> ## Documentation Index
> Fetch the complete documentation index at: https://docs.kinetica.com/llms.txt
> Use this file to discover all available pages before exploring further.

# System Properties

<a id="sql-system-properties" />

*Kinetica* provides a SQL interface for managing
[system properties](/content/config), which control everything from
GPUs, hostnames, storage, graph server, and more.

The ability to manage system properties is available through SQL, using the
following commands:

* [ALTER SYSTEM SET PROPERTIES](#alter-system-set-properties)
* [SHOW SYSTEM PROPERTIES](#show-system-properties)

<a id="alter-system-set-properties" />

<a id="sql-alter-system-properties" />

## ALTER SYSTEM SET PROPERTIES

Only a small subset of the system properties can be altered at runtime. See the
[/alter/system/properties](/content/api/rest/alter_system_properties_rest) endpoint documentation for the
full list. Only users with the `system_admin`
[permission](/content/security/sec_concepts#security-concepts-permissions) can issue this command.

```sql title="ALTER SYSTEM SET PROPERTIES Syntax" theme={null}
ALTER SYSTEM SET PROPERTIES ('<property key>' = '<property value>'[,...])
[WITH OPTIONS ('persist' = < 'true' | 'false' >)]
```

Use the `WITH OPTIONS` clause to specify whether the setting should be saved
to the system configuration to be used after future database restarts.  Set the
`persist` option to `false` to only change the property temporarily, until
the database is restarted.  By default, the change will be persisted.

### Alterable Properties

Not all system properties can be modified while the system is running.  The
following is a list of those that can be modified.

<AccordionGroup>
  <Accordion title="enable_audit" id="enable_audit" defaultOpen>
    Enable or disable auditing.
  </Accordion>

  <Accordion title="audit_headers" id="audit_headers" defaultOpen>
    Enable or disable auditing of request headers.
  </Accordion>

  <Accordion title="audit_body" id="audit_body" defaultOpen>
    Enable or disable auditing of request bodies.
  </Accordion>

  <Accordion title="audit_data" id="audit_data" defaultOpen>
    Enable or disable auditing of request data.
  </Accordion>

  <Accordion title="audit_response" id="audit_response" defaultOpen>
    Enable or disable auditing of response information.
  </Accordion>

  <Accordion title="tps_per_tom" id="tps_per_tom" defaultOpen>
    Size of the worker rank data processing thread pool.  This includes operations such as
    inserts, updates, & deletes on table data.  Multi-head inserts are not affected by this
    limit. The minimum allowed value is `2`. The maximum allowed value is `8192`.
  </Accordion>

  <Accordion title="tcs_per_tom" id="tcs_per_tom" defaultOpen>
    Size of the worker rank data calculation thread pool.  This is primarily used for
    computation-based operations such as aggregates and record retrieval. The minimum allowed
    value is `2`. The maximum allowed value is `8192`.
  </Accordion>

  <Accordion title="subtask_concurrency_limit" id="subtask_concurrency_limit" defaultOpen>
    Maximum number of simultaneous threads allocated to a given request, per rank.  Note that
    thread allocation may also be limited by resource group limits and/or system load.
  </Accordion>

  <Accordion title="concurrent_kernel_execution" id="concurrent_kernel_execution" defaultOpen>
    Enable or disable concurrent kernel execution.
  </Accordion>

  <Accordion title="max_concurrent_kernels" id="max_concurrent_kernels" defaultOpen>
    Maximum number of kernels that can be running at the same time on a given GPU.  Set to
    `0` for no limit.  Only takes effect if `concurrent_kernel_execution` is `true`.
    The maximum allowed value is `256`.
  </Accordion>

  <Accordion title="max_get_records_size" id="max_get_records_size" defaultOpen>
    The maximum number of records the database will serve for a given data retrieval call.  The
    maximum allowed value is `1000000`.
  </Accordion>

  <Accordion title="request_timeout" id="request_timeout" defaultOpen>
    Number of minutes after which filtering (e.g., [/filter](/content/api/rest/filter_rest)) and
    aggregating  (e.g., [/aggregate/groupby](/content/api/rest/aggregate_groupby_rest)) queries will time out.
    The maximum allowed value is `1440`.
  </Accordion>

