homework, pet project DE Dmitry_Medvedev #1
@@ -4,7 +4,7 @@
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DROP TABLE IF EXISTS dsolovianov.products ON CLUSTER clickhouse_cluster SYNC;
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DROP TABLE IF EXISTS dsolovianov.prices ON CLUSTER clickhouse_cluster SYNC;
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CREATE TABLE products
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CREATE TABLE dsolovianov.products
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ON CLUSTER clickhouse_cluster
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(
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product_id UInt32,
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@@ -16,12 +16,12 @@ ON CLUSTER clickhouse_cluster
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ORDER BY product_id;
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INSERT INTO products VALUES
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INSERT INTO dsolovianov.products VALUES
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(101, 'iPhone 14'),
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(102, 'Galaxy S22'),
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(103, 'Pixel 7');
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CREATE TABLE prices
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CREATE TABLE dsolovianov.prices
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ON CLUSTER clickhouse_cluster
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(
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product_id UInt32,
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@@ -33,7 +33,7 @@ ON CLUSTER clickhouse_cluster
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)
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ORDER BY product_id;
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INSERT INTO prices VALUES
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INSERT INTO dsolovianov.prices VALUES
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(101, 999, 'US'),
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(101, 1049, 'EU'),
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(102, 850, 'US'),
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@@ -48,8 +48,8 @@ SELECT
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p.name,
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pr.price,
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pr.region
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FROM products AS p
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ANY LEFT JOIN prices AS pr ON p.product_id = pr.product_id;
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FROM dsolovianov.products AS p
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ANY LEFT JOIN dsolovianov.prices AS pr ON p.product_id = pr.product_id;
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--№2 Что будет, если в таблице `prices` несколько цен на один `product_id`?
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@@ -62,8 +62,8 @@ SELECT
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p.name,
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pr.price,
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pr.region
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FROM products AS p
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ALL LEFT JOIN prices AS pr ON p.product_id = pr.product_id;
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FROM dsolovianov.products AS p
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ALL LEFT JOIN dsolovianov.prices AS pr ON p.product_id = pr.product_id;
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/* `ALL LEFT JOIN` в Clickhouse ведет себя также, как LEFT JOIN в SQL, то есть собирает все совпадения.
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Начинается перегон данных между таблицами. Из-за этого растет нагрузка на ОЗУ и CPU.
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