BitmapBitPosition¶

Overview¶

The BitmapBitPosition expression calculates the bit position for a given long value in bitmap operations. This is a utility function used in bitmap-based data processing to determine the position of a bit within a bitmap structure based on the input value.

Syntax¶

bitmap_bit_position(value)

col("column_name").expr("bitmap_bit_position(column_name)")

Arguments¶

Argument	Type	Description
value	BIGINT	The long value for which to calculate the bit position

Return Type¶

BIGINT - Returns a long value representing the bit position.

Supported Data Types¶

Input: BIGINT (LongType)
Implicit casting is supported for compatible numeric types

Algorithm¶

Takes a single long value as input
Delegates computation to the BitmapExpressionUtils.bitmapBitPosition method via static invocation
Performs bit position calculation based on the input value
Returns the computed bit position as a long value
Does not return null for valid inputs (returnNullable = false)

Partitioning Behavior¶

This expression preserves partitioning behavior:

Does not require data shuffling
Can be evaluated independently on each partition
Does not affect existing partitioning schemes

Edge Cases¶

Null handling: Input nulls are handled according to standard Spark null propagation rules
Type safety: Automatic implicit casting ensures input is converted to LongType when possible
Non-nullable result: The expression is designed to always return a valid long value for non-null inputs
Deterministic behavior: Always produces the same output for the same input value

Code Generation¶

This expression uses runtime replacement and static method invocation:

Does not generate custom code via Tungsten code generation
Falls back to interpreted mode using static method calls
Leverages the RuntimeReplaceable trait for expression substitution

Examples¶

-- Calculate bit position for literal values
SELECT bitmap_bit_position(42) AS bit_pos;

-- Use with table columns
SELECT id, bitmap_bit_position(user_id) AS bit_position 
FROM user_events;

-- Use in WHERE clauses for filtering
SELECT * FROM data 
WHERE bitmap_bit_position(category_id) < 100;

// DataFrame API usage
import org.apache.spark.sql.functions._

// Calculate bit position for a column
df.select(expr("bitmap_bit_position(user_id)").alias("bit_pos"))

// Use in transformations
df.withColumn("bit_position", expr("bitmap_bit_position(category_id)"))

// Filter based on bit position
df.filter(expr("bitmap_bit_position(item_id) BETWEEN 10 AND 50"))