mysql数据库有information_schema.tables系统表记录表相关元数据，clickhouse对应的有system.parts表。下面是查看clickhouse数据库和表大小、行数及压缩率等方法。
-- 查看数据库容量，以测试数据为参考
select
sum(rows) as "总行数",
formatReadableSize(sum(data_uncompressed_bytes)) as "原始大小",
formatReadableSize(sum(data_compressed_bytes)) as "压缩大小",
round(sum(data_compressed_bytes) / sum(data_uncompressed_bytes) * 100, 0) "压缩率"
from system.parts
┌──────总行数─┬─原始大小──┬─压缩大小─┬─压缩率─┐
│ 169851144587 │ 30.76 TiB │ 4.51 TiB │ 15 │
└─────────────┴───────────┴──────────┴────────┘
1 rows in set. Elapsed: 1.462 sec. Processed 90.35 thousand rows, 42.81 MB (63.76 thousand rows/s., 30.60 MB/s.)
-- 查询test表，2019年10月份的数据容量
select
table as "表名",
sum(rows) as "总行数",
formatReadableSize(sum(data_uncompressed_bytes)) as "原始大小",
formatReadableSize(sum(data_compressed_bytes)) as "压缩大小",
round(sum(data_compressed_bytes) / sum(data_uncompressed_bytes) * 100, 0) "压缩率"
from system.parts
-- 根据实际情况加查询条件
where table in('test')
and partition like '2019-10-%'
group by table
┌─────总行数─┬─原始大小───┬─压缩大小──┬─压缩率─┐
│ 3015199559 │ 727.83 GiB │ 60.34 GiB │ 8 │
└────────────┴────────────┴───────────┴────────┘
1 rows in set. Elapsed: 0.227 sec. Processed 3.52 thousand rows, 1.70 MB (15.48 thousand rows/s., 7.50 MB/s.)
