Re: Re: [COMMITTERS] pgsql: Map basebackup tablespaces using a tablespace_map file

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: Andrew Dunstan <andrew(at)dunslane(dot)net>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, hlinnaka <hlinnaka(at)iki(dot)fi>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Re: [COMMITTERS] pgsql: Map basebackup tablespaces using a tablespace_map file
Date: 2015-05-15 06:21:00
Message-ID: CAA4eK1KEFoTJ8kRxsTid=ZRx8Rd593B+86-GCDDey5s2Mqqw_g@mail.gmail.com
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On Thu, May 14, 2015 at 10:29 PM, Andrew Dunstan <andrew(at)dunslane(dot)net>
wrote:
>
>
> On 05/14/2015 10:52 AM, Robert Haas wrote:
>>
>> On Thu, May 14, 2015 at 12:12 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
wrote:
>>>
>>> On Thu, May 14, 2015 at 2:10 AM, Andrew Dunstan <andrew(at)dunslane(dot)net>
wrote:
>>>>
>>>> How about if we simply abort if we find a non-symlink where we want the
>>>> symlink to be, and only remove something that is actually a symlink
(or a
>>>> junction point, which is more or less the same thing)?
>>>
>>> We can do that way and for that I think we need to use rmdir
>>> instead of rmtree in the code being discussed (recovery path),
>>> OTOH we should try to minimize the errors raised during
>>> recovery.
>>
>> I'm not sure I understand this issue in detail, but why would using
>> rmtree() on something you expect to be a symlink ever be a good idea?
>> It seems like if things are the way you expect them to be, it has no
>> benefit, but if they are different from what you expect, you might
>> blow away a ton of important data.
>>
>> Maybe I am just confused.
>>
>
>
> The suggestion is to get rid of using rmtree. Instead, if we find a
non-symlink in pg_tblspc we'll make the user clean it up before we can
continue. So your instinct is in tune with my suggestion.
>

Find the patch which gets rid of rmtree usage. I have made it as
a separate function because the same code is used from
create_tablespace_directories() as well. I thought of extending the
same API for using it from destroy_tablespace_directories() as well,
but due to special handling (especially for ENOENT) in that function,
I left it as of now.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

Attachment Content-Type Size
remove_only_symlinks_during_recovery_v1.patch application/octet-stream 3.8 KB

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