Subject Re: [Firebird-Architect] PR and EX locks compatibility
Author Dimitry Sibiryakov
05.11.2013 21:33, IBO Support List wrote:
> It depends upon the nature of the typical read lock. If that read lock is
> being coordinated with other things that might cause it to be locked
> significantly longer than it would take to copy things out, perhaps it could
> be worth it.

Even if read lock isn't long, there can be more of them. And if page manager still have
read-locked copy of page when a new reader is coming but writer is still working, the
reader can get "a bit old but still valid" copy of the page without waiting.
In fact, this way writers don't block readers at all.