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From Erick Erickson <erickerick...@gmail.com>
Subject Re: What is the best way to handle the primary key case during lucene indexing
Date Mon, 16 Nov 2009 17:45:40 GMT
What is the form of the unique key? I'm a bit confused here by your comment:
"which can contain one or multi fields".

But it seems like IndexWriter.deleteDocuments should work here. It's easy
if your PKs are single terms, there's even a deleteDocuments(Term[]) form.
But this really *requires* that your PKs are single terms in a field. If
your PKs
are some sort of composite field, perhaps the iw.DeleteDocuments(Query[])
would help where each query is enough to uniquely identify your document.

Best
Erick

On Mon, Nov 16, 2009 at 12:15 PM, java8964 java8964 <java8964@hotmail.com>wrote:

>
> Hi,
>
> In our application, we will allow the user to create a primary key defined
> in the document. We are using lucene 2.9.
> In this case, when we index the data coming from the client, if the
> metadata contains the primary key defined,
> we have to do the search/update for every row based on the primary key.
>
> Here is our current problems:
>
> 1) If the meta data coming from client defined a primary key (which can
> contain one or multi fields),
>    then for the data supplied from the client, we have to make sure that
> later row will override the previous row, if they have the same primary key
> as the data.
> 2) To do the above, we have to loop through the data first, to check if any
> later rows containing the same PK as the previous rows, so we will build the
> MAP in the memory to override the previous one by the latest ones.
> This is a very expensive operation.
> 3) Even in this case, for every row after the above filter steps, we still
> have to search the current index to see if any data with the same PK exist
> or not. So we have to do the remove before we add the new data in the index.
>
> I want to know if anyone has the same requirement like this PK using the
> lucene? What is the best way to index data in this case?
>
> First, I am thinking if it is possible to remove the above step2?
> the problem for the lucene is that when we add document in the index, we
> can NOT search it before commit it.
> But we only commit once when the whole data file is finished. So we have to
> loop through the data once to check to see if any data sharing the same PK
> in the data file.
> I am wondering if there is a way in the index writer, before it commits
> anything, when we add the new document into it, it can do the merging of the
> PK data? What I mean is that if the same PK data already exist in any
> previous added document, just remove it and let the new added data
> containing the same PK data take the place? If we can do this, then the
> whole pre checking data step can be removed.
>
> Second, for the above step 3, if the searching the existing index is NOT
> avoidable, what is the fast way to search by the PK? Of course we already
> indexed all the PK fields. When we add new data, we have to search every row
> of existing index by the PK fields, to see if it exist or not. If it does,
> remove it and add the new one.
> We constructor the query by the PK fields at run time, then search it row
> by row. This is also very bad as the indexing the data for performance.
>
> Here is what I am thinking?
> 1) Can I use the Indexreader.term(terms)? I heard it is much faster than
> the query searching? Is that right?
> 2) Currently we are do the search row by row? Should I do it in batching?
> Like I will combine 100 PK search into one search, using Boolean term? So
> one search will give me back all the data in this 100 PK which are in the
> index. Then I can remove them from the index using the result set. In this
> case, I only need to do 1/100 search requests as before? This will much
> faster than row by row in theory.
>
>
> Please let me know any feedbacks? If you ever dealed with PK data support,
> please share some thougths and experience.
>
> Thanks for your kind help.
>
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