bugfix: columns part of a PRIMARY KEY cannot be NULL
bugfix: columns part of a PRIMARY KEY cannot be NULL

Ensembl/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara