add sign math function

[ucasfl]

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Changelog category (leave one):

• New Feature

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Add sign math function.

[kitaisreal]

@ucasfl could you please add documentation to this sign function ?

[kitaisreal]

Looks good to me.

[kitaisreal]

@ucasfl maybe it make sense to extract that ColumnsWithTypeAndName{left, right} in variable without creating it for each function execute in next lines ?

[ucasfl]

Done!

[ucasfl]

@ucasfl could you please add documentation to this sign function ?

Ok.

[kitaisreal]

@ucasfl after small discussion maybe it will be better to implement it using existing framework FunctionUnaryArithmetic?
Please check for example implementation of abs.cpp.
Also could you please add performance tests for this sign function ?

[ucasfl]

@ucasfl after small discussion maybe it will be better to implement it using existing framework FunctionUnaryArithmetic?
Please check for example implementation of abs.cpp.
Also could you please add performance tests for this sign function ?

Ok, I have rewrite it with FunctionUnaryArithmetic.

[ucasfl]

 01508_query_obfuscator:                                                 [ FAIL ] - result differs with reference:
2021-01-26 15:04:00 --- /ClickHouse/tests/queries/0_stateless/01508_query_obfuscator.reference	2021-01-26 14:36:59.361547309 +0300
2021-01-26 15:04:00 +++ /ClickHouse/tests/queries/0_stateless/01508_query_obfuscator.stdout	2021-01-26 15:04:00.586005177 +0300
2021-01-26 15:04:00 @@ -12,5 +12,5 @@
2021-01-26 15:04:00      AND MasonryID = 30750384
2021-01-26 15:04:00      AND intHash32(EyeballID) = 448362928 AND intHash64(EyeballID) = 12572659331310383983
2021-01-26 15:04:00      AND EarthquakeID IN (8195672321757027078, 7079643623150622129, 5057006826979676478, 7886875230160484653, 7494974311229040743)
2021-01-26 15:04:00 -    AND Photography = 1
2021-01-26 15:04:00 +    AND Sign = 1

I checked that obfuscator can't obfuscate reserve words like function name, so I made a little change on this test.

[kitaisreal]

@ucasfl looks good to me, lets wait for CI and merge.