This PR tries to enable Spark SQL to convert resolved logical plans back to SQL query strings. For now, the major use case is to canonicalize Spark SQL native view support. The major entry point is `SQLBuilder.toSQL`, which returns an `Option[String]` if the logical plan is recognized.
The current version is still in WIP status, and is quite limited. Known limitations include:
1. The logical plan must be analyzed but not optimized
The optimizer erases `Subquery` operators, which contain necessary scope information for SQL generation. Future versions should be able to recover erased scope information by inserting subqueries when necessary.
1. The logical plan must be created using HiveQL query string
Query plans generated by composing arbitrary DataFrame API combinations are not supported yet. Operators within these query plans need to be rearranged into a canonical form that is more suitable for direct SQL generation. For example, the following query plan
```
Filter (a#1 < 10)
+- MetastoreRelation default, src, None
```
need to be canonicalized into the following form before SQL generation:
```
Project [a#1, b#2, c#3]
+- Filter (a#1 < 10)
+- MetastoreRelation default, src, None
```
Otherwise, the SQL generation process will have to handle a large number of special cases.
1. Only a fraction of expressions and basic logical plan operators are supported in this PR
Currently, 95.7% (1720 out of 1798) query plans in `HiveCompatibilitySuite` can be successfully converted to SQL query strings.
Known unsupported components are:
- Expressions
- Part of math expressions
- Part of string expressions (buggy?)
- Null expressions
- Calendar interval literal
- Part of date time expressions
- Complex type creators
- Special `NOT` expressions, e.g. `NOT LIKE` and `NOT IN`
- Logical plan operators/patterns
- Cube, rollup, and grouping set
- Script transformation
- Generator
- Distinct aggregation patterns that fit `DistinctAggregationRewriter` analysis rule
- Window functions
Support for window functions, generators, and cubes etc. will be added in follow-up PRs.
This PR leverages `HiveCompatibilitySuite` for testing SQL generation in a "round-trip" manner:
* For all select queries, we try to convert it back to SQL
* If the query plan is convertible, we parse the generated SQL into a new logical plan
* Run the new logical plan instead of the original one
If the query plan is inconvertible, the test case simply falls back to the original logic.
TODO
- [x] Fix failed test cases
- [x] Support for more basic expressions and logical plan operators (e.g. distinct aggregation etc.)
- [x] Comments and documentation
Author: Cheng Lian <lian@databricks.com>
Closes#10541 from liancheng/sql-generation.
JIRA: https://issues.apache.org/jira/browse/SPARK-12687
Some queries such as `(select 1 as a) union (select 2 as a)` can't work. This patch fixes it.
Author: Liang-Chi Hsieh <viirya@gmail.com>
Closes#10660 from viirya/fix-union.
Use multi-line string literals for ExpressionDescription with ``// scalastyle:off line.size.limit`` and ``// scalastyle:on line.size.limit``
The policy is here, as describe at https://github.com/apache/spark/pull/10488
Let's use multi-line string literals. If we have to have a line with more than 100 characters, let's use ``// scalastyle:off line.size.limit`` and ``// scalastyle:on line.size.limit`` to just bypass the line number requirement.
Author: Kazuaki Ishizaki <ishizaki@jp.ibm.com>
Closes#10524 from kiszk/SPARK-12580.
To avoid to have a huge Java source (over 64K loc), that can't be compiled.
cc hvanhovell
Author: Davies Liu <davies@databricks.com>
Closes#10624 from davies/split_ident.
This PR moves a major part of the new SQL parser to Catalyst. This is a prelude to start using this parser for all of our SQL parsing. The following key changes have been made:
The ANTLR Parser & Supporting classes have been moved to the Catalyst project. They are now part of the ```org.apache.spark.sql.catalyst.parser``` package. These classes contained quite a bit of code that was originally from the Hive project, I have added aknowledgements whenever this applied. All Hive dependencies have been factored out. I have also taken this chance to clean-up the ```ASTNode``` class, and to improve the error handling.
The HiveQl object that provides the functionality to convert an AST into a LogicalPlan has been refactored into three different classes, one for every SQL sub-project:
- ```CatalystQl```: This implements Query and Expression parsing functionality.
- ```SparkQl```: This is a subclass of CatalystQL and provides SQL/Core only functionality such as Explain and Describe.
- ```HiveQl```: This is a subclass of ```SparkQl``` and this adds Hive-only functionality to the parser such as Analyze, Drop, Views, CTAS & Transforms. This class still depends on Hive.
cc rxin
Author: Herman van Hovell <hvanhovell@questtec.nl>
Closes#10583 from hvanhovell/SPARK-12575.
