[SPARK-24957][SQL][FOLLOW-UP] Clean the code for AVERAGE

[gatorsmile]

What changes were proposed in this pull request?

This PR is to refactor the code in AVERAGE by dsl.

How was this patch tested?

N/A

[holdensmagicalunicorn]

@gatorsmile, thanks! I am a bot who has found some folks who might be able to help with the review:@rxin, @cloud-fan and @ueshin

[gatorsmile]

cc @hvanhovell @rednaxelafx @cloud-fan

[SparkQA]

Test build #93918 has finished for PR 21951 at commit 511b7b6.

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

[rxin]

Why would we want to use the DSL here? Do we use it in other expressions?

[gatorsmile]

This will simplify the code and improve the readability. We can do the same in the other expression.

[rxin]

LGTM.

…

On Thu, Aug 2, 2018 at 1:14 AM Xiao Li ***@***.***> wrote: This will simplify the code and improve the readability. We can do the same in the other expression. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#21951 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AATvPIEkrQyLFUXLOl66_94V2f6MY7Obks5uMoqrgaJpZM4VrcXh> .

[rednaxelafx]

LGTM as well. Thanks a lot!

[cloud-fan]

LGTM. shall we create a JIRA ticket to apply this to other DeclarativeAggregates?

[gatorsmile]

Thanks! Merged to master.

Please ignore the last commit. The last commit is not merged.

[gatorsmile]

https://issues.apache.org/jira/browse/SPARK-24996 is created,

[SparkQA]

Test build #93956 has finished for PR 21951 at commit a5762d7.

• This patch fails to build.
• This patch merges cleanly.
• This patch adds no public classes.