The Ensembl Browser

I am trying to learn how Ensembl is structured. As Ensembl itself does not have a wiki nor a forum nor a public mailing list for user discussions, I'll document it here.

Some ideas:

• Everything is in mysql databases. No flat text files. Database schema documentation
• Can be accessed via Perl API (slow) or via biomart.org (~table browser, fast and convenient) or via direct sql queries (very complex schema)
• A whole, complete update of everything is done every 6 months. The old code, the old API and all databases are archived. Different mysql servers running on different ports are used to separated older archived from current versions.
• The current version (oct 09) is 56
• Usually, each species has its own database, like in the UCSC browser. The current human one is 'homo_sapiens_core_56_37a'
• The Web interface is called "webcode", written in Perl and makes extensive use of inheritance (uh-oh), tool-support for reading the code might be helpful

The tables:

• Sequences can be accessed using different "coordinate systems", e.g. you can type in a chromsome location or alternatively a contig location. Both will be mapped to chromsome sequences. They are set up in the table 'coord_system'
• The sequences themselved are stored in the table 'dna' and information about them in 'seq_region'. There is a table dnac for compressed sequences but its empty.

The pipeline:

• Their pipeline systems inserts jobs into a mysql database as well
• The genebuild step is predicting genes
• The xref step is connecting predicted genes to external identifiers
• The compara step is aligning all genomes and predicted genes and then building phylogenetic trees for all proteins
• The biomart step is de-normalizing all databases for faster access (It seems that biomart is not archived. If this is true, then one cannot rely on it for whole-genome work as one might end up with inconsistent data)