> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-revert-104359-revert-104251-parquet-single.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# iceberg_* session settings

> ClickHouse session settings in the iceberg_* generated group.

export const ExperimentalBadge = () => {
  return <a href="https://clickhouse.com/docs/reference/settings/beta-and-experimental-features#experimental-features" className="experimentalBadge">
            <div className="experimentalIcon">
            <svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg">
                <path strokeWidth="1.25" d="M5.5 2H10.5" stroke="currentColor" strokeLinecap="round" strokeLinejoin="round" />
                <path strokeWidth="1.25" d="M9.50015 2V6.19625L13.4283 12.7425C13.4738 12.8183 13.4985 12.9049 13.4996 12.9934C13.5008 13.0818 13.4785 13.169 13.435 13.246C13.3914 13.323 13.3283 13.3871 13.2519 13.4317C13.1755 13.4764 13.0886 13.4999 13.0002 13.5H3.00015C2.91164 13.5 2.8247 13.4766 2.74822 13.432C2.67174 13.3874 2.60847 13.3233 2.56487 13.2463C2.52126 13.1693 2.49889 13.082 2.50004 12.9935C2.50119 12.905 2.52582 12.8184 2.5714 12.7425L6.50015 6.19625V2" stroke="currentColor" strokeLinecap="round" strokeLinejoin="round" />
                <path strokeWidth="1.25" d="M4.47656 9.56754C5.30344 9.41254 6.47656 9.47942 7.99969 10.25C10.0153 11.2707 11.4216 11.0569 12.2184 10.7282" stroke="currentColor" strokeLinecap="round" strokeLinejoin="round" />
            </svg>
        </div>
            Experimental feature
        </a>;
};

export const VersionHistory = ({rows = []}) => {
  if (rows.length === 0) {
    return null;
  }
  const headers = ["Version", "Default value", "Comment"];
  const border = "1px solid rgba(128, 128, 128, 0.3)";
  const cell = {
    border,
    padding: "0.25rem 0.5rem",
    textAlign: "start",
    verticalAlign: "top"
  };
  return <details className="not-prose" style={{
    border,
    borderRadius: "0.5rem",
    margin: "0.5rem 0",
    padding: "0.5rem 0.75rem",
    fontSize: "0.8125rem",
    lineHeight: "1.125rem"
  }}>
      <summary style={{
    cursor: "pointer",
    fontWeight: 600,
    opacity: 0.72
  }}>
        Version history
      </summary>
      <table style={{
    borderCollapse: "collapse",
    width: "100%",
    margin: "0.5rem 0 0"
  }}>
        <thead>
          <tr>
            {headers.map(header => <th key={header} style={{
    ...cell,
    fontWeight: 600,
    opacity: 0.72
  }}>
                {header}
              </th>)}
          </tr>
        </thead>
        <tbody>
          {rows.map((row, row_index) => <tr key={row.id ?? row_index}>
              {(row.items ?? []).map((item, item_index) => <td key={item_index} style={{
    ...cell,
    overflowWrap: "anywhere"
  }}>
                  {item?.label}
                </td>)}
            </tr>)}
        </tbody>
      </table>
    </details>;
};

export const SettingsInfoBlock = ({type, default_value, changeable_without_restart}) => {
  return <div className="not-prose" style={{
    display: "flex",
    flexWrap: "wrap",
    alignItems: "baseline",
    columnGap: "0.5rem",
    rowGap: "0.125rem",
    margin: "0.375rem 0",
    fontSize: "0.8125rem",
    lineHeight: "1.125rem"
  }}>
      <div style={{
    fontWeight: 600,
    opacity: 0.72
  }}>Type</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{type}</div>
      <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>Default</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{default_value}</div>
      {changeable_without_restart && <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>
          Changeable without restart
        </div>}
      {changeable_without_restart && <div style={{
    overflowWrap: "anywhere"
  }}>
          {changeable_without_restart}
        </div>}
    </div>;
};

These settings are available in [system.settings](/reference/system-tables/settings) and are autogenerated from [source](https://github.com/ClickHouse/ClickHouse/blob/master/src/Core/Settings.cpp).

