On Tuesday 11 November 2003 18:55, Jan Wieck wrote:
And how does a newly mmap'ed segment propagate into a running backend?
It wouldn't. Just like we allocate fixed amount of shared memory at startup now, we would do same for mmaped segments. Allocate maximum configured on startup. But it won't be into kernel space as much shared memory segment would be.
I don't understand that, can you explain this like you would to a child?
I want to configure my postmaster for a maximum of 256MB shared memory (or 32768 pages), but I want to start it using 128MB (16384 pages) only. Now while some backends that inherited the 128MB are running, I want to increase the shared memory to 256MB, run some job and shrink it back to 128MB. How do the backends that inherited 128MB access a buffer in the other 128MB if they happen to get a cache hit? How does that all work with anon mmap segments?
Jan
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