[Xapian-tickets] [Xapian] #752: Segmentation fault in matcher/queryoptimiser

Xapian nobody at xapian.org
Wed Aug 9 05:46:56 BST 2017

#752: Segmentation fault in matcher/queryoptimiser
 Reporter:  rsto     |             Owner:  olly
     Type:  defect   |            Status:  assigned
 Priority:  normal   |         Milestone:  1.4.5
Component:  Matcher  |           Version:  git master
 Severity:  normal   |        Resolution:
 Keywords:           |        Blocked By:
 Blocking:           |  Operating System:  All

Comment (by olly):

 I've compared the current approach of handing over ownership of the hint
 to the `QueryOptimiser` object with just setting the hint to `NULL` in
 situations where it might be invalidated.

 The differences each way in my tests were very small, and similar in size
 but in opposite directions.  As you'd expect, handing over ownership
 incurs a little extra overhead; but the gain in a small-scale test for the
 hint being set when it gets used was also small.

 I think the conclusion is actually to keep the ownership mechanism -
 although it didn't give us a big gain in my tests, those were small scale
 tests and the gain with a larger database should be greater, while
 overhead for tracking ownership is essentially fixed.  The key point is
 really that that we pay a small fixed cost which can save us nothing to

Ticket URL: <https://trac.xapian.org/ticket/752#comment:4>
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