Re: [HACKERS] [PATCH]make pg_rewind to not copy useless WAL files
От | Alexander Korotkov |
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Тема | Re: [HACKERS] [PATCH]make pg_rewind to not copy useless WAL files |
Дата | |
Msg-id | CAPpHfdsmBjtQDbAUzTQJZ9Jnpj7aT8n=oPHtiKB=bJ0yedTwGQ@mail.gmail.com обсуждение исходный текст |
Ответ на | Re: [HACKERS] [PATCH]make pg_rewind to not copy useless WALfiles (chenhj <chjischj@163.com>) |
Ответы |
Re: [HACKERS] [PATCH]make pg_rewind to not copy useless WALfiles
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Список | pgsql-hackers |
On Thu, Sep 28, 2017 at 10:52 PM, chenhj <chjischj@163.com> wrote:
On 2017-09-29 00:43:18,"Alexander Korotkov" <a.korotkov@postgrespro.ru> wrote:On 2017-09-28 01:29:29,"Alexander Korotkov" <a.korotkov@postgrespro.ru> wrote:It appears that your patch conflicts with fc49e24f. Please, rebase it.Yes, i had rebased it, Please check the new patch.Good, now it applies cleanly.else if (strncmp(path, XLOGDIR"/", strlen(XLOGDIR"/")) == 0 &&
IsXLogFileName(path + strlen(XLOGDIR"/")) &&
(strcmp(path + strlen(XLOGDIR"/") + 8, divergence_wal_filename + 8) < 0 ||
strcmp(path + strlen(XLOGDIR"/") + 8, last_source_wal_filename + 8) > 0))According to our conding style, you should leave a space betwen XLOGDIF and "/".Also, you do a trick by comparison xlog segment numbers using strcmp(). It's nice, but I would prefer seeing XLogFromFileName() here. It would improve code readability and be less error prone during further modifications.Thanks for advice!I had modified it.
OK. Patch becomes better.
I also have more general question. Why do we need upper bound for segment number (last_source_segno)? I understand the purpose of lower bound (divergence_segno) which save us from copying extra WAL files, but what is upper bound for? As I understood, we anyway need to replay most recent WAL records to reach consistent state after pg_rewind. I propose to remove last_source_segno unless I'm missing something.
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
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