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LUCENE-4447: fixups for .doc/skipdata

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git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1396610 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Robert Muir 2012-10-10 14:07:44 +00:00
parent e4b5a7d907
commit 01a284047e
1 changed files with 18 additions and 4 deletions
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22
lucene/codecs/src/java/org/apache/lucene/codecs/block/BlockPostingsFormat.java
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@ -199,7 +199,7 @@ import org.apache.lucene.util.packed.PackedInts;
* <li>SkipDatum --&gt; DocSkip, DocFPSkip, &lt;PosFPSkip, PosBlockOffset, PayLength?,
* PayFPSkip?&gt;?, SkipChildLevelPointer?</li>
* <li>PackedDocDeltaBlock, PackedFreqBlock --&gt; {@link PackedInts PackedInts}</li>
* <li>DocDelta, Freq, DocSkip, DocFPSkip, PosFPSkip, PosBlockOffset, PayLength, OffsetStart, PayFPSkip
* <li>DocDelta, Freq, DocSkip, DocFPSkip, PosFPSkip, PosBlockOffset, PayByteUpto, PayFPSkip
* --&gt;
* {@link DataOutput#writeVInt VInt}</li>
* <li>SkipChildLevelPointer --&gt; {@link DataOutput#writeVLong VLong}</li>
@ -216,8 +216,21 @@ import org.apache.lucene.util.packed.PackedInts;
* If frequencies are not omitted, PackedFreqBlock will be generated without d-gap step.
* </li>
* <li>VIntBlock stores remaining d-gaps (along with frequencies when possible) with a format
* mentioned in
* <a href="{@docRoot}/../core/org/apache/lucene/codecs/lucene40/Lucene40PostingsFormat.html#Frequencies">Lucene40PostingsFormat:Frequencies</a>
* that encodes DocDelta and Freq:
* <p>DocDelta: if frequencies are indexed, this determines both the document
* number and the frequency. In particular, DocDelta/2 is the difference between
* this document number and the previous document number (or zero when this is the
* first document in a TermFreqs). When DocDelta is odd, the frequency is one.
* When DocDelta is even, the frequency is read as another VInt. If frequencies
* are omitted, DocDelta contains the gap (not multiplied by 2) between document
* numbers and no frequency information is stored.</p>
* <p>For example, the TermFreqs for a term which occurs once in document seven
* and three times in document eleven, with frequencies indexed, would be the
* following sequence of VInts:</p>
* <p>15, 8, 3</p>
* <p>If frequencies were omitted ({@link IndexOptions#DOCS_ONLY}) it would be this
* sequence of VInts instead:</p>
* <p>7,4</p>
* </li>
* <li>PackedDocBlockNum is the number of packed blocks for current term's docids or frequencies.
* In particular, PackedDocBlockNum = floor(DocFreq/PackedBlockSize) </li>
@ -244,7 +257,8 @@ import org.apache.lucene.util.packed.PackedInts;
* which value to fetch inside the related block (PayBlockOffset is unnecessary since it is always
* equal to PosBlockOffset). Same as DocFPSkip, the file offsets are relative to the start of
* current term's TermFreqs, and stored as a difference sequence.</li>
* <li>PayLength indicates the length of last payload.</li>
* <li>PayByteUpto indicates the start offset of the current payload. It is equivalent to
* the sum of the payload lengths in the current block up to PosBlockOffset</li>
* </ul>
* </dd>
* </dl>