5.5 Value Operations

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5.5.1 RSI_QUERY_VALUES #

Returns every layer's entry for one value, or for all of a key's values when the request sets the query-all flag:

-- single value
SELECT name, layer, type, data, sequence
FROM main.[values] WHERE key_guid = ? AND name_folded = ?
UNION ALL
SELECT name, layer, type, data, sequence
FROM volatile.[values] WHERE key_guid = ? AND name_folded = ?

-- query all
SELECT name, layer, type, data, sequence
FROM main.[values] WHERE key_guid = ?
UNION ALL
SELECT name, layer, type, data, sequence
FROM volatile.[values] WHERE key_guid = ?

The response also carries the key's blanket-tombstone state:

SELECT layer, sequence
FROM main.blanket_tombstones WHERE key_guid = ?
UNION ALL
SELECT layer, sequence
FROM volatile.blanket_tombstones WHERE key_guid = ?

Value entries and blanket tombstones are both sorted (§5.2).

An unresolvable GUID returns RSI_NOT_FOUND. An existing key with no values returns RSI_OK with empty arrays.

5.5.2 RSI_SET_VALUE #

The store containing the key selects the target table (§5.1). A key GUID in neither store returns RSI_NOT_FOUND.

INSERT OR REPLACE INTO [values]
    (key_guid, name, name_folded, layer, type, data, sequence)
VALUES (?, ?, fold(?), ?, ?, ?, ?)

5.5.2.1 Conditional writes #

When the request carries a non-zero expected_sequence, the write is a compare-and-swap. loregd reads the current entry's sequence and writes only if it matches:

SELECT sequence FROM [values]
WHERE key_guid = ? AND name_folded = ? AND layer = ?

If the row is absent, or its sequence differs, the operation returns RSI_CAS_FAILED and writes nothing.

Outside a transaction, the check and the write are wrapped in their own BEGIN IMMEDIATE transaction so no other writer can interleave. If that transaction cannot begin because the database is busy, the operation returns RSI_TXN_BUSY. Inside a transaction, the caller's transaction already provides the isolation.

5.5.3 RSI_DELETE_VALUE_ENTRY #

Removes one layer's entry for one value, from both stores:

DELETE FROM [values]
WHERE key_guid = ? AND name_folded = ? AND layer = ?

No rows-affected check, so deleting an absent entry succeeds. A GUID that resolves to no hive returns RSI_NOT_FOUND.

5.5.4 RSI_SET_BLANKET_TOMBSTONE #

Sets or clears the tombstone that masks every value a key holds in lower layers. The store containing the key selects the target table (§5.1). A GUID in neither returns RSI_NOT_FOUND.

-- set
INSERT OR REPLACE INTO blanket_tombstones (key_guid, layer, sequence)
VALUES (?, ?, ?)

-- clear
DELETE FROM blanket_tombstones WHERE key_guid = ? AND layer = ?

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