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备份特定分区

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问题​

如何在 ClickHouse 中备份特定分区？

解答​

请参阅以下示例，此示例使用 S3(Minio) 磁盘配置，该配置列在我们的docker compose 示例页面中。

注意

这**不适用于** ClickHouse 云

创建表

ch_minio_s3 :) CREATE TABLE my_table
               (
                   `event_time` DateTime,
                   `field_foo` String,
                   `field_bar` String,
                   `number` UInt256
               )
               ENGINE = MergeTree
               PARTITION BY number % 2
               ORDER BY tuple()

CREATE TABLE my_table
(
    `event_time` DateTime,
    `field_foo` String,
    `field_bar` String,
    `number` UInt256
)
ENGINE = MergeTree
PARTITION BY number % 2
ORDER BY tuple()

Query id: a1a54a5a-eac0-477c-b847-b40acaa62780

Ok.

0 rows in set. Elapsed: 0.016 sec.

添加一些数据，使两个分区的数据量大致相等

ch_minio_s3 :) INSERT INTO my_table SELECT
                   toDateTime(now() + number) AS event_time,
                   randomPrintableASCII(10) AS field_foo,
                   randomPrintableASCII(20) AS field_bar,
                   number
               FROM numbers(1000000)

INSERT INTO my_table SELECT
    toDateTime(now() + number) AS event_time,
    randomPrintableASCII(10) AS field_foo,
    randomPrintableASCII(20) AS field_bar,
    number
FROM numbers(1000000)

Query id: bf6ef803-5747-4ea1-ad00-a17967e349b6

Ok.

0 rows in set. Elapsed: 0.282 sec. Processed 1.00 million rows, 8.00 MB (3.55 million rows/s., 28.39 MB/s.)

验证数据

ch_minio_s3 :) SELECT
                   _partition_id AS partition_id,
                   cityHash64(sum(number)) AS hash,
                   count() AS count
               FROM my_table
               GROUP BY partition_id

SELECT
    _partition_id AS partition_id,
    cityHash64(sum(number)) AS hash,
    count() AS count
FROM my_table
GROUP BY partition_id

Query id: d8febfb0-5339-4f97-aefa-ef0003128526

┌─partition_id─┬─cityHash64(sum(number))─┬──count─┐
│ 0            │    15460940821314360342 │ 500000 │
│ 1            │    11827822647069388611 │ 500000 │
└──────────────┴─────────────────────────┴────────┘

2 rows in set. Elapsed: 0.025 sec. Processed 1.00 million rows, 32.00 MB (39.97 million rows/s., 1.28 GB/s.)

将 id 为 1 的分区备份到已配置的 s3 磁盘

ch_minio_s3 :) BACKUP TABLE my_table PARTITION 1 TO Disk('s3','backups/');

BACKUP TABLE my_table PARTITION  1 TO Disk('s3', 'backups/')

Query id: 810f6144-e282-42e2-99d0-9a80c75a927d

┌─id───────────────────────────────────┬─status─────────┐
│ 4d1da197-c4c9-4b6e-966c-76202eadbd53 │ BACKUP_CREATED │
└──────────────────────────────────────┴────────────────┘

1 row in set. Elapsed: 0.095 sec.

删除表

ch_minio_s3 :) DROP TABLE my_table

DROP TABLE my_table

Query id: c3456044-4689-406e-82ac-8d08b8b618fe

Ok.

0 rows in set. Elapsed: 0.007 sec.

仅从备份中恢复 id 为 1 的分区

ch_minio_s3 :) RESTORE TABLE my_table PARTITION 1 FROM Disk('s3','backups/');

RESTORE TABLE my_table PARTITION  1 FROM Disk('s3', 'backups/')

Query id: ea306c73-83c5-479f-9c0c-391594facc69

┌─id───────────────────────────────────┬─status───┐
│ ec6841a8-0607-465e-bc4d-d446f960d40a │ RESTORED │
└──────────────────────────────────────┴──────────┘

1 row in set. Elapsed: 0.065 sec.

验证已恢复的数据

ch_minio_s3 :) SELECT
                   _partition_id AS partition_id,
                   cityHash64(sum(number)) AS hash,
                   count() AS count
               FROM my_table
               GROUP BY partition_id

SELECT
    _partition_id AS partition_id,
    cityHash64(sum(number)) AS hash,
    count() AS count
FROM my_table
GROUP BY partition_id

Query id: a916176d-6a6e-47fc-ba7d-79bb33b152d8

┌─partition_id─┬─────────────────hash─┬──count─┐
│ 1            │ 11827822647069388611 │ 500000 │
└──────────────┴──────────────────────┴────────┘

1 row in set. Elapsed: 0.012 sec. Processed 500.00 thousand rows, 16.00 MB (41.00 million rows/s., 1.31 GB/s.)