Re: block-level incremental backup

On Wed, Aug 7, 2019 at 5:46 AM Jeevan Chalke
<jeevan(dot)chalke(at)enterprisedb(dot)com> wrote:
> So, do you mean we should just do fread() and fwrite() for the whole file?
>
> I thought it is better if it was done by the OS itself instead of reading 1GB
> into the memory and writing the same to the file.

Well, 'cp' is just a C program. If they can write code to copy a
file, so can we, and then we're not dependent on 'cp' being installed,
working properly, being in the user's path or at the hard-coded
pathname we expect, etc. There's an existing copy_file() function in
src/backed/storage/file/copydir.c which I'd probably look into
adapting for frontend use. I'm not sure whether it would be important
to adapt the data-flushing code that's present in that routine or
whether we could get by with just the loop to read() and write() data.

--
Robert Haas
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