Re: [RFC] Incremental backup v2: add backup profile to base backup

On Mon, Oct 6, 2014 at 12:06 PM, Marco Nenciarini
<marco(dot)nenciarini(at)2ndquadrant(dot)it> wrote:
> Il 06/10/14 17:55, Robert Haas ha scritto:
>> On Mon, Oct 6, 2014 at 11:51 AM, Marco Nenciarini
>> <marco(dot)nenciarini(at)2ndquadrant(dot)it> wrote:
>>> I agree that a full backup does not need to include a profile.
>>>
>>> I've added the option to require the profile even for a full backup, as
>>> it can be useful for backup softwares. We could remove the option and
>>> build the profile only during incremental backups, if required. However,
>>> I would avoid the needing to scan the whole backup to know the size of
>>> the recovered data directory, hence the backup profile.
>>
>> That doesn't seem to be buying you much. Calling stat() on every file
>> in a directory tree is a pretty cheap operation.
>>
>
> In case of incremental backup it is not true. You have to read the delta
> file to know the final size. You can optimize it putting this
> information in the first few bytes, but in case of compressed tar format
> you will need to scan the whole archive.

Well, sure. But I never objected to sending a profile in a
differential backup. I'm just objecting to sending one in a full
backup. At least not without a more compelling reason why we need it.

--
Robert Haas
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