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Bitstring Functions

This section describes functions and operators for examining and manipulating BITSTRING values. Bitstrings must be of equal length when performing the bitwise operands AND, OR and XOR. When bit shifting, the original length of the string is preserved.

Bitstring Operators

The table below shows the available mathematical operators for BIT type.

Operator Description Example Result
& Bitwise AND '10101'::BITSTRING & '10001'::BITSTRING 10001
| Bitwise OR '1011'::BITSTRING | '0001'::BITSTRING 1011
xor Bitwise XOR xor('101'::BITSTRING, '001'::BITSTRING) 100
~ Bitwise NOT ~('101'::BITSTRING) 010
<< Bitwise shift left '1001011'::BITSTRING << 3 1011000
>> Bitwise shift right '1001011'::BITSTRING >> 3 0001001

Bitstring Functions

The table below shows the available scalar functions for BIT type.

Name Description
bit_count(bitstring) Returns the number of set bits in the bitstring.
bit_length(bitstring) Returns the number of bits in the bitstring.
bit_position(substring, bitstring) Returns first starting index of the specified substring within bits, or zero if it's not present. The first (leftmost) bit is indexed 1.
bitstring(bitstring, length) Returns a bitstring of determined length.
get_bit(bitstring, index) Extracts the nth bit from bitstring; the first (leftmost) bit is indexed 0.
length(bitstring) Alias for bit_length.
octet_length(bitstring) Returns the number of bytes in the bitstring.
set_bit(bitstring, index, new_value) Sets the nth bit in bitstring to newvalue; the first (leftmost) bit is indexed 0. Returns a new bitstring.

bit_count(bitstring)

Description Returns the number of set bits in the bitstring.
Example bit_count('1101011'::BITSTRING)
Result 5

bit_length(bitstring)

Description Returns the number of bits in the bitstring.
Example bit_length('1101011'::BITSTRING)
Result 7

bit_position(substring, bitstring)

Description Returns first starting index of the specified substring within bits, or zero if it's not present. The first (leftmost) bit is indexed 1
Example bit_position('010'::BITSTRING, '1110101'::BITSTRING)
Result 4

bitstring(bitstring, length)

Description Returns a bitstring of determined length.
Example bitstring('1010'::BITSTRING, 7)
Result 0001010

get_bit(bitstring, index)

Description Extracts the nth bit from bitstring; the first (leftmost) bit is indexed 0.
Example get_bit('0110010'::BITSTRING, 2)
Result 1

length(bitstring)

Description Alias for bit_length.
Example length('1101011'::BITSTRING)
Result 7

octet_length(bitstring)

Description Returns the number of bytes in the bitstring.
Example octet_length('1101011'::BITSTRING)
Result 1

set_bit(bitstring, index, new_value)

Description Sets the nth bit in bitstring to newvalue; the first (leftmost) bit is indexed 0. Returns a new bitstring.
Example set_bit('0110010'::BITSTRING, 2, 0)
Result 0100010

Bitstring Aggregate Functions

These aggregate functions are available for BIT type.

Name Description
bit_and(arg) Returns the bitwise AND operation performed on all bitstrings in a given expression.
bit_or(arg) Returns the bitwise OR operation performed on all bitstrings in a given expression.
bit_xor(arg) Returns the bitwise XOR operation performed on all bitstrings in a given expression.
bitstring_agg(arg) Returns a bitstring with bits set for each distinct position defined in arg.
bitstring_agg(arg, min, max) Returns a bitstring with bits set for each distinct position defined in arg. All positions must be within the range [min, max] or an Out of Range Error will be thrown.

bit_and(arg)

Description Returns the bitwise AND operation performed on all bitstrings in a given expression.
Example bit_and(A)

bit_or(arg)

Description Returns the bitwise OR operation performed on all bitstrings in a given expression.
Example bit_or(A)

bit_xor(arg)

Description Returns the bitwise XOR operation performed on all bitstrings in a given expression.
Example bit_xor(A)

bitstring_agg(arg)

Description The bitstring_agg function takes any integer type as input and returns a bitstring with bits set for each distinct value. The left-most bit represents the smallest value in the column and the right-most bit the maximum value. If possible, the min and max are retrieved from the column statistics. Otherwise, it is also possible to provide the min and max values.
Example bitstring_agg(A)

Tip The combination of bit_count and bitstring_agg can be used as an alternative to count(DISTINCT ...), with possible performance improvements in cases of low cardinality and dense values.

bitstring_agg(arg, min, max)

Description Returns a bitstring with bits set for each distinct position defined in arg. All positions must be within the range [min, max] or an Out of Range Error will be thrown.
Example bitstring_agg(A, 1, 42)
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