Re: block-level incremental backup

On Mon, Aug 12, 2019 at 4:57 PM Jeevan Chalke <
jeevan(dot)chalke(at)enterprisedb(dot)com> wrote:

>
>
> On Fri, Aug 9, 2019 at 6:36 PM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>
>> 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.
>>
>
> Agree that we can certainly use open(), read(), write(), and close() here,
> but
> given that pg_basebackup.c and basbackup.c are using file operations, I
> think
> using fopen(), fread(), fwrite(), and fclose() will be better here,
> at-least
> for consistetncy.
>

+1 for using fopen(), fread(), fwrite(), and fclose()

> Let me know if we still want to go with native OS calls.
>
>

-1 for OS call

>
>> --
>> Robert Haas
>> EnterpriseDB: http://www.enterprisedb.com
>> The Enterprise PostgreSQL Company
>>
>
>
> --
> Jeevan Chalke
> Technical Architect, Product Development
> EnterpriseDB Corporation
> The Enterprise PostgreSQL Company
>
>

--
Ibrar Ahmed