadata) {
...
this.writables = new Writable[fileSchema.getFieldCount()];
...
}
{noformat}

This is always allocated even if we only select a specific number of columns. Let's say 2 columns from a table of 50 columns. 50 objects are allocated. Only 2 are used, and 48 are unused.

We should be able to allocate only the requested number of columns in order to save memory usage.



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