Which data is exported with "EXPORT TO PARQUET" ? How to get the real size ?
when we use the EXPORT command to Parquet, which data is really downloaded ? The one of the super projection ? We try to figure out the size of an archive, and as it is difficult to get the file size by itself, we try to compute it from the ROS size with this kind of query (we work on partitions)
ROUND(SUM(ros_size_bytes)/(1024^2)) as space_Mb
from partitions P,
where p.table_schema = pr.projection_schema
and p.projection_name = pr.projection_name
group by p.table_schema, pr.anchor_table_name, p.partition_key;
But I am afraid we take too much data here, when a table has several projections ?
How can we estimate the exported size (on top of number of rows) ?