17 docs tagged with "performance"

clickhouse-benchmark is a powerfull tool. Here's how to benchmark a query against different ClickHouse servers that might have different versions or configurations.

Wondering when to use PREWHERE in ClickHouse? Here's how to optimize filtering with PREWHERE and minimize scan size in ClickHouse.

Does the order of ClickHouse sorting keys affect performance? Read this to learn the answer.

Does the order of your GROUP BY in ClickHouse affect query performance? Read this to learn why GROUP BY order matters.

Sorting keys are critical to query performance in ClickHouse. Read this to learn when and how to optimize query performance using an inverted index.

ClickHouse is a perfect database for time series data. Here's how to improve time series performance in ClickHouse by choosing the right table engine.

Want to speed up your joins in ClickHouse? Here is a smart approach to improving ClickHouse join speed by applying your filters earlier in a subquery.

Adjusting the ClickHouse index granularity has tradeoffs, but can help with some use cases. Here's how adjusting the granularity can help with filters on high cardinality columns.

Slow queries in ClickHouse? Here's a trick that could significantly reduce the amount of data your ClickHouse queries process.

ClickHouse has different algorithms for join operations. Here's how to choose which join algorithm to use to reduce memory usage.

Sum() and Count() are the most common ClickHouse aggregations. Here's how to speed up queries in ClickHouse that use a sum and count aggregation.

Want to optimize your queries in ClickHouse? Here's how to use column compression to speed up ClickHouse queries.

Wondering how to optimize single row joins in ClickHouse? Use a CROSS JOIN to improve join efficiency in ClickHouse.

ClickHouse currently is not able to use the knowledge of the sort key from a table to speed up aggregations. This means that to get the ARGMIN() or ARGMAX() values from a table it will read all values even if it's sorted by that column:

Ever wondered how to improve performance when querying many columns in ClickHouse? Here's how to use compact parts to do so.

The EXPLAIN SYNTAX statement in ClickHouse often provides clues on how to optimize your ClickHouse queries. Here's how to use it.

ClickHouse LowCardinality types can improve the speed of your queries. Here is how and when to use LowCardinality to optimize column storage for faster queries.