You are viewing a plain text version of this content. The canonical link for it is here.
Posted to issues-all@impala.apache.org by "Quanlong Huang (Jira)" <ji...@apache.org> on 2020/06/19 09:39:00 UTC
[jira] [Updated] (IMPALA-9228) ORC scanner could be vectorized
[ https://issues.apache.org/jira/browse/IMPALA-9228?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Quanlong Huang updated IMPALA-9228:
-----------------------------------
Fix Version/s: Impala 3.4.0
> ORC scanner could be vectorized
> -------------------------------
>
> Key: IMPALA-9228
> URL: https://issues.apache.org/jira/browse/IMPALA-9228
> Project: IMPALA
> Issue Type: Improvement
> Reporter: Zoltán Borók-Nagy
> Assignee: Gabor Kaszab
> Priority: Major
> Labels: orc
> Fix For: Impala 4.0, Impala 3.4.0
>
> Attachments: 1-4_col_measurement_int_only.png
>
>
> The ORC scanners uses an external library to read ORC files. The library reads the file contents into its own memory representation. It is a vectorized representation similar to the Arrow format.
> Impala needs to convert the ORC row batch to an Impala row batch. Currently the conversion happens row-wise via virtual function calls:
> [https://github.com/apache/impala/blob/85425b81f04c856d7d5ec375242303f78ec7964e/be/src/exec/hdfs-orc-scanner.cc#L671]
> [https://github.com/apache/impala/blob/85425b81f04c856d7d5ec375242303f78ec7964e/be/src/exec/orc-column-readers.cc#L352]
> Instead of this approach it could work similarly to the Parquet scanner that fills the columns one-by-one into a scratch batch, then evaluate the conjuncts on the scratch batch. For more details see HdfsParquetScanner::AssembleRows():
> [https://github.com/apache/impala/blob/85425b81f04c856d7d5ec375242303f78ec7964e/be/src/exec/parquet/hdfs-parquet-scanner.cc#L1077-L1088]
> This way we'll need a lot less virtual function calls, also the memory reads/writes will be much more localized and predictable.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-all-unsubscribe@impala.apache.org
For additional commands, e-mail: issues-all-help@impala.apache.org