Commit graph

920 commits

Author SHA1 Message Date
Sameer Agarwal 19f4ac6dc7 [SPARK-13759][SQL] Add IsNotNull constraints for expressions with an inequality
## What changes were proposed in this pull request?

This PR adds support for inferring `IsNotNull` constraints from expressions with an `!==`. More specifically, if an operator has a condition on `a !== b`, we know that both `a` and `b` in the operator output can no longer be null.

## How was this patch tested?

1. Modified a test in `ConstraintPropagationSuite` to test for expressions with an inequality.
2. Added a test in `NullFilteringSuite` for making sure an Inner join with a "non-equal" condition appropriately filters out null from their input.

cc nongli

Author: Sameer Agarwal <sameer@databricks.com>

Closes #11594 from sameeragarwal/isnotequal-constraints.
2016-03-10 12:16:46 -08:00
hyukjinkwon aa0eba2c35 [SPARK-13766][SQL] Consistent file extensions for files written by internal data sources
## What changes were proposed in this pull request?

https://issues.apache.org/jira/browse/SPARK-13766
This PR makes the file extensions (written by internal datasource) consistent.

**Before**

- TEXT, CSV and JSON
```
[.COMPRESSION_CODEC_NAME]
```

- Parquet
```
[.COMPRESSION_CODEC_NAME].parquet
```

- ORC
```
.orc
```

**After**

- TEXT, CSV and JSON
```
.txt[.COMPRESSION_CODEC_NAME]
.csv[.COMPRESSION_CODEC_NAME]
.json[.COMPRESSION_CODEC_NAME]
```

- Parquet
```
[.COMPRESSION_CODEC_NAME].parquet
```

- ORC
```
[.COMPRESSION_CODEC_NAME].orc
```

When the compression codec is set,
- For Parquet and ORC, each still stays in Parquet and ORC format but just have compressed data internally. So, I think it is okay to name `.parquet` and `.orc` at the end.

- For Text, CSV and JSON, each does not stays in each format but it has different data format according to compression codec. So, each has the names `.json`, `.csv` and `.txt` before the compression extension.

## How was this patch tested?

Unit tests are used and `./dev/run_tests` for coding style tests.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #11604 from HyukjinKwon/SPARK-13766.
2016-03-09 19:12:46 -08:00
hyukjinkwon cad29a40b2 [SPARK-13728][SQL] Fix ORC PPD test so that pushed filters can be checked.
## What changes were proposed in this pull request?
https://issues.apache.org/jira/browse/SPARK-13728

https://github.com/apache/spark/pull/11509 makes the output only single ORC file.
It was 10 files but this PR writes only single file. So, this could not skip stripes in ORC by the pushed down filters.
So, this PR simply repartitions data into 10 so that the test could pass.
## How was this patch tested?

unittest and `./dev/run_tests` for code style test.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #11593 from HyukjinKwon/SPARK-13728.
2016-03-09 10:48:53 -08:00
Dilip Biswal 53ba6d6e59 [SPARK-13698][SQL] Fix Analysis Exceptions when Using Backticks in Generate
## What changes were proposed in this pull request?
Analysis exception occurs while running the following query.
```
SELECT ints FROM nestedArray LATERAL VIEW explode(a.b) `a` AS `ints`
```
```
Failed to analyze query: org.apache.spark.sql.AnalysisException: cannot resolve '`ints`' given input columns: [a, `ints`]; line 1 pos 7
'Project ['ints]
+- Generate explode(a#0.b), true, false, Some(a), [`ints`#8]
   +- SubqueryAlias nestedarray
      +- LocalRelation [a#0], [[[[1,2,3]]]]
```

## How was this patch tested?

Added new unit tests in SQLQuerySuite and HiveQlSuite

Author: Dilip Biswal <dbiswal@us.ibm.com>

Closes #11538 from dilipbiswal/SPARK-13698.
2016-03-09 21:49:37 +08:00
Dongjoon Hyun c3689bc24e [SPARK-13702][CORE][SQL][MLLIB] Use diamond operator for generic instance creation in Java code.
## What changes were proposed in this pull request?

In order to make `docs/examples` (and other related code) more simple/readable/user-friendly, this PR replaces existing codes like the followings by using `diamond` operator.

```
-    final ArrayList<Product2<Object, Object>> dataToWrite =
-      new ArrayList<Product2<Object, Object>>();
+    final ArrayList<Product2<Object, Object>> dataToWrite = new ArrayList<>();
```

Java 7 or higher supports **diamond** operator which replaces the type arguments required to invoke the constructor of a generic class with an empty set of type parameters (<>). Currently, Spark Java code use mixed usage of this.

## How was this patch tested?

Manual.
Pass the existing tests.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #11541 from dongjoon-hyun/SPARK-13702.
2016-03-09 10:31:26 +00:00
Jakob Odersky 035d3acdf3 [SPARK-7286][SQL] Deprecate !== in favour of =!=
This PR replaces #9925 which had issues with CI. **Please see the original PR for any previous discussions.**

## What changes were proposed in this pull request?
Deprecate the SparkSQL column operator !== and use =!= as an alternative.
Fixes subtle issues related to operator precedence (basically, !== does not have the same priority as its logical negation, ===).

## How was this patch tested?
All currently existing tests.

Author: Jakob Odersky <jodersky@gmail.com>

Closes #11588 from jodersky/SPARK-7286.
2016-03-08 18:11:09 -08:00
Michael Armbrust 1e28840594 [SPARK-13738][SQL] Cleanup Data Source resolution
Follow-up to #11509, that simply refactors the interface that we use when resolving a pluggable `DataSource`.
 - Multiple functions share the same set of arguments so we make this a case class, called `DataSource`.  Actual resolution is now done by calling a function on this class.
 - Instead of having multiple methods named `apply` (some of which do writing some of which do reading) we now explicitly have `resolveRelation()` and `write(mode, df)`.
 - Get rid of `Array[String]` since this is an internal API and was forcing us to awkwardly call `toArray` in a bunch of places.

Author: Michael Armbrust <michael@databricks.com>

Closes #11572 from marmbrus/dataSourceResolution.
2016-03-08 15:19:26 -08:00
Dongjoon Hyun 076009b949 [SPARK-13400] Stop using deprecated Octal escape literals
## What changes were proposed in this pull request?

