docs/en/operations/server-configuration-parameters/_snippets/_system-log-parameters.md
The following settings can be configured by sub-tags:
| Setting | Description | Default | Note |
|---|---|---|---|
database | Name of the database. | ||
table | Name of the system table. | ||
engine | MergeTree Engine Definition for a system table. | Cannot be used if partition_by or order_by defined. If not specified MergeTree is selected by default | |
partition_by | Custom partitioning key for a system table. | If engine is specified for system table, partition_by parameter should be specified directly inside 'engine' | |
ttl | Specifies the table TTL. | If engine is specified for system table, ttl parameter should be specified directly inside 'engine' | |
order_by | Custom sorting key for a system table. Can't be used if engine defined. | If engine is specified for system table, order_by parameter should be specified directly inside 'engine' | |
storage_policy | Name of the storage policy to use for the table (optional). | If engine is specified for system table, storage_policy parameter should be specified directly inside 'engine' | |
settings | Additional parameters that control the behavior of the MergeTree (optional). | If engine is specified for system table, settings parameter should be specified directly inside 'engine' | |
flush_interval_milliseconds | Interval for flushing data from the buffer in memory to the table. | 7500 | |
max_size_rows | Maximal size in lines for the logs. When the amount of non-flushed logs reaches the max_size, logs are dumped to the disk. | 1048576 | |
reserved_size_rows | Pre-allocated memory size in lines for the logs. | 8192 | |
buffer_size_rows_flush_threshold | Threshold for amount of lines. If the threshold is reached, flushing logs to the disk is launched in background. | max_size_rows / 2 | |
flush_on_crash | Sets whether logs should be dumped to the disk in case of a crash. | false |