Skip to main content

Documentation Index

Fetch the complete documentation index at: https://private-7c7dfe99-page-updates.mintlify.app/llms.txt

Use this file to discover all available pages before exploring further.

Querying in ClickHouse CloudThe data in this system table is held locally on each node in ClickHouse Cloud. Obtaining a complete view of all data, therefore, requires the clusterAllReplicas function. See here for further details.

​
Description

Contains information about disks defined in the server configuration.

​
Columns

  • name (String) — Name of a disk in the server configuration.
  • path (String) — Path to the mount point in the file system.
  • free_space (UInt64) — Free space on disk in bytes.
  • total_space (UInt64) — Disk volume in bytes.
  • unreserved_space (UInt64) — Free space which is not taken by reservations (free_space minus the size of reservations taken by merges, inserts, and other disk write operations currently running).
  • keep_free_space (UInt64) — Amount of disk space that should stay free on disk in bytes. Defined in the keep_free_space_bytes parameter of disk configuration.
  • type (String) — The disk type which tells where this disk stores the data - RAM, local drive or remote storage.
  • object_storage_type (String) — Type of object storage if disk type is object_storage
  • metadata_type (String) — Type of metadata storage if disk type is object_storage
  • is_encrypted (UInt8) — Flag which shows whether this disk encrypts the underlying data.
  • is_read_only (UInt8) — Flag which indicates that you can only perform read operations with this disk.
  • is_write_once (UInt8) — Flag which indicates if disk is write-once. Which means that it does support BACKUP to this disk, but does not support INSERT into MergeTree table on this disk.
  • is_remote (UInt8) — Flag which indicated what operations with this disk involve network interaction.
  • is_broken (UInt8) — Flag which indicates if disk is broken. Broken disks will have 0 space and cannot be used.
  • cache_path (String) — The path to the cache directory on local drive in case when the disk supports caching.

​
Example

SELECT * FROM system.disks;

┌─name────┬─path─────────────────┬───free_space─┬──total_space─┬─keep_free_space─┐
│ default │ /var/lib/clickhouse/ │ 276392587264 │ 490652508160 │               0 │
└─────────┴──────────────────────┴──────────────┴──────────────┴─────────────────┘

1 rows in set. Elapsed: 0.001 sec.