Add typeof function.

[Yury-Fridlyand]

Signed-off-by: Yury-Fridlyand yuryf@bitquilltech.com

Description

TYPEOF function is useful for debugging to check types of other functions. Extremely useful for testing and debugging upcoming PRs with datetime functions.
Not added to documentation, because it is not supposed for an end user.
See team review discussion in Bit-Quill#123.

Usage

opensearchsql> SELECT typeof(DATETIME('1961-04-12 09:07:00')), typeof(CAST('1961-04-12 09:07:00' AS TIMESTAMP)), typeof(CAST('09:07:00' AS TIME)), typeof(CAST('1961-04-12' AS DATE));
Output longer than terminal width
Do you want to display data vertically for better visual effect? [y/N]: y
fetched rows / total rows = 1/1
-[ RECORD 1 ]-------------------------
typeof(DATETIME('1961-04-12 09:07:00')           | DATETIME
typeof(CAST('1961-04-12 09:07:00' AS TIMESTAMP)) | TIMESTAMP
typeof(CAST('09:07:00' AS TIME))                 | TIME
typeof(CAST('1961-04-12' AS DATE))               | DATE

UPD

TYPEOF function perfectly works with SQL types. It works with some OpenSearch (OpenSearchDataType) types, which could be implicitly casted to SQL ones. Unfortunately, function can't accept OpenSearch types, so some information lost.
IP, GEO_POINT, BINARY and NESTED types cause crash.
https://github.com/Bit-Quill/opensearch-project-sql/blob/d02e16f147a9f3e6afa065f701efa7ece70d310b/opensearch/src/main/java/org/opensearch/sql/opensearch/data/type/OpenSearchDataType.java#L49-L53

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

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[dai-chen]

Just a minor comment. Thanks for the changes!

Btw, do we want to add this to user manual like PGSQL? Doc: https://www.postgresql.org/docs/current/functions-info.html

[Yury-Fridlyand]

Just a minor comment. Thanks for the changes!

Btw, do we want to add this to user manual like PGSQL? Doc: https://www.postgresql.org/docs/current/functions-info.html

Added in b4dc828.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.10%. Comparing base (3ca6450) to head (b4dc828).
Report is 540 commits behind head on 2.x.

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x     #867      +/-   ##
============================================
- Coverage     97.85%   95.10%   -2.75%     
- Complexity     2989     3075      +86     
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  Files           281      304      +23     
  Lines          7357     8258     +901     
  Branches        467      609     +142     
============================================
+ Hits           7199     7854     +655     
- Misses          157      350     +193     
- Partials          1       54      +53     

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query-workbench	62.76% <ø> (?)
sql-engine	97.90% <100.00%> (+0.05%)	⬆️

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[dai-chen]

Thanks for the changes!