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

# shared_merge_* 会话设置

> ClickHouse 在 shared_merge_* 自动生成组中的会话设置。

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
  }}>类型</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{type}</div>
      <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>默认值</div>
      <div style={{
    overflowWrap: "anywhere"
  }}>{default_value}</div>
      {changeable_without_restart && <div style={{
    fontWeight: 600,
    opacity: 0.72,
    marginInlineStart: "0.5rem"
  }}>
          无需重启即可更改
        </div>}
      {changeable_without_restart && <div style={{
    overflowWrap: "anywhere"
  }}>
          {changeable_without_restart}
        </div>}
    </div>;
};

这些设置可在 [system.settings](/docs/zh/reference/system-tables/settings) 中查看，并由 [源文件](https://github.com/ClickHouse/ClickHouse/blob/master/src/Core/Settings.cpp) 自动生成。

<div id="shared_merge_tree_sequential_consistency_initial_parts_update_backoff_ms">
  ## shared\_merge\_tree\_sequential\_consistency\_initial\_parts\_update\_backoff\_ms
</div>

<SettingsInfoBlock type="UInt64" default_value="50" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.5"},{"label": "50"},{"label": "用于减少 SharedMergeTree 中采用顺序一致性的查询偶发 UNFINISHED 错误的新设置。"}]}]} />

在 `SharedMergeTree` 中使用 `select_sequential_consistency` 时，parts 更新的初始退避时间 (毫秒) 。仅在 ClickHouse Cloud 中可用。

<div id="shared_merge_tree_sequential_consistency_max_parts_update_backoff_ms">
  ## shared\_merge\_tree\_sequential\_consistency\_max\_parts\_update\_backoff\_ms
</div>

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

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.5"},{"label": "1000"},{"label": "新增此设置，用于减少 SharedMergeTree 在采用顺序一致性的查询中偶发的 UNFINISHED 错误。"}]}]} />

将 `select_sequential_consistency` 与 `SharedMergeTree` 一起使用时，parts 更新的最大退避时间 (毫秒) 。仅在 ClickHouse Cloud 中可用。

<div id="shared_merge_tree_sequential_consistency_parts_update_max_retries">
  ## shared\_merge\_tree\_sequential\_consistency\_parts\_update\_max\_retries
</div>

<SettingsInfoBlock type="UInt64" default_value="10" />

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.5"},{"label": "10"},{"label": "用于减少对 SharedMergeTree 使用 sequential consistency 的查询中偶发 UNFINISHED 错误的新设置。"}]}]} />

在 `SharedMergeTree` 中使用 `select_sequential_consistency` 时，parts 更新的最大重试次数。仅在 ClickHouse Cloud 中可用。

<div id="shared_merge_tree_sync_parts_on_partition_operations">
  ## shared\_merge\_tree\_sync\_parts\_on\_partition\_operations
</div>

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

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.12"},{"label": "1"},{"label": "新设置。默认始终同步数据分区parts"}]}]} />

在 SMT 表中执行 MOVE|REPLACE|ATTACH 分区操作后，自动同步一组数据分区parts。仅限 Cloud