BITMAP_TO_RB32 Function

bitmap_to_rb32(expr)

Overview

The BITMAP_TO_RB32 function converts a Singdata internal BITMAP type to binary data in the standard Roaring Bitmap 32-bit serialization format. This function is primarily used for data export and interoperability with external systems (such as ClickHouse, Druid, and other systems using the standard Roaring Bitmap format).

Syntax

bitmap_to_rb32(expr)

Parameters

• expr: An expression of type BITMAP, containing Singdata internal BITMAP data.

Return Result

Returns BINARY type, with content being binary data in the Roaring Bitmap 32-bit serialization format. Returns NULL if the input is NULL.

Examples

1. Round-trip conversion between BITMAP and Roaring Bitmap 32-bit format using rb32_to_bitmap:

   SELECT bitmap_to_string(rb32_to_bitmap(bitmap_to_rb32(bitmap_build(array(1, 2, 3)))));
   +--------------------------------------------------------------------------------+
   | bitmap_to_string(rb32_to_bitmap(bitmap_to_rb32(bitmap_build(array(1, 2, 3))))) |
   +--------------------------------------------------------------------------------+
   | 1,2,3                                                                          |
   +--------------------------------------------------------------------------------+
   

2. View the converted binary data using base64 encoding:

   SELECT base64(bitmap_to_rb32(bitmap_build(array(1, 2, 3, 4))));
   +---------------------------------------------------------+
   | base64(bitmap_to_rb32(bitmap_build(array(1, 2, 3, 4)))) |
   +---------------------------------------------------------+
   | OjAAAAEAAAAAAAMAEAAAAAEAAgADAAQA                        |
   +---------------------------------------------------------+
   

3. Returns NULL when the input is NULL:

   SELECT bitmap_to_rb32(NULL);
   +----------------------+
   | bitmap_to_rb32(NULL) |
   +----------------------+
   | NULL                 |
   +----------------------+
   

Notes

• When the input parameter is NULL, the result is NULL.
• The Roaring Bitmap 32-bit format only supports values within the 32-bit unsigned integer range (0 ~ 4294967295). If the Singdata BITMAP contains values beyond this range, consider using bitmap_to_rb64 for 64-bit format conversion.
• The inverse operation of this function is rb32_to_bitmap, which converts binary data in Roaring Bitmap 32-bit serialization format to a Singdata BITMAP.