  <Accordion title="enable_overlapped_equi_join" id="enable_overlapped_equi_join" defaultOpen>
    Enable or disable the overlapped-equi-join filter.
  </Accordion>

  <Accordion title="chunk_size" id="chunk_size" defaultOpen>
    Number of records per chunk, applied to all new tables.  To disable chunking, use `0`.
  </Accordion>

  <Accordion title="chunk_column_max_memory" id="chunk_column_max_memory" defaultOpen>
    Maximum data size, in bytes, for each column in a chunk, applied to all new tables.  Use
    `0` for no maximum.
  </Accordion>

  <Accordion title="chunk_max_memory" id="chunk_max_memory" defaultOpen>
    Maximum data size for all columns in a chunk, applied to all new tables.  Use `0` for no
    maximum; use `-1` to use the default, based on RAM tier limits or host memory per rank.
  </Accordion>

  <Accordion title="execution_mode" id="execution_mode" defaultOpen>
    Scheme to use for kernel executions.  Possible values:

    <div>
      <table class="table w-full [&_td]:min-w-[150px] [&_th]:text-left [&_td[data-numeric]]:tabular-nums">
        <thead>
          <tr>
            <th>Mode</th>
            <th>Description</th>
          </tr>
        </thead>

        <tbody>
          <tr>
            <td><code>host</code></td>
            <td>Execute kernels only on the *host* (CPU)</td>
          </tr>

          <tr>
            <td><code>device</code></td>
            <td>Execute kernels only on the *device* (GPU)</td>
          </tr>

          <tr>
            <td><code>default</code></td>
            <td>Execution engine decides whether to execute kernels on the *host* or the *device*</td>
          </tr>

          <tr>
            <td><code>\<rows></code></td>
            <td>Execute kernels on the host if the chunked column contains the given number of rows or fewer; otherwise, execute on the device</td>
          </tr>
        </tbody>
      </table>
    </div>
  </Accordion>

  <Accordion title="shadow_agg_size" id="shadow_agg_size" defaultOpen>
    Maximum number of bytes in the *shadow aggregate chunk cache*.  The maximum allowed value
    is `2147483647`.
  </Accordion>

  <Accordion title="shadow_filter_size" id="shadow_filter_size" defaultOpen>
    Maximum number of bytes in the *shadow filter chunk cache*.  The maximum allowed value is
    `2147483647`.
  </Accordion>

  <Accordion title="telm_persist_query_metrics" id="telm_persist_query_metrics" defaultOpen>
    Enable or disable persisting of query metrics in a table.  If disabled, metrics will still
    be available for point-in-time export.
  </Accordion>

  <Accordion title="postgres_proxy_idle_connection_timeout" id="postgres_proxy_idle_connection_timeout" defaultOpen>
    PostgreSQL Wire Protocol service idle connection timeout, in seconds
  </Accordion>

  <Accordion title="postgres_proxy_keep_alive" id="postgres_proxy_keep_alive" defaultOpen>
    Enable or disable PostgreSQL Wire Protocol service's keep alive.
  </Accordion>

  <Accordion title="ai_enable_rag" id="ai_enable_rag" defaultOpen>
    Enable or disable [SQL-GPT RAG](/content/sql-gpt/concepts#sql-gpt-overview-rag).
  </Accordion>

  <Accordion title="ai_api_provider" id="ai_api_provider" defaultOpen>
    AI API provider type
  </Accordion>

  <Accordion title="ai_api_url" id="ai_api_url" defaultOpen>
    AI API URL
  </Accordion>

  <Accordion title="ai_api_key" id="ai_api_key" defaultOpen>
    AI API key
  </Accordion>

  <Accordion title="ai_api_embeddings_model" id="ai_api_embeddings_model" defaultOpen>
    AI API embeddings model name
  </Accordion>

  <Accordion title="ai_api_connection_timeout" id="ai_api_connection_timeout" defaultOpen>
    AI API connection timeout, in seconds
  </Accordion>

  <Accordion title="external_files_directory" id="external_files_directory" defaultOpen>
    Root directory path, on the head node of the cluster, from where external table data files
    are accessed.
  </Accordion>

