timeSeriesLastTwoSamples

Introducido en: v25.6.0 Función de agregación para remuestrear datos de series temporales y calcular irate e idelta al estilo de PromQL. Función de agregación que toma datos de series temporales como pares de marcas de tiempo y valores, y almacena como máximo las 2 muestras más recientes. Esta función de agregación está pensada para usarse con una vista materializada y una tabla agregada que almacena datos de series temporales remuestreados para marcas de tiempo alineadas con la cuadrícula. La tabla agregada almacena solo los 2 últimos valores para cada marca de tiempo alineada. Esto permite calcular irate e idelta al estilo de PromQL leyendo muchos menos datos de los que se almacenan en la tabla sin procesar.

Esta función es experimental; actívela estableciendo allow_experimental_ts_to_grid_aggregate_function=true.

Sintaxis

timeSeriesLastTwoSamples(timestamp, value)

Argumentos

timestamp — Marca temporal de la muestra. DateTime o DateTime64 o (U)Int* o Int*
value — Valor de la serie temporal correspondiente a la marca temporal. Float32 o Float64

Valor devuelto Devuelve un par de arrays de la misma longitud, entre 0 y 2. El primer array contiene las marcas temporales de las series temporales muestreadas; el segundo array contiene los valores correspondientes de las series temporales. Tuple(Array(DateTime), Array(Float64)) Ejemplos Tabla de ejemplo para datos sin procesar y otra tabla para almacenar datos remuestreados

Query

-- Tabla para datos sin procesar
CREATE TABLE t_raw_timeseries
(
    metric_id UInt64,
    timestamp DateTime64(3, 'UTC') CODEC(DoubleDelta, ZSTD),
    value Float64 CODEC(DoubleDelta)
)
ENGINE = MergeTree()
ORDER BY (metric_id, timestamp);

-- Tabla con datos remuestreados a intervalos de tiempo mayores (15 seg)
CREATE TABLE t_resampled_timeseries_15_sec
(
    metric_id UInt64,
    grid_timestamp DateTime('UTC') CODEC(DoubleDelta, ZSTD), -- Timestamp alineado a 15 seg
    samples AggregateFunction(timeSeriesLastTwoSamples, DateTime64(3, 'UTC'), Float64)
)
ENGINE = AggregatingMergeTree()
ORDER BY (metric_id, grid_timestamp);

-- Vista materializada para poblar la tabla remuestreada
CREATE MATERIALIZED VIEW mv_resampled_timeseries TO t_resampled_timeseries_15_sec
(
    metric_id UInt64,
    grid_timestamp DateTime('UTC') CODEC(DoubleDelta, ZSTD),
    samples AggregateFunction(timeSeriesLastTwoSamples, DateTime64(3, 'UTC'), Float64)
)
AS SELECT
    metric_id,
    ceil(toUnixTimestamp(timestamp + interval 999 millisecond) / 15, 0) * 15 AS grid_timestamp, -- Redondear el timestamp hacia arriba al siguiente punto de la cuadrícula
    initializeAggregation('timeSeriesLastTwoSamplesState', timestamp, value) AS samples
FROM t_raw_timeseries
ORDER BY metric_id, grid_timestamp;

-- Insertar algunos datos
INSERT INTO t_raw_timeseries(metric_id, timestamp, value) SELECT number%10 AS metric_id, '2024-12-12 12:00:00'::DateTime64(3, 'UTC') + interval ((number/10)%100)*900 millisecond as timestamp, number%3+number%29 AS value FROM numbers(1000);

-- Verificar datos sin procesar
SELECT *
FROM t_raw_timeseries
WHERE metric_id = 3 AND timestamp BETWEEN '2024-12-12 12:00:12' AND '2024-12-12 12:00:31'
ORDER BY metric_id, timestamp;

