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From shanghaihyj <>
Subject Re:Re: Why Two Levels of Indirection in BytesRefHash class ?
Date Mon, 09 May 2016 02:20:28 GMT
I see. 
Yes, if a logical mapping of "byte[] ---> (offset and*arbitrary data)" is required, this
indirection is necessary.

Yijian Huang

At 2016-05-08 23:06:14,"Adrien Grand" <> wrote:
>That would work if you are only interested in using BytesRefHash as a hash
>set for byte[]. However these incremental ids are useful if you want to
>associate data with each byte[]: you can create parallel arrays and use the
>ids returned by the BytesRefHash as indices in these arrays.
>Le dim. 8 mai 2016 à 14:45, shanghaihyj <> a écrit :
>> I'm studying the BytesRefHash class, a mapping from bytes to a generated
>> ID for the bytes.
>> In the BytesRefHash class, there are two levels of reference:
>> (1) ids[bytes' hash code] ---> count, where count is the self-incremental
>> size of the this hashmap.
>> (2) bytesStart[count] ---> offset in the ByteBlockPool, where the original
>> bytes are stored.
>> My question is, can the above two references be collapsed into one, as
>> follows ?
>> ids[bytes' hash code] ---> offset in the ByteBlockPool.
>> I've searched the code, and cannot grab an idea what's the benefit to have
>> another indirection via bytesStart.
>> p.s. Regarding such questions about Lucene source code, should I ask in
>> instead ? These questions may be too easy and thus
>> bothering to the developers...
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