[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14961513#comment-14961513 ] Sandy Ryza commented on SPARK-: --- So ClassTags would work for case classes and Avro specific records, but wouldn't work for tuples (or anywhere else types get erased). Blrgh. I wonder if the former is enough? Tuples are pretty useful though. > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[
https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14961518#comment-14961518
]
Michael Armbrust commented on SPARK-:
-
Yeah, I think tuples are a pretty important use case. Perhaps more importantly
though, I think having a concept of encoders instead of relying on JVM types
future proofs the API by giving us more control. If you look closely at the
test case examples, there are some pretty crazy macro examples (i.e., {{R(a =
1, b = 2L)}}) where we actually create something like named tuples that codegen
at compile time the logic required to directly encode the users results into
tungsten format without needing to allocate an intermediate object.
> RDD-like API on top of Catalyst/DataFrame
> -
>
> Key: SPARK-
> URL: https://issues.apache.org/jira/browse/SPARK-
> Project: Spark
> Issue Type: Story
> Components: SQL
>Reporter: Reynold Xin
>Assignee: Michael Armbrust
>
> The RDD API is very flexible, and as a result harder to optimize its
> execution in some cases. The DataFrame API, on the other hand, is much easier
> to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to
> use UDFs, lack of strong types in Scala/Java).
> The goal of Spark Datasets is to provide an API that allows users to easily
> express transformations on domain objects, while also providing the
> performance and robustness advantages of the Spark SQL execution engine.
> h2. Requirements
> - *Fast* - In most cases, the performance of Datasets should be equal to or
> better than working with RDDs. Encoders should be as fast or faster than
> Kryo and Java serialization, and unnecessary conversion should be avoided.
> - *Typesafe* - Similar to RDDs, objects and functions that operate on those
> objects should provide compile-time safety where possible. When converting
> from data where the schema is not known at compile-time (for example data
> read from an external source such as JSON), the conversion function should
> fail-fast if there is a schema mismatch.
> - *Support for a variety of object models* - Default encoders should be
> provided for a variety of object models: primitive types, case classes,
> tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard
> conventions, such as Avro SpecificRecords, should also work out of the box.
> - *Java Compatible* - Datasets should provide a single API that works in
> both Scala and Java. Where possible, shared types like Array will be used in
> the API. Where not possible, overloaded functions should be provided for
> both languages. Scala concepts, such as ClassTags should not be required in
> the user-facing API.
> - *Interoperates with DataFrames* - Users should be able to seamlessly
> transition between Datasets and DataFrames, without specifying conversion
> boiler-plate. When names used in the input schema line-up with fields in the
> given class, no extra mapping should be necessary. Libraries like MLlib
> should not need to provide different interfaces for accepting DataFrames and
> Datasets as input.
> For a detailed outline of the complete proposed API:
> [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files]
> For an initial discussion of the design considerations in this API: [design
> doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#]
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[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14961567#comment-14961567 ] Matei Zaharia commented on SPARK-: -- Beyond tuples, you'll also want encoders for other generic classes, such as Seq[T]. They're the cleanest mechanism to get the most type info. Also, from a software engineering point of view it's nice to avoid a central object where you register stuff to allow composition between libraries (basically, see the problems that the Kryo registry creates today). > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[
https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14959347#comment-14959347
]
Michael Armbrust commented on SPARK-:
-
Yeah, that Scala code should work. Regarding the Java version, the only
difference is the API I have in mind would be {{Encoder.for(MyClass2.class)}}.
Passing in an encoder instead of a raw {{Class[_]}} gives us some extra
indirection in case we want to support custom encoders some day.
I'll add that we can also play reflection tricks in cases where things are not
erased for Java, and this is the part of the proposal that is the least thought
out at the moment. Any help making this part as powerful/robust as possible
would be greatly appreciated.
I think that is possible that in the long term we will do as you propose and
remake the RDD API as a compatibility layer with the option to infer the
encoder based on the class tag. The problem with this being the primary
implementation is erasure.
{code}
scala> import scala.reflect._
scala> classTag[(Int, Int)].erasure.getTypeParameters
res0: Array[java.lang.reflect.TypeVariable[Class[_$1]]] forSome { type _$1 } =
Array(T1, T2)
{code}
We've lost the type of {{_1}} and {{_2}} and so we are going to have to fall
back on runtime reflection again, per tuple. Where as the encoders that are
checked into master could extract primitive int without any additional boxing
and encode them directly into tungsten buffers.
