HASHMAP and BYNET

Database
sri
Enthusiast

HASHMAP and BYNET

Hi Experts,

 

In Teradata 15 doc I read that "BYNET maintain HASHMAP", this means Hashmap stored in BYNET and when PE send rowhash then BYNET identify the AMP based on Hashmap entries available with it. Please correct me if I am wrong. If Hashmap not present in BYNET, then where it exist?

 

Thanks,

Sri.

5 REPLIES
Junior Contributor

Re: HASHMAP and BYNET

Hashmaps are so-called globally distributed objects (gdo), i.e. flat files stored on each node (in /etc/opt/teradata/tdconfig) and loaded into memory during startup.

sri
Enthusiast

Re: HASHMAP and BYNET

Hi dnoeth,

 

could you please explain? into which memory they load? How BYNET get AMP information?

 

Thanks,

Sri.

Junior Contributor

Re: HASHMAP and BYNET

Reading the hashmap.gdo into RAM is part of the PDE startup.

I don't know if/where the startup procedure is explained in detail, but the Support Utilities manual has some topics, e.g.

System Initializer (sysinit)

Teradata Employee

Re: HASHMAP and BYNET

The map is stored in the GDO for persistence. During startup it is read into bynet software memory in each node so that the bynet software has fast access to the map to route messages from both PEs and AMPs.
sri
Enthusiast

Re: HASHMAP and BYNET

Thanks Todd and dnoeth, I understood.

 

Sri.