This removes the remaining deprecated Octal escape literals. The followings are the warnings on those two lines.
```
LiteralExpressionSuite.scala:99: Octal escape literals are deprecated, use \u0000 instead.
HiveQlSuite.scala:74: Octal escape literals are deprecated, use \u002c instead.
```

## How was this patch tested?

Manual.
During building, there should be no warning on `Octal escape literals`.
```
mvn -DskipTests clean install
```

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #11584 from dongjoon-hyun/SPARK-13400.
2016-03-08 15:00:26 -08:00
Wenchen Fan 46881b4ea2 [SPARK-12727][SQL] support SQL generation for aggregate with multi-distinct
## What changes were proposed in this pull request?

This PR add SQL generation support for aggregate with multi-distinct, by simply moving the `DistinctAggregationRewriter` rule to optimizer.

More discussions are needed as this breaks an import contract: analyzed plan should be able to run without optimization.  However, the `ComputeCurrentTime` rule has kind of broken it already, and I think maybe we should add a new phase for this kind of rules, because strictly speaking they don't belong to analysis and is coupled with the physical plan implementation.

## How was this patch tested?

existing tests

Author: Wenchen Fan <wenchen@databricks.com>

Closes #11579 from cloud-fan/distinct.
2016-03-08 11:45:08 -08:00
Andrew Or da7bfac488 [SPARK-13689][SQL] Move helper things in CatalystQl to new utils object
## What changes were proposed in this pull request?

When we add more DDL parsing logic in the future, SparkQl will become very big. To keep it smaller, we'll introduce helper "parser objects", e.g. one to parse alter table commands. However, these parser objects will need to access some helper methods that exist in CatalystQl. The proposal is to move those methods to an isolated ParserUtils object.

This is based on viirya's changes in #11048. It prefaces the bigger fix for SPARK-13139 to make the diff of that patch smaller.

## How was this patch tested?

No change in functionality, so just Jenkins.

Author: Andrew Or <andrew@databricks.com>

Closes #11529 from andrewor14/parser-utils.
2016-03-07 18:01:27 -08:00
Tim Preece 46f25c2413 [SPARK-13648] Add Hive Cli to classes for isolated classloader
## What changes were proposed in this pull request?

Adding the hive-cli classes to the classloader

## How was this patch tested?

The hive Versionssuite tests were run

This is my original work and I license the work to the project under the project's open source license.

Author: Tim Preece <tim.preece.in.oz@gmail.com>

Closes #11495 from preecet/master.
2016-03-07 15:23:07 -08:00
Michael Armbrust e720dda42e [SPARK-13665][SQL] Separate the concerns of HadoopFsRelation
`HadoopFsRelation` is used for reading most files into Spark SQL.  However today this class mixes the concerns of file management, schema reconciliation, scan building, bucketing, partitioning, and writing data.  As a result, many data sources are forced to reimplement the same functionality and the various layers have accumulated a fair bit of inefficiency.  This PR is a first cut at separating this into several components / interfaces that are each described below.  Additionally, all implementations inside of Spark (parquet, csv, json, text, orc, svmlib) have been ported to the new API `FileFormat`.  External libraries, such as spark-avro will also need to be ported to work with Spark 2.0.

### HadoopFsRelation
A simple `case class` that acts as a container for all of the metadata required to read from a datasource.  All discovery, resolution and merging logic for schemas and partitions has been removed.  This an internal representation that no longer needs to be exposed to developers.

```scala
case class HadoopFsRelation(
    sqlContext: SQLContext,
    location: FileCatalog,
    partitionSchema: StructType,
    dataSchema: StructType,
    bucketSpec: Option[BucketSpec],
    fileFormat: FileFormat,
    options: Map[String, String]) extends BaseRelation
```

### FileFormat
The primary interface that will be implemented by each different format including external libraries.  Implementors are responsible for reading a given format and converting it into `InternalRow` as well as writing out an `InternalRow`.  A format can optionally return a schema that is inferred from a set of files.

```scala
trait FileFormat {
  def inferSchema(
      sqlContext: SQLContext,
      options: Map[String, String],
      files: Seq[FileStatus]): Option[StructType]

  def prepareWrite(
      sqlContext: SQLContext,
      job: Job,
      options: Map[String, String],
      dataSchema: StructType): OutputWriterFactory

  def buildInternalScan(
      sqlContext: SQLContext,
      dataSchema: StructType,
      requiredColumns: Array[String],
      filters: Array[Filter],
      bucketSet: Option[BitSet],
      inputFiles: Array[FileStatus],
      broadcastedConf: Broadcast[SerializableConfiguration],
      options: Map[String, String]): RDD[InternalRow]
}
```

The current interface is based on what was required to get all the tests passing again, but still mixes a couple of concerns (i.e. `bucketSet` is passed down to the scan instead of being resolved by the planner).  Additionally, scans are still returning `RDD`s instead of iterators for single files.  In a future PR, bucketing should be removed from this interface and the scan should be isolated to a single file.

### FileCatalog
This interface is used to list the files that make up a given relation, as well as handle directory based partitioning.

```scala
trait FileCatalog {
  def paths: Seq[Path]
  def partitionSpec(schema: Option[StructType]): PartitionSpec
  def allFiles(): Seq[FileStatus]
  def getStatus(path: Path): Array[FileStatus]
  def refresh(): Unit
}
```

Currently there are two implementations:
 - `HDFSFileCatalog` - based on code from the old `HadoopFsRelation`.  Infers partitioning by recursive listing and caches this data for performance
 - `HiveFileCatalog` - based on the above, but it uses the partition spec from the Hive Metastore.

### ResolvedDataSource
Produces a logical plan given the following description of a Data Source (which can come from DataFrameReader or a metastore):
 - `paths: Seq[String] = Nil`
 - `userSpecifiedSchema: Option[StructType] = None`
 - `partitionColumns: Array[String] = Array.empty`
 - `bucketSpec: Option[BucketSpec] = None`
 - `provider: String`
 - `options: Map[String, String]`

This class is responsible for deciding which of the Data Source APIs a given provider is using (including the non-file based ones).  All reconciliation of partitions, buckets, schema from metastores or inference is done here.

### DataSourceAnalysis / DataSourceStrategy
Responsible for analyzing and planning reading/writing of data using any of the Data Source APIs, including:
 - pruning the files from partitions that will be read based on filters.
 - appending partition columns*
 - applying additional filters when a data source can not evaluate them internally.
 - constructing an RDD that is bucketed correctly when required*
 - sanity checking schema match-up and other analysis when writing.

