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harish.palakuri 3 posts Joined 02/13
28 Feb 2013
Enabling ALC, Pros and cons

Hi
I want to do compression on the VARCHAR column and it throws me an error
Error: algorithmic compression feature is not yet enabled
Can someone please tell me how i can enable the feature.
2) What are the pros and cons of enabling this feature?
Are there any known bugs with this feature.
 
 
Thanks
Harish 

simhadrijk 18 posts Joined 04/10
05 Mar 2013

Hi Harish,

For the character data type, before Teradata 13.10, MVC (multi value compression) was restricted to fixed-length char¬acter columns (CHAR data type) and columns up to 255 characters wide.
For Teradata 13.10, MVC was enhanced so it can now be used with variable-length character columns (VARCHAR data type) and columns up to 510 characters wide. It can support any numeric type, all character data, GRAPHIC, VARGRAPHIC, BYTE and VARBYTE.

Here is the example

CREATE TABLE Customer
(Customer_Account_Number INTEGER
,Customer_Name VARCHAR(50) COMPRESS (‘Joe’,‘Mary’)
,Customer_Address CHAR(200));

Hope this helps
Please check with the version of TD,you are using.

thanks
Jagdish

Jagdish Kumar Simhadri

simhadrijk 18 posts Joined 04/10
05 Mar 2013

So enabling the ALC will not cause you any impact. But please remember the during application of compression of UNICODE fields.
In our project, we faced with data corruption for UNICODE fields upon applying compression.
Performance wise, it will not cause any problem.

Jagdish Kumar Simhadri

harish.palakuri 3 posts Joined 02/13
07 Mar 2013

I Really Appreciate your response Simha.
we are using Teradata 13.10.0506 version .
 
Can you please tell me what is the way to Enable ALC?
 
Thanks
Harish 
 

simhadrijk 18 posts Joined 04/10
08 Mar 2013

By default you should be able to create columns with compression.
PLease check with your DBA once, he should be helpful to you in resolving it on your TD settings.

Jagdish Kumar Simhadri

AbeK 24 posts Joined 08/09
12 Mar 2013

DBSControlParameter No13dot0Backdown should be enabled (TRUE).

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