SummingMergeTree

SummingMergeTree

Nested structures

In certain conditions it could make sense to collapse one of dimensions to set of arrays. It’s usually profitable to do if this dimension is not commonly used in queries. It would reduce amount of rows in aggregated table and speed up queries which doesn’t care about this dimension in exchange of aggregation performance by collapsed dimension.

CREATE TABLE traffic
(
    `key1` UInt32,
    `key2` UInt32,
    `port` UInt16,
    `bits_in` UInt32 CODEC (T64,LZ4),
    `bits_out` UInt32 CODEC (T64,LZ4),
    `packets_in` UInt32 CODEC (T64,LZ4),
    `packets_out` UInt32 CODEC (T64,LZ4)
)
ENGINE = SummingMergeTree
ORDER BY (key1, key2, port);

INSERT INTO traffic SELECT
    number % 1000,
    intDiv(number, 10000),
    rand() % 20,
    rand() % 753,
    rand64() % 800,
    rand() % 140,
    rand64() % 231
FROM numbers(100000000);

CREATE TABLE default.traffic_map
(
    `key1` UInt32,
    `key2` UInt32,
    `bits_in` UInt32 CODEC(T64, LZ4),
    `bits_out` UInt32 CODEC(T64, LZ4),
    `packets_in` UInt32 CODEC(T64, LZ4),
    `packets_out` UInt32 CODEC(T64, LZ4),
    `portMap.port` Array(UInt16),
    `portMap.bits_in` Array(UInt32) CODEC(T64, LZ4),
    `portMap.bits_out` Array(UInt32) CODEC(T64, LZ4),
    `portMap.packets_in` Array(UInt32) CODEC(T64, LZ4),
    `portMap.packets_out` Array(UInt32) CODEC(T64, LZ4)
)
ENGINE = SummingMergeTree
ORDER BY (key1, key2);

INSERT INTO traffic_map WITH rand() % 20 AS port
SELECT
    number % 1000 AS key1,
    intDiv(number, 10000) AS key2,
    rand() % 753 AS bits_in,
    rand64() % 800 AS bits_out,
    rand() % 140 AS packets_in,
    rand64() % 231 AS packets_out,
    [port],
    [bits_in],
    [bits_out],
    [packets_in],
    [packets_out]
FROM numbers(100000000);

┌─table───────┬─column──────────────┬─────rows─┬─compressed─┬─uncompressed─┬──ratio─┐
 traffic      bits_out             80252317  109.09 MiB  306.14 MiB      2.81 
 traffic      bits_in              80252317  108.34 MiB  306.14 MiB      2.83 
 traffic      port                 80252317  99.21 MiB   153.07 MiB      1.54 
 traffic      packets_out          80252317  91.36 MiB   306.14 MiB      3.35 
 traffic      packets_in           80252317  84.61 MiB   306.14 MiB      3.62 
 traffic      key2                 80252317  47.88 MiB   306.14 MiB      6.39 
 traffic      key1                 80252317  1.38 MiB    306.14 MiB    221.42 
 traffic_map  portMap.bits_out     10000000  108.96 MiB  306.13 MiB      2.81 
 traffic_map  portMap.bits_in      10000000  108.32 MiB  306.13 MiB      2.83 
 traffic_map  portMap.port         10000000  92.00 MiB   229.36 MiB      2.49 
 traffic_map  portMap.packets_out  10000000  90.95 MiB   306.13 MiB      3.37 
 traffic_map  portMap.packets_in   10000000  84.19 MiB   306.13 MiB      3.64 
 traffic_map  key2                 10000000  23.46 MiB   38.15 MiB       1.63 
 traffic_map  bits_in              10000000  15.59 MiB   38.15 MiB       2.45 
 traffic_map  bits_out             10000000  15.59 MiB   38.15 MiB       2.45 
 traffic_map  packets_out          10000000  13.22 MiB   38.15 MiB       2.89 
 traffic_map  packets_in           10000000  12.62 MiB   38.15 MiB       3.02 
 traffic_map  key1                 10000000  180.29 KiB  38.15 MiB     216.66 
└─────────────┴─────────────────────┴──────────┴────────────┴──────────────┴────────┘

-- Queries

SELECT
    key1,
    sum(packets_in),
    sum(bits_out)
FROM traffic
GROUP BY key1
FORMAT `Null`

0 rows in set. Elapsed: 0.488 sec. Processed 80.25 million rows, 963.03 MB (164.31 million rows/s., 1.97 GB/s.)

SELECT
    key1,
    sum(packets_in),
    sum(bits_out)
FROM traffic_map
GROUP BY key1
FORMAT `Null`

0 rows in set. Elapsed: 0.063 sec. Processed 10.00 million rows, 120.00 MB (159.43 million rows/s., 1.91 GB/s.)


SELECT
    key1,
    port,
    sum(packets_in),
    sum(bits_out)
FROM traffic
GROUP BY
    key1,
    port
FORMAT `Null`

0 rows in set. Elapsed: 0.668 sec. Processed 80.25 million rows, 1.12 GB (120.14 million rows/s., 1.68 GB/s.)

WITH arrayJoin(arrayZip(untuple(sumMap(portMap.port, portMap.packets_in, portMap.bits_out)))) AS tpl
SELECT
    key1,
    tpl.1 AS port,
    tpl.2 AS packets_in,
    tpl.3 AS bits_out
FROM traffic_map
GROUP BY key1
FORMAT `Null`

0 rows in set. Elapsed: 0.915 sec. Processed 10.00 million rows, 1.08 GB (10.93 million rows/s., 1.18 GB/s.)