> RDD-like API on top of Catalyst/DataFrame
> -
>
> Key: SPARK-
> URL: https://issues.apache.org/jira/browse/SPARK-
> Project: Spark
> Issue Type: Story
> Components: SQL
>Reporter: Reynold Xin
>Assignee: Michael Armbrust
>
> The RDD API is very flexible, and as a result harder to optimize its
> execution in some cases. The DataFrame API, on the other hand, is much easier
> to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to
> use UDFs, lack of strong types in Scala/Java).
> The goal of Spark Datasets is to provide an API that allows users to easily
> express transformations on domain objects, while also providing the
> performance and robustness advantages of the Spark SQL execution engine.
> h2. Requirements
> - *Fast* - In most cases, the performance of Datasets should be equal to or
> better than working with RDDs. Encoders should be as fast or faster than
> Kryo and Java serialization, and unnecessary conversion should be avoided.
> - *Typesafe* - Similar to RDDs, objects and functions that operate on those
> objects should provide compile-time safety where possible. When converting
> from data where the schema is not known at compile-time (for example data
> read from an external source such as JSON), the conversion function should
> fail-fast if there is a schema mismatch.
> - *Support for a variety of object models* - Default encoders should be
> provided for a variety of object models: primitive types, case classes,
> tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard
> conventions, such as Avro SpecificRecords, should also work out of the box.
> - *Java Compatible* - Datasets should provide a single API that works in
> both Scala and Java. Where possible, shared types like Array will be used in
> the API. Where not possible, overloaded functions should be provided for
> both languages. Scala concepts, such as ClassTags should not be required in
> the user-facing API.
> - *Interoperates with DataFrames* - Users should be able to seamlessly
> transition between Datasets and DataFrames, without specifying conversion
> boiler-plate. When names used in the input schema line-up with fields in the
> given class, no extra mapping should be necessary. Libraries like MLlib
> should not need to provide different interfaces for accepting DataFrames and
> Datasets as input.
> For a detailed outline of the complete proposed API:
> [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files]
> For an initial discussion of the design considerations in this API: [design
> doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#]
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[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14957144#comment-14957144 ] Sandy Ryza commented on SPARK-: --- Maybe you all have thought through this as well, but I had some more thoughts on the proposed API. Fundamentally, it seems a weird to me that the user is responsible for having a matching Encoder around every time they want to map to a class of a particular type. In 99% of cases, the Encoder used to encode any given type will be the same, and it seems more intuitive to me to specify this up front. To be more concrete, suppose I want to use case classes in my app and have a function that can auto-generate an Encoder from a class object (though this might be a little bit time consuming because it needs to use reflection). With the current proposal, any time I want to map my Dataset to a Dataset of some case class, I need to either have a line of code that generates an Encoder for that case class, or have an Encoder already lying around. If I perform this operation within a method, I need to pass the Encoder down to the method and include it in the signature. Ideally I would be able to register an EncoderSystem up front that caches Encoders and generates new Encoders whenever it sees a new class used. This still of course requires the user to pass in type information when they call map, but it's easier for them to get this information than an actual encoder. If there's not some principled way to get this working implicitly with ClassTags, the user could just pass in classOf[MyCaseClass] as the second argument to map. > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14956341#comment-14956341 ] Sandy Ryza commented on SPARK-: --- Thanks for the explanation [~rxin] and [~marmbrus]. I understand the problem and don't have any great ideas for an alternative workable solution. > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[
https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14957926#comment-14957926
]
Michael Armbrust commented on SPARK-:
-
[~sandyr] did you look at the test cases [in
scala|https://github.com/marmbrus/spark/blob/d0277f5013fd9e5e758c607b5c833cf5aa7bb93c/sql/core/src/test/scala/org/apache/spark/sql/DatasetSuite.scala]
and
[java|https://github.com/marmbrus/spark/blob/d0277f5013fd9e5e758c607b5c833cf5aa7bb93c/sql/core/src/test/java/test/org/apache/spark/sql/JavaDatasetSuite.java]
linked from the attached design doc?
