Mailing List Archive

> From: jean-christian.gagne@prasahewitt.ch
>
> It looks like Lucene supports concurrent searchs as long as
> the index is not
> modified with add, delete, or optimize actions (and maybe
> others?).

Searches may be made at any time, including while the index is being
modified by the add, delete and optimize operations.

> For those
> actions, it is not clear what is happening (at least for me) with open
> searchers, readers and writers. Can those be reused freely ?
> When should they be opened/closed ?

Searchers and readers may be used freely until they are closed. A single
searcher and reader may be shared by many threads, conducting concurrent
searches. That is in fact recommended. A reader will close itself when
garbage collected, so don't worry about explicitly closing readers (unless
you are near yout file descriptor limit).

Only a single writer should exist at once. Readers opened after it is
closed will see the changes made to it.

> Can I add/delete documents while another
> thread is looping on
> Hits ?

Yes.

> A brief summary of what can/cannot be done when modifying an
> index (and related
> issues) would be very appreciated.

The prohibitions are:
- don't use a reader/writer after it has been closed;
- don't try to write simultaneously from different processes

Doug

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Thanks a lot for the complete answer Doug !

JCG




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