Re: Reviewing freeze map code

On Thu, Jul 7, 2016 at 3:36 AM, Andres Freund <andres(at)anarazel(dot)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