GitHub user tejasapatil opened a pull request:
https://github.com/apache/spark/pull/17184
[SPARK-19843] [SQL] UTF8String => (int / long) conversion expensive for
invalid inputs
## What changes were proposed in this pull request?
Jira : https://issues.apache.org/jira/browse/SPARK-19843
Added cheap checks to `UTF8String` to check if it can be converted to int /
long. The logic is motivated from [LazyUtils.isNumberMaybe in
Hive](https://github.com/apache/hive/blob/ff67cdda1c538dc65087878eeba3e165cf3230f4/serde/src/java/org/apache/hadoop/hive/serde2/lazy/LazyUtils.java#L90).
## How was this patch tested?
- Added new unit tests
- Ran a prod job which had conversion from string -> int and verified the
outputs
## Performance
Attached `UTF8StringBenchmark` with the PR. Here is the summary:
```
conversion to int: Best/Avg Time(ms) Rate(M/s)
Per Row(ns) Relative
------------------------------------------------------------------------------------------------
without check over valid integers 500 / 503 33.6
29.8 1.0X
with check over valid integers 1069 / 1072 15.7
63.7 0.5X
without check over in-valid integers 34515 / 36096 0.5
2057.3 0.0X
with check over in-valid integers 718 / 895 23.4
42.8 0.7X
```
Note that this PR is a tradeoff. If the data does not have any invalid
inputs, then performance of conversion is hurt by 2x. Based on the numbers in
the benchmark, if more than 2.5% of input cannot be converted to `int`, then it
will add perf. gains. For my workloads, I could see on average 37% savings
(best case 2.08x performance gain).
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/tejasapatil/spark SPARK-19843_is_numeric_maybe
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/17184.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 #17184
----
commit adcb405bc889345c662ddda1742d3ea95191570d
Author: Tejas Patil <tej...@fb.com>
Date: 2017-03-07T00:56:32Z
[SPARK-19843] [SQL] UTF8String => (int / long) conversion expensive for
invalid inputs
----
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