Hi,
thank you for an advice - I set it and tested for several days.
Good news is we do not have "drowsy" sessions any more.
But performance of queries on huge tables went seriously down. Even with parallel processing.
It is understandable regarding memory management but not sustainable for the future since our tables are growing almost exponentially. In these days we have weekly increase in size >100GB and it goes still higher. Database now have 2,5 TB. We had to move some of our queries from PostgreSQL to Bigquery because performance was really bad...
I checked history of this database and previously PostgreSQL 9.5 was running on Google GCE instance with Ubuntu 14.04 now we have new instance with Debian 8 and PostgeSQL 9.6.
On previous instance with Ubuntu we did not have all these problems at all. I checked and Ubuntu 14.04 has by default hugepages enabled (value “always”) + fixed setting of number of huge pages but Debian 8 has default setting “madvise” - memory adviser.
Please has someone here some deeper experiences with differences between Ubuntu and Debian as environment for PostgreSQL as highly used OLAP database? Because so far it looks like switching to Debian was rather bad choice....
Thanks
Josef