*In the future we should do that following:
 - Break out file handling into its own Strategy as its sufficiently complex / isolated.
 - Push the appending of partition columns down in to `FileFormat` to avoid an extra copy / unvectorization.
 - Use a custom RDD for scans instead of `SQLNewNewHadoopRDD2`

Author: Michael Armbrust <michael@databricks.com>
Author: Wenchen Fan <wenchen@databricks.com>

Closes #11509 from marmbrus/fileDataSource.
2016-03-07 15:15:10 -08:00
Sameer Agarwal ef77003178 [SPARK-13495][SQL] Add Null Filters in the query plan for Filters/Joins based on their data constraints
## What changes were proposed in this pull request?

This PR adds an optimizer rule to eliminate reading (unnecessary) NULL values if they are not required for correctness by inserting `isNotNull` filters is the query plan. These filters are currently inserted beneath existing `Filter` and `Join` operators and are inferred based on their data constraints.

Note: While this optimization is applicable to all types of join, it primarily benefits `Inner` and `LeftSemi` joins.

## How was this patch tested?

1. Added a new `NullFilteringSuite` that tests for `IsNotNull` filters in the query plan for joins and filters. Also, tests interaction with the `CombineFilters` optimizer rules.
2. Test generated ExpressionTrees via `OrcFilterSuite`
3. Test filter source pushdown logic via `SimpleTextHadoopFsRelationSuite`

cc yhuai nongli

Author: Sameer Agarwal <sameer@databricks.com>

Closes #11372 from sameeragarwal/gen-isnotnull.
2016-03-07 12:04:59 -08:00
Dilip Biswal d7eac9d795 [SPARK-13651] Generator outputs are not resolved correctly resulting in run time error
## What changes were proposed in this pull request?

```
Seq(("id1", "value1")).toDF("key", "value").registerTempTable("src")
sqlContext.sql("SELECT t1.* FROM src LATERAL VIEW explode(map('key1', 100, 'key2', 200)) t1 AS key, value")
```
Results in following logical plan

```
Project [key#2,value#3]
+- Generate explode(HiveGenericUDF#org.apache.hadoop.hive.ql.udf.generic.GenericUDFMap(key1,100,key2,200)), true, false, Some(genoutput), [key#2,value#3]
   +- SubqueryAlias src
      +- Project [_1#0 AS key#2,_2#1 AS value#3]
         +- LocalRelation [_1#0,_2#1], [[id1,value1]]
```

The above query fails with following runtime error.
```
java.lang.ClassCastException: java.lang.Integer cannot be cast to org.apache.spark.unsafe.types.UTF8String
	at org.apache.spark.sql.catalyst.expressions.BaseGenericInternalRow$class.getUTF8String(rows.scala:46)
	at org.apache.spark.sql.catalyst.expressions.GenericInternalRow.getUTF8String(rows.scala:221)
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$SpecificUnsafeProjection.apply(generated.java:42)
	at org.apache.spark.sql.execution.Generate$$anonfun$doExecute$1$$anonfun$apply$9.apply(Generate.scala:98)
	at org.apache.spark.sql.execution.Generate$$anonfun$doExecute$1$$anonfun$apply$9.apply(Generate.scala:96)
	at scala.collection.Iterator$$anon$11.next(Iterator.scala:370)
	at scala.collection.Iterator$$anon$11.next(Iterator.scala:370)
	at scala.collection.Iterator$class.foreach(Iterator.scala:742)
	at scala.collection.AbstractIterator.foreach(Iterator.scala:1194)
        <stack-trace omitted.....>
```
In this case the generated outputs are wrongly resolved from its child (LocalRelation) due to
https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala#L537-L548
## How was this patch tested?

(Please explain how this patch was tested. E.g. unit tests, integration tests, manual tests)

Added unit tests in hive/SQLQuerySuite and AnalysisSuite

Author: Dilip Biswal <dbiswal@us.ibm.com>

Closes #11497 from dilipbiswal/spark-13651.
2016-03-07 09:46:28 -08:00
Andrew Or bc7a3ec290 [SPARK-13685][SQL] Rename catalog.Catalog to ExternalCatalog
## What changes were proposed in this pull request?

Today we have `analysis.Catalog` and `catalog.Catalog`. In the future the former will call the latter. When that happens, if both of them are still called `Catalog` it will be very confusing. This patch renames the latter `ExternalCatalog` because it is expected to talk to external systems.

## How was this patch tested?

Jenkins.

Author: Andrew Or <andrew@databricks.com>

Closes #11526 from andrewor14/rename-catalog.
2016-03-07 00:14:40 -08:00
Cheng Lian 8ff88094da Revert "[SPARK-13616][SQL] Let SQLBuilder convert logical plan without a project on top of it"
This reverts commit f87ce0504e.

According to discussion in #11466, let's revert PR #11466 for safe.

Author: Cheng Lian <lian@databricks.com>

Closes #11539 from liancheng/revert-pr-11466.
2016-03-06 12:54:04 +08:00
gatorsmile adce5ee721 [SPARK-12720][SQL] SQL Generation Support for Cube, Rollup, and Grouping Sets
#### What changes were proposed in this pull request?

This PR is for supporting SQL generation for cube, rollup and grouping sets.

For example, a query using rollup:
```SQL
SELECT count(*) as cnt, key % 5, grouping_id() FROM t1 GROUP BY key % 5 WITH ROLLUP
```
Original logical plan:
```
  Aggregate [(key#17L % cast(5 as bigint))#47L,grouping__id#46],
            [(count(1),mode=Complete,isDistinct=false) AS cnt#43L,
             (key#17L % cast(5 as bigint))#47L AS _c1#45L,
             grouping__id#46 AS _c2#44]
  +- Expand [List(key#17L, value#18, (key#17L % cast(5 as bigint))#47L, 0),
             List(key#17L, value#18, null, 1)],
            [key#17L,value#18,(key#17L % cast(5 as bigint))#47L,grouping__id#46]
     +- Project [key#17L,
                 value#18,
                 (key#17L % cast(5 as bigint)) AS (key#17L % cast(5 as bigint))#47L]
        +- Subquery t1
           +- Relation[key#17L,value#18] ParquetRelation
```
Converted SQL:
```SQL
  SELECT count( 1) AS `cnt`,
         (`t1`.`key` % CAST(5 AS BIGINT)),
         grouping_id() AS `_c2`
  FROM `default`.`t1`
  GROUP BY (`t1`.`key` % CAST(5 AS BIGINT))
  GROUPING SETS (((`t1`.`key` % CAST(5 AS BIGINT))), ())
```

#### How was the this patch tested?

Added eight test cases in `LogicalPlanToSQLSuite`.