<h2 id="iceberg_delete_data_on_drop">
  iceberg\_delete\_data\_on\_drop
</h2>

<SettingsInfoBlock type="Bool" default_value="0" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.9"},{"label": "0"},{"label": "New setting"}]}]} />

Whether to delete all iceberg files on drop or not.

<h2 id="iceberg_file_entries_queue_size">
  iceberg\_file\_entries\_queue\_size
</h2>

<SettingsInfoBlock type="NonZeroUInt64" default_value="100" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.9"},{"label": "100"},{"label": "New setting for the previously hardcoded capacity of the queue between the Iceberg data manifest decode tasks and the query."}]}]} />

Capacity of the queue between the Iceberg data manifest decode tasks and the query, in data file entries.

The decode tasks pause once the queue is full and the query is not consuming, so this also bounds the read-ahead.

Must be greater than zero.

<h2 id="iceberg_manifest_decode_concurrency">
  iceberg\_manifest\_decode\_concurrency
</h2>

**Aliases**: `iceberg_delete_manifest_decode_concurrency`

<SettingsInfoBlock type="NonZeroUInt64" default_value="4" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.9"},{"label": "4"},{"label": "New setting bounding how many Iceberg manifest files are decoded concurrently, for delete and data manifests alike. It replaces `iceberg_delete_manifest_decode_concurrency` (kept as an alias). `2` approximates the pre-26.9 data path, which decoded one manifest at a time with the next one's fetch already in flight; under `compatibility` at or below 26.8 the delete decode therefore also runs at 2 rather than its released default of 4, preserving the older data-path memory envelope at the cost of some delete-decode overlap."}]}]} />

Maximum number of Iceberg manifest files decoded concurrently while reading a table.

Delete manifests are all decoded before any data file is read; data manifests are decoded while the list of data files for the query is produced, and new ones are decoded only as the query consumes already decoded entries. Decoding several manifests at a time overlaps the object storage round-trips and the per-entry pruning work.

Higher values raise peak memory when the Iceberg metadata files cache is disabled or full, since each in-flight manifest then holds its own decoded contents.

Must be greater than zero; `1` decodes the manifests one at a time.

<h2 id="iceberg_manifest_min_count_to_compact">
  iceberg\_manifest\_min\_count\_to\_compact
</h2>

<ExperimentalBadge />

<SettingsInfoBlock type="UInt64" default_value="30" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.7"},{"label": "30"},{"label": "New setting to control manifest compaction for Iceberg tables."}]}]} />

Minimum number of manifest files required to trigger manifest-only compaction via OPTIMIZE TABLE ... MANIFEST.
If the current number of manifest files is less than or equal to this threshold, compaction is skipped.
Requires allow\_experimental\_iceberg\_compaction to be enabled.

<h2 id="iceberg_max_number_datafiles_to_compact">
  iceberg\_max\_number\_datafiles\_to\_compact
</h2>

<SettingsInfoBlock type="UInt64" default_value="1000" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.5"},{"label": "1000"},{"label": "New setting"}]}]} />

Threshold for compaction data files in iceberg.

<h2 id="iceberg_orphan_files_older_than_seconds">
  iceberg\_orphan\_files\_older\_than\_seconds
</h2>

<ExperimentalBadge />

<SettingsInfoBlock type="UInt64" default_value="259200" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.4"},{"label": "259200"},{"label": "New setting for default orphan file age threshold"}]}]} />

Default age threshold in seconds for orphan file removal in Iceberg tables. Files newer than this are not considered orphans. Used when the older\_than argument is omitted from the remove\_orphan\_files() procedure call. Default is 259200 (3 days).

<h2 id="iceberg_snapshot_id">
  iceberg\_snapshot\_id
</h2>

<SettingsInfoBlock type="Int64" default_value="0" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.4"},{"label": "0"},{"label": "New setting."}]}]} />

Query Iceberg table using the specific snapshot id.

<h2 id="iceberg_timestamp_ms">
  iceberg\_timestamp\_ms
</h2>

<SettingsInfoBlock type="Int64" default_value="0" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "25.4"},{"label": "0"},{"label": "New setting."}]}]} />

Query Iceberg table using the snapshot that was current at a specific timestamp.