In Scala, users should never have to think about Encoders as long as their data
can be represented as primitives, case classes, tuples, or collections.
Implicits (provided by {{sqlContext.implicits._}}) automatically pass the
required information to the function.
In Java, the compiler is not helping us out as much, so the user must do as you
suggest. The prototype shows {{ProductEncoder.tuple(Long.class, Long.class)}},
but we will have a similar interface that works for class objects for POJOs /
JavaBeans. The problem with doing this using a registry (like kryo in RDDs
today) is that then you aren't finding out the object type until you have an
example object from realizing the computation. That is often too late to do
the kinds of optimizations that we are trying to enable. Instead we'd like to
statically realize the schema at Dataset construction time.
Encoders are just an encapsulation of the required information and provide an
interface if we ever want to allow someone to specify a custom encoder.
Regarding the performance concerns with reflection, the implementation that is
already present in Spark master ([SPARK-10993] and [SPARK-11090]) is based on
catalyst expressions. Reflection is done once on the driver, and the existing
code generation caching framework is taking care of caching generated encoder
bytecode on the executors.
> RDD-like API on top of Catalyst/DataFrame
> -
>
> Key: SPARK-
> URL: https://issues.apache.org/jira/browse/SPARK-
> Project: Spark
> Issue Type: Story
> Components: SQL
>Reporter: Reynold Xin
>Assignee: Michael Armbrust
>
> The RDD API is very flexible, and as a result harder to optimize its
> execution in some cases. The DataFrame API, on the other hand, is much easier
> to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to
> use UDFs, lack of strong types in Scala/Java).
> The goal of Spark Datasets is to provide an API that allows users to easily
> express transformations on domain objects, while also providing the
> performance and robustness advantages of the Spark SQL execution engine.
> h2. Requirements
> - *Fast* - In most cases, the performance of Datasets should be equal to or
> better than working with RDDs. Encoders should be as fast or faster than
> Kryo and Java serialization, and unnecessary conversion should be avoided.
> - *Typesafe* - Similar to RDDs, objects and functions that operate on those
> objects should provide compile-time safety where possible. When converting
> from data where the schema is not known at compile-time (for example data
> read from an external source such as JSON), the conversion function should
> fail-fast if there is a schema mismatch.
> - *Support for a variety of object models* - Default encoders should be
> provided for a variety of object models: primitive types, case classes,
> tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard
> conventions, such as Avro SpecificRecords, should also work out of the box.
> - *Java Compatible* - Datasets should provide a single API that works in
> both Scala and Java. Where possible, shared types like Array will be used in
> the API. Where not possible, overloaded functions should be provided for
> both languages. Scala concepts, such as ClassTags should not be required in
> the user-facing API.
> - *Interoperates with DataFrames* - Users should be able to seamlessly
> transition between Datasets and DataFrames, without specifying conversion
> boiler-plate. When names used in the input schema line-up with fields in the
> given class, no extra mapping should be necessary. Libraries like MLlib
> should not need to provide different interfaces for accepting DataFrames and
> Datasets as input.
> For a detailed outline of the complete proposed API:
> [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files]
> For an initial discussion of the design considerations in this API: [design
> doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#]
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[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[
https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14958022#comment-14958022
]
Sandy Ryza commented on SPARK-:
---
bq. The problem with doing this using a registry (like kryo in RDDs today) is
that then you aren't finding out the object type until you have an example
object from realizing the computation.
My suggestion was that the user would still need to pass the class object, so
this shouldn't be a problem, unless I'm misunderstanding.
Thanks to the pointer to the test suite. So am I to understand correctly that
with Scala implicits magic I can do the following without any additional
boilerplate?
{code}
import
case class MyClass1()
case class MyClass2()
val ds : Dataset[MyClass1] = ...
val ds2: Dataset[MyClass2] = ds.map(funcThatConvertsFromMyClass1ToMyClass2)
{code}
and in Java, imagining those case classes above were POJOs, we'd be able to
support the following?
{code}
Dataset ds2 = ds1.map(funcThatConvertsFromMyClass1ToMyClass2,
MyClass2.class);
{code}
If that's the case, then that resolves my concerns above.
