Parallel Query

2018-01-10 Thread Krithika Venkatesh 
Hi All,

I was reading about parallel queries in postgresql 10.

I came across the property max_parallel_workers_per_gather. It sets the
maximum number of workers that can be started by a single Gather or Gather
Merge node.

I am not able to understand gather and gather merge node.

What is the difference between max_parallel_workers_per_gather and
max_parallel_processes. What is meant by gather node.

Please let me know.

Thanks,
Krithika

Parallel Btree index scan

2018-01-16 Thread Krithika Venkatesh 
Hi All,

Can you please help me to understand what is parallel btree index scan in
Postgres 10.


And what is the difference between index scan and index only scan.

Thanks,
Krithika