Mamta Satoor wrote:
Hi,
I just finished committing a patch (revision 525568) which has added
collation type and collation derivation to DataTypeDescriptor and there
are apis to set and get those values out of DTDs.
As a next step on language based ordering Jira entry, I want to tackle
CREATE TABLE. Create table should pick up the collation requested by the
user at create database time and use that for character string type
columns. I have not though much about it and going to start researching
into it. But what is coming to my mind is that I can write a new api in
DataDictionary to return the right collation type
(UCS_BASIC/TERRITORY_BASED) for user defined tables and CREATE TABLE
will use that collation type to set into DTDs.
I am not sure if that will cause a problem with system tables because I
don't know if system table creation goes through CREATE TABLE node. If
they do not, then I think what I am suggesting will work. System table
creations will need to make another api call on DataDictionary which
will return the collation type for character string types associated
with system schema, which is always UCS_BASIC. Another alternative is to
hard code UCS_BASIC for system table columns wherever they get created
but I think it will be better to have one central location to get both
user and system collation types.
So, 2 new apis in DataDictionary
public int getCollationTypeForPersistentUserCharacterColumns() - this
will return value based on collation property
public int getCollationTypeForPersistentSystemCharacterColumns() - this
will return hard coded UCS_BASIC.
One improvement could be to have a single api in DataDictionary and pass
the user schema vs system schema flag to it and have DataDictionary
check that flag and return the correct collation.
public int getCollationType(boolean systemSchema) - if systemSchema true
then return UCS_BASIC, if systemSchema false, then return collation type
based on collation property.
Does anyone have an opinion on if I am on the right track?
The collation you are looking for is a property of the schema, see this
from your 1478 wiki page:
2)<column definition> (of character string type) SQL spec Section 11.1 <schema
definition>, General Rule 3 specifies that the character set associated with schema is used as
the default character set for all <column definitions>.
Thus, since it's a property of the schema, the most logical place for
this is as a method on SchemaDescriptor,
e.g.
public int getCollationType();
Dan.
