SkipLevelLength
SkipLevel
SkipLevelLength
SkipLevel
SkipLevel
... ...
level = N
level = 1
level = 0
SkipDatum
SkipDatum
... ...
DocSkip
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PosFPSkip
PosBlockOffset
PayLength
PayFPSkip
ImpactsLength
Impacts
SkipChildLevelPointer
Header
TermFreqs
SkipData
TermFreqs
SkipData
Footer
... ...
索引文件.doc（Lucene 8.4.0）
SkipDatum
SkipDatum
SkipDatum
SkipDatum
... ...
DocSkip
DocFPSkip
PosFPSkip
PosBlockOffset
PayLength
PayFPSkip
ImpactsLength
Impacts
Impact
Impact
Impact
... ...
freq
freq
normValue