Lastly, though, IIUC, it seems like for all the common cases, we could register
an object with the SparkContext that converts from ClassTag to Encoder, and the
RDD API would work. Where does that break down?
> RDD-like API on top of Catalyst/DataFrame
> -
>
> Key: SPARK-
> URL: https://issues.apache.org/jira/browse/SPARK-
> Project: Spark
> Issue Type: Story
> Components: SQL
>Reporter: Reynold Xin
>Assignee: Michael Armbrust
>
> The RDD API is very flexible, and as a result harder to optimize its
> execution in some cases. The DataFrame API, on the other hand, is much easier
> to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to
> use UDFs, lack of strong types in Scala/Java).
> The goal of Spark Datasets is to provide an API that allows users to easily
> express transformations on domain objects, while also providing the
> performance and robustness advantages of the Spark SQL execution engine.
> h2. Requirements
> - *Fast* - In most cases, the performance of Datasets should be equal to or
> better than working with RDDs. Encoders should be as fast or faster than
> Kryo and Java serialization, and unnecessary conversion should be avoided.
> - *Typesafe* - Similar to RDDs, objects and functions that operate on those
> objects should provide compile-time safety where possible. When converting
> from data where the schema is not known at compile-time (for example data
> read from an external source such as JSON), the conversion function should
> fail-fast if there is a schema mismatch.
> - *Support for a variety of object models* - Default encoders should be
> provided for a variety of object models: primitive types, case classes,
> tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard
> conventions, such as Avro SpecificRecords, should also work out of the box.
> - *Java Compatible* - Datasets should provide a single API that works in
> both Scala and Java. Where possible, shared types like Array will be used in
> the API. Where not possible, overloaded functions should be provided for
> both languages. Scala concepts, such as ClassTags should not be required in
> the user-facing API.
> - *Interoperates with DataFrames* - Users should be able to seamlessly
> transition between Datasets and DataFrames, without specifying conversion
> boiler-plate. When names used in the input schema line-up with fields in the
> given class, no extra mapping should be necessary. Libraries like MLlib
> should not need to provide different interfaces for accepting DataFrames and
> Datasets as input.
> For a detailed outline of the complete proposed API:
> [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files]
> For an initial discussion of the design considerations in this API: [design
> doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#]
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[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14955308#comment-14955308 ] Reynold Xin commented on SPARK-: [~sandyr] I thought a lot about doing this on top of the existing RDD API for a while, and that was my preference. However, we would need to break the RDD API, which breaks all existing applications. > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14955304#comment-14955304 ] Sean Owen commented on SPARK-: -- I had a similar question about how much more this is than the current RDD API. For example, is the idea that, with the help of caller-provided annotations and/or some code analysis perhaps you could deduce more about operations and optimize them more? A lot of the API already covers the basics, like assuming reduce functions are associative, etc. I get transformations on domain objects in the style of Spark SQL but I can already "groupBy(customer.name)" in a normal RDD. I can also go sorta easily from DataFrames to RDDs and back. So I assume it's about static analysis of user functions, in the main? Or about getting to/from a Row faster? > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14955335#comment-14955335 ] Reynold Xin commented on SPARK-: The big ones are: 1. encoders (which breaks almost every function that has a type parameter that's not T) 2. "partitions" (partitioning is a physical concept, and shouldn't be required as part of API semantics) 3. groupBy ... ... > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14955286#comment-14955286 ] Sandy Ryza commented on SPARK-: --- To ask the obvious question: what are the reasons that the RDD API couldn't be adapted to these purposes? If I understand correctly, a summarization of the differences is that Datasets: 1. Support encoders for conversion to schema'd / efficiently serializable data 2. Have a GroupedDataset concept 3. Execute on Catalyst instead of directly on top of the DAGScheduler How difficult would it be to add encoders on top of RDDs, as well as a GroupedRDD? Is there anything in the RDD API contract that says RDDs can't be executed on top of Catalyst? Surely this creates some dependency hell as well given that SQL depends on core, but surely that's better than exposing an entirely new API that looks almost like the original one. > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14955320#comment-14955320 ] Sandy Ryza commented on SPARK-: --- [~rxin] where are the places where the API would need to break? > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14955368#comment-14955368 ] Michael Armbrust commented on SPARK-: - Other compatibility breaking things include: getting rid of class tags from the public API (a common complaint from java users) and not using a separate class for Java users (JavaRDD). > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14955840#comment-14955840 ] Sandy Ryza commented on SPARK-: --- If I understand correctly, it seems like there are ways to work around each of these issues that, necessarily, make the API dirtier, but avoid the need for a whole new public API. * groupBy: deprecate the old groupBy and add a groupWith or groupby method that returns a GroupedRDD. * partitions: have -1 be a special value that means "determined by the planner" * encoders: what are the main obstacles to addressing this with an EncodedRDD that extends RDD? Regarding the issues Michael brought up: I'd love to get rid of class tags from the public API as well as take out JavaRDD, but these seem more like "nice to have" than core to the proposal. Am I misunderstanding? All of these of course add ugliness, but I think it's really easy to underestimate the cost of introducing a new API. Applications everywhere become legacy and need to be rewritten to take advantage of new features. Code examples and training materials everywhere become invalidated. Can we point to systems that have successfully made a transition like this at this point in their maturity? > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14955868#comment-14955868 ] Reynold Xin commented on SPARK-: [~sandyr] Your concern is absolutely valid, but I don't think your EncodedRDD proposal works. For one, the map function (every other function that returns a type different from RDD's own T) will break. For two, the whole concept of PairRDDFunctions should go away with this new API. As I said, it's actually my preference to just use the RDD API. But if you take a look at what's needed here, it'd break too many functions. So we have the following choices: 1. Don't create a new API, and break the RDD API. People then can't update to newer versions of Spark unless they rewrite their apps. We did this with the SchemaRDD -> DataFrame change, which went well -- but SchemaRDD wasn't really an advertised API back then. 2. Create a new API, and keep RDD API intact. People can update to new versions of Spark, but it can't take full advantage of all the Tungsten/DataFrame work immediately unless they rewrite their apps. Maybe we can implement the RDD API later in some cases using the new API so legacy apps can still take advantage whenever possible (e.g. inferring encoder based on classtags when possible). Also the RDD API as I see it today is actually a pretty good way for developers to provide data (i.e. used for data sources). If we break it, we'd still need to come up with a new data input API. > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14955878#comment-14955878 ] Michael Armbrust commented on SPARK-: - I think improving Java compatibility and getting rid of the ClassTags is more than a _nice to have_. Having a separate class hierarchy for Java/Scala makes it very hard for people to build higher level libraries that work with both Scala and Java. As a result, I think Java adoption suffers. ClassTags are burdensome for [both Scala and Java|https://twitter.com/posco/status/633505168747687936] users. In order to make encoders work they way we want, nearly every function that takes a ClassTag today will need to be changed to take an encoder. As [~rxin] points out, I think that kind of compatibly breaking is actually more damaging for a project of Spark's maturity than providing a higher-level parallel API to RDDs. That said, I think source compatibility for common code between RDDs -> Datasets would be great to make sure users can make the transition with as little pain as possible. > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14955877#comment-14955877 ] Reynold Xin commented on SPARK-: BTW another possible approach that we haven't discussed is that we can start with an experimental new API, and in Spark 2.0 rename it to RDD. I'm less in favor of this because it still means applications can't update to Spark 2.0 without rewriting. > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin >Assignee: Michael Armbrust > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > The goal of Spark Datasets is to provide an API that allows users to easily > express transformations on domain objects, while also providing the > performance and robustness advantages of the Spark SQL execution engine. > h2. Requirements > - *Fast* - In most cases, the performance of Datasets should be equal to or > better than working with RDDs. Encoders should be as fast or faster than > Kryo and Java serialization, and unnecessary conversion should be avoided. > - *Typesafe* - Similar to RDDs, objects and functions that operate on those > objects should provide compile-time safety where possible. When converting > from data where the schema is not known at compile-time (for example data > read from an external source such as JSON), the conversion function should > fail-fast if there is a schema mismatch. > - *Support for a variety of object models* - Default