FAQ

On Thursday, October 23, 2003, at 06:15 AM, Daniel Penning wrote:
EH> Do you have some performance numbers to go with this?

+_key:23/* -> 801 hits 80-90 ms
+24:8397 -> 10 hits <10 ms
+24:8397 +_key:23/* -> 5 hits 80-90 ms

Info: The index size is 118kb.
Thanks for the numbers.
The execution time when using a QueryFilter is nearly the same (~10ms
faster).
Keep in mind that QueryFilter will only be faster on successive uses of
it (the same instance, that is) as it caches the bitset of matching
documents, so successive calls only search the matched ones from the
first time around.

Erik


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  • Dmitry Serebrennikov at Oct 23, 2003 at 5:37 pm
    I am not familiar enough with the query parser syntax, but is the * a
    wildcard? If so, that's what is causing the extra delay. If you want to
    speed this type of query up, the QueryFilter should be probably created
    on the wildcard query, not on the most restrictive one.

    Lucene's internals are somewhat different than a typical database
    system. For instance, to execute a wildcard query, it needs to retrieve
    all tokens found in this field in all documents that match the wildcard.
    Then it turns this into an "OR" query and goes from there. Things get a
    bit better with a "starts with" type of wildcard, but it still ends up
    with some prep work and an OR-type query, I believe.

    Dmitry.


    Erik Hatcher wrote:
    On Thursday, October 23, 2003, at 06:15 AM, Daniel Penning wrote:

    EH> Do you have some performance numbers to go with this?

    +_key:23/* -> 801 hits 80-90 ms
    +24:8397 -> 10 hits <10 ms
    +24:8397 +_key:23/* -> 5 hits 80-90 ms

    Info: The index size is 118kb.

    Thanks for the numbers.
    The execution time when using a QueryFilter is nearly the same (~10ms
    faster).

    Keep in mind that QueryFilter will only be faster on successive uses
    of it (the same instance, that is) as it caches the bitset of matching
    documents, so successive calls only search the matched ones from the
    first time around.

    Erik


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postedOct 23, '03 at 12:22p
activeOct 23, '03 at 5:37p
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