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Hi All,
What is the best options to compress BLOB data? BLC Vs ALC
We are loading large volume of Binary files in teradata. We are thinking to use ALC, is there UPDs to compress and uncompress BOLB data?
Thanks
Khom
 
 
 
 
 
 

As space saving initiative, we are applying BLC on certain tables in our Teradata system.

I have few questions on BLC(Block Level Compression):

a) Can a table be partially compressed using BLC and partially

remain uncompressed?If this is true, how to know if 

a table is partially compressed using BLC.

 

b) Does stats collection on a table compressed using BLC

Hi,
Please can some tell me how to identify tables that have been Block-level compressed using SQL.
Hopefully from one of the DBC. <tables>.
 
Note: I do not have access to Ferret tool or anyother tools an admin has access to.

Hi all,

 

I tried to using BLC for the first time, but encountered some unusual case.

One of my table cannot be compressed using BLC.

Ferret says "The input table can't be compressed".

why is that? 

 

Thanks,

Anung

Go in-depth on how NULLs and Compression are managed in a Teradata system.

Teradata 13.10 features Block Level Compression (BLC), which provides the capability to perform compression on whole data blocks at the file system level before the data blocks are actually written to storage. Like any compression features, BLC helps save space and reduce I/O.

This BLC utility is for Teradata users to run against TD 13.10 system to select the list of BLC candidate tables and evaluate BLC impact on space and speed for each specific table in interest, to get information for selecting appropriate tables to apply BLC.

Hi,

what is the recommended update strategy for BLC tables?

Scenario is to insert new rows - no deletes, no updates.

Ulrich

Hi all,
It's my understanding that the only way you can tell what tables are block level compressed is by using the Ferret utility. Is this true? Does anyone know the Ferret command to list tables that are BLC'd?

This session will focus on block-level compression (BLC), how it works, what compression rates you can expect, and where it is appropriate to define. Examples of the impact on CPU usage and elapsed time when queries access compressed tables will be shared, and the overhead while performing different database operations on these tables will be explored. Plenty of tips and techniques for successful use of BLC are offered.

One of the new compression features in Teradata 13.10 is Block Level Compression (BLC), which provides the capability to perform compression on whole data blocks at the file system level before the data blocks are actually written to storage. Like any compression features, BLC helps save space and reduce I/O. 

There is a CPU cost to perform compression on inserting data. And there is a CPU cost to perform decompression on whole data blocks whenever the compressed data blocks are accessed. Even when only one column of a single row is needed, the whole data block must be decompressed. For updates, the compressed data blocks have to be decompressed first and then recompressed. Careful evaluations shall be done before applying BLC in your production systems.