https://github.com/eschmar/postgresql-popcount
PostgreSQL Extension introducing popcount[|32|64|Asm|Asm64|256](bit(n)).
https://github.com/eschmar/postgresql-popcount
bitcount extension hamming-weight look-up-table popcnt popcount postgresql
Last synced: 10 months ago
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PostgreSQL Extension introducing popcount[|32|64|Asm|Asm64|256](bit(n)).
- Host: GitHub
- URL: https://github.com/eschmar/postgresql-popcount
- Owner: eschmar
- License: mit
- Created: 2018-05-18T12:56:31.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2023-04-22T15:28:50.000Z (about 3 years ago)
- Last Synced: 2025-05-24T07:02:17.282Z (about 1 year ago)
- Topics: bitcount, extension, hamming-weight, look-up-table, popcnt, popcount, postgresql
- Language: C
- Homepage:