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https://issues.apache.org/jira/browse/LUCENE-855?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Shai Erera closed LUCENE-855.
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Resolution: Duplicate
We already have FieldCacheRangeFilter (introduced in LUCENE-1461), so closing
as duplicate.
> MemoryCachedRangeFilter to boost performance of Range queries
> -------------------------------------------------------------
>
> Key: LUCENE-855
> URL: https://issues.apache.org/jira/browse/LUCENE-855
> Project: Lucene - Java
> Issue Type: Improvement
> Components: Search
> Affects Versions: 2.1
> Reporter: Andy Liu
> Attachments: contrib-filters.tar.gz, FieldCacheRangeFilter.patch,
> FieldCacheRangeFilter.patch, FieldCacheRangeFilter.patch,
> FieldCacheRangeFilter.patch, FieldCacheRangeFilter.patch,
> FieldCacheRangeFilter.patch, FieldCacheRangeFilter_Lucene_2.3.0.patch,
> MemoryCachedRangeFilter.patch, MemoryCachedRangeFilter_1.4.patch,
> TestRangeFilterPerformanceComparison.java,
> TestRangeFilterPerformanceComparison.java
>
>
> Currently RangeFilter uses TermEnum and TermDocs to find documents that fall
> within the specified range. This requires iterating through every single
> term in the index and can get rather slow for large document sets.
> MemoryCachedRangeFilter reads all <docId, value> pairs of a given field,
> sorts by value, and stores in a SortedFieldCache. During bits(), binary
> searches are used to find the start and end indices of the lower and upper
> bound values. The BitSet is populated by all the docId values that fall in
> between the start and end indices.
> TestMemoryCachedRangeFilterPerformance creates a 100K RAMDirectory-backed
> index with random date values within a 5 year range. Executing bits() 1000
> times on standard RangeQuery using random date intervals took 63904ms. Using
> MemoryCachedRangeFilter, it took 876ms. Performance increase is less
> dramatic when you have less unique terms in a field or using less number of
> documents.
> Currently MemoryCachedRangeFilter only works with numeric values (values are
> stored in a long[] array) but it can be easily changed to support Strings. A
> side "benefit" of storing the values are stored as longs, is that there's no
> longer the need to make the values lexographically comparable, i.e. padding
> numeric values with zeros.
> The downside of using MemoryCachedRangeFilter is there's a fairly significant
> memory requirement. So it's designed to be used in situations where range
> filter performance is critical and memory consumption is not an issue. The
> memory requirements are: (sizeof(int) + sizeof(long)) * numDocs.
> MemoryCachedRangeFilter also requires a warmup step which can take a while to
> run in large datasets (it took 40s to run on a 3M document corpus). Warmup
> can be called explicitly or is automatically called the first time
> MemoryCachedRangeFilter is applied using a given field.
> So in summery, MemoryCachedRangeFilter can be useful when:
> - Performance is critical
> - Memory is not an issue
> - Field contains many unique numeric values
> - Index contains large amount of documents
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