Re: Reviewing freeze map code

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От Amit Kapila
Тема Re: Reviewing freeze map code
Дата
Msg-id CAA4eK1L4U0JOvyPya2ykuH45waHfdF0NqmNaf20Nr+ULuw8ZbQ@mail.gmail.com
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Ответ на Re: Reviewing freeze map code  (Andres Freund <andres@anarazel.de>)
Список pgsql-hackers
On Thu, Jul 7, 2016 at 3:36 AM, Andres Freund <andres@anarazel.de> wrote:
> On 2016-07-05 23:37:59 +0900, Masahiko Sawada wrote:
>
>> @@ -8694,6 +8761,23 @@ heap_xlog_lock(XLogReaderState *record)
>>               }
>>               HeapTupleHeaderSetXmax(htup, xlrec->locking_xid);
>>               HeapTupleHeaderSetCmax(htup, FirstCommandId, false);
>> +
>> +             /* The visibility map need to be cleared */
>> +             if ((xlrec->infobits_set & XLHL_ALL_VISIBLE_CLEARED) != 0)
>> +             {
>> +                     RelFileNode     rnode;
>> +                     Buffer          vmbuffer = InvalidBuffer;
>> +                     BlockNumber     blkno;
>> +                     Relation        reln;
>> +
>> +                     XLogRecGetBlockTag(record, 0, &rnode, NULL, &blkno);
>> +                     reln = CreateFakeRelcacheEntry(rnode);
>> +
>> +                     visibilitymap_pin(reln, blkno, &vmbuffer);
>> +                     visibilitymap_clear(reln, blkno, vmbuffer);
>> +                     PageClearAllVisible(page);
>> +             }
>> +
>
>
>>               PageSetLSN(page, lsn);
>>               MarkBufferDirty(buffer);
>>       }
>> diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h
>> index a822d0b..41b3c54 100644
>> --- a/src/include/access/heapam_xlog.h
>> +++ b/src/include/access/heapam_xlog.h
>> @@ -242,6 +242,7 @@ typedef struct xl_heap_cleanup_info
>>  #define XLHL_XMAX_EXCL_LOCK          0x04
>>  #define XLHL_XMAX_KEYSHR_LOCK        0x08
>>  #define XLHL_KEYS_UPDATED            0x10
>> +#define XLHL_ALL_VISIBLE_CLEARED 0x20
>
> Hm. We can't easily do that in the back-patched version; because a
> standby won't know to check for the flag . That's kinda ok, since we
> don't yet need to clear all-visible yet at that point of
> heap_update. But that better means we don't do so on the master either.
>

To clarify, do you mean to say that lets have XLHL_ALL_FROZEN_CLEARED
and do that just for master.  For back-branches no need to clear
visibility any flags?

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



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