[SPARK-23058][SQL] Show non printable field delim as unicode

[wangyum]

What changes were proposed in this pull request?

Create a table with non printable delim like below:

CREATE EXTERNAL TABLE t1(col1 bigint)
ROW FORMAT SERDE 'org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe'
WITH SERDEPROPERTIES (
  'field.delim' = '\177',
  'serialization.format' = '\003'
)
STORED AS
  INPUTFORMAT 'org.apache.hadoop.mapred.SequenceFileInputFormat'
  OUTPUTFORMAT 'org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat'
LOCATION 'file:/tmp/t1';

When show create table t1. Before this PR::

CREATE EXTERNAL TABLE `t1`(`col1` bigint)
ROW FORMAT SERDE 'org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe'
WITH SERDEPROPERTIES (
  'field.delim' = '�',
  'serialization.format' = ''
)
STORED AS
  INPUTFORMAT 'org.apache.hadoop.mapred.SequenceFileInputFormat'
  OUTPUTFORMAT 'org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat'
LOCATION 'file:/tmp/t1'
TBLPROPERTIES (
  'transient_lastDdlTime' = '1515766958'
)

After this PR:

CREATE EXTERNAL TABLE `t1`(`col1` bigint)
ROW FORMAT SERDE 'org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe'
WITH SERDEPROPERTIES (
  'field.delim' = '\u007F',
  'serialization.format' = '\u0003'
)
STORED AS
  INPUTFORMAT 'org.apache.hadoop.mapred.SequenceFileInputFormat'
  OUTPUTFORMAT 'org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat'
LOCATION 'file:/tmp/t1'
TBLPROPERTIES (
  'transient_lastDdlTime' = '1516066260'
)

This PR show non printable field delim as unicode when show create table ... and we can recreate table use this message now.

How was this patch tested?

unit tests

[wangyum]

Non printable characters:

[srowen]

I think you want Character.isISOControl here. But this is a bit hacky as you're here hard-coding assumptions about the encoding. Why print non-printable chars, and why octal? what goes wrong?

[wangyum]

I need to copy an external table to another environment, but lost the create table statement. So I want to get this create table statement by show create table ..., but it can't show non printable field delim.

[srowen]

I see, so when the same properties are specified, they can be specified as an octal escape sequence. That makes sense to render it back that way. I'd still use isISOControl for better generality.

[SparkQA]

Test build #86040 has finished for PR 20248 at commit d44f242.

• This patch fails from timeout after a configured wait of `250m`.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #86081 has finished for PR 20248 at commit edf5fa6.

• This patch fails due to an unknown error code, -9.
• This patch merges cleanly.
• This patch adds no public classes.

[wangyum]

retest this please

[SparkQA]

Test build #86088 has finished for PR 20248 at commit edf5fa6.

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

[wangyum]

retest this please

[SparkQA]

Test build #86095 has finished for PR 20248 at commit edf5fa6.

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