sequence gi number of updated sequences

Question

[arfaj a]

Hello,

I have a question regarding sequence gi number.

If I have 2 versions of blast database say OldDatabaseVersion and NewDatabaseVersion. The NewDatabaseVersion may have new sequences added, some sequences removed, or some sequences modified.

If the sequence is removed from OldDatabaseVersio, Is its gi number will be used for another sequence? If the sequence is modified, Is its gi number in the OldDatabaseVersion will be the same as its gi number in the NewDatabaseVersion or another gi number will be assigned to it in the NewDatabaseVersion?

Thanks.

[Michael]

I believe gi's were unique and not reused. Note that ncbi is phasing out gi's.

Answer 1

[piet]

GI numbers are the primary keys in NCBI nucleotide database. Entries in this database may become obsolete or invisible (after request of the submitter), but entries are never removed. Thus is is safe to use GI numbers to compare two versions of your Blast database.

[Naren]

Blast output to any query gives out first few letters in the Fasta header of both query and hits whether it has gi or new accession.version format it will be present in output.