23rd May 2019: PostgreSQL 12 Beta 1 Released!

This section describes functions and operators for examining and manipulating bit strings, that is values of the types `bit`

and `bit varying`

. Aside from the usual comparison operators, the operators shown in Table 9.13 can be used. Bit string operands of `&`

, `|`

, and `#`

must be of equal length. When bit shifting, the original length of the string is preserved, as shown in the examples.

**Table 9.13. Bit String Operators**

Operator | Description | Example | Result |
---|---|---|---|

`||` |
concatenation | `B'10001' || B'011'` |
`10001011` |

`&` |
bitwise AND | `B'10001' & B'01101'` |
`00001` |

`|` |
bitwise OR | `B'10001' | B'01101'` |
`11101` |

`#` |
bitwise XOR | `B'10001' # B'01101'` |
`11100` |

`~` |
bitwise NOT | `~ B'10001'` |
`01110` |

`<<` |
bitwise shift left | `B'10001' << 3` |
`01000` |

`>>` |
bitwise shift right | `B'10001' >> 2` |
`00100` |

The following SQL-standard functions work on bit strings as well as character strings:

, `length`

, `bit_length`

, `octet_length`

, `position`

, `substring`

.`overlay`

The following functions work on bit strings as well as binary strings:

, `get_bit`

. When working with a bit string, these functions number the first (leftmost) bit of the string as bit 0.`set_bit`

In addition, it is possible to cast integral values to and from type `bit`

. Some examples:

44::bit(10)000010110044::bit(3)100cast(-44 as bit(12))111111010100'1110'::bit(4)::integer14

Note that casting to just “bit” means casting to `bit(1)`

, and so will deliver only the least significant bit of the integer.

Casting an integer to `bit(n)`

copies the rightmost `n`

bits. Casting an integer to a bit string width wider than the integer itself will sign-extend on the left.

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