JIRA: https://issues.apache.org/jira/browse/SPARK-12439
In toCatalystArray, we should look at the data type returned by dataTypeFor instead of silentSchemaFor, to determine if the element is native type. An obvious problem is when the element is Option[Int] class, catalsilentSchemaFor will return Int, then we will wrongly recognize the element is native type.
There is another problem when using Option as array element. When we encode data like Seq(Some(1), Some(2), None) with encoder, we will use MapObjects to construct an array for it later. But in MapObjects, we don't check if the return value of lambdaFunction is null or not. That causes a bug that the decoded data for Seq(Some(1), Some(2), None) would be Seq(1, 2, -1), instead of Seq(1, 2, null).
Author: Liang-Chi Hsieh <viirya@gmail.com>
Closes#10391 from viirya/fix-catalystarray.
address comments in #10435
This makes the API easier to use if user programmatically generate the call to hash, and they will get analysis exception if the arguments of hash is empty.
Author: Wenchen Fan <wenchen@databricks.com>
Closes#10588 from cloud-fan/hash.
just write the arguments into unsafe row and use murmur3 to calculate hash code
Author: Wenchen Fan <wenchen@databricks.com>
Closes#10435 from cloud-fan/hash-expr.
The reader was previously not setting the row length meaning it was wrong if there were variable
length columns. This problem does not manifest usually, since the value in the column is correct and
projecting the row fixes the issue.
Author: Nong Li <nong@databricks.com>
Closes#10576 from nongli/spark-12589.
This PR enable cube/rollup as function, so they can be used as this:
```
select a, b, sum(c) from t group by rollup(a, b)
```
Author: Davies Liu <davies@databricks.com>
Closes#10522 from davies/rollup.
It is currently possible to change the values of the supposedly immutable ```GenericRow``` and ```GenericInternalRow``` classes. This is caused by the fact that scala's ArrayOps ```toArray``` (returned by calling ```toSeq```) will return the backing array instead of a copy. This PR fixes this problem.
This PR was inspired by https://github.com/apache/spark/pull/10374 by apo1.
cc apo1 sarutak marmbrus cloud-fan nongli (everyone in the previous conversation).
Author: Herman van Hovell <hvanhovell@questtec.nl>
Closes#10553 from hvanhovell/SPARK-12421.
Avoiding the the No such table exception and throwing analysis exception as per the bug: SPARK-12533
Author: thomastechs <thomas.sebastian@tcs.com>
Closes#10529 from thomastechs/topic-branch.
Right now, numFields will be passed in by pointTo(), then bitSetWidthInBytes is calculated, making pointTo() a little bit heavy.
It should be part of constructor of UnsafeRow.
Author: Davies Liu <davies@databricks.com>
Closes#10528 from davies/numFields.
Most of cases we should propagate null when call `NewInstance`, and so far there is only one case we should stop null propagation: create product/java bean. So I think it makes more sense to propagate null by dafault.
This also fixes a bug when encode null array/map, which is firstly discovered in https://github.com/apache/spark/pull/10401
Author: Wenchen Fan <wenchen@databricks.com>
Closes#10443 from cloud-fan/encoder.
```
org.apache.spark.sql.AnalysisException: cannot resolve 'value' given input columns text;
```
lets put a `:` after `columns` and put the columns in `[]` so that they match the toString of DataFrame.
Author: gatorsmile <gatorsmile@gmail.com>
Closes#10518 from gatorsmile/improveAnalysisExceptionMsg.
In Spark we allow UDFs to declare its expected input types in order to apply type coercion. The expected input type parameter takes a Seq[DataType] and uses Nil when no type coercion is applied. It makes more sense to take Option[Seq[DataType]] instead, so we can differentiate a no-arg function vs function with no expected input type specified.
Author: Reynold Xin <rxin@databricks.com>
Closes#10504 from rxin/SPARK-12549.
When explain any plan with Generate, we will see an exclamation mark in the plan. Normally, when we see this mark, it means the plan has an error. This PR is to correct the `missingInput` in `Generate`.
