Mamta Satoor wrote:
Mike, I am not sure if your question, about how in store DVD with
correction collation type is loaded, was answered or not. In other
words, you had question about following piece of pseudo code from Dan
if (dvd instanceof StringDataValue)
dvd = dvd.getValue(dvf.getCharacterCollator(type));
Let me attempt to answer it. It will help clear up things in my mind too
and make sure that I am understanding this correctly.
Currently,
derby.impl.dtore.access.conglomerate.OpenConglomerateScratchSpace has
get_row_for_export which first gets a class template row using
RowUtil.newClassInfoTemplate This method in RowUtil calls
Monitor.classFromIdentifier to get the InstanceGetter for each of the
format ids identified by store. Once
OpenConglomerateScratchSpace.get_row_for_export has the class template
row, it will call RowUtil.newRowFromClassInfoTemplate. This is the
method, Dan is proposing to modify, ie store should pass an additional
array of int to RowUtil.newRowFromClassInfoTemplate which will have the
collation type associated with the formatids of the template row.
RowUtil.newRowFromClassInfoTemplate will first get the DVD as it does
today using following
columns[column_index] =
(DataValueDescriptor) classinfo_template[column_index].getNewInstance();
In addition, it will need to do something like following
if (columns[column_index] instanceof StringDataValue)
dvd =
columns[column_index].getValue(dvf.getCharacterCollator(collationTypesForTemplateRows[column_index]));
My opinion is that this work should be done in the datavalue factory and
not outside. Dan suggested at one point that some of the work of
generating classes/instances should move from Monitor to datavalue factory.
So I was assuming something like RowUtil.newClassInfoTemplate instead
of calling Monitor.classFromIdentifier(format_ids[i]) get an array of
InstanceGetter's, it would call something like
datavaluefactory.classFromIdentifier(format_ids[i], collator_ids[i]) -
then every InstanceGetter would produce the right type with collator set
from then on.
Internal to dvf it can do the work of checking for instanceof if it
needs to, but because it is inside dvf maybe it can do something smarter .
Dan, let me know if I understood you right. This will help me answer
your question on the Derby wiki page
http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478
<http://wiki.apache.org/db-derby/BuiltInLanguageBasedOrderingDERBY-1478> I
know that we don't need to get into the implementation code details in
the design phase, but I need to be able to picture this particular case
in my mind to understand where I am going.
thanks,
Mamta
On 3/15/07, *Mike Matrigali* <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
Daniel John Debrunner wrote:
> Mamta Satoor wrote:
>
...
>
> - At recovery time the btree uses the collation type and the data
value
> factory to setup its template row array correctly. Something like
> for each dvd in row array
> if (dvd instanceof StringDataValue)
> dvd = dvd.getValue(dvf.getCharacterCollator (type));
Note that the store issue is not just a recovery time issue, templates
are required during normal runtime. Creation of these templates used
to show up (a long time ago) in performance analysis and work was done
to optimize the performance. So I am interested in making these
template creations as efficient as possible.
Your proposal above does not look right to me - it could just be I don't
understand where the psuedo code is. The code I expect in store would
be something like below - letting the datafactory do whatever is right
based on the format id and the collation, if store is going to "own"
knowing
the collation of a given column then I would expect something like:
for each format id in row array
dvd = datavaluefactory.getObject(format id, character_collator_type)
note this means extra overhead for every object creation in the
template.
To me it seems unfortunate to pass in this info per column, when at
least in 10.3 the current code it is one per database. I saw the
direction as:
o 10.3 only needs one collation per database so hide the info in the
datafactory, basically there is one DEFAULT collation per database.
Thus no need for second argument to datavaluefactory.getObject()
o future release needs to have different collations per conglomerate,
then at that time we can store a collator type per conglomerate - we
have mechanism today to upgrade on the fly. If we want to support
adding a collation to an existing database I would suggest continueing
the DEFAULT collation concept with some magic number representing
DEFAULT db collation in the datavaluefactory.getObject() call - which
would mean use db wide default rather than specify specific one. For
new databases we would not need default, we could at that time
specify
one per conglomerate.
At this point we either change all the datavaluefactory.getObject()
calls to have 2 args and support DEFAULT_VALUE as second argument, or
maybe support both 1 and 2 arg calls - not sure.
0 future future release needs to have different collations per column,
then at that time we can store a collator type per column - we
continue to have mechanism to upgrade on fly as long as we can come up
with a default value for old tables. Same issues as above.
>
> - setting the collation property remains in the data dictionary
>
> - basic database sets the locale for the DataValueFactory after
it boots
> it, using a new method on DVF
> void setLocale(Locale locale);
>
> I think approaching the problem this way will lead to a cleaner
solution
> in the long term and be somewhat easier to implement.
>
> Thanks,
> Dan.
>
>
>
>
>
>
