mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-15 02:41:59 +00:00
27 lines
2.4 KiB
Markdown
27 lines
2.4 KiB
Markdown
---
|
|
slug: /en/operations/system-tables/storage_policies
|
|
---
|
|
# storage_policies
|
|
|
|
Contains information about storage policies and volumes defined in the [server configuration](../../engines/table-engines/mergetree-family/mergetree.md#table_engine-mergetree-multiple-volumes_configure).
|
|
|
|
Columns:
|
|
|
|
- `policy_name` ([String](../../sql-reference/data-types/string.md)) — Name of the storage policy.
|
|
- `volume_name` ([String](../../sql-reference/data-types/string.md)) — Volume name defined in the storage policy.
|
|
- `volume_priority` ([UInt64](../../sql-reference/data-types/int-uint.md)) — Volume order number in the configuration, the data fills the volumes according this priority, i.e. data during inserts and merges is written to volumes with a lower priority (taking into account other rules: TTL, `max_data_part_size`, `move_factor`).
|
|
- `disks` ([Array(String)](../../sql-reference/data-types/array.md)) — Disk names, defined in the storage policy.
|
|
- `volume_type` ([Enum8](../../sql-reference/data-types/enum.md)) — Type of volume. Can have one of the following values:
|
|
- `JBOD`
|
|
- `SINGLE_DISK`
|
|
- `UNKNOWN`
|
|
- `max_data_part_size` ([UInt64](../../sql-reference/data-types/int-uint.md)) — Maximum size of a data part that can be stored on volume disks (0 — no limit).
|
|
- `move_factor` ([Float64](../../sql-reference/data-types/float.md)) — Ratio of free disk space. When the ratio exceeds the value of configuration parameter, ClickHouse start to move data to the next volume in order.
|
|
- `prefer_not_to_merge` ([UInt8](../../sql-reference/data-types/int-uint.md)) — Value of the `prefer_not_to_merge` setting. When this setting is enabled, merging data on this volume is not allowed. This allows controlling how ClickHouse works with slow disks.
|
|
- `perform_ttl_move_on_insert` ([UInt8](../../sql-reference/data-types/int-uint.md)) — Value of the `perform_ttl_move_on_insert` setting. — Disables TTL move on data part INSERT. By default if we insert a data part that already expired by the TTL move rule it immediately goes to a volume/disk declared in move rule. This can significantly slowdown insert in case if destination volume/disk is slow (e.g. S3).
|
|
- `load_balancing` ([Enum8](../../sql-reference/data-types/enum.md)) — Policy for disk balancing. Can have one of the following values:
|
|
- `ROUND_ROBIN`
|
|
- `LEAST_USED`
|
|
|
|
If the storage policy contains more then one volume, then information for each volume is stored in the individual row of the table.
|