The Vertica Database Forums

HI

How Exactly data is compressed in Multinode Vertica set up ? Is there any difference in Compression ratio with number of nodes ?

Reply soon !!!!!!

Hi,

I don't think the compression ratio would change significantly based on the number of nodes. That is, the sum of the compressed data on all nodes should have a similar size to the compressed data on a single node. But that's assuming you have optimized projections. Default super projections might not optimize database performance, resulting in slow query performance and low data compression.

i have loaded 39 GB of raw data
In single node it is compressed to 5.1 GB and in 3 node it is compressed to 12.01 GB with K safety 1 (Original data + 1 backup copy)


1 GB differece .....


All Table structure , Optimized Query , Db designs are same in both the single and 3 node Vertica ..

why this large difference ?

Are you sure the physical designs are the same?

What are the projection counts from PROJECTIONS table in each solution? What are the projection counts where the is_super_projection = t?

On the single node I bet all projections are super projections that can be poorly compressed as expressed by the documentation.

IN single node vertica , For super projection Compression ratio was 12.71 GB .

So now the compression size is matching in your single node and your 3 node cluster.