GitHub user nongli opened a pull request:
https://github.com/apache/spark/pull/10628
[SPARK-12635][SQL] Add ColumnarBatch, an in memory columnar format for
execution.
There are many potential benefits of having an efficient in memory columnar
format as an alternate
to UnsafeRow. This patch introduces ColumnarBatch/ColumnarVector which
starts this effort. The
remaining implementation can be done as follow up patches.
As stated in the in the JIRA, there are useful external components that
operate on memory in a
simple columnar format. ColumnarBatch would serve that purpose and could
server as a
zero-serialization/zero-copy exchange for this use case.
This patch supports running the underlying data either on heap or off heap.
On heap runs a bit
faster but we would need offheap for zero-copy exchanges. Currently, this
mode is hidden behind one
interface (ColumnVector).
This differs from Parquet or the existing columnar cache because this is
*not* intended to be used
as a storage format. The focus is entirely on CPU efficiency as we expect
to only have 1 of these
batches in memory per task. The layout of the values is just dense arrays
of the value type.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/nongli/spark spark-12635
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/10628.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #10628
----
commit 381492eee072a8e1a536103db1e6afcff008b6b1
Author: Nong <[email protected]>
Date: 2016-01-01T05:12:44Z
[SPARK-12635][SQL] Add ColumnarBatch, an in memory columnar format for
execution.
There are many potential benefits of having an efficient in memory columnar
format as an alternate
to UnsafeRow. This patch introduces ColumnarBatch/ColumnarVector which
starts this effort. The
remaining implementation can be done as follow up patches.
As stated in the in the JIRA, there are useful external components that
operate on memory in a
simple columnar format. ColumnarBatch would serve that purpose and could
server as a
zero-serialization/zero-copy exchange for this use case.
This patch supports running the underlying data either on heap or off heap.
On heap runs a bit
faster but we would need offheap for zero-copy exchanges. Currently, this
mode is hidden behind one
interface (ColumnVector).
This differs from Parquet or the existing columnar cache because this is
*not* intended to be used
as a storage format. The focus is entirely on CPU efficiency as we expect
to only have 1 of these
batches in memory per task.
----
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