Apache Spark - A unified analytics engine for large-scale data processing
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Bruce Robbins 7781c6fd73 [SPARK-26378][SQL] Restore performance of queries against wide CSV/JSON tables
## What changes were proposed in this pull request?

After [recent changes](11e5f1bcd4) to CSV parsing to return partial results for bad CSV records, queries of wide CSV tables slowed considerably. That recent change resulted in every row being recreated, even when the associated input record had no parsing issues and the user specified no corrupt record field in his/her schema.

The change to FailureSafeParser.scala also impacted queries against wide JSON tables as well.

In this PR, I propose that a row should be recreated only if columns need to be shifted due to the existence of a corrupt column field in the user-supplied schema. Otherwise, the code should use the row as-is (For CSV input, it will have values for the columns that could be converted, and also null values for columns that could not be converted).

See benchmarks below. The CSV benchmark for 1000 columns went from 120144 ms to 89069 ms, a savings of 25% (this only brings the cost down to baseline levels. Again, see benchmarks below).

Similarly, the JSON benchmark for 1000 columns (added in this PR) went from 109621 ms to 80871 ms, also a savings of 25%.

Still, partial results functionality is preserved:

<pre>
bash-3.2$ cat test2.csv
"hello",1999-08-01,"last"
"there","bad date","field"
"again","2017-11-22","in file"
bash-3.2$ bin/spark-shell
...etc...
scala> val df = spark.read.schema("a string, b date, c string").csv("test2.csv")
df: org.apache.spark.sql.DataFrame = [a: string, b: date ... 1 more field]
scala> df.show
+-----+----------+-------+
|    a|         b|      c|
+-----+----------+-------+
|hello|1999-08-01|   last|
|there|      null|  field|
|again|2017-11-22|in file|
+-----+----------+-------+
scala> val df = spark.read.schema("badRecord string, a string, b date, c string").
     | option("columnNameOfCorruptRecord", "badRecord").
     | csv("test2.csv")
df: org.apache.spark.sql.DataFrame = [badRecord: string, a: string ... 2 more fields]
scala> df.show
+--------------------+-----+----------+-------+
|           badRecord|    a|         b|      c|
+--------------------+-----+----------+-------+
|                null|hello|1999-08-01|   last|
|"there","bad date...|there|      null|  field|
|                null|again|2017-11-22|in file|
+--------------------+-----+----------+-------+
scala>
</pre>

### CSVBenchmark Benchmarks:

baseline = commit before partial results change
PR = this PR
master = master branch

[baseline_CSVBenchmark-results.txt](https://github.com/apache/spark/files/2697109/baseline_CSVBenchmark-results.txt)
[pr_CSVBenchmark-results.txt](https://github.com/apache/spark/files/2697110/pr_CSVBenchmark-results.txt)
[master_CSVBenchmark-results.txt](https://github.com/apache/spark/files/2697111/master_CSVBenchmark-results.txt)

### JSONBenchmark Benchmarks:

baseline = commit before partial results change
PR = this PR
master = master branch

[baseline_JSONBenchmark-results.txt](https://github.com/apache/spark/files/2711040/baseline_JSONBenchmark-results.txt)
[pr_JSONBenchmark-results.txt](https://github.com/apache/spark/files/2711041/pr_JSONBenchmark-results.txt)
[master_JSONBenchmark-results.txt](https://github.com/apache/spark/files/2711042/master_JSONBenchmark-results.txt)

## How was this patch tested?

- All SQL unit tests.
- Added 2 CSV benchmarks
- Python core and SQL tests

Closes #23336 from bersprockets/csv-wide-row-opt2.

