Package org.apache.lucene.util.packed
Class DirectWriter
java.lang.Object
org.apache.lucene.util.packed.DirectWriter
Class for writing packed integers to be directly read from Directory. Integers can be read
on-the-fly via
DirectReader.
Unlike PackedInts, it optimizes for read i/o operations and supports > 2B values. Example usage:
int bitsPerValue = DirectWriter.bitsRequired(100); // values up to and including 100
IndexOutput output = dir.createOutput("packed", IOContext.DEFAULT);
DirectWriter writer = DirectWriter.getInstance(output, numberOfValues, bitsPerValue);
for (int i = 0; i < numberOfValues; i++) {
writer.add(value);
}
writer.finish();
output.close();
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Method Summary
Modifier and TypeMethodDescriptionvoidadd(long l) Adds a value to this writerstatic intbitsRequired(long maxValue) Returns how many bits are required to hold values up to and including maxValuevoidfinish()finishes writingstatic DirectWritergetInstance(DataOutput output, long numValues, int bitsPerValue) Returns an instance suitable for encodingnumValuesusingbitsPerValuestatic intunsignedBitsRequired(long maxValue) Returns how many bits are required to hold values up to and including maxValue, interpreted as an unsigned value.
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Method Details
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add
Adds a value to this writer- Throws:
IOException
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finish
finishes writing- Throws:
IOException
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getInstance
Returns an instance suitable for encodingnumValuesusingbitsPerValue -
bitsRequired
public static int bitsRequired(long maxValue) Returns how many bits are required to hold values up to and including maxValue- Parameters:
maxValue- the maximum value that should be representable.- Returns:
- the amount of bits needed to represent values from 0 to maxValue.
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unsignedBitsRequired
public static int unsignedBitsRequired(long maxValue) Returns how many bits are required to hold values up to and including maxValue, interpreted as an unsigned value.- Parameters:
maxValue- the maximum value that should be representable.- Returns:
- the amount of bits needed to represent values from 0 to maxValue.
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