Author: gatorsmile <gatorsmile@gmail.com>
Author: xiaoli <lixiao1983@gmail.com>
Author: Xiao Li <xiaoli@Xiaos-MacBook-Pro.local>

Closes #11283 from gatorsmile/groupingSetsToSQL.
2016-03-05 19:25:03 +08:00
Andrew Or b7d4147421 [SPARK-13633][SQL] Move things into catalyst.parser package
## What changes were proposed in this pull request?

This patch simply moves things to existing package `o.a.s.sql.catalyst.parser` in an effort to reduce the size of the diff in #11048. This is conceptually the same as a recently merged patch #11482.

## How was this patch tested?

Jenkins.

Author: Andrew Or <andrew@databricks.com>

Closes #11506 from andrewor14/parser-package.
2016-03-04 10:32:00 -08:00
Rajesh Balamohan 204b02b56a [SPARK-12925] Improve HiveInspectors.unwrap for StringObjectInspector.…
Earlier fix did not copy the bytes and it is possible for higher level to reuse Text object. This was causing issues. Proposed fix now copies the bytes from Text. This still avoids the expensive encoding/decoding

Author: Rajesh Balamohan <rbalamohan@apache.org>

Closes #11477 from rajeshbalamohan/SPARK-12925.2.
2016-03-04 10:59:40 +00:00
Davies Liu dd83c209f1 [SPARK-13603][SQL] support SQL generation for subquery
## What changes were proposed in this pull request?

This is support SQL generation for subquery expressions, which will be replaced to a SubqueryHolder inside SQLBuilder recursively.

## How was this patch tested?

Added unit tests.

Author: Davies Liu <davies@databricks.com>

Closes #11453 from davies/sql_subquery.
2016-03-04 16:18:15 +08:00
Davies Liu d062587dd2 [SPARK-13601] [TESTS] use 1 partition in tests to avoid race conditions
## What changes were proposed in this pull request?

Fix race conditions when cleanup files.

## How was this patch tested?

Existing tests.

Author: Davies Liu <davies@databricks.com>

Closes #11507 from davies/flaky.
2016-03-03 17:46:28 -08:00
Andrew Or 3edcc40223 [SPARK-13632][SQL] Move commands.scala to command package
## What changes were proposed in this pull request?

This patch simply moves things to a new package in an effort to reduce the size of the diff in #11048. Currently the new package only has one file, but in the future we'll add many new commands in SPARK-13139.

## How was this patch tested?

Jenkins.

Author: Andrew Or <andrew@databricks.com>

Closes #11482 from andrewor14/commands-package.
2016-03-03 15:24:38 -08:00
hyukjinkwon cf95d728c6 [SPARK-13543][SQL] Support for specifying compression codec for Parquet/ORC via option()
## What changes were proposed in this pull request?

This PR adds the support to specify compression codecs for both ORC and Parquet.

## How was this patch tested?

unittests within IDE and code style tests with `dev/run_tests`.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #11464 from HyukjinKwon/SPARK-13543.
2016-03-03 10:30:55 -08:00
Dongjoon Hyun b5f02d6743 [SPARK-13583][CORE][STREAMING] Remove unused imports and add checkstyle rule
## What changes were proposed in this pull request?

After SPARK-6990, `dev/lint-java` keeps Java code healthy and helps PR review by saving much time.
This issue aims remove unused imports from Java/Scala code and add `UnusedImports` checkstyle rule to help developers.

## How was this patch tested?
```
./dev/lint-java
./build/sbt compile
```

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #11438 from dongjoon-hyun/SPARK-13583.
2016-03-03 10:12:32 +00:00
Sean Owen e97fc7f176 [SPARK-13423][WIP][CORE][SQL][STREAMING] Static analysis fixes for 2.x
## What changes were proposed in this pull request?

Make some cross-cutting code improvements according to static analysis. These are individually up for discussion since they exist in separate commits that can be reverted. The changes are broadly:

- Inner class should be static
- Mismatched hashCode/equals
- Overflow in compareTo
- Unchecked warnings
- Misuse of assert, vs junit.assert
- get(a) + getOrElse(b) -> getOrElse(a,b)
- Array/String .size -> .length (occasionally, -> .isEmpty / .nonEmpty) to avoid implicit conversions
- Dead code
- tailrec
- exists(_ == ) -> contains find + nonEmpty -> exists filter + size -> count
- reduce(_+_) -> sum map + flatten -> map

The most controversial may be .size -> .length simply because of its size. It is intended to avoid implicits that might be expensive in some places.

## How was the this patch tested?

Existing Jenkins unit tests.

Author: Sean Owen <sowen@cloudera.com>

Closes #11292 from srowen/SPARK-13423.
2016-03-03 09:54:09 +00:00
Liang-Chi Hsieh f87ce0504e [SPARK-13616][SQL] Let SQLBuilder convert logical plan without a project on top of it
JIRA: https://issues.apache.org/jira/browse/SPARK-13616

## What changes were proposed in this pull request?

It is possibly that a logical plan has been removed `Project` from the top of it. Or the plan doesn't has a top `Project` from the beginning because it is not necessary. Currently the `SQLBuilder` can't convert such plans back to SQL. This change is to add this feature.

## How was this patch tested?

A test is added to `LogicalPlanToSQLSuite`.

Author: Liang-Chi Hsieh <viirya@gmail.com>

Closes #11466 from viirya/sqlbuilder-notopselect.
2016-03-02 22:21:49 -08:00
Davies Liu b5a59a0fe2 [SPARK-13601] call failure callbacks before writer.close()
## What changes were proposed in this pull request?

In order to tell OutputStream that the task has failed or not, we should call the failure callbacks BEFORE calling writer.close().

## How was this patch tested?

Added new unit tests.

