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[FLINK-39188][docs] Documentation for BITMAP type #27835

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lincoln-lil merged 1 commit into from
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[FLINK-39188][docs] Documentation for BITMAP type #27835

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6 changes: 6 additions & 0 deletions docs/content.zh/docs/sql/functions/built-in-functions.md
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Expand Up @@ -124,6 +124,12 @@ JSON 函数使用符合 ISO/IEC TR 19075-6 SQL标准的 JSON 路径表达式。

### 位图聚合函数

**性能建议：**

- 强烈建议开启 [MiniBatch 聚合]({{< ref "docs/dev/table/tuning" >}})或在[窗口聚合]({{< ref "docs/sql/reference/queries/window-agg" >}})中使用位图聚合函数，以优化状态访问开销、显著提升性能。
- 位图聚合函数在处理仅追加（Append-Only）输入时性能最佳。处理回撤（Retraction）输入时性能会明显下降，因此应尽量避免对 BITMAP 列进行多级 GROUP BY 聚合。
- 在仅需要基数统计而不需要中间位图的场景中，建议使用 `BITMAP_XX_CARDINALITY_AGG()` 替代 `BITMAP_CARDINALITY(BITMAP_XX_AGG())`。两者功能一致，但前者避免了中间位图的物化，性能更优。

{{< sql_functions_zh "bitmapagg" >}}

时间间隔单位和时间点单位标识符
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