-- The data a module declares, as the mesh found it on each machine (novox/hq ADR 0233).
--
-- A module's manifest says what data it keeps and of which class. The self-check asks each machine's
-- backup holder what it measured of every declared item — its size, its last write, its last good
-- backup — and keeps that here: so a shrink is read against what the item held before, an item a
-- machine no longer declares is still known to be there, and an empty copy of an item is told from a
-- full one somewhere else.
--
-- **Keyed by the machine's name, not a reference.** The data outlives the machine record, as a
-- binding's provider does (migration 0071): a machine leaving the mesh must not turn the record of
-- what it holds into nothing.
--
-- **Retired, never removed.** An irreplaceable or valuable item in a module's own directory that its
-- machine no longer declares — its module unassigned — is marked retired, with when and why, and stays
-- until a person deletes it through `cleanup delete` (ADR 0230); the deletion is recorded here too,
-- never by dropping the row. An item on an operator's path (an access) is never the mesh's to retire.
--
-- Numbered 0072, past 0071, the highest on main or any open branch when this was written.
create table data_item (
    machine      text        not null,
    module       text        not null,
    item         text        not null,
    class        text        not null,
    -- Whether it is in the module's own directory (the mesh's to retire) or an operator's path, and
    -- how it is protected: backup, redundancy, both, or none.
    owned        boolean     not null default true,
    protection   text        not null default '',
    -- Where it is on the machine, as the backup holder last said; empty until one has.
    path         text        not null default '',
    first_seen   timestamptz not null default now(),
    -- When a composition of the machine last declared it.
    declared_at  timestamptz not null default now(),
    -- The newest measurement: size in bytes, the newest write inside it, and when it was measured.
    size_bytes   bigint,
    last_write   timestamptz,
    measured_at  timestamptz,
    -- The newest good backup that covers it.
    last_backup  timestamptz,
    -- What the holder could not measure, when it could not: the path gone, a walk refused.
    measure_error text,
    -- What the newest size is: exact, a dataset's whole size, partial (a lower bound) or none.
    precision     text,
    -- The redundant storage it is on, as the holder read it: zfs, md or btrfs, which pool or device,
    -- whether it is healthy, and what it said.
    redundancy_kind    text,
    redundancy_where   text,
    redundancy_healthy boolean,
    redundancy_said    text,
    retired_at   timestamptz,
    retired_why  text,
    deleted_at   timestamptz,
    deleted_by   text,
    deleted_why  text,
    primary key (machine, module, item)
);

-- One row per measurement kept, at most one an hour per item, for ninety days: what a shrink is
-- read against. Only a comparable size is kept: exact, or a dataset's own counters — never a partial
-- walk's lower bound.
create table data_reading (
    machine     text        not null,
    module      text        not null,
    item        text        not null,
    at          timestamptz not null,
    size_bytes  bigint      not null,
    last_write  timestamptz,
    primary key (machine, module, item, at)
);