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These settings are available in system.merge_tree_settings and are autogenerated from ClickHouse source.

table_disk

This is table disk, the path/endpoint should point to the table data, not to the database data. Can be set only for s3_plain/s3_plain_rewritable/web.

table_readonly

If set to true, the table is in read-only mode and performs no modifications on disk. All foreground operations that would modify the table are rejected: inserts, mutations, OPTIMIZE, and the data-mutating partition commands (ATTACH/MOVE/DROP/DROP DETACHED/FETCH/REPLACE PARTITION, as well as MOVE PARTITION ... TO TABLE targeting this table). Operations that do not modify the table’s data, such as FREEZE/UNFREEZE and FORGET PARTITION, remain allowed. No background work is scheduled either: regular merges, TTL merges (DELETE/MOVE/recompression), recompression merges, background mutations, and background part moves are all suppressed. As a consequence, a table with a TTL no longer reclaims or moves its expired data while this setting is enabled. The setting can always be toggled back with ALTER TABLE ... MODIFY SETTING table_readonly = 0 (or RESET SETTING). It is not supported for ReplicatedMergeTree.
Last modified on July 22, 2026