Makeblastdb Hash_Index: What For? When To Use?

Question

[cpcantalapiedra]

The makeblastdb program that comes with blast distribution has the hash_index option that states:

-hash_index Create index of sequence hash values.

What is for? When should I use it?

Answer 1

[Biojl]

Quoted directly from one of the manuals:

hash_index: Enables the creation of sequence hash values. These hash values can then be used to quickly determine if a given sequence data exists in this BLAST database.

It's all about speed and efficiency.

[cpcantalapiedra]

thank you very much. you have been fast and efficient too