Author: Davies Liu <davies@databricks.com>

Closes #11450 from davies/callback.
2016-03-02 14:35:44 -08:00
gatorsmile 9e01fe2ed1 [SPARK-13535][SQL] Fix Analysis Exceptions when Using Backticks in Transform Clause
#### What changes were proposed in this pull request?
```SQL
FROM
(FROM test SELECT TRANSFORM(key, value) USING 'cat' AS (`thing1` int, thing2 string)) t
SELECT thing1 + 1
```
This query returns an analysis error, like:
```
Failed to analyze query: org.apache.spark.sql.AnalysisException: cannot resolve '`thing1`' given input columns: [`thing1`, thing2]; line 3 pos 7
'Project [unresolvedalias(('thing1 + 1), None)]
+- SubqueryAlias t
   +- ScriptTransformation [key#2,value#3], cat, [`thing1`#6,thing2#7], HiveScriptIOSchema(List(),List(),Some(org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe),Some(org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe),List((field.delim,	)),List((field.delim,	)),Some(org.apache.hadoop.hive.ql.exec.TextRecordReader),Some(org.apache.hadoop.hive.ql.exec.TextRecordWriter),false)
      +- SubqueryAlias test
         +- Project [_1#0 AS key#2,_2#1 AS value#3]
            +- LocalRelation [_1#0,_2#1], [[1,1],[2,2],[3,3],[4,4],[5,5]]
```

The backpacks of \`thing1\` should be cleaned before entering Parser/Analyzer. This PR fixes this issue.

#### How was this patch tested?

Added a test case and modified an existing test case

Author: gatorsmile <gatorsmile@gmail.com>

Closes #11415 from gatorsmile/scriptTransform.
2016-03-02 23:07:48 +01:00
Liang-Chi Hsieh 6dfc4a764c [SPARK-13537][SQL] Fix readBytes in VectorizedPlainValuesReader
JIRA: https://issues.apache.org/jira/browse/SPARK-13537

## What changes were proposed in this pull request?

In readBytes of VectorizedPlainValuesReader, we use buffer[offset] to access bytes in buffer. It is incorrect because offset is added with Platform.BYTE_ARRAY_OFFSET when initialization. We should fix it.

## How was this patch tested?

`ParquetHadoopFsRelationSuite` sometimes (depending on the randomly generated data) will be [failed](https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/52136/consoleFull) by this bug. After applying this, the test can be passed.

I added a test to `ParquetHadoopFsRelationSuite` with the data which will fail without this patch.

The error exception:

    [info] ParquetHadoopFsRelationSuite:
    [info] - test all data types - StringType (440 milliseconds)
    [info] - test all data types - BinaryType (434 milliseconds)
    [info] - test all data types - BooleanType (406 milliseconds)
    20:59:38.618 ERROR org.apache.spark.executor.Executor: Exception in task 0.0 in stage 2597.0 (TID 67966)
    java.lang.ArrayIndexOutOfBoundsException: 46
	at org.apache.spark.sql.execution.datasources.parquet.VectorizedPlainValuesReader.readBytes(VectorizedPlainValuesReader.java:88)

Author: Liang-Chi Hsieh <viirya@gmail.com>

Closes #11418 from viirya/fix-readbytes.
2016-02-28 21:16:06 -08:00
Andrew Or cca79fad66 [SPARK-13526][SQL] Move SQLContext per-session states to new class
## What changes were proposed in this pull request?

This creates a `SessionState`, which groups a few fields that existed in `SQLContext`. Because `HiveContext` extends `SQLContext` we also need to make changes there. This is mainly a cleanup task that will soon pave the way for merging the two contexts.

## How was this patch tested?

Existing unit tests; this patch introduces no change in behavior.

Author: Andrew Or <andrew@databricks.com>

Closes #11405 from andrewor14/refactor-session.
2016-02-27 19:51:28 -08:00
Cheng Lian 99dfcedbfd [SPARK-13457][SQL] Removes DataFrame RDD operations
## What changes were proposed in this pull request?

This is another try of PR #11323.

This PR removes DataFrame RDD operations except for `foreach` and `foreachPartitions` (they are actions rather than transformations). Original calls are now replaced by calls to methods of `DataFrame.rdd`.

PR #11323 was reverted because it introduced a regression: both `DataFrame.foreach` and `DataFrame.foreachPartitions` wrap underlying RDD operations with `withNewExecutionId` to track Spark jobs. But they are removed in #11323.

## How was the this patch tested?

No extra tests are added. Existing tests should do the work.

Author: Cheng Lian <lian@databricks.com>

Closes #11388 from liancheng/remove-df-rdd-ops.
2016-02-27 00:28:30 +08:00
Josh Rosen 633d63a48a [SPARK-12757] Add block-level read/write locks to BlockManager
## Motivation

As a pre-requisite to off-heap caching of blocks, we need a mechanism to prevent pages / blocks from being evicted while they are being read. With on-heap objects, evicting a block while it is being read merely leads to memory-accounting problems (because we assume that an evicted block is a candidate for garbage-collection, which will not be true during a read), but with off-heap memory this will lead to either data corruption or segmentation faults.

## Changes

### BlockInfoManager and reader/writer locks

This patch adds block-level read/write locks to the BlockManager. It introduces a new `BlockInfoManager` component, which is contained within the `BlockManager`, holds the `BlockInfo` objects that the `BlockManager` uses for tracking block metadata, and exposes APIs for locking blocks in either shared read or exclusive write modes.

`BlockManager`'s `get*()` and `put*()` methods now implicitly acquire the necessary locks. After a `get()` call successfully retrieves a block, that block is locked in a shared read mode. A `put()` call will block until it acquires an exclusive write lock. If the write succeeds, the write lock will be downgraded to a shared read lock before returning to the caller. This `put()` locking behavior allows us store a block and then immediately turn around and read it without having to worry about it having been evicted between the write and the read, which will allow us to significantly simplify `CacheManager` in the future (see #10748).

See `BlockInfoManagerSuite`'s test cases for a more detailed specification of the locking semantics.

### Auto-release of locks at the end of tasks

Our locking APIs support explicit release of locks (by calling `unlock()`), but it's not always possible to guarantee that locks will be released prior to the end of the task. One reason for this is our iterator interface: since our iterators don't support an explicit `close()` operator to signal that no more records will be consumed, operations like `take()` or `limit()` don't have a good means to release locks on their input iterators' blocks. Another example is broadcast variables, whose block locks can only be released at the end of the task.

To address this, `BlockInfoManager` uses a pair of maps to track the set of locks acquired by each task. Lock acquisitions automatically record the current task attempt id by obtaining it from `TaskContext`. When a task finishes, code in `Executor` calls `BlockInfoManager.unlockAllLocksForTask(taskAttemptId)` to free locks.

