GitHub user wzhfy opened a pull request:
https://github.com/apache/spark/pull/19743
[SPARK-22515] [SQL] Estimation relation size based on numRows * rowSize
## What changes were proposed in this pull request?
Currently, relation size is computed as the sum of file size, which is
error-prone because storage format like parquet may have a much smaller file
size compared to in-memory size. When we choose broadcast join based on file
size, there's a risk of OOM. But if the number of rows is available in
statistics, we can get a better estimation by `numRows * rowSize`, which helps
to alleviate this problem.
## How was this patch tested?
Added a new test case for data source table and hive table.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/wzhfy/spark better_leaf_size
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/19743.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 #19743
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commit cc9ecc68901de5bcaa082021d867ecb79d0ae00c
Author: Zhenhua Wang <[email protected]>
Date: 2017-11-14T09:06:17Z
relation estimation
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