> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-parallel-read-in-order-multi-part.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# enable_join_* session settings

> ClickHouse session settings in the enable_join_* generated group.

export const BetaBadge = ({link, galaxyTrack, galaxyEvent}) => {
  if (link) {
    return <a href={link} target="_blank" rel="noopener noreferrer" className="betaBadge" onClick={galaxyTrack && galaxyEvent ? galaxyOnClick(galaxyEvent) : undefined}>
                <span>Beta</span>
            </a>;
  }
  return <a href="https://clickhouse.com/docs/reference/settings/beta-and-experimental-features#beta-features" className="betaBadge">
            <span>Beta feature</span>
        </a>;
};

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="enable_join_fixed_hash_table_conversion">
  enable\_join\_fixed\_hash\_table\_conversion
</h2>

<SettingsInfoBlock type="Bool" default_value="1" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.4"},{"label": "1"},{"label": "New setting to enable converting the hash table to a flat array for joins when the key is a single integer with a small value range."}]}]} />

Enable converting the hash table to a flat array for joins when the key is a single integer with a small value range.

<h2 id="enable_join_key_only_hash_tables">
  enable\_join\_key\_only\_hash\_tables
</h2>

<SettingsInfoBlock type="Bool" default_value="1" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.9"},{"label": "1"},{"label": "New setting to store the join keys alone, without a reference to a right row, in the hash tables of joins whose result can never contain a value taken from a right row (`LEFT ANTI`, and `LEFT SEMI` when no right column is selected)."}]}]} />

Use hash tables that store the join keys alone, without a reference to a right row, for joins whose result can never contain a value taken from a right row: `LEFT ANTI`, and `LEFT SEMI` when no right column is selected. Such a table has a smaller cell and lets the right blocks be dropped instead of stored.

<h2 id="enable_join_runtime_filters">
  enable\_join\_runtime\_filters
</h2>

<SettingsInfoBlock type="Bool" default_value="1" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.9"},{"label": "1"},{"label": "The JOIN runtime filters became a Production tier feature."}]}, {"id": "row-2","items": [{"label": "26.2"},{"label": "1"},{"label": "Enabled this optimization"}]}, {"id": "row-3","items": [{"label": "25.10"},{"label": "0"},{"label": "New setting"}]}]} />

Filter left side by set of JOIN keys collected from the right side at runtime.

<h2 id="enable_join_runtime_filters_index_analysis">
  enable\_join\_runtime\_filters\_index\_analysis
</h2>

<SettingsInfoBlock type="Bool" default_value="1" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.9"},{"label": "0"},{"label": "The JOIN runtime filters became a Production tier feature."}]}, {"id": "row-2","items": [{"label": "26.7"},{"label": "0"},{"label": "New setting to enable join filtering using dynamic index analysis"}]}, {"id": "row-3","items": [{"label": "26.10"},{"label": "1"},{"label": "Enable pruning of granules on the probe (left) side of a JOIN by the runtime filter collected from the build (right) side."}]}]} />

Prune granules on the probe side of a JOIN with the runtime filter collected from the build side, see `enable_join_runtime_filters`.
Only has an effect if `use_skip_indexes_on_data_read = 1`.
Only a join key that is a primary key column of the probe side, or is covered by a `minmax`, `set` or `bloom_filter` skip index, can be pruned.
If the runtime filter kept the exact key values, the pruning predicate is an `IN` set of them, otherwise the minimum/maximum key range is used (this has a lower pruning power).

Takes effect only when the probe side of the join is read locally. The descriptors that drive the pruning are attached to the read step while the query plan is optimized, and they are not carried over when that step is rebuilt for remote execution, so the granule pruning does not happen with parallel replicas (`enable_parallel_replicas = 1`) or with a distributed query plan (`make_distributed_plan = 1`). In those modes the setting is a no-op: the query returns the same result and the JOIN runtime filter itself behaves exactly as it does with this setting disabled, only the granule pruning is lost.

The granule pruning is also skipped for a probe side read with `FINAL` (the pruning is not implemented for `FINAL` reads, and `optimizeLazyFinal` rebuilds such a read without the descriptors), and for a table with pending data or `ALTER` mutations or patch parts. These cases are a no-op in the same sense.

<h2 id="enable_join_seal_gated_reading">
  enable\_join\_seal\_gated\_reading
</h2>

<ExperimentalBadge />

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

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.10"},{"label": "0"},{"label": "New experimental setting to gate the probe-side reading of a hash JOIN on the build-side runtime filter completion and prune read ranges by it."}]}]} />

Gate the probe-side reading of a hash JOIN on the completion of the build-side runtime filter (see `enable_join_runtime_filters`): nothing is read on the probe side until the filter is complete, and the filter is then used to prune whole mark ranges by the primary key before read tasks are created, in addition to the ordinary row-level filtering. The gating is expressed as an edge of the query pipeline. On a gated read, the read-time index analysis of the same runtime filter (see `enable_join_runtime_filters_index_analysis`) is skipped as redundant.

Experimental. Local reads are gated, including single-threaded and in-order reading; reads under FINAL, parallel replicas, or a join sharded by primary key ranges fall back to ungated reading with row-level filtering.

<h2 id="enable_join_transitive_predicates">
  enable\_join\_transitive\_predicates
</h2>

<BetaBadge />

<SettingsInfoBlock type="Bool" default_value="1" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.6"},{"label": "1"},{"label": "Turn on enable_join_transitive_predicates by default"}]}, {"id": "row-2","items": [{"label": "26.4"},{"label": "0"},{"label": "New setting to infer transitive equi-join predicates for join order optimization."}]}]} />

Infer transitive equi-join predicates from existing join conditions.
For example, given `A.x = B.x` and `B.x = C.x`, a synthetic `A.x = C.x` predicate
is added so the join order optimizer can consider direct (A JOIN C) plans.