Authored-by: Bruce Robbins <bersprockets@gmail.com>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>
2019-01-30 15:15:29 +08:00
.github [SPARK-18073][DOCS][WIP] Migrate wiki to spark.apache.org web site 2016-11-23 11:25:47 +00:00
assembly [SPARK-26134][CORE] Upgrading Hadoop to 2.7.4 to fix java.version problem 2018-11-21 23:09:57 -08:00
bin [SPARK-26687][K8S] Fix handling of custom Dockerfile paths 2019-01-24 10:11:55 -08:00
build [SPARK-26144][BUILD] build/mvn should detect scala.version based on scala.binary.version 2018-11-22 14:49:41 -08:00
common [SPARK-24938][CORE] Prevent Netty from using onheap memory for headers without regard for configuration 2019-01-22 08:41:42 -06:00
conf [SPARK-22466][SPARK SUBMIT] export SPARK_CONF_DIR while conf is default 2017-11-09 14:33:08 +09:00
core [SPARK-26595][CORE] Allow credential renewal based on kerberos ticket cache. 2019-01-28 13:32:34 -08:00
data [SPARK-22666][ML][SQL] Spark datasource for image format 2018-09-05 11:59:00 -07:00
dev [SPARK-26566][PYTHON][SQL] Upgrade Apache Arrow to version 0.12.0 2019-01-29 14:18:45 +08:00
docs [SPARK-11215][ML] Add multiple columns support to StringIndexer 2019-01-29 09:21:25 -06:00
examples [SPARK-26640][CORE][ML][SQL][STREAMING][PYSPARK] Code cleanup from lgtm.com analysis 2019-01-17 19:40:39 -06:00
external [SPARK-26718][SS] Fixed integer overflow in SS kafka rateLimit calculation 2019-01-29 10:58:10 -08:00
graphx [GRAPHX] Remove unused variables left over by previous refactoring. 2018-11-22 15:43:04 -06:00
hadoop-cloud [SPARK-25956] Make Scala 2.12 as default Scala version in Spark 3.0 2018-11-14 16:22:23 -08:00
launcher [SPARK-26640][CORE][ML][SQL][STREAMING][PYSPARK] Code cleanup from lgtm.com analysis 2019-01-17 19:40:39 -06:00
licenses [SPARK-24654][BUILD] Update, fix LICENSE and NOTICE, and specialize for source vs binary 2018-06-30 19:27:16 -05:00
licenses-binary [SPARK-23654][BUILD] remove jets3t as a dependency of spark 2018-08-16 12:34:23 -07:00
mllib [SPARK-11215][ML] Add multiple columns support to StringIndexer 2019-01-29 09:21:25 -06:00
mllib-local [SPARK-19591][ML][MLLIB] Add sample weights to decision trees 2019-01-24 18:20:28 -07:00
project [SPARK-11215][ML] Add multiple columns support to StringIndexer 2019-01-29 09:21:25 -06:00
python [SPARK-26776][PYTHON] Reduce Py4J communication cost in PySpark's execution barrier check 2019-01-30 12:24:27 +08:00
R [SPARK-11215][ML] Add multiple columns support to StringIndexer 2019-01-29 09:21:25 -06:00
repl [SPARK-26633][REPL] Add ExecutorClassLoader.getResourceAsStream 2019-01-16 15:21:11 -08:00
resource-managers [SPARK-26595][CORE] Allow credential renewal based on kerberos ticket cache. 2019-01-28 13:32:34 -08:00
sbin [SPARK-25891][PYTHON] Upgrade to Py4J 0.10.8.1 2018-10-31 09:55:03 -07:00
sql [SPARK-26378][SQL] Restore performance of queries against wide CSV/JSON tables 2019-01-30 15:15:29 +08:00
streaming [SPARK-26725][TEST] Fix the input values of UnifiedMemoryManager constructor in test suites 2019-01-28 12:42:14 +08:00
tools [SPARK-25956] Make Scala 2.12 as default Scala version in Spark 3.0 2018-11-14 16:22:23 -08:00
.gitattributes [SPARK-3870] EOL character enforcement 2014-10-31 12:39:52 -07:00
.gitignore [MINOR][DOC] Documentation on JVM options for SBT 2019-01-22 18:27:24 -06:00
appveyor.yml [MINOR][BUILD] Remove -Phive-thriftserver profile within appveyor.yml 2018-07-30 10:01:18 +08:00
CONTRIBUTING.md [SPARK-18073][DOCS][WIP] Migrate wiki to spark.apache.org web site 2016-11-23 11:25:47 +00:00
LICENSE [SPARK-24654][BUILD] Update, fix LICENSE and NOTICE, and specialize for source vs binary 2018-06-30 19:27:16 -05:00
LICENSE-binary [SPARK-23654][BUILD] remove jets3t as a dependency of spark 2018-08-16 12:34:23 -07:00
NOTICE [SPARK-23654][BUILD] remove jets3t as a dependency of spark 2018-08-16 12:34:23 -07:00
NOTICE-binary [SPARK-23654][BUILD] remove jets3t as a dependency of spark 2018-08-16 12:34:23 -07:00
pom.xml [SPARK-26566][PYTHON][SQL] Upgrade Apache Arrow to version 0.12.0 2019-01-29 14:18:45 +08:00
README.md [MINOR] Add Jenkins and AppVeyor badges at README.md 2019-01-25 10:04:21 +08:00
scalastyle-config.xml [SPARK-25986][BUILD] Add rules to ban throw Errors in application code 2018-11-14 13:05:18 -08:00