### Locking and the MemoryStore

In order to prevent in-memory blocks from being evicted while they are being read, the `MemoryStore`'s `evictBlocksToFreeSpace()` method acquires write locks on blocks which it is considering as candidates for eviction. These lock acquisitions are non-blocking, so a block which is being read will not be evicted. By holding write locks until the eviction is performed or skipped (in case evicting the blocks would not free enough memory), we avoid a race where a new reader starts to read a block after the block has been marked as an eviction candidate but before it has been removed.

### Locking and remote block transfer

This patch makes small changes to to block transfer and network layer code so that locks acquired by the BlockTransferService are released as soon as block transfer messages are consumed and released by Netty. This builds on top of #11193, a bug fix related to freeing of network layer ManagedBuffers.

## FAQ

- **Why not use Java's built-in [`ReadWriteLock`](https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/locks/ReadWriteLock.html)?**

  Our locks operate on a per-task rather than per-thread level. Under certain circumstances a task may consist of multiple threads, so using `ReadWriteLock` would mean that we might call `unlock()` from a thread which didn't hold the lock in question, an operation which has undefined semantics. If we could rely on Java 8 classes, we might be able to use [`StampedLock`](https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/locks/StampedLock.html) to work around this issue.

- **Why not detect "leaked" locks in tests?**:

  See above notes about `take()` and `limit`.

Author: Josh Rosen <joshrosen@databricks.com>

Closes #10705 from JoshRosen/pin-pages.
2016-02-25 17:17:56 -08:00
Davies Liu 751724b132 Revert "[SPARK-13457][SQL] Removes DataFrame RDD operations"
This reverts commit 157fe64f3e.
2016-02-25 11:53:48 -08:00
Cheng Lian 157fe64f3e [SPARK-13457][SQL] Removes DataFrame RDD operations
## What changes were proposed in this pull request?

This PR removes DataFrame RDD operations. Original calls are now replaced by calls to methods of `DataFrame.rdd`.

## How was the this patch tested?

No extra tests are added. Existing tests should do the work.

Author: Cheng Lian <lian@databricks.com>

Closes #11323 from liancheng/remove-df-rdd-ops.
2016-02-25 23:07:59 +08:00
Reynold Xin 2b2c8c3323 [SPARK-13486][SQL] Move SQLConf into an internal package
## What changes were proposed in this pull request?
This patch moves SQLConf into org.apache.spark.sql.internal package to make it very explicit that it is internal. Soon I will also submit more API work that creates implementations of interfaces in this internal package.

## How was this patch tested?
If it compiles, then the refactoring should work.

Author: Reynold Xin <rxin@databricks.com>

Closes #11363 from rxin/SPARK-13486.
2016-02-25 17:49:50 +08:00
Nong Li 5a7af9e7ac [SPARK-13250] [SQL] Update PhysicallRDD to convert to UnsafeRow if using the vectorized scanner.
Some parts of the engine rely on UnsafeRow which the vectorized parquet scanner does not want
to produce. This add a conversion in Physical RDD. In the case where codegen is used (and the
scan is the start of the pipeline), there is no requirement to use UnsafeRow. This patch adds
update PhysicallRDD to support codegen, which eliminates the need for the UnsafeRow conversion
in all cases.

The result of these changes for TPCDS-Q19 at the 10gb sf reduces the query time from 9.5 seconds
to 6.5 seconds.

Author: Nong Li <nong@databricks.com>

Closes #11141 from nongli/spark-13250.
2016-02-24 17:16:45 -08:00
gatorsmile 5289837a72 [HOT][TEST] Disable a Test that Requires Nested Union Support.
## What changes were proposed in this pull request?
Since "[SPARK-13321][SQL] Support nested UNION in parser" is reverted, we need to disable the test case that requires this PR. Thanks!

rxin yhuai marmbrus

## How was this patch tested?

N/A

Author: gatorsmile <gatorsmile@gmail.com>

Closes #11352 from gatorsmile/disableTestCase.
2016-02-24 13:30:23 -08:00
Davies Liu 9cdd867da9 [SPARK-13373] [SQL] generate sort merge join
## What changes were proposed in this pull request?

Generates code for SortMergeJoin.

## How was the this patch tested?

Unit tests and manually tested with TPCDS Q72, which showed 70% performance improvements (from 42s to 25s), but micro benchmark only show minor improvements, it may depends the distribution of data and number of columns.

Author: Davies Liu <davies@databricks.com>

Closes #11248 from davies/gen_smj.
2016-02-23 15:00:10 -08:00
gatorsmile 87250580f2 [SPARK-13263][SQL] SQL Generation Support for Tablesample
In the parser, tableSample clause is part of tableSource.
```
tableSource
init { gParent.pushMsg("table source", state); }
after { gParent.popMsg(state); }
    : tabname=tableName
    ((tableProperties) => props=tableProperties)?
    ((tableSample) => ts=tableSample)?
    ((KW_AS) => (KW_AS alias=Identifier)
    |
    (Identifier) => (alias=Identifier))?
    -> ^(TOK_TABREF $tabname $props? $ts? $alias?)
    ;
```

Two typical query samples using TABLESAMPLE are:
```
    "SELECT s.id FROM t0 TABLESAMPLE(10 PERCENT) s"
    "SELECT * FROM t0 TABLESAMPLE(0.1 PERCENT)"
```

FYI, the logical plan of a TABLESAMPLE query:
```
sql("SELECT * FROM t0 TABLESAMPLE(0.1 PERCENT)").explain(true)

== Analyzed Logical Plan ==
id: bigint
Project [id#16L]
+- Sample 0.0, 0.001, false, 381
   +- Subquery t0
      +- Relation[id#16L] ParquetRelation
```

Thanks! cc liancheng

Author: gatorsmile <gatorsmile@gmail.com>
Author: xiaoli <lixiao1983@gmail.com>
Author: Xiao Li <xiaoli@Xiaos-MacBook-Pro.local>

This patch had conflicts when merged, resolved by
Committer: Cheng Lian <lian@databricks.com>

Closes #11148 from gatorsmile/tablesplitsample.
2016-02-23 16:13:09 +08:00
gatorsmile 01e10c9fef [SPARK-13236] SQL Generation for Set Operations
This PR is to implement SQL generation for the following three set operations:
- Union Distinct
- Intersect
- Except

liancheng Thanks!

