Re:could not access status of transaction

Hi,

This database has not had the same failure again 2019/09/16(reported at 2019/09/29), so this is a very low probability failure, but it is uncertain whether it will happen again in the future. Now add some information for incident at 2019/09/16, may be useful for analyze the cause of this problem.

> Block 32291 ********************************************************
> <Header> -----
> Block Offset: 0x0fc46000 Offsets: Lower 236 (0x00ec)
> Block: Size 8192 Version 4 Upper 2112 (0x0840)
> LSN: logid 254 recoff 0xa3a598c8 Special 8192 (0x2000)
> Items: 53 Free Space: 1876
> Checksum: 0x8355 Prune XID: 0x02186566 Flags: 0x0001 (HAS_FREE_LINES)
> Length (including item array): 236
> ...
> Item 8 -- Length: 151 Offset: 4696 (0x1258) Flags: NORMAL
> XMIN: 35153480 XMAX: 35153545 CID|XVAC: 0
> Block Id: 163363 linp Index: 9 Attributes: 20 Size: 32
> infomask: 0x2503 (HASNULL|HASVARWIDTH|XMIN_COMMITTED|XMAX_COMMITTED|UPDATED|HOT_UPDATED|HEAP_ONLY)
> t_bits: [0]: 0xff [1]: 0xff [2]: 0x07
>
>
>
> Item 9 -- Length: 151 Offset: 4544 (0x11c0) Flags: NORMAL
> XMIN: 35153545 XMAX: 0 CID|XVAC: 0
> Block Id: 163363 linp Index: 9 Attributes: 20 Size: 32
> infomask: 0x2803 (HASNULL|HASVARWIDTH|XMAX_INVALID|UPDATED|HEAP_ONLY)
> t_bits: [0]: 0xff [1]: 0xff [2]: 0x07

According to above information, the flags of the heap page (163363) with the problem tuple (163363, 9) is 0x0001 (HAS_FREE_LINES), that is, ALL_VISIBLE is not set.

However, according hexdump content of the corresponding vm file, that block(location is 9F88 + 6bit) has set VISIBILITYMAP_ALL_FROZEN and VISIBILITYMAP_ALL_VISIBLE flags. That is, the heap file and the vm file are inconsistent.

# vi 19548_vm.hexdump

0000000 0215 0000 0858 857c 8cee 0000 0018 2000
0000010 2000 2004 0000 0000 ffff ffff ffff ffff
0000020 ffff ffff ffff ffff ffff ffff ffff ffff
*
0002000 0215 0000 1680 857c 3bb1 0000 0018 2000
0002010 2000 2004 0000 0000 ffff ffff ffff ffff
0002020 ffff ffff ffff ffff ffff ffff ffff ffff
*
0004000 0215 0000 20e8 857c 07f7 0000 0018 2000
0004010 2000 2004 0000 0000 ffff ffff ffff ffff
0004020 ffff ffff ffff ffff ffff ffff ffff ffff
*
0006000 0215 0000 3618 857c 4792 0000 0018 2000
0006010 2000 2004 0000 0000 ffff ffff ffff ffff
0006020 ffff ffff ffff ffff ffff ffff ffff ffff
*
0008000 0215 0000 17a8 8580 3d7e 0000 0018 2000
0008010 2000 2004 0000 0000 ffff ffff ffff ffff
0008020 ffff ffff ffff ffff ffff ffff ffff ffff
*
000a000 0215 0000 3558 8585 1239 0000 0018 2000
000a010 2000 2004 0000 0000 ffff ffff ffff ffff
000a020 ffff ffff ffff ffff ffff ffff ffff ffff
*
000c000 0215 0000 72a8 871b 1a23 0000 0018 2000
000c010 2000 2004 0000 0000 ffff ffff ffff ffff
000c020 ffff ffff ffff ffff ffff ffff ffff ffff
...
000e000 0215 0000 93d0 8794 506a 0000 0018 2000
000e010 2000 2004 0000 0000 fc03 ffff ffff ffff
000e020 ffff f3ff cccf fffc ffff ffff f3cf ff3f
...
000f6c0 3f0f 3303 c33f 00f0 00c3 0303 0003 0000
000f6d0 0000 0000 0000 0000 0000 0000 0000 0000
*
0010000

Regards,
Chen Huajun