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Kishore_1 208 posts Joined 03/10
07 Feb 2016
After Initial BLC Loading

As space saving initiative, we are applying BLC on certain tables in our Teradata system.
We are using queryband "SET QUERY_BAND='BLOCKCOMPRESSION=YES;' FOR SESSION;" to compress the data and insert into a table.After the initial load, we are dropping  the old table and renaming the compressed table as original.My question is after the  initial load, do we need to use the querybanding on a daily basis for the incremental loads on that table?Will be data inserted into that table be compressed  automatically , or we have to specify compression query band in the job session that loads data on a daily basis?

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dnoeth 4628 posts Joined 11/04
08 Feb 2016

The file system will notice that existing data blocks are compressed and compress new data, too. But when the table is truncated (DELETE ALL) there are no existing blocks and new data will be compressed on queryband.

Dieter

Kishore_1 208 posts Joined 03/10
09 Feb 2016

Thanks Dieter:)

Huzain 3 posts Joined 02/13
04 May 2016

Hi Dieter, 
in our system BLC is enable on database level and vie Ferret , we have identfied the tables on whic BLC is enable.
now there is requirment to calculate the actual size of these tables without blc, Can some body help me how will can i extract actual size of BLC tables without out compression.
 
thanks,

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