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Re: Field size become unlimited in union...

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On 05/03/2016 04:28 AM, Durumdara wrote:
Hello!

As I experienced, PGSQL changes the result field sizes to unlimited
varchar, when I passed different field size in same column of the union.

SP.Key - varchar(100)
SP.Value - varchar(200)

Example:

  select 'a', value from sp
  union all
  select key, value from sp


The first field is not limited to 100, it's unlimited varchar() (= Text,
Memo, CLOB).

So PG don't use the maximal field size (100).


If I did cast on the field to resize to 100, the result is limited
correctly.


  select cast('a' as varchar(100)), value from sp
  union all
  select key, value from sp


Can I force somehow to PG use the maximal size?

Or must I know and equalize all field sizes in union?

Or must I use temporary tables and inserts to not get this problem?


See below for complete explanation:

http://www.postgresql.org/docs/9.5/static/typeconv-union-case.html

10.5. UNION, CASE, and Related Constructs


Thanks

Regards
    dd




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Adrian Klaver
adrian.klaver@xxxxxxxxxxx


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