Apache Spark

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Spark is a fast and general cluster computing system for Big Data. It provides high-level APIs in Scala, Java, Python, and R, and an optimized engine that supports general computation graphs for data analysis. It also supports a rich set of higher-level tools including Spark SQL for SQL and DataFrames, MLlib for machine learning, GraphX for graph processing, and Spark Streaming for stream processing.

http://spark.apache.org/

Online Documentation

You can find the latest Spark documentation, including a programming guide, on the project web page. This README file only contains basic setup instructions.

Building Spark

Spark is built using Apache Maven. To build Spark and its example programs, run:

build/mvn -DskipTests clean package

(You do not need to do this if you downloaded a pre-built package.)

You can build Spark using more than one thread by using the -T option with Maven, see "Parallel builds in Maven 3". More detailed documentation is available from the project site, at "Building Spark".

For general development tips, including info on developing Spark using an IDE, see "Useful Developer Tools".

Interactive Scala Shell

The easiest way to start using Spark is through the Scala shell:

./bin/spark-shell

Try the following command, which should return 1000:

scala> sc.parallelize(1 to 1000).count()

Interactive Python Shell

Alternatively, if you prefer Python, you can use the Python shell:

./bin/pyspark

And run the following command, which should also return 1000:

>>> sc.parallelize(range(1000)).count()

Example Programs

Spark also comes with several sample programs in the examples directory. To run one of them, use ./bin/run-example <class> [params]. For example:

./bin/run-example SparkPi

will run the Pi example locally.

You can set the MASTER environment variable when running examples to submit examples to a cluster. This can be a mesos:// or spark:// URL, "yarn" to run on YARN, and "local" to run locally with one thread, or "local[N]" to run locally with N threads. You can also use an abbreviated class name if the class is in the examples package. For instance:

MASTER=spark://host:7077 ./bin/run-example SparkPi

Many of the example programs print usage help if no params are given.

Running Tests

Testing first requires building Spark. Once Spark is built, tests can be run using:

./dev/run-tests

Please see the guidance on how to run tests for a module, or individual tests.

There is also a Kubernetes integration test, see resource-managers/kubernetes/integration-tests/README.md

A Note About Hadoop Versions

Spark uses the Hadoop core library to talk to HDFS and other Hadoop-supported storage systems. Because the protocols have changed in different versions of Hadoop, you must build Spark against the same version that your cluster runs.

Please refer to the build documentation at "Specifying the Hadoop Version and Enabling YARN" for detailed guidance on building for a particular distribution of Hadoop, including building for particular Hive and Hive Thriftserver distributions.

Configuration

Please refer to the Configuration Guide in the online documentation for an overview on how to configure Spark.

Contributing

Please review the Contribution to Spark guide for information on how to get started contributing to the project.