[Xapian-tickets] [Xapian] #333: Keep track of last modification time of database

[Xapian]

#333: Keep track of last modification time of database
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 Reporter:  richard        |       Owner:  olly     
     Type:  enhancement    |      Status:  new      
 Priority:  normal         |   Milestone:           
Component:  Backend-Chert  |     Version:  SVN trunk
 Severity:  normal         |   Blockedby:           
 Platform:  All            |    Blocking:           
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 It would be useful to be able to find out the time at which a modification
 was last made to a database.  Two possible uses for this information:

  - supporting caching in an HTTP search server: for example, this would
 allow if-modified-since requests to be satisfied without having to perform
 a search (when not modified since).

  - displaying status information about a database to users.

 To implement this, we'd need to store the modification time in the
 database somewhere, since we want to know the time of the last successful
 commit; this can't be derived by looking at the timestamp of the files,
 since it's possible that a commit nearly happened, but was cancelled or
 failed at the last minute (or, indeed, since we use fdatasync(), that a
 commit succeeded, but the timestamp information about the file
 modification never got written to disk due to a machine crash immediately
 after the commit).

 This could be emulated by storing the current time in a metadata value
 each time that flush() is called, but this wouldn't cover modifications
 made by implicit flushes.  Currently, to implement this correctly on top
 of xapian, you'd need to use explicit transactions.

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Ticket URL: <http://trac.xapian.org/ticket/333>
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