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Chado FAQ

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About this FAQ

What is this FAQ?

It is the list of Frequently Asked Questions about Chado. It summarises the questions that have come up on the Chado mailing list.

How is it maintained?

It is now maintained as a Wiki on this site. You can help maintain it by adding questions and answers.

Chado Questions

How do you pronounce chado?

Chado is usually pronounced like this.

How does one represent BLAST results in Chado? or alignments? or...

Questions about the best ways to represent a variety of observations are answered at the Chado Best Practices page. There is also a worked example for this at Load_BLAST_Into_Chado.

Where do I find a list of tables in Chado?

The Chado Tables page.

What are the modules in Chado?

They are listed in the Chado Manual page.

Is there a Chado for Beginners?

The best place to start would be the Chado Manual or Overview.

Loading data into Chado

When I try to load data into Chado using the GFF bulk loader (, I get this error:
 DBD::Pg::db pg_endcopy failed: ERROR:  invalid input syntax for integer: ""
 CONTEXT:  COPY feature_relationship, line 1, column type_id: "" at /usr/lib/perl5/site_perl/5.8.8/Bio/GMOD/DB/ line 2723, <$fh> line 64298.
Why is that and what do I do?
Unfortunately there is a bug in one of the prerequisites for the Chado loader, a perl module called DBIx::DBStag, which does the actual writing of ontology data to the database. When it loads the Gene Ontology (and possibly other ontologies), it destroys the 'part_of' cvterm that belongs to the relationship ontology and makes it part of GO instead. This is the wrong behavior, but at the moment, there is nothing we can do about it.
Instead, you must run a SQL command to repair the database:
 UPDATE cvterm SET cv_id = (SELECT cv_id FROM cv WHERE name = 'relationship')
  WHERE name = 'part_of'
   AND cv_id IN (SELECT cv_id FROM cv WHERE name='gene_ontology');
Then, rerunning the loader with the --recreate_cache option should allow the database to load. Sorry for the hassle.

Why is loading GFF3 data so slow and what can I do about it?

The script has to do quite a bit of work that the similarly named does not have to do. Since Chado makes extensive use of constraints and foreign key relationships, the bulk loader has to keep track of all of those constraints while parsing the GFF3 file. Also, when it is loading data, it does it in a single database transaction, which can take quite a while if there is a lot of data.
So, what to do about it. First, I would suggest breaking up the load in to several smaller chunks and loading them sequentially. The script has options for splitting GFF3 files in several ways, like by chromosome or by the "source" (the value in the second column of the GFF3 file). Typically, when I do this, I create a simple bash script that will load the files one by one and then run it and check back periodically to make sure it is doing ok. By breaking the load up into several smaller files, the load process is easier to follow typically goes faster (particularly if the load fails for some reason, the database will rollback to the last known good state and you only have to continue the load from where things went bad).
Also, there are command line options for trying to increase speed, but I haven't spent much time benchmarking them. In particular, their is an option to drop indexes and then recreate them after the load, as well as an option to not load the database in a single transaction.

I get a weird error when loading ontologies; what do I do?

When I try to use `make ontologies` to load ontologies, I get this message:
 install_driver(Pg) failed: DBD::Pg object version v2.15.1 does not match bootstrap parameter 2.15.1 at /System/Library/Perl/5.8.8/darwin-thread-multi-2level/ line 253, <STDIN> line 1.
 Compilation failed in require at (eval 91) line 3, <STDIN> line 1.
What can I do about it?
This problem has happened to me a few times and usually indicates that there was a problem when DBD::Pg was installed. The first option to try is to reinstall it, using the UNINST=1 directive on the install command, like this:
 perl Makefile.PL
 make test
 sudo make install UNINST=1
If that doesn't solve the problem, it is possible to edit DBD::Pg in place to fix the version string. In the particular example sited above, I think it is fairly safe to change the version string in from '2.15.1' to 'v2.15.1', but making a real change between version numbers could cause DBD::Pg to fail, or worse, could cause it to seem to work but fail in some subtle, not very noticeable, way.

Is it possible to load ontologies without the DBIx::DBStag Module?

I have errors associated with loading ontologies that appear to be related to the DBIx::DBStag module. When attempting to load ontologies with, I get the error message:

 Cannot quote a reference at /Library/Perl/5.8.8/DBIx/ line 3732.

I am using the latest version (0.10) of the Module, and installed it by hand. The tests on Installation also failed with a similar error message for 'cv.t' . Are there alternatives for loading ontologies that do not require the DBIx::DBStag module.

FWIW: I got around this by using CPAN to "install Bundle::GMOD" - which installs v0.12 of DBIx::DBStag and maybe that's the key. Installing Bundle::GMOD had trouble with both XML::LibXSLT and DBIx:DBStag. Whereas using "force" worked for the latter, the former required installing related packages (ex: via aptitude) such as libxslt and libxml - including the *-dev packages. (This was on Ubuntu 10.04 Lucid.)

Loading Ontologies takes forever! There has to be a better way?

There are Precompiled Chado Databases (including all five ontologies), made available online. These are updated on a weekly basis.