[Bioperl-l] Database Retrieval

Sendu Bala bix at sendu.me.uk
Tue Aug 8 08:44:13 EDT 2006


Sean Davis wrote:
> That is certainly possible--this is perl, right?  I'll think about it, but I
> doubt that I have the time to put together a satisfactory "grand" solution
> that allows arbitrary queries without specifying SQL, returns bioperl
> objects, and doesn't reflect some of the underlying schema.  If one settles
> on a set of objects that one wants to return, the process will be easier,
> but that limits the information that one can get from the database.
> 
> Practically, to have a "table-browser-like" code interface will require
> exposing some of the SQL schema, as column names and table names will need
> to come into it.

Not necessarily. You only have to have a mapping from the conceptual 
purpose of the table to its current name (and likewise for columns). So 
instead of a module called 'refLink' because there is a table called 
'refLink', you might have something called refseq_mrna_links which maps 
to 'refLink'. Oh, and given the sheer number of tables, I don't think it 
would be appropriate to have a module per table.

How about some single module that does the selection of the relevant 
database and table given $db and $table_concept? Perhaps:

# map 'human' to the possible human databases, default 'hgXX'
my $db = Bio::DB::UCSC::Databases('human');

# map 'refseq_mrna_links' to 'refLink' and return a
# Bio::DB::UCSC::Queryable
my $queryable = new Bio::DB::UCSC::Table($db, 'refseq_mrna_links');

# map mrna_accession method and its args to
# query => [mrnaAcc => {like => 'NM_00002%'}]
my $row_data = $queryable->mrna_accession(-like => 'NM_00002%');


Even that's not so hot; you still have to know some massive list of 
inflexible table-concept names like 'refseq_mrna_links'. Perhaps it 
would be even better if it was truly concept based. You say what you 
want and it figures out the correct table:

my $queryable = new Bio::DB::UCSC::Table($db, 'mrna_accession', 
'genomic_coordinates');


Sane? Reasonable? Desirable? Possible? I'm just throwing ideas out; you 
may see a better way of achieving similar ends.


> Taking such an approach, either based on RDBO or with
> hand-coded SQL management, precludes returning bioperl-type objects.   On the
> other hand, if one wants only bioperl-type objects returned, the information
> that can be returned is quite limited and the query structure (from a perl
> point of view) will need to be limited to a set of fields that can
> ultimately be used to look up only the information associated with bioperl
> objects.  I think the table-browser-like approach is the better way to go to
> start; let the user deal with making bioperl objects as he/she sees fit once
> the data is back.  As a second round of development, one could certainly
> build a compatibility layer that uses the primary query engine to pull out
> information for constructing key bioperl objects, but I don't think that
> should be the primary goal, but a secondary one.

Yes, that's the way it should be done, but the interface for the primary 
query engine ought still be independent of the table structure.


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