ClickHouse性能查看

1、集群详情

select * from system.clusters;

2、merge状态查看

SELECT

    database,

    table,

    round(elapsed, 2) AS time_use,

    round(progress, 2) AS progress,

    num_parts,

    round(((total_size_bytes_compressed / 1024) / 1024) / 1024, 2) AS total_size_bytes_compressed_GB,

    round(((bytes_read_uncompressed / 1024) / 1024) / 1024, 2) AS bytes_read_uncompressed_GB,

    rows_read / 10000 AS rows_read_w,

    rows_written / 10000000 AS rows_written_kw,

    round((memory_usage / 1024) / 1024) AS memory_usage_MB

FROM system.merges

ORDER BY time_use DESC;

3、统计压缩比

select table,countDistinct(name) as num_cols,formatReadableSize(sum(data_compressed_bytes) as c) as comp,formatReadableSize(sum(data_uncompressed_bytes) as r) as raw,c / r as compress_ratio from system.columns group by table order by raw desc limit 10;

4、统计parts

SELECT

    database,

    table,

    engine,

    active,

    count(*) AS parts_total,

    countDistinct(partition) AS partition_total,

    round(sum(rows) / 10000, 2) AS rows_w,

    round(((sum(bytes) / 1024) / 1024) / 1024, 2) AS size_GB

FROM system.parts

WHERE active = 1

GROUP BY

    database,

    table,

    engine,

    active

ORDER BY size_GB DESC

LIMIT 5;

5、查询状态检查

select * from system.processes where ( elapsed > 10000 ) and query like '%select%' limit 2;

最后

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