Response

  2024-12-12 12:00:12.870    29
  2024-12-12 12:00:13.770    8
  2024-12-12 12:00:14.670    19
  2024-12-12 12:00:15.570    30
  2024-12-12 12:00:16.470    9
  2024-12-12 12:00:17.370    20
  2024-12-12 12:00:18.270    2
  2024-12-12 12:00:19.170    10
  2024-12-12 12:00:20.070    21
  2024-12-12 12:00:20.970    3
  2024-12-12 12:00:21.870    11
  2024-12-12 12:00:22.770    22
  2024-12-12 12:00:23.670    4
  2024-12-12 12:00:24.570    12
  2024-12-12 12:00:25.470    23
  2024-12-12 12:00:26.370    5
  2024-12-12 12:00:27.270    13
  2024-12-12 12:00:28.170    24
  2024-12-12 12:00:29.069    6
  2024-12-12 12:00:29.969    14
  2024-12-12 12:00:30.869    25

Consultar las 2 últimas muestras de las marcas de tiempo ‘2024-12-12 12:00:15’ y ‘2024-12-12 12:00:30’

Query

-- Verificar datos remuestreados
SELECT metric_id, grid_timestamp, (finalizeAggregation(samples).1 as timestamp, finalizeAggregation(samples).2 as value)
FROM t_resampled_timeseries_15_sec
WHERE metric_id = 3 AND grid_timestamp BETWEEN '2024-12-12 12:00:15' AND '2024-12-12 12:00:30'
ORDER BY metric_id, grid_timestamp;

Response

3    2024-12-12 12:00:15    (['2024-12-12 12:00:14.670','2024-12-12 12:00:13.770'],[19,8])
3    2024-12-12 12:00:30    (['2024-12-12 12:00:29.969','2024-12-12 12:00:29.069'],[14,6])

Calcular idelta e irate a partir de datos sin procesar

Query

-- La tabla agregada almacena solo los últimos 2 valores para cada marca de tiempo alineada a 15 segundos.
-- Esto permite calcular irate e idelta al estilo de PromQL leyendo muchos menos datos que los almacenados en la tabla sin procesar.

WITH
    '2024-12-12 12:00:15'::DateTime64(3,'UTC') AS start_ts,       -- inicio de la cuadrícula de timestamps
    start_ts + INTERVAL 60 SECOND AS end_ts,   -- fin de la cuadrícula de timestamps
    15 AS step_seconds,   -- paso de la cuadrícula de timestamps
    45 AS window_seconds  -- ventana de "obsolescencia"
SELECT
    metric_id,
    timeSeriesInstantDeltaToGrid(start_ts, end_ts, step_seconds, window_seconds)(timestamp, value),
    timeSeriesInstantRateToGrid(start_ts, end_ts, step_seconds, window_seconds)(timestamp, value)
FROM t_raw_timeseries
WHERE metric_id = 3 AND timestamp BETWEEN start_ts - interval window_seconds seconds AND end_ts
GROUP BY metric_id;

Response

3    [11,8,-18,8,11]    [12.222222222222221,8.88888888888889,1.1111111111111112,8.88888888888889,12.222222222222221]

Calcular idelta e irate a partir de datos remuestreados

Query

WITH
    '2024-12-12 12:00:15'::DateTime64(3,'UTC') AS start_ts,       -- inicio de la cuadrícula de timestamps
    start_ts + INTERVAL 60 SECOND AS end_ts,   -- fin de la cuadrícula de timestamps
    15 AS step_seconds,   -- paso de la cuadrícula de timestamps
    45 AS window_seconds  -- ventana de "obsolescencia"
SELECT
    metric_id,
    timeSeriesInstantDeltaToGrid(start_ts, end_ts, step_seconds, window_seconds)(timestamps, values),
    timeSeriesInstantRateToGrid(start_ts, end_ts, step_seconds, window_seconds)(timestamps, values)
FROM (
    SELECT
        metric_id,
        finalizeAggregation(samples).1 AS timestamps,
        finalizeAggregation(samples).2 AS values
    FROM t_resampled_timeseries_15_sec
    WHERE metric_id = 3 AND grid_timestamp BETWEEN start_ts - interval window_seconds seconds AND end_ts
)
GROUP BY metric_id;

Response

3    [11,8,-18,8,11]    [12.222222222222221,8.88888888888889,1.1111111111111112,8.88888888888889,12.222222222222221]

​timeSeriesLastTwoSamples

timeSeriesLastTwoSamples