Re: Multiple files per database in Objectivity

[Henrik Nordberg <hnordberg@lbl.gov>]

Arie Shoshani wrote:
> 
> The directory will not contain the names of individual files, only the
> name of the database.  However, a function will be provided to get the
> container size and the file size for each database.  Thus, given an

Do you mean "the file sizes for the files that make up the database"? So
it will return a list of file sizes? Can the container size change from 
container to container in a DB? If it can (which it probably can) then
you need a list of all container sizes too.

> object_id, one can use the container_id and the sizes to calculate the
> file_number.  Using the database_id, one can get the database_name from
> the directory.  Concatenating the database_name and the file_number is
> the unique file name.
> 
> p.s.  I asked if it will be possible to have open_file, close_file
> functions, so that when writing one does not have to keep tracks which
> containers to write to.  A "close" could be fake, only having the effect
> of stopping the writes into a file.  An "open" will have the effect of
> starting the following write to the first container of the next file.

Above you wrote:
> However, if one wished to terminate a file before all of its containers
> are full, that can be done by asking to write to the first container of
> the next file.  For example, suppose, one wishes to close the first file

How is this different from your close_file/open_file?

> The answer was "no", but they said they'll put this request on the list
> of requested features.  If this is important to people who generate
> files, they should make it clear to Objectivity as early as possible.

 -  Henrik
_________________________________________
Henrik Nordberg       <hnordberg@lbl.gov>
Scientific Data Management Research Group
Lawrence Berkeley National Laboratory