Author: gatorsmile <gatorsmile@gmail.com>
Author: xiaoli <lixiao1983@gmail.com>
Author: Xiao Li <xiaoli@Xiaos-MacBook-Pro.local>

Closes #11195 from gatorsmile/setOpSQLGen.
2016-02-23 15:16:59 +08:00
gatorsmile 9dd5399d78 [SPARK-12723][SQL] Comprehensive Verification and Fixing of SQL Generation Support for Expressions
#### What changes were proposed in this pull request?

Ensure that all built-in expressions can be mapped to its SQL representation if there is one (e.g. ScalaUDF doesn't have a SQL representation). The function lists are from the expression list in `FunctionRegistry`.

window functions, grouping sets functions (`cube`, `rollup`, `grouping`, `grouping_id`), generator functions (`explode` and `json_tuple`) are covered by separate JIRA and PRs. Thus, this PR does not cover them. Except these functions, all the built-in expressions are covered. For details, see the list in `ExpressionToSQLSuite`.

Fixed a few issues. For example, the `prettyName` of `approx_count_distinct` is not right. The `sql` of `hash` function is not right, since the `hash` function does not accept `seed`.

Additionally, also correct the order of expressions in `FunctionRegistry` so that people are easier to find which functions are missing.

cc liancheng

#### How was the this patch tested?
Added two test cases in LogicalPlanToSQLSuite for covering `not like` and `not in`.

Added a new test suite `ExpressionToSQLSuite` to cover the functions:

1. misc non-aggregate functions + complex type creators + null expressions
2. math functions
3. aggregate functions
4. string functions
5. date time functions + calendar interval
6. collection functions
7. misc functions

Author: gatorsmile <gatorsmile@gmail.com>

Closes #11314 from gatorsmile/expressionToSQL.
2016-02-22 22:17:56 -08:00
Daoyuan Wang 5d80fac58f [SPARK-11624][SPARK-11972][SQL] fix commands that need hive to exec
In SparkSQLCLI, we have created a `CliSessionState`, but then we call `SparkSQLEnv.init()`, which will start another `SessionState`. This would lead to exception because `processCmd` need to get the `CliSessionState` instance by calling `SessionState.get()`, but the return value would be a instance of `SessionState`. See the exception below.

spark-sql> !echo "test";
Exception in thread "main" java.lang.ClassCastException: org.apache.hadoop.hive.ql.session.SessionState cannot be cast to org.apache.hadoop.hive.cli.CliSessionState
	at org.apache.hadoop.hive.cli.CliDriver.processCmd(CliDriver.java:112)
	at org.apache.spark.sql.hive.thriftserver.SparkSQLCLIDriver.processCmd(SparkSQLCLIDriver.scala:301)
	at org.apache.hadoop.hive.cli.CliDriver.processLine(CliDriver.java:376)
	at org.apache.spark.sql.hive.thriftserver.SparkSQLCLIDriver$.main(SparkSQLCLIDriver.scala:242)
	at org.apache.spark.sql.hive.thriftserver.SparkSQLCLIDriver.main(SparkSQLCLIDriver.scala)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.apache.spark.deploy.SparkSubmit$.org$apache$spark$deploy$SparkSubmit$$runMain(SparkSubmit.scala:691)
	at org.apache.spark.deploy.SparkSubmit$.doRunMain$1(SparkSubmit.scala:180)
	at org.apache.spark.deploy.SparkSubmit$.submit(SparkSubmit.scala:205)
	at org.apache.spark.deploy.SparkSubmit$.main(SparkSubmit.scala:120)
	at org.apache.spark.deploy.SparkSubmit.main(SparkSubmit.scala)

Author: Daoyuan Wang <daoyuan.wang@intel.com>

Closes #9589 from adrian-wang/clicommand.
2016-02-22 18:13:32 -08:00
Shixiong Zhu 0cbadf28c9 [SPARK-13271][SQL] Better error message if 'path' is not specified
Improved the error message as per discussion in https://github.com/apache/spark/pull/11034#discussion_r52111238. Also made `path` and `metadataPath` in FileStreamSource case insensitive.

Author: Shixiong Zhu <shixiong@databricks.com>

Closes #11154 from zsxwing/path.
2016-02-21 15:34:39 -08:00
Andrew Or 6c3832b26e [SPARK-13080][SQL] Implement new Catalog API using Hive
## What changes were proposed in this pull request?

This is a step towards merging `SQLContext` and `HiveContext`. A new internal Catalog API was introduced in #10982 and extended in #11069. This patch introduces an implementation of this API using `HiveClient`, an existing interface to Hive. It also extends `HiveClient` with additional calls to Hive that are needed to complete the catalog implementation.

*Where should I start reviewing?* The new catalog introduced is `HiveCatalog`. This class is relatively simple because it just calls `HiveClientImpl`, where most of the new logic is. I would not start with `HiveClient`, `HiveQl`, or `HiveMetastoreCatalog`, which are modified mainly because of a refactor.

*Why is this patch so big?* I had to refactor HiveClient to remove an intermediate representation of databases, tables, partitions etc. After this refactor `CatalogTable` convert directly to and from `HiveTable` (etc.). Otherwise we would have to first convert `CatalogTable` to the intermediate representation and then convert that to HiveTable, which is messy.

The new class hierarchy is as follows:
```
org.apache.spark.sql.catalyst.catalog.Catalog
  - org.apache.spark.sql.catalyst.catalog.InMemoryCatalog
  - org.apache.spark.sql.hive.HiveCatalog
```

Note that, as of this patch, none of these classes are currently used anywhere yet. This will come in the future before the Spark 2.0 release.

## How was the this patch tested?
All existing unit tests, and HiveCatalogSuite that extends CatalogTestCases.

Author: Andrew Or <andrew@databricks.com>
Author: Reynold Xin <rxin@databricks.com>

Closes #11293 from rxin/hive-catalog.
2016-02-21 15:00:24 -08:00
Herman van Hovell b6a873d6d4 [SPARK-13136][SQL] Create a dedicated Broadcast exchange operator
Quite a few Spark SQL join operators broadcast one side of the join to all nodes. The are a few problems with this:

- This conflates broadcasting (a data exchange) with joining. Data exchanges should be managed by a different operator.
- All these nodes implement their own (duplicate) broadcasting logic.
- Re-use of indices is quite hard.

