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Last Value Cache

Sub-10 ms access to the latest state of each time series. Uses a trigger-maintained cache table with PRIMARY KEY on the key columns — writes upsert into the cache automatically.

enable_lvc(p_table_name, p_key_columns, p_value_columns, p_schema_name)​

Creates the cache table _lvc_{table} and installs an AFTER INSERT trigger that upserts the latest row on every insert to the source ChronoTable.

ParameterTypeDefaultDescription
p_table_nameTEXT—Source ChronoTable
p_key_columnsTEXT[]—Columns that identify a unique series
p_value_columnsTEXT[]—Columns to cache the latest values of
p_schema_nameTEXT'public'Schema

Returns: VOID

-- Cache latest sensor readings by device
SELECT lakets.enable_lvc(
    'sensor_data',
    ARRAY['device_id'],
    ARRAY['temperature', 'humidity']
);

-- Insert new data — LVC cache updates automatically
INSERT INTO sensor_data VALUES (now(), 'device-42', 23.5, 65.2);

latest_values(p_table_name, p_schema_name)​

Reads from the LVC cache table. Sub-10 ms response regardless of the source table size.

Returns: SETOF RECORD

SELECT * FROM lakets.latest_values('sensor_data')
    AS t(device_id TEXT, temperature DOUBLE PRECISION, humidity DOUBLE PRECISION);

disable_lvc(p_table_name, p_schema_name)​

Removes the cache table and trigger.

lvc_stats()​

Overview of all LVC-enabled tables with cache statistics.

Returns: TABLE — chronotable, cache_table, cached_series, key_columns, value_columns, enabled