GROUP_BITMAP_OR_STATE

Introduction

The GROUP_BITMAP_OR_STATE function is used to compute the bitwise OR operation on a set of Bitmap data and returns an intermediate BITMAP object. This function is highly efficient when dealing with large-scale datasets, especially in scenarios where union operations on multiple Bitmaps are required. The returned intermediate state can be used for subsequent merge operations, enabling more complex aggregation logic.

Syntax

group_bitmap_or_state(bitmap)

Parameters

• bitmap: An expression of type BITMAP, representing the Bitmap data to be operated on.

Return Value

The function returns an intermediate BITMAP object, representing the intermediate result of the bitwise OR operation. This intermediate state can be used for subsequent merge operations.

Usage Example

Example 1: Basic Usage

SELECT bitmapToArray(group_bitmap_or_state(bitmapBuild(v))) AS res FROM VALUES (array(1, 2, 3)), (array(1, 2)), (array(1)) AS t(v); +---------+ | res | +---------+ | [1,2,3] | +---------+

Result: Returns an intermediate Bitmap object representing the intermediate result of the bitwise OR operation.

Example 2: Combined with group_bitmap_merge

The group_bitmap_merge function is used to merge multiple intermediate Bitmap objects and generate a complete Bitmap.

SELECT group_bitmap_merge(or_state) AS final_bitmap FROM ( SELECT group_bitmap_or_state(bitmapBuild(v)) AS or_state FROM VALUES (array(1, 2, 3)), (array(1, 2)), (array(1)) AS t(v) ); +--------------+ | final_bitmap | +--------------+ | 3 | +--------------+

Result: Returns a complete Bitmap representing the result of the bitwise OR operation on all input Bitmaps.