KnowForgeBolt Backend Window Function Support
qianmoQ· 更新于 2026-10-02· 阅读 4 分钟· 0 次阅读登录后可跨设备保存划线和私人笔记登录
Window Functions Support Status in Bolt
| Spark Functions | Spark Expressions | Status | Restrictions |
|---|---|---|---|
| cume_dist | CumeDist | S | Returns a DOUBLE cumulative distribution value within the partition. |
| dense_rank | DenseRank | S | Returns the dense rank within each partition. |
| lag | Lag | S | Offset must be ≥ 0; offset = 0 returns the current row. Optional default value is supported. IGNORE NULLS is supported and lag operates over the whole partition, not limited by frame. |
| lead | Lead | S | Same rules as lag: offset ≥ 0, offset = 0 returns the current row, optional default value and IGNORE NULLS are supported, operates over the whole partition. |
| nth_value | NthValue | S | Return type matches the value expression. Offset must be ≥ 1 for both constant and column offsets; smaller values are rejected. IGNORE NULLS is supported in the engine for the PrestoSQL mapping. |
| ntile | NTile | S | Number of buckets must be > 0; 0 or negative values are rejected. When buckets exceed the partition size, the bucket index effectively follows the row number. If the bucket expression is NULL, the result is NULL. |
| percent_rank | PercentRank | S | Returns a DOUBLE in \[0, 1], computed as (rank - 1) / (partition_row_count - 1) (0 when there is only one row in the partition). |
| rank | Rank | S | Returns the rank within each partition using standard SQL rank semantics. |
| row_number | RowNumber | S | Assigns a sequential row number within each partition. |
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