clickhouse查看數據庫和表的容量大小

說明

在mysql中information_schema這個數據庫中保存了mysql服務器所有數據庫的信息，
而在clickhouse，我們可以通過system.parts查看clickhouse數據庫和表的容量大小、行數、壓縮率以及分區信息。在此通過測試數據庫來說明。

1.查看數據庫容量、行數、壓縮率

SELECT 
    sum(rows) AS `總行數`,
    formatReadableSize(sum(data_uncompressed_bytes)) AS `原始大小`,
    formatReadableSize(sum(data_compressed_bytes)) AS `壓縮大小`,
    round((sum(data_compressed_bytes) / sum(data_uncompressed_bytes)) * 100, 0) AS `壓縮率`
FROM system.parts

┌────總行數─┬─原始大小──┬─壓縮大小─┬─壓縮率─┐
│ 326819026 │ 77.15 GiB │ 5.75 GiB │      7 │
└───────────┴───────────┴──────────┴────────┘

1 rows in set. Elapsed: 0.047 sec. Processed 1.04 thousand rows, 520.93 KB (21.95 thousand
rows/s., 11.02 MB/s.) 
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2.查看數據表容量、行數、壓縮率

--在此查詢一張臨時表的信息
SELECT 
    table AS `表名`,
    sum(rows) AS `總行數`,
    formatReadableSize(sum(data_uncompressed_bytes)) AS `原始大小`,
    formatReadableSize(sum(data_compressed_bytes)) AS `壓縮大小`,
    round((sum(data_compressed_bytes) / sum(data_uncompressed_bytes)) * 100, 0) AS `壓縮率`
FROM system.parts
WHERE table IN ('temp_1')
GROUP BY table

┌─表名───┬──總行數─┬─原始大小───┬─壓縮大小──┬─壓縮率─┐
│ temp_1 │ 3127523 │ 838.21 MiB │ 60.04 MiB │      7 │
└────────┴─────────┴────────────┴───────────┴────────┘

1 rows in set. Elapsed: 0.008 sec.
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3.查看數據表分區信息

--查看測試表在19年12月的分區信息
SELECT 
    partition AS `分區`,
    sum(rows) AS `總行數`,
    formatReadableSize(sum(data_uncompressed_bytes)) AS `原始大小`,
    formatReadableSize(sum(data_compressed_bytes)) AS `壓縮大小`,
    round((sum(data_compressed_bytes) / sum(data_uncompressed_bytes)) * 100, 0) AS `壓縮率`
FROM system.parts
WHERE (database IN ('default')) AND (table IN ('temp_1')) AND (partition LIKE '2019-12-%')
GROUP BY partition
ORDER BY partition ASC

┌─分區───────┬─總行數─┬─原始大小──┬─壓縮大小───┬─壓縮率─┐
│ 2019-12-01 │     24 │ 6.17 KiB  │ 2.51 KiB   │     41 │
│ 2019-12-02 │   9215 │ 2.45 MiB  │ 209.74 KiB │      8 │
│ 2019-12-03 │  17265 │ 4.46 MiB  │ 453.78 KiB │     10 │
│ 2019-12-04 │  27741 │ 7.34 MiB  │ 677.25 KiB │      9 │
│ 2019-12-05 │  31500 │ 8.98 MiB  │ 469.30 KiB │      5 │
│ 2019-12-06 │    157 │ 37.50 KiB │ 4.95 KiB   │     13 │
│ 2019-12-07 │    110 │ 32.75 KiB │ 3.86 KiB   │     12 │
└────────────┴────────┴───────────┴────────────┴────────┘

7 rows in set. Elapsed: 0.005 sec. 
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4.查看數據表字段的信息

SELECT 
    column AS `字段名`,
    any(type) AS `類型`,
    formatReadableSize(sum(column_data_uncompressed_bytes)) AS `原始大小`,
    formatReadableSize(sum(column_data_compressed_bytes)) AS `壓縮大小`,
    sum(rows) AS `行數`
FROM system.parts_columns
WHERE (database = 'default') AND (table = 'temp_1')
GROUP BY column
ORDER BY column ASC

┌─字段名───────────┬─類型─────┬─原始大小───┬─壓縮大小───┬────行數─┐
│ a                │ String   │ 23.83 MiB  │ 134.13 KiB │ 3127523 │
│ b                │ String   │ 19.02 MiB  │ 127.72 KiB │ 3127523 │
│ c                │ String   │ 5.97 MiB   │ 49.09 KiB  │ 3127523 │
│ d        		   │ String   │ 3.95 MiB   │ 532.86 KiB │ 3127523 │
│ e                │ String   │ 5.17 MiB   │ 49.47 KiB  │ 3127523 │
│ totalDate        │ DateTime │ 11.93 MiB  │ 1.26 MiB   │ 3127523 │
└──────────────────┴──────────┴────────────┴────────────┴─────────┘