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4d27816ea5
* factor out different varbit schemes and include Beorn's "optimum" for buckets Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * use more compact dod encoding scheme for SHS chunk columns Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * remove FB VB and xor dod encoding because we won't use it Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * HistoChunk metadata encoding Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * add SparseHistogram.Copy() Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * histogram test: test appending a few histograms Signed-off-by: Dieter Plaetinck <dieter@grafana.com> * add license headers Signed-off-by: Dieter Plaetinck <dieter@grafana.com>
50 lines
3.1 KiB
Markdown
50 lines
3.1 KiB
Markdown
# Chunks Disk Format
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The following describes the format of a chunks file,
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which is created in the `chunks/` directory of a block.
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The maximum size per segment file is 512MiB.
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Chunks in the files are referenced from the index by uint64 composed of
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in-file offset (lower 4 bytes) and segment sequence number (upper 4 bytes).
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```
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┌──────────────────────────────┐
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│ magic(0x85BD40DD) <4 byte> │
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├──────────────────────────────┤
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│ version(1) <1 byte> │
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├──────────────────────────────┤
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│ padding(0) <3 byte> │
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├──────────────────────────────┤
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│ ┌──────────────────────────┐ │
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│ │ Chunk 1 │ │
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│ ├──────────────────────────┤ │
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│ │ ... │ │
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│ ├──────────────────────────┤ │
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│ │ Chunk N │ │
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│ └──────────────────────────┘ │
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└──────────────────────────────┘
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```
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# Chunk
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```
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┌───────────────┬───────────────────┬──────────────┬────────────────┐
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│ len <uvarint> │ encoding <1 byte> │ data <bytes> │ CRC32 <4 byte> │
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└───────────────┴───────────────────┴──────────────┴────────────────┘
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```
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## Histogram chunk
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```
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┌──────────────┬─────────────────┬──────────────────────────┬──────────────────────────┬──────────────┐
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│ len <uint16> │ schema <varint> │ pos-spans <span-section> │ neg-spans <span-section> │ data <bytes> │
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└──────────────┴─────────────────┴──────────────────────────┴──────────────────────────┴──────────────┘
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span-section:
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┌──────────────┬──────────────────┬──────────────────┬────────────┐
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│ len <varint> │ length1 <varint> │ offset1 <varint> │ length2... │
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└──────────────┴──────────────────┴──────────────────┴────────────┘
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```
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