  <Accordion title="egress_single_file_max_size" id="egress_single_file_max_size" defaultOpen>
    Maximum file size, in MB, to allow saving to a single file.  May be overridden by target
    limitations.  The maximum allowed value is `200000`.
  </Accordion>

  <Accordion title="egress_parquet_compression" id="egress_parquet_compression" defaultOpen>
    Parquet file compression type.  The supported values are:

    * `uncompressed`
    * `snappy`
    * `gzip`
  </Accordion>

  <Accordion title="kafka_batch_size" id="kafka_batch_size" defaultOpen>
    Maximum number of Kafka records to be ingested in a single batch.  The maximum allowed
    value is `10000000`.
  </Accordion>

  <Accordion title="kafka_wait_time" id="kafka_wait_time" defaultOpen>
    Maximum time, in seconds, to buffer records received from Kafka before ingestion.  The
    maximum allowed value is `120`.
  </Accordion>

  <Accordion title="kafka_poll_timeout" id="kafka_poll_timeout" defaultOpen>
    Maximum time, in milliseconds, for each poll to get records from Kafka.  The maximum
    allowed value is `1000`.
  </Accordion>

  <Accordion title="system_metadata_retention_period" id="system_metadata_retention_period" defaultOpen>
    For persistent metadata tables, the time, in seconds, to retain rows prior to deletion.
    Note that records are deleted periodically, so this retention period is the minimum
    lifetime of a given metadata record.
  </Accordion>

  <Accordion title="kifs_directory_data_limit" id="kifs_directory_data_limit" defaultOpen>
    Default maximum capacity to apply to a newly-created KiFS directory, in bytes.  Use `-1`
    for no limit.
  </Accordion>

  <Accordion title="enable_one_step_compound_equi_join" id="enable_one_step_compound_equi_join" defaultOpen>
    Enable or disable the *one-step compound equi-join* algorithm.
  </Accordion>
</AccordionGroup>

### Examples

To increase the request timeout and the maximum `/get/records`
size permanently (in the startup configuration):

```sql ALTER SYSTEM SET PROPERTIES Example theme={null}
ALTER SYSTEM SET PROPERTIES (
    'request_timeout' = '25',
    'max_get_records_size' = '25000'
)
```

To set the default [embeddings model](/content/vector_search#vector-model) until the
database is restarted:

```sql ALTER SYSTEM SET Default Embedding Model Temporarily Example theme={null}
ALTER SYSTEM SET PROPERTIES ('ai_enable_rag' = 'true')
WITH OPTIONS ('persist' = 'false')
```

<a id="show-system-properties" />

<a id="sql-show-system-properties" />

## SHOW SYSTEM PROPERTIES

System properties can be shown by any user.

```sql title="SHOW SYSTEM PROPERTIES Syntax" theme={null}
SHOW SYSTEM PROPERTIES
[WITH OPTIONS ('properties' = '<config parameter name>[,...]')]
```

### Examples

To show all system properties:

```sql SHOW SYSTEM PROPERTIES Example theme={null}
SHOW SYSTEM PROPERTIES
```

To show the internal & external cluster node URLs:

```sql SHOW SYSTEM PROPERTIES Individually Example theme={null}
SHOW SYSTEM PROPERTIES
WITH OPTIONS ('properties' = 'conf.worker_http_server_urls,conf.worker_http_server_urls_private')
```

To show all [RAM tier](/content/rm/concepts#rm-concepts-tiers-ram) properties:

```sql SHOW RAM Tier Properties Example theme={null}
SHOW SYSTEM PROPERTIES
WITH OPTIONS
(
    'properties' =
    '
        conf.tier.ram.default.high_watermark,
        conf.tier.ram.default.limit,
        conf.tier.ram.default.low_watermark,
        conf.tier.ram.rank0.high_watermark,
        conf.tier.ram.rank0.limit,
        conf.tier.ram.rank0.low_watermark,
        conf.tier.ram.rank1.high_watermark,
        conf.tier.ram.rank1.limit,
        conf.tier.ram.rank1.low_watermark,
        conf.tier.ram.rank2.high_watermark,
        conf.tier.ram.rank2.limit,
        conf.tier.ram.rank2.low_watermark
    '
)
```