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https://issues.apache.org/jira/browse/LUCENE-9619?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17237347#comment-17237347
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Adrien Grand commented on LUCENE-9619:
--------------------------------------
Here is what I have in mind in terms of API. The main downside compared to
today is that it makes more assumptions about how points are implemented under
the hood, e.g. it suggests a tree structure, which the current API doesn't. But
I like that it would give us more control over how matching is performed as
mentioned in the issue description. I still tried to push too many requirements
to possible implementations, e.g. not enforcing an arity of 2 on inner nodes
and not enforcing that the tree is balanced.
{code:java}
import java.io.IOException;
import java.util.function.IntConsumer;
import org.apache.lucene.search.DocIdSetIterator;
public abstract class PointValues {
/* Global statistics, that don't change when moving from a node to another
node. */
/** Returns how many dimensions are represented in the values */
public abstract int getNumDimensions() throws IOException;
/** Returns how many dimensions are used for the index */
public abstract int getNumIndexDimensions() throws IOException;
/** Returns the number of bytes per dimension */
public abstract int getBytesPerDimension() throws IOException;
/** Return the total number of documents that have a value for this field,
across all nodes. */
public abstract int getTotalDocCount();
/* Per-node statistics */
/** Return the minimum packed value of the current node. */
public abstract byte[] getMinPackedValue();
/** Return the maximum packed value of the current node. */
public abstract byte[] getMaxPackedValue();
/** Return the total number of points under the current node. On the root
node this returns the
* total number of points in the field on the current segment. */
public abstract long size();
/* API to walk the tree. */
/** Move to the first child node and return {@code true} upon success.
Returns {@code false} for
* leaf nodes and {@code true} otherwise. */
public abstract boolean moveToChild();
/** Move to the parent node and return {@code true} upon success. Returns
{@code false} for the
* root node and {@code true} otherwise. */
public abstract boolean moveToParent();
/** Move to the next sibling node and return {@code true} upon success.
Returns {@code false} if
* the current node has no more siblings. */
public abstract boolean moveToSibling();
/** A visitor for the content of the tree. */
@FunctionalInterface
public interface IntersectVisitor {
/** Called for all documents in a leaf cell that crosses the query. The
consumer
* should scrutinize the packedValue to decide whether to accept it. In
the 1D case,
* values are visited in increasing order, and in the case of ties, in
increasing
* docID order. */
void visit(int docID, byte[] packedValue) throws IOException;
/** Similar to {@link IntersectVisitor#visit(int, byte[])} but in this case
the packedValue
* can have more than one docID associated to it. The provided iterator
should not escape the
* scope of this method so that implementations of PointValues are free to
reuse it,*/
default void visit(DocIdSetIterator iterator, byte[] packedValue) throws
IOException {
int docID;
while ((docID = iterator.nextDoc()) != DocIdSetIterator.NO_MORE_DOCS) {
visit(docID, packedValue);
}
}
}
/** Visit all (document,value) pairs under the current node. {@link
IntersectVisitor#visit} will
* be called {@link #size()} times. */
public abstract void intersect(IntersectVisitor visitor);
/** Visit all documents under the current node. {@link IntConsumer#accept}
will be called
* {@link #size()} times. */
public abstract void intersectAll(IntConsumer visitor);
}
{code}
Opinions?
> Move Points from a visitor API to a custor-style API?
> -----------------------------------------------------
>
> Key: LUCENE-9619
> URL: https://issues.apache.org/jira/browse/LUCENE-9619
> Project: Lucene - Core
> Issue Type: Improvement
> Reporter: Adrien Grand
> Priority: Minor
>
> Points' visitor API work well but there are a couple things we could make
> better if we moved to a cursor API, e.g.
> - Term queries could return a DocIdSetIterator without having to materialize
> a BitSet.
> - Nearest-neighbor search could work on top of the regular API instead of
> casting to BKDReader
> https://github.com/apache/lucene-solr/blob/6a7131ee246d700c2436a85ddc537575de2aeacf/lucene/sandbox/src/java/org/apache/lucene/sandbox/document/FloatPointNearestNeighbor.java#L296
> - We could optimize counting the number of matches of a query by adding the
> number of points in a leaf without visiting documents where there are no
> deleted documents and a leaf fully matches the query.
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