It doesn't write out all of RAM, only the amount in use by the particular backend that crashed (plus all the shared segments attached by that backend, including the main shared_buffers, unless you disable that as previously mentioned).
And yes, it can take a long time to generate a large core file.
-- Andrew (irc:RhodiumToad)
Based on the Alvaro's response, I thought it is reasonably possible that that *could* include nearly all of RAM, because that was my original question. If shared buffers is say 50G and my OS has 1T, shared buffers is a small portion of that. But really my question is what should we reasonably assume is possible - meaning what kind of space should I provision for a volume to be able to contain the core dump in case of crash? The time of writing the core file would definitely be a concern if it could indeed be that large.
Could someone provide more information on exactly how to do that coredump_filter?
We are looking to enable core dumps to aid in case of unexpected crashes and wondering if there are any recommendations in general in terms of balancing costs/benefits of enabling core dumps.
