Re: Corrupted index

Akash Garg <akash(dot)garg(at)gmail(dot)com> writes:
> Ok, I ran that command on the index files -- they are attached.

I'm a bit confused --- you mean you extracted block 41661 from each of
the index's segments? If so, only the first one is actually relevant
here.

> I notice that in file2, file2 and file3, I notice a pattern like this:
> 0002660 8980 0020 8970 0020 8960 0020 8950 0020
> 0002700 8940 0020 8930 0020 8920 0020 8910 0020
> 0002720 0900 0020 0000 0000 0000 0000 0000 0000
> 0002740 0000 0000 0000 0000 0000 0000 0000 0000
> *
> 0004400 000f 611c 003e 0010 70d9 0b69 0000 0000
> 0004420 000f 5f97 0003 0010 70d8 0b69 0000 0000
> 0004440 000f 6118 0077 0010 70d7 0b69 0000 0000
> 0004460 000f 6118 0075 0010 70d6 0b69 0000 0000

That's what it should look like --- "*" is od's notation for "more of
the same", in this case lines containing all zeroes. Those pages look
exactly like what I'd expect a PG index page to look like.

The file1 extract, however, is pure text and not PG data of any kind.
The first part of it looks like

00000000: 732c 205c 725c 6e77 6861 7420 646f 6573 s, \r\nwhat does
00000010: 2061 2068 756d 616e 6974 6172 6961 6e20 a humanitarian
00000020: 6561 743f 205c 725c 6e5c 725c 6e53 6f6d eat? \r\n\r\nSom
00000030: 6574 696d 6573 2c20 4920 7468 696e 6b20 etimes, I think
00000040: 616c 6c20 7468 6520 666f 6c6b 7320 7768 all the folks wh
00000050: 6f20 6772 6577 2075 7020 7370 6561 6b69 o grew up speaki
00000060: 6e67 2045 6e67 6c69 7368 205c 725c 6e73 ng English \r\ns
00000070: 686f 756c 6420 6265 2063 6f6d 6d69 7474 hould be committ
00000080: 6564 2074 6f20 616e 2061 7379 6c75 6d20 ed to an asylum
00000090: 666f 7220 7468 6520 7665 7262 616c 6c79 for the verbally
000000a0: 2069 6e73 616e 652e 205c 725c 6e5c 725c insane. \r\n\r\
000000b0: 6e49 6e20 7768 6174 206f 7468 6572 206c nIn what other l

and it goes downhill from there (something out of a spam folder maybe?)

What it looks like to me is that a page of an entirely unrelated file
got dropped into the Postgres index. This suggests either a disk drive
error (writing someplace else than it was commanded to) or a kernel
bug (writing the wrong buffer). I'd suggest some disk-drive testing
as well as checking into bug fixes for your kernel. I'm pretty well
convinced that this wasn't Postgres' fault.

regards, tom lane