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Subject [GitHub] pnowojski commented on issue #6519: [FLINK-9559] [table] The type of a union of CHAR columns of different lengths should be VARCHAR
Date Fri, 24 Aug 2018 15:13:22 GMT
pnowojski commented on issue #6519: [FLINK-9559] [table] The type of a union of CHAR columns
of different lengths should be VARCHAR
URL: https://github.com/apache/flink/pull/6519#issuecomment-415789873
 
 
   @hequn8128 I'm pretty sure that what you have just pointed out is bug in Flink SQL. I'm
not 100% sure (maybe 95%), but when comparing different types like `CHAR(3)` with `CHAR(5)`
or `VARCHAR(2)`, all of the operands should be first converted to same type (adding/ignoring
padding when necessary) and only then compared.
   
   In other words `'A  ' == 'A'` should return true, and this PR is not a proper fix to this
problem. It doesn't fix for example:
   
   ```
   SELECT * FROM country WHERE country_name = 'GERMANY  '
   ```
   
   This further convinces me that:
   > and our CHAR(x) support seems to be broken (for example 'A ' || 'B ' should return
'A B ')
   
   Probably either we should convert string literals to `VARCHAR` or properly implement support
for `CHAR`

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