For example,
```scala
val df = Seq((1, "a b c"), (2, "a b"), (3, "a")).toDF("number", "letters")
val df2 =
df.explode('letters) {
case Row(letters: String) => letters.split(" ").map(Tuple1(_)).toSeq
}
df2.explain(true)
```
Before the fix, the plan is like
```
== Parsed Logical Plan ==
'Generate UserDefinedGenerator('letters), true, false, None
+- Project [_1#0 AS number#2,_2#1 AS letters#3]
+- LocalRelation [_1#0,_2#1], [[1,a b c],[2,a b],[3,a]]
== Analyzed Logical Plan ==
number: int, letters: string, _1: string
Generate UserDefinedGenerator(letters#3), true, false, None, [_1#8]
+- Project [_1#0 AS number#2,_2#1 AS letters#3]
+- LocalRelation [_1#0,_2#1], [[1,a b c],[2,a b],[3,a]]
== Optimized Logical Plan ==
Generate UserDefinedGenerator(letters#3), true, false, None, [_1#8]
+- LocalRelation [number#2,letters#3], [[1,a b c],[2,a b],[3,a]]
== Physical Plan ==
!Generate UserDefinedGenerator(letters#3), true, false, [number#2,letters#3,_1#8]
+- LocalTableScan [number#2,letters#3], [[1,a b c],[2,a b],[3,a]]
```
**Updates**: The same issues are also found in the other four Dataset operators: `MapPartitions`/`AppendColumns`/`MapGroups`/`CoGroup`. Fixed all these four.
Author: gatorsmile <gatorsmile@gmail.com>
Author: xiaoli <lixiao1983@gmail.com>
Author: Xiao Li <xiaoli@Xiaos-MacBook-Pro.local>
Closes#10393 from gatorsmile/generateExplain.
Moved (case) classes Strategy, Once, FixedPoint and Batch to the companion object. This is necessary if we want to have the Optimizer easily extendable in the following sense: Usually a user wants to add additional rules, and just take the ones that are already there. However, inner classes made that impossible since the code did not compile
This allows easy extension of existing Optimizers see the DefaultOptimizerExtendableSuite for a corresponding test case.
Author: Stephan Kessler <stephan.kessler@sap.com>
Closes#10174 from stephankessler/SPARK-7727.
Accessing null elements in an array field fails when tungsten is enabled.
It works in Spark 1.3.1, and in Spark > 1.5 with Tungsten disabled.
This PR solves this by checking if the accessed element in the array field is null, in the generated code.
Example:
```
// Array of String
case class AS( as: Seq[String] )
val dfAS = sc.parallelize( Seq( AS ( Seq("a",null,"b") ) ) ).toDF
dfAS.registerTempTable("T_AS")
for (i <- 0 to 2) { println(i + " = " + sqlContext.sql(s"select as[$i] from T_AS").collect.mkString(","))}
```
With Tungsten disabled:
```
0 = [a]
1 = [null]
2 = [b]
```
With Tungsten enabled:
```
0 = [a]
15/12/22 09:32:50 ERROR Executor: Exception in task 7.0 in stage 1.0 (TID 15)
java.lang.NullPointerException
at org.apache.spark.sql.catalyst.expressions.UnsafeRowWriters$UTF8StringWriter.getSize(UnsafeRowWriters.java:90)
at org.apache.spark.sql.catalyst.expressions.GeneratedClass$SpecificUnsafeProjection.apply(Unknown Source)
at org.apache.spark.sql.execution.TungstenProject$$anonfun$3$$anonfun$apply$3.apply(basicOperators.scala:90)
at org.apache.spark.sql.execution.TungstenProject$$anonfun$3$$anonfun$apply$3.apply(basicOperators.scala:88)
at scala.collection.Iterator$$anon$11.next(Iterator.scala:328)
at scala.collection.Iterator$$anon$11.next(Iterator.scala:328)
at scala.collection.Iterator$class.foreach(Iterator.scala:727)
at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
```
Author: pierre-borckmans <pierre.borckmans@realimpactanalytics.com>
Closes#10429 from pierre-borckmans/SPARK-12477_Tungsten-Projection-Null-Element-In-Array.
When creating extractors for product types (i.e. case classes and tuples), a null check is missing, thus we always assume input product values are non-null.
This PR adds a null check in the extractor expression for product types. The null check is stripped off for top level product fields, which are mapped to the outermost `Row`s, since they can't be null.
Thanks cloud-fan for helping investigating this issue!
Author: Cheng Lian <lian@databricks.com>
Closes#10431 from liancheng/spark-12478.top-level-null-field.
Compare both left and right side of the case expression ignoring nullablity when checking for type equality.
Author: Dilip Biswal <dbiswal@us.ibm.com>
Closes#10156 from dilipbiswal/spark-12102.
First try, not sure how much information we need to provide in the usage part.
Author: Xiu Guo <xguo27@gmail.com>
Closes#10423 from xguo27/SPARK-12456.
This PR adds a new expression `AssertNotNull` to ensure non-nullable fields of products and case classes don't receive null values at runtime.
