package granary

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package granary
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Module Granary_encoding.Schema_fingerprintSource

Stable 64-bit fingerprint of a table's schema *shape*, for corruption recovery (#174 / #85), schema-drift detection on open, and replication schema-matching (#92 / #172).

The fingerprint is a pure function of the column list (names, types, and every flag that affects how a stored row decodes) plus the without_rowid flag. It deliberately excludes volatile / identity fields — the table name, tree_id, and the rowid counter — so it is stable across table renames and captures only what is required to decode a row.

It is computed with FNV-1a 64-bit over a versioned, length-delimited canonical serialization, so it is deterministic and stable across runs, machines, and library versions (unlike Hashtbl.hash).

Sourceval compute : columns:Row.column list -> without_rowid:bool -> int64

compute ~columns ~without_rowid is the 64-bit schema fingerprint.

Sourceval low32 : int64 -> int32

Low 32 bits of a fingerprint — used to stamp the 4-byte reserved page header field (#174 page-stamp).