> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-postgresql-tls-support.mintlify.site/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 VersionHistory = ({rows = []}) => {
  if (rows.length === 0) {
    return null;
  }
  const headers = ["版本", "默认值", "注释"];
  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
  }}>
        版本历史
      </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
  }}>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](/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" />

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" />

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" />

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" />

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