GitHub user viirya opened a pull request:
https://github.com/apache/spark/pull/17186
[SPARK-19846][SQL] Add a flag to disable constraint propagation
## What changes were proposed in this pull request?
Constraint propagation can be computation expensive and block the driver
execution for long time. For example, the below benchmark needs 30mins.
Compared with previous PRs #16998, #16785, this is a much simpler option:
add a flag to disable constraint propagation.
### Benchmark
Run the following codes locally.
import org.apache.spark.ml.{Pipeline, PipelineStage}
import org.apache.spark.ml.feature.{OneHotEncoder, StringIndexer,
VectorAssembler}
import org.apache.spark.sql.internal.SQLConf
spark.conf.set(SQLConf.CONSTRAINT_PROPAGATION_ENABLED.key, false)
val df = (1 to 40).foldLeft(Seq((1, "foo"), (2, "bar"), (3,
"baz")).toDF("id", "x0"))((df, i) => df.withColumn(s"x$i", $"x0"))
val indexers = df.columns.tail.map(c => new StringIndexer()
.setInputCol(c)
.setOutputCol(s"${c}_indexed")
.setHandleInvalid("skip"))
val encoders = indexers.map(indexer => new OneHotEncoder()
.setInputCol(indexer.getOutputCol)
.setOutputCol(s"${indexer.getOutputCol}_encoded")
.setDropLast(true))
val stages: Array[PipelineStage] = indexers ++ encoders
val pipeline = new Pipeline().setStages(stages)
val startTime = System.nanoTime
pipeline.fit(df).transform(df).show
val runningTime = System.nanoTime - startTime
Before this patch: 1786001 ms ~= 30 mins
After this patch: 33105 ms = about half of a minute
Related PRs: #16998, #16785.
## How was this patch tested?
Jenkins tests.
Please review http://spark.apache.org/contributing.html before opening a
pull request.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/viirya/spark-1
add-flag-disable-constraint-propagation
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/17186.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 #17186
----
commit 44e494bd1725645a2ce13321ec846098d8da6ae4
Author: Liang-Chi Hsieh <[email protected]>
Date: 2017-03-07T04:59:32Z
Add a flag to disable constraint propagation.
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