[Xapian-tickets] [Xapian] #615: xapian-compact -m (multipass) trashes value 0 (chert 1.2.13)

[Xapian]

#615: xapian-compact -m (multipass) trashes value 0 (chert 1.2.13)
---------------------------+------------------------------------------------
 Reporter:  mjy            |       Owner:  olly  
     Type:  defect         |      Status:  new   
 Priority:  normal         |   Milestone:        
Component:  Backend-Chert  |     Version:  1.2.13
 Severity:  normal         |    Keywords:        
Blockedby:                 |    Platform:  Linux 
 Blocking:                 |  
---------------------------+------------------------------------------------

Old description:

> When compacting multiple databases into one with xapian-compact, the
> option -m causes data corruption at value 0 of the document (sometimes?).
> xapian-check reports this on the created database:
>
> [...]
> Value slot 0 has value above upper bound: ' ' > ''
> Value slot 0 has value above upper bound: ' ' > ''
> Value slot 0 has value above upper bound: ' ' > ''
> Value slot 0 has value above upper bound: '¨' > ''
> Value slot 0 has value above upper bound: ' ' > ''
>
> The resulting database will be fine without -m though (with and without
> --no-renumber).
>
> This can be reproduced with a set of databases created with 1.2.13, Linux
> x86-64 (total size 643MB and confidential-ish, so not attaching).

New description:

 When compacting multiple databases into one with xapian-compact, the
 option -m causes data corruption at value 0 of the document (sometimes?).
 xapian-check reports this on the created database:

 {{{
 [...]
 Value slot 0 has value above upper bound: ' ' > ''
 Value slot 0 has value above upper bound: ' ' > ''
 Value slot 0 has value above upper bound: ' ' > ''
 Value slot 0 has value above upper bound: '¨' > ''
 Value slot 0 has value above upper bound: ' ' > ''
 }}}

 The resulting database will be fine without -m though (with and without
 --no-renumber).

 This can be reproduced with a set of databases created with 1.2.13, Linux
 x86-64 (total size 643MB and confidential-ish, so not attaching).

--

Comment(by olly):

 Are you putting anything in value slot 0?  If not, are you value slots at
 all?

 I'm not clear if the bounds are getting updated incorrectly, or if we're
 somehow accidentally creating entries in slot 0 which shouldn't be there.

 Also, how many databases are you merging?

-- 
Ticket URL: <http://trac.xapian.org/ticket/615#comment:1>
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