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

On Mon, Oct 6, 2014 at 8:59 AM, Marco Nenciarini
<marco.nenciarini@2ndquadrant.it> wrote:
> Il 04/10/14 08:35, Michael Paquier ha scritto:
>> On Sat, Oct 4, 2014 at 12:31 AM, Marco Nenciarini
>> <marco.nenciarini@2ndquadrant.it> wrote:
>>> Compared to first version, we switched from a timestamp+checksum based
>>> approach to one based on LSN.
>> Cool.
>>
>>> This patch adds an option to pg_basebackup and to replication protocol
>>> BASE_BACKUP command to generate a backup_profile file. It is almost
>>> useless by itself, but it is the foundation on which we will build the
>>> file based incremental backup (and hopefully a block based incremental
>>> backup after it).
>> Hm. I am not convinced by the backup profile file. What's wrong with
>> having a client send only an LSN position to get a set of files (or
>> partial files filed with blocks) newer than the position given, and
>> have the client do all the rebuild analysis?
>>
>
> The main problem I see is the following: how a client can detect a
> truncated or removed file?

When you take a differential backup, the server needs to send some
piece of information about every file so that the client can compare
that list against what it already has.  But a full backup does not
need to include similar information.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
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