[Xapian-tickets] [Xapian] #696: Use after free with WILDCARD_LIMIT_MOST_FREQUENT

[Xapian]

#696: Use after free with WILDCARD_LIMIT_MOST_FREQUENT
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 Reporter:  coventry                           |             Owner:  olly
     Type:  defect                             |            Status:
                                               |  assigned
 Priority:  normal                             |         Milestone:  1.3.4
Component:  Library API                        |           Version:  1.3.3
 Severity:  major                              |        Resolution:
 Keywords:  1.3.3 segfault git master 9c9213d  |        Blocked By:
 Blocking:                                     |  Operating System:  Linux
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Comment (by olly):

 Should be fixed by [2299e1d21e39f1295c81833ccd5037f746f4744a].  Can you
 confirm that deals with the segfaults?

 That bug doesn't explain the OOM errors - I think they are likely mostly
 down to the memory used by the postlists for all the terms the wildcard
 expands to.

 I'd expect you can avoid those by using the "glass" backend (not the
 default yet) - glass reference counts cursor blocks, which makes a huge
 difference to wildcards (because all the terms are together and so most of
 the cursor blocks can be reused several times over).

 The downside is that the on-disk format for glass isn't completely fixed
 yet, so you potentially need to reindex after an upgrade.  The simplest
 way to select it is probably just to `export XAPIAN_PREFER_GLASS=1` before
 running the indexer - that changes the default when creating a new
 database.

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Ticket URL: <http://trac.xapian.org/ticket/696#comment:8>
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