> ## 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.

# ignore_* 会话设置

> ClickHouse 在 ignore_* 生成分组中的会话设置。

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>;
};

export const CloudOnlyBadge = () => {
  return <div className="cloudBadge">
            <div className="cloudIcon">
            <svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg">
                <path fillRule="evenodd" clipRule="evenodd" d="M5.33395 12.6667H12.3739C13.6593 12.6667 14.7073 11.6187 14.7073 10.3334C14.7073 9.04804 13.6593 8.00004 12.3739 8.00004H12.0839V7.33337C12.0839 5.12671 10.2906 3.33337 8.08395 3.33337C6.09928 3.33337 4.45395 4.78537 4.14195 6.68204C2.55728 6.76271 1.29395 8.06204 1.29395 9.66671C1.29395 11.3234 2.63728 12.6667 4.29395 12.6667H5.33395Z" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" />
            </svg>
        </div>
            {'仅限 ClickHouse Cloud'}
        </div>;
};

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

<div id="ignore_cold_parts_seconds">
  ## ignore\_cold\_parts\_seconds
</div>

<CloudOnlyBadge />

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

仅在 ClickHouse Cloud 中生效。在新的数据分区片段被预热 (参见 [cache\_populated\_by\_fetch](/docs/zh/reference/settings/merge-tree-settings#cache_populated_by_fetch)) 或达到指定秒数之前，会将其排除在 SELECT 查询之外。仅适用于 Replicated-/SharedMergeTree。

<div id="ignore_data_skipping_indices">
  ## ignore\_data\_skipping\_indices
</div>

如果查询会使用指定的跳过索引，则忽略这些索引。

请看下面的示例：

```sql theme={null}
CREATE TABLE data
(
    key Int,
    x Int,
    y Int,
    INDEX x_idx x TYPE minmax GRANULARITY 1,
    INDEX y_idx y TYPE minmax GRANULARITY 1,
    INDEX xy_idx (x,y) TYPE minmax GRANULARITY 1
)
Engine=MergeTree()
ORDER BY key;

INSERT INTO data VALUES (1, 2, 3);

SELECT * FROM data;
SELECT * FROM data SETTINGS ignore_data_skipping_indices=''; -- query will produce CANNOT_PARSE_TEXT error.
SELECT * FROM data SETTINGS ignore_data_skipping_indices='x_idx'; -- Ok.
SELECT * FROM data SETTINGS ignore_data_skipping_indices='na_idx'; -- Ok.

SELECT * FROM data WHERE x = 1 AND y = 1 SETTINGS ignore_data_skipping_indices='xy_idx',force_data_skipping_indices='xy_idx' ; -- query will produce INDEX_NOT_USED error, since xy_idx is explicitly ignored.
SELECT * FROM data WHERE x = 1 AND y = 2 SETTINGS ignore_data_skipping_indices='xy_idx';
```

不忽略任何索引时的查询：

```sql theme={null}
EXPLAIN indexes = 1 SELECT * FROM data WHERE x = 1 AND y = 2;

Expression ((Projection + Before ORDER BY))
  Filter (WHERE)
    ReadFromMergeTree (default.data)
    Indexes:
      PrimaryKey
        Condition: true
        Parts: 1/1
        Granules: 1/1
      Skip
        Name: x_idx
        Description: minmax GRANULARITY 1
        Parts: 0/1
        Granules: 0/1
      Skip
        Name: y_idx
        Description: minmax GRANULARITY 1
        Parts: 0/0
        Granules: 0/0
      Skip
        Name: xy_idx
        Description: minmax GRANULARITY 1
        Parts: 0/0
        Granules: 0/0
```

忽略 `xy_idx` 索引：

```sql theme={null}
EXPLAIN indexes = 1 SELECT * FROM data WHERE x = 1 AND y = 2 SETTINGS ignore_data_skipping_indices='xy_idx';

Expression ((Projection + Before ORDER BY))
  Filter (WHERE)
    ReadFromMergeTree (default.data)
    Indexes:
      PrimaryKey
        Condition: true
        Parts: 1/1
        Granules: 1/1
      Skip
        Name: x_idx
        Description: minmax GRANULARITY 1
        Parts: 0/1
        Granules: 0/1
      Skip
        Name: y_idx
        Description: minmax GRANULARITY 1
        Parts: 0/0
        Granules: 0/0
```

适用于 MergeTree 家族中的表。

<div id="ignore_drop_queries_probability">
  ## ignore\_drop\_queries\_probability
</div>

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

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.4"},{"label": "0"},{"label": "允许服务器出于测试目的，以指定概率忽略 DROP 查询"}]}]} />

如果启用，服务器将以指定的概率忽略所有 DROP 表查询 (对于 Memory 和 JOIN 引擎，会将 DROP 替换为 TRUNCATE) 。用于测试目的

<div id="ignore_format_null_for_explain">
  ## ignore\_format\_null\_for\_explain
</div>

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

<VersionHistory rows={[{"id": "row-1","items": [{"label": "26.2"},{"label": "1"},{"label": "现在默认会在 EXPLAIN 查询中忽略 FORMAT Null"}]}]} />

如果启用，`EXPLAIN` 查询中的 `FORMAT Null` 将被忽略，改为使用默认输出格式。
如果禁用，带有 `FORMAT Null` 的 `EXPLAIN` 查询将不会产生任何输出 (向后兼容行为) 。

<div id="ignore_materialized_views_with_dropped_target_table">
  ## ignore\_materialized\_views\_with\_dropped\_target\_table
</div>

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

<VersionHistory rows={[{"id": "row-1","items": [{"label": "24.1"},{"label": "0"},{"label": "添加新设置，以允许忽略目标表已被删除的 materialized view"}]}]} />

在推送到视图时，忽略目标表已被删除的 MV