alter_* session settings

ClickHouse session settings in the alter_* generated group.

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

alter_move_to_space_execute_async

Execute ALTER TABLE MOVE … TO [DISK|VOLUME] asynchronously

alter_partition_verbose_result

Enables or disables the display of information about the parts to which the manipulation operations with partitions and parts have been successfully applied. Applicable to ATTACH PARTITION|PART and to FREEZE PARTITION.

Possible values:

• 0 — disable verbosity.
• 1 — enable verbosity.

Example

CREATE TABLE test(a Int64, d Date, s String) ENGINE = MergeTree PARTITION BY toYYYYMDECLARE(d) ORDER BY a;
INSERT INTO test VALUES(1, '2021-01-01', '');
INSERT INTO test VALUES(1, '2021-01-01', '');
ALTER TABLE test DETACH PARTITION ID '202101';

ALTER TABLE test ATTACH PARTITION ID '202101' SETTINGS alter_partition_verbose_result = 1;

┌─command_type─────┬─partition_id─┬─part_name────┬─old_part_name─┐
│ ATTACH PARTITION │ 202101       │ 202101_7_7_0 │ 202101_5_5_0  │
│ ATTACH PARTITION │ 202101       │ 202101_8_8_0 │ 202101_6_6_0  │
└──────────────────┴──────────────┴──────────────┴───────────────┘

ALTER TABLE test FREEZE SETTINGS alter_partition_verbose_result = 1;

┌─command_type─┬─partition_id─┬─part_name────┬─backup_name─┬─backup_path───────────────────┬─part_backup_path────────────────────────────────────────────┐
│ FREEZE ALL   │ 202101       │ 202101_7_7_0 │ 8           │ /var/lib/clickhouse/shadow/8/ │ /var/lib/clickhouse/shadow/8/data/default/test/202101_7_7_0 │
│ FREEZE ALL   │ 202101       │ 202101_8_8_0 │ 8           │ /var/lib/clickhouse/shadow/8/ │ /var/lib/clickhouse/shadow/8/data/default/test/202101_8_8_0 │
└──────────────┴──────────────┴──────────────┴─────────────┴───────────────────────────────┴─────────────────────────────────────────────────────────────┘

alter_sync

Aliases: replication_alter_partitions_sync

Allows you to specify how ALTER, OPTIMIZE, or TRUNCATE queries wait for their operations to complete.

Possible values:

• 0 — Do not wait.
• 1 — Wait for own execution.
• 2 — Wait for everyone.
• 3 - Only wait for active replicas. Inactive replicas apply the change when they become active.

Cloud default value: 0.

alter_sync applies to ALTER queries on MergeTree-family tables. Values 2 and 3 wait for replicas only on ReplicatedMergeTree and SharedMergeTree tables.

alter_update_mode

A mode for ALTER queries that have the UPDATE commands.

Possible values:

• heavy - run regular mutation.
• lightweight - run lightweight update if possible, run regular mutation otherwise.
• lightweight_force - run lightweight update if possible, throw otherwise.