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2022-07-23 07:28:33 +00:00
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# mdb
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2022-07-25 05:39:16 +00:00
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An in-process, in-memory database for Go.
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## TO DO
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2022-07-25 21:16:58 +00:00
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* [ ] kvstore: tests
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2022-07-25 05:39:16 +00:00
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## Structure
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### Files
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```
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wal/<id>/data
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wal/<id>/length
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wal/<id>/archived
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max-committed-id
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write-lock
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commit-lock
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```
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`<day-ts>` is the unix timestamp / 86400. Therefore a new segment will be
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created every day. The data file is append-only, and the length is written
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atomically.
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`write-lock` is used by `flock` to ensure there's only one
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writer. `commit-lock` is used by the commit routine. This routine will commit
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data to the database and update `max-committed-id` atomically.
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### Code
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```
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retry/
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wal/
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segment/
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storage/
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```
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## WAL File Format
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The WAL file consists of an 8 byte minimum ID followed by a stream of entries
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of the form
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```
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(4) Data length
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(Data length) Data
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(8) ID.
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```
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This allows us to quickly get the min and max IDs from the file, and iterate
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though the segment from the beginning.
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