[SPARK-26756][SQL] Support session conf for thriftserver

[caneGuy]

What changes were proposed in this pull request?

We can add support for session conf.like:
set spark.sql.xxx.xxx=xxx
which can be useful for users.

How was this patch tested?

Exist UT

[SparkQA]

Test build #101789 has finished for PR 23680 at commit 5090e9f.

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

[caneGuy]

Could you help review this? @maropu thanks

[nrchakradhar]

Can you please provide an example of what kind of parameters are to be used here. May be documentation update is also needed.

[maropu]

Yea, how do we set the parameters in JDBC?

[caneGuy]

@maropu @nrchakradhar Thanks!
Config start with 'spark.sql' and which is non static can be set by execute command like below:
set spark.sql.xxx.xxx=xxx
I will update the documentation later.

[HyukjinKwon]

?? do you mean we cannot set the configuration by set ... via Spark thriftserver if we use beeline?

[HyukjinKwon]

Can you provide reproducible steps?

[caneGuy]

Thanks @HyukjinKwon i will try to reproduce later.Since we may change some logic of STS

[AmplabJenkins]

Can one of the admins verify this patch?

[HyukjinKwon]

Closing this due to author's inactivity.