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From Daniel John Debrunner <...@apache.org>
Subject Re: more on system schema vs. user schema and character constants.
Date Mon, 04 Jun 2007 00:54:46 GMT
Mamta Satoor wrote:
> OK, so maybe I spoke too soon when I said that I understand the 
> difference between compilation schema vs current schema.
> Let me take following eg for a database with collation=territory_based
> create schema a;
> set schema a;
> create table t (id int, type char(10));
> insert into t values (1,'CAR'),(2,'SUV');
> set schema sys;
> select * from A.T where TYPE = CAST('CAR' AS CHAR(10));
> For the last sql statement, I thought the compilation schema will be A 

Why? The previous statement sets the schema to sys. Imagine if the 
statement was instead

    select * FROM A.T, B.T ...

then how would the system pick A or B as the compilaton schema?

> and hence the result of the CAST will have collation type of territory 
> based because result of CAST is supposed to pick up it's collation from 
> the compilation schema. But when I try the above set of sql statements 
> inside ij, the last sql statement fails because the collation type of 
> column "TYPE" is not same as collation type of CAST. It appears that the 
> result of CAST has picked up collation of SYS schema which is UCS_BASIC. 
> So, for character constants, CAST etc, does the compilation schema end 
> up being the the current connection schema since they are not tied to 
> any physical schema?

No, a statement has a single compilation schema. Usually it is the same 
as the current schema, but in cases like views, trigger action 
statements and sps (meta data queries) it isn't.

I think that constants, parameters etc. picking up their collation from 
the compilation schema is going to cause issues, it may not be what an 
app developer is expecting.


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