This PR defines both a ```BroadcastDistribution``` and ```BroadcastPartitioning```, these contain a `BroadcastMode`. The `BroadcastMode` defines the way in which we transform the Array of `InternalRow`'s into an index. We currently support the following `BroadcastMode`'s:

- IdentityBroadcastMode: This broadcasts the rows in their original form.
- HashSetBroadcastMode: This applies a projection to the input rows, deduplicates these rows and broadcasts the resulting `Set`.
- HashedRelationBroadcastMode: This transforms the input rows into a `HashedRelation`, and broadcasts this index.

To match this distribution we implement a ```BroadcastExchange``` operator which will perform the broadcast for us, and have ```EnsureRequirements``` plan this operator. The old Exchange operator has been renamed into ShuffleExchange in order to clearly separate between Shuffled and Broadcasted exchanges. Finally the classes in Exchange.scala have been moved to a dedicated package.

cc rxin davies

Author: Herman van Hovell <hvanhovell@questtec.nl>

Closes #11083 from hvanhovell/SPARK-13136.
2016-02-21 12:32:31 -08:00
Reynold Xin 0947f0989b [SPARK-13420][SQL] Rename Subquery logical plan to SubqueryAlias
## What changes were proposed in this pull request?
This patch renames logical.Subquery to logical.SubqueryAlias, which is a more appropriate name for this operator (versus subqueries as expressions).

## How was the this patch tested?
Unit tests.

Author: Reynold Xin <rxin@databricks.com>

Closes #11288 from rxin/SPARK-13420.
2016-02-21 11:31:46 -08:00
Cheng Lian d9efe63ecd [SPARK-12799] Simplify various string output for expressions
This PR introduces several major changes:

1. Replacing `Expression.prettyString` with `Expression.sql`

   The `prettyString` method is mostly an internal, developer faced facility for debugging purposes, and shouldn't be exposed to users.

1. Using SQL-like representation as column names for selected fields that are not named expression (back-ticks and double quotes should be removed)

   Before, we were using `prettyString` as column names when possible, and sometimes the result column names can be weird.  Here are several examples:

   Expression         | `prettyString` | `sql`      | Note
   ------------------ | -------------- | ---------- | ---------------
   `a && b`           | `a && b`       | `a AND b`  |
   `a.getField("f")`  | `a[f]`         | `a.f`      | `a` is a struct

1. Adding trait `NonSQLExpression` extending from `Expression` for expressions that don't have a SQL representation (e.g. Scala UDF/UDAF and Java/Scala object expressions used for encoders)

   `NonSQLExpression.sql` may return an arbitrary user facing string representation of the expression.

Author: Cheng Lian <lian@databricks.com>

Closes #10757 from liancheng/spark-12799.simplify-expression-string-methods.
2016-02-21 22:53:15 +08:00
gatorsmile f88c641bc8 [SPARK-13310] [SQL] Resolve Missing Sorting Columns in Generate
```scala
// case 1: missing sort columns are resolvable if join is true
sql("SELECT explode(a) AS val, b FROM data WHERE b < 2 order by val, c")
// case 2: missing sort columns are not resolvable if join is false. Thus, issue an error message in this case
sql("SELECT explode(a) AS val FROM data order by val, c")
```

When sort columns are not in `Generate`, we can resolve them when `join` is equal to `true`. Still trying to add more test cases for the other `UnaryNode` types.

Could you review the changes? davies cloud-fan Thanks!

Author: gatorsmile <gatorsmile@gmail.com>

Closes #11198 from gatorsmile/missingInSort.
2016-02-20 13:53:23 -08:00
gatorsmile fee739f07b [SPARK-13221] [SQL] Fixing GroupingSets when Aggregate Functions Containing GroupBy Columns
Using GroupingSets will generate a wrong result when Aggregate Functions containing GroupBy columns.

This PR is to fix it. Since the code changes are very small. Maybe we also can merge it to 1.6

For example, the following query returns a wrong result:
```scala
sql("select course, sum(earnings) as sum from courseSales group by course, earnings" +
     " grouping sets((), (course), (course, earnings))" +
     " order by course, sum").show()
```
Before the fix, the results are like
```
[null,null]
[Java,null]
[Java,20000.0]
[Java,30000.0]
[dotNET,null]
[dotNET,5000.0]
[dotNET,10000.0]
[dotNET,48000.0]
```
After the fix, the results become correct:
```
[null,113000.0]
[Java,20000.0]
[Java,30000.0]
[Java,50000.0]
[dotNET,5000.0]
[dotNET,10000.0]
[dotNET,48000.0]
[dotNET,63000.0]
```

UPDATE:  This PR also deprecated the external column: GROUPING__ID.

Author: gatorsmile <gatorsmile@gmail.com>

Closes #11100 from gatorsmile/groupingSets.
2016-02-15 23:16:58 -08:00
Josh Rosen a8bbc4f50e [SPARK-12503][SPARK-12505] Limit pushdown in UNION ALL and OUTER JOIN
This patch adds a new optimizer rule for performing limit pushdown. Limits will now be pushed down in two cases:

- If a limit is on top of a `UNION ALL` operator, then a partition-local limit operator will be pushed to each of the union operator's children.
- If a limit is on top of an `OUTER JOIN` then a partition-local limit will be pushed to one side of the join. For `LEFT OUTER` and `RIGHT OUTER` joins, the limit will be pushed to the left and right side, respectively. For `FULL OUTER` join, we will only push limits when at most one of the inputs is already limited: if one input is limited we will push a smaller limit on top of it and if neither input is limited then we will limit the input which is estimated to be larger.

These optimizations were proposed previously by gatorsmile in #10451 and #10454, but those earlier PRs were closed and deferred for later because at that time Spark's physical `Limit` operator would trigger a full shuffle to perform global limits so there was a chance that pushdowns could actually harm performance by causing additional shuffles/stages. In #7334, we split the `Limit` operator into separate `LocalLimit` and `GlobalLimit` operators, so we can now push down only local limits (which don't require extra shuffles). This patch is based on both of gatorsmile's patches, with changes and simplifications due to partition-local-limiting.

When we push down the limit, we still keep the original limit in place, so we need a mechanism to ensure that the optimizer rule doesn't keep pattern-matching once the limit has been pushed down. In order to handle this, this patch adds a `maxRows` method to `SparkPlan` which returns the maximum number of rows that the plan can compute, then defines the pushdown rules to only push limits to children if the children's maxRows are greater than the limit's maxRows. This idea is carried over from #10451; see that patch for additional discussion.

Author: Josh Rosen <joshrosen@databricks.com>

Closes #11121 from JoshRosen/limit-pushdown-2.
2016-02-14 17:32:21 -08:00