Author: Cheng Lian <lian@databricks.com>
Closes#10331 from liancheng/dataset-nullability-check.
Based on the suggestions from marmbrus , added logical/physical operators for Range for improving the performance.
Also added another API for resolving the JIRA Spark-12150.
Could you take a look at my implementation, marmbrus ? If not good, I can rework it. : )
Thank you very much!
Author: gatorsmile <gatorsmile@gmail.com>
Closes#10335 from gatorsmile/rangeOperators.
When a DataFrame or Dataset has a long schema, we should intelligently truncate to avoid flooding the screen with unreadable information.
// Standard output
[a: int, b: int]
// Truncate many top level fields
[a: int, b, string ... 10 more fields]
// Truncate long inner structs
[a: struct<a: Int ... 10 more fields>]
Author: Dilip Biswal <dbiswal@us.ibm.com>
Closes#10373 from dilipbiswal/spark-12398.
Now `StaticInvoke` receives `Any` as a object and `StaticInvoke` can be serialized but sometimes the object passed is not serializable.
For example, following code raises Exception because `RowEncoder#extractorsFor` invoked indirectly makes `StaticInvoke`.
```
case class TimestampContainer(timestamp: java.sql.Timestamp)
val rdd = sc.parallelize(1 to 2).map(_ => TimestampContainer(System.currentTimeMillis))
val df = rdd.toDF
val ds = df.as[TimestampContainer]
val rdd2 = ds.rdd <----------------- invokes extractorsFor indirectory
```
I'll add test cases.
Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>
Author: Michael Armbrust <michael@databricks.com>
Closes#10357 from sarutak/SPARK-12404.
This could simplify the generated code for expressions that is not nullable.
This PR fix lots of bugs about nullability.
Author: Davies Liu <davies@databricks.com>
Closes#10333 from davies/skip_nullable.
Description of the problem from cloud-fan
Actually this line: https://github.com/apache/spark/blob/branch-1.5/sql/core/src/main/scala/org/apache/spark/sql/DataFrame.scala#L689
When we use `selectExpr`, we pass in `UnresolvedFunction` to `DataFrame.select` and fall in the last case. A workaround is to do special handling for UDTF like we did for `explode`(and `json_tuple` in 1.6), wrap it with `MultiAlias`.
Another workaround is using `expr`, for example, `df.select(expr("explode(a)").as(Nil))`, I think `selectExpr` is no longer needed after we have the `expr` function....
Author: Dilip Biswal <dbiswal@us.ibm.com>
Closes#9981 from dilipbiswal/spark-11619.
This PR removes Hive windows functions from Spark and replaces them with (native) Spark ones. The PR is on par with Hive in terms of features.
This has the following advantages:
* Better memory management.
* The ability to use spark UDAFs in Window functions.
cc rxin / yhuai
Author: Herman van Hovell <hvanhovell@questtec.nl>
Closes#9819 from hvanhovell/SPARK-8641-2.
I think it was a mistake, and we have not catched it so far until https://github.com/apache/spark/pull/10260 which begin to check if the `fromRowExpression` is resolved.
Author: Wenchen Fan <wenchen@databricks.com>
Closes#10263 from cloud-fan/encoder.
Currently, we could generate different plans for query with single distinct (depends on spark.sql.specializeSingleDistinctAggPlanning), one works better on low cardinality columns, the other
works better for high cardinality column (default one).
This PR change to generate a single plan (three aggregations and two exchanges), which work better in both cases, then we could safely remove the flag `spark.sql.specializeSingleDistinctAggPlanning` (introduced in 1.6).
For a query like `SELECT COUNT(DISTINCT a) FROM table` will be
```
AGG-4 (count distinct)
Shuffle to a single reducer
Partial-AGG-3 (count distinct, no grouping)
Partial-AGG-2 (grouping on a)
Shuffle by a
Partial-AGG-1 (grouping on a)
```
This PR also includes large refactor for aggregation (reduce 500+ lines of code)
cc yhuai nongli marmbrus
Author: Davies Liu <davies@databricks.com>
Closes#10228 from davies/single_distinct.
in https://github.com/apache/spark/pull/10133 we found that, we shoud ensure the children of `TreeNode` are all accessible in the `productIterator`, or the behavior will be very confusing.
In this PR, I try to fix this problem by expsing the `loopVar`.
This also fixes SPARK-12131 which is caused by the hacky `MapObjects`.
Author: Wenchen Fan <wenchen@databricks.com>
Closes#10239 from cloud-fan/map-objects.