[SPARK-11553] [SQL] Primitive Row accessors should not convert null to default value

[alberskib]

Invocation of getters for type extending AnyVal returns default value (if field value is null) instead of throwing NPE. Please check comments for SPARK-11553 issue for more details.

[rxin]

This change breaks binary compatibility. I think we should just update the documentation to say use isNull to check for primitive types.

[alberskib]

We could also change only implementation of methods for primitive types (getInt, getDouble etc) to do null check internally and do not change code of getAs but update documentation as you said.

[marmbrus]

ok to test

[marmbrus]

Please change the PR title to something more descriptive: [SPARK-11553] [SQL] Primitive Row accessors should not convert null to default value

[SparkQA]

Test build #45772 has finished for PR 9642 at commit f498f4a.

• This patch fails Scala style tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #45777 has finished for PR 9642 at commit eef5778.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #45852 has finished for PR 9642 at commit 858b9a1.

• This patch fails Scala style tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #45853 has finished for PR 9642 at commit be382bc.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[alberskib]

The only failing test is 'Sessions of SQLContext' in org.apache.spark.sql.SQLContextSuite. Unfortunately on my machine I am not able to reproduce the problem - it is working well. What is more I think that it is not related to my change.

[SparkQA]

Test build #45894 has finished for PR 9642 at commit 181b075.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[alberskib]

After rebasing to current master all tests are passing

[hvanhovell]

UnsafeRow and SpecificRow have similar problems. Shouldn't we fix those as well? For example:

import org.apache.spark.sql.types.IntegerType
import org.apache.spark.sql.catalyst.expressions.SpecificMutableRow
import org.apache.spark.sql.catalyst.expressions.UnsafeRow

val srow = new SpecificMutableRow(IntegerType :: Nil)
srow.isNullAt(0)
srow.getInt(0)

val urow = new UnsafeRow()
urow.pointTo(new Array[Byte](16), 1, 16)
urow.setNullAt(0)
urow.isNullAt(0)
urow.getInt(0)

// Result:
import org.apache.spark.sql.types.IntegerType
import org.apache.spark.sql.catalyst.expressions.SpecificMutableRow
import org.apache.spark.sql.catalyst.expressions.UnsafeRow
srow: org.apache.spark.sql.catalyst.expressions.SpecificMutableRow = [null]
res129: Boolean = true
res130: Int = 0
urow: org.apache.spark.sql.catalyst.expressions.UnsafeRow = []
res133: Boolean = true
res134: Int = 0

I'd actualy rather not touch this at all. When you are using internal API you should be more carefull and expect some quirkiness.

I can currently think of only one place in which this causes some problems: UDFs with primitive parameters. The engine will pass in default values instead of nulls. Are there any other situations in which this causes problems?

[alberskib]

Hey @hvanhovell ! Thanks for the comment. I agree with you that if we want to introduce this change we need to take care of UnsafeRow and SpecificRow as well.
I have couple of questions for you:

I'd actualy rather not touch this at all ...

You mean discard change and only update documentation? Yes this is one option - I even think that it is not so bad.
On the other hand it could be misleading and many users will not notice the difference in documentation - this leads them to making the same errors. I think that right now there is lot of code that is calculating wrong outcomes as a result of this bug.

I can currently think of only one place in which this causes some problems

You mean problem caused by not introducing this change?

I think that we should analyse pros and cons and decide how to proceed.

[hvanhovell]

You mean discard change and only update documentation? Yes this is one option - I even think that it is not so bad.

I would only update the documentation. Internal mutable rows are among the most performance critical classes in Spark SQL, so I am not that keen to add (potentially unnecessary) branching to every primitive getter. When someone is using InternalRows he or she is using a SparkSQL internal API anyway, and really should be knowing what (s)he is doing.

You mean problem caused by not introducing this change?

Yes, do you know any other problems caused by this?

[alberskib]

Yes, do you know any other problems caused by this?

Right now I did not find any other potential problem.

[alberskib]

There is no scaladoc for primitive getters in UnsafeRow and SpecificRow (and super classes) - everything remains there as is.

[hvanhovell]

So I have been making a lot of fuss about internal classes, which you are not touching. Sorry about that.

This change is much more benign, but I still wonder if you need to start throwing NPE's. I'd prefer to update the documentation.

[alberskib]

No problem.
I am not sure which option is better. At the beginning I was thinking that it is easier to notice exception being throwned rather than change in the documentation, but right now it looks like changing only documentation will be more consistent.
It will be good if more people will express opinion.

[marmbrus]

The original behavior of these classes was to throw if you tried to retrieve a null primitive value and I think thats a lot less confusing. Unfortunately it seems that the tungsten refactoring changed this behavior, but since it was the original behavior I'm in favor of returning to it.

[marmbrus]

Regarding the internal classes, my preferred option would be to add assertions that we can elide for performance in production.

[marmbrus]

Thanks, I'm going to merge this to master and 1.6.