Cost of creating an emply WAL segment

Hi,

Has anyone measured the cost of creating empty WAL segments while the
database is running?

Actually, when is the new file created? Just after one segment is filled
up, or some time before then? What happens during WAL segment creation?
If there are pending transactions to be committed, do we see a delay?

I was looking at how Oracle manages this, and I was told that you can
create empty segments during installation, so I'm wondering whether it
might be a good addition to initdb or not:

initdb -S 30 -- create 30 empty segments during initdb

Regards,
--
Devrim GÜNDÜZ
Principal Systems Engineer @ EnterpriseDB: http://www.enterprisedb.com
PostgreSQL Danışmanı/Consultant, Red Hat Certified Engineer
Community: devrim~PostgreSQL.org, devrim.gunduz~linux.org.tr
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