encoders should be > provided for a variety of object models: primitive types, case classes, > tuples, POJOs, JavaBeans, etc. Ideally, objects that follow standard > conventions, such as Avro SpecificRecords, should also work out of the box. > - *Java Compatible* - Datasets should provide a single API that works in > both Scala and Java. Where possible, shared types like Array will be used in > the API. Where not possible, overloaded functions should be provided for > both languages. Scala concepts, such as ClassTags should not be required in > the user-facing API. > - *Interoperates with DataFrames* - Users should be able to seamlessly > transition between Datasets and DataFrames, without specifying conversion > boiler-plate. When names used in the input schema line-up with fields in the > given class, no extra mapping should be necessary. Libraries like MLlib > should not need to provide different interfaces for accepting DataFrames and > Datasets as input. > For a detailed outline of the complete proposed API: > [marmbrus/dataset-api|https://github.com/marmbrus/spark/pull/18/files] > For an initial discussion of the design considerations in this API: [design > doc|https://docs.google.com/document/d/1ZVaDqOcLm2-NcS0TElmslHLsEIEwqzt0vBvzpLrV6Ik/edit#] -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=14936268#comment-14936268 ] Sen Fang commented on SPARK-: - Another idea is do something similar to F# TypeProvider approach: http://fsharp.github.io/FSharp.Data/ I haven't looked into this extensively just yet but as far as I understand this uses compile time macro to generate classes based on data sources. In that sense, it is slightly similar to protobuf where you generate Java class based on schema definition. This makes dataframe type safe at the very upstream. With a bit of IDE plugin, you will even able to have autocomplete and type check when you write code, which would be very nice. I'm not sure if it will be scalable to propagate these type information down stream (in aggregation or transformed dataframe) though. As I understand, the macro and type provider in Scala provides similar capabilities. > RDD-like API on top of Catalyst/DataFrame > - > > Key: SPARK- > URL: https://issues.apache.org/jira/browse/SPARK- > Project: Spark > Issue Type: Story > Components: SQL >Reporter: Reynold Xin > > The RDD API is very flexible, and as a result harder to optimize its > execution in some cases. The DataFrame API, on the other hand, is much easier > to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to > use UDFs, lack of strong types in Scala/Java). > As a Spark user, I want an API that sits somewhere in the middle of the > spectrum so I can write most of my applications with that API, and yet it can > be optimized well by Spark to achieve performance and stability. -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=14706244#comment-14706244 ] Reynold Xin commented on SPARK-: This needs to be designed first. I'm not sure if static code analysis is a great idea since they fail often. I'm open to ideas though. RDD-like API on top of Catalyst/DataFrame - Key: SPARK- URL: https://issues.apache.org/jira/browse/SPARK- Project: Spark Issue Type: Story Components: SQL Reporter: Reynold Xin The RDD API is very flexible, and as a result harder to optimize its execution in some cases. The DataFrame API, on the other hand, is much easier to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to use UDFs, lack of strong types in Scala/Java). As a Spark user, I want an API that sits somewhere in the middle of the spectrum so I can write most of my applications with that API, and yet it can be optimized well by Spark to achieve performance and stability. -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-9999) RDD-like API on top of Catalyst/DataFrame
[ https://issues.apache.org/jira/browse/SPARK-?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=14699512#comment-14699512 ] Herman van Hovell commented on SPARK-: -- This sounds interesting. In order to get this working, we need to get more information on the (black-box) operators used. So some analysis capability, or some predefined building blocks (SQL-lite if you will) are probably needed. Apache Flink uses static code analysis and annotations for to achieve a similar goal: http://flink.apache.org/news/2015/06/24/announcing-apache-flink-0.9.0-release.html https://ci.apache.org/projects/flink/flink-docs-release-0.9/apis/programming_guide.html#semantic-annotations Any other ideas? RDD-like API on top of Catalyst/DataFrame - Key: SPARK- URL: https://issues.apache.org/jira/browse/SPARK- Project: Spark Issue Type: Story Components: SQL Reporter: Reynold Xin The RDD API is very flexible, and as a result harder to optimize its execution in some cases. The DataFrame API, on the other hand, is much easier to optimize, but lacks some of the nice perks of the RDD API (e.g. harder to use UDFs, lack of strong types in Scala/Java). As a Spark user, I want an API that sits somewhere in the middle of the spectrum so I can write most of my applications with that API, and yet it can be optimized well by Spark to achieve performance and stability. -- This message was sent by Atlassian JIRA (v6.3.4#6332) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
