data LIMIT N SELECT min(pickup_date), max(pickup_date) FROM ( SELECT pickup_date FROM trips_mergetree_third LIMIT 1000 ) ┌─min(pickup_date)─┬─max(pickup_date)─┐ │ 2009-01-01 │ 2009-01-01 │ └──── fixed sample query › Only for MergeTree 11 / 62 How to sample data SAMPLE x OFFSET y CREATE TABLE trips_sample_time ( pickup_datetime DateTime ) ENGINE = MergeTree ORDER BY sipHash64(pickup_datetime) store model as aggregate function state in a separate table Example CREATE TABLE models ENGINE = MergeTree ORDER BY tuple() AS SELECT stochasticLinearRegressionState(total_amount, trip_distance) AS model

data LIMIT N SELECT min(pickup_date), max(pickup_date) FROM ( SELECT pickup_date FROM trips_mergetree_third LIMIT 1000 ) ┌─min(pickup_date)─┬─max(pickup_date)─┐ │ 2009-01-01 │ 2009-01-01 │ └──── fixed sample query › Only for MergeTree 11 / 62 How to sample data SAMPLE x OFFSET y CREATE TABLE trips_sample_time ( pickup_datetime DateTime ) ENGINE = MergeTree ORDER BY sipHash64(pickup_datetime) store model as aggregate function state in a separate table Example CREATE TABLE models ENGINE = MergeTree ORDER BY tuple() AS SELECT stochasticLinearRegressionState(total_amount, trip_distance) AS model

`Name` String, `Age` UInt8, ..., `HeartRate` UInt8, `Humidity` Float32, ... ) ENGINE = MergeTree() PARTITION BY toYYYYMM(Time) ORDER BY (Name, Time, Age, ...); ► Column-Orient Model How we LowCardinality(String), `Age` UInt8, ..., `HeartRate` UInt8, `Humidity` Float32, ... ) ENGINE = MergeTree() PARTITION BY toYYYYMM(Time) ORDER BY (Name, Time, Age, ...); ► Column-Orient Model How we

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MaterializeMySQL Database Engine • Mapping to MySQL database • Consume MySQL BINLOG and store to MergeTree • Experimental feature (20.8, recommend latest stable version) MaterializeMySQL Database Engine

rows. 53 / 97 In ClickHouse: Local Log Copy CREATE TABLE EventLogLocal AS EventLogHDFS ENGINE = MergeTree() ORDER BY BannerID; Ok. INSERT INTO EventLogLocal SELECT * FROM EventLogHDFS; Ok. 0 rows in