> ## 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.

# aggregation_* 会话设置

> 属于 aggregation_* 自动生成组的 ClickHouse 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，并根据 [源代码](https://github.com/ClickHouse/ClickHouse/blob/master/src/Core/Settings.cpp) 自动生成。

<div id="aggregation_in_order_max_block_bytes">
  ## aggregation\_in\_order\_max\_block\_bytes
</div>

<SettingsInfoBlock type="UInt64" default_value="50000000" />

按主键顺序聚合时累积的块的最大大小 (以字节为单位) 。块大小越小，越有利于提高聚合最终合并阶段的并行度。

<div id="aggregation_memory_efficient_merge_threads">
  ## aggregation\_memory\_efficient\_merge\_threads
</div>

<SettingsInfoBlock type="UInt64" default_value="0" />

在内存高效模式下，用于合并中间聚合结果的线程数。值越大，消耗的内存越多。0 表示与 'max\_threads' 相同。