Re: Include WAL in base backup - Mailing list pgsql-hackers

From Fujii Masao
Subject Re: Include WAL in base backup
Date
Msg-id AANLkTimx-hbNzn2v-nMeyG03w7Vhup6fx+eqwrjdPB+F@mail.gmail.com
Whole thread Raw
In response to Re: Include WAL in base backup  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
Responses Re: Include WAL in base backup  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
List pgsql-hackers
On Sat, Jan 29, 2011 at 6:02 AM, Heikki Linnakangas
<heikki.linnakangas@enterprisedb.com> wrote:
> On 27.01.2011 06:44, Fujii Masao wrote:
>>
>> +               XLByteToSeg(endptr, endlogid, endlogseg);
>> <snip>
>> +                       /* Have we reached our stop position yet? */
>> +                       if (logid>  endlogid ||
>> +                               (logid == endlogid&&  logseg>= endlogseg))
>> +                               break;
>>
>> What I said in upthread is wrong. We should use XLByteToPrevSeg
>> for endptr and check "logseg>  endlogseg". Otherwise, if endptr is
>> not a boundary byte, endlogid/endlogseg indicates the last
>> necessary WAL file, but it's not sent.
>
> We should use XLByteToPrevSeg, but I believe >= is still correct.
> logid/logseg is the last WAL segment we've successfully sent, and
> endlogif/endlogid is the last WAL segment we need to send. When they are the
> same, we're done.

Really? logid/logseg is incremented just before the check as follows.
So, when they are the same, the WAL file which logid/logseg indicates
has not been sent yet. Am I missing something?

+            /* Advance to the next WAL file */
+            NextLogSeg(logid, logseg);
+
+            /* Have we reached our stop position yet? */
+            if (logid > endlogid ||
+                (logid == endlogid && logseg >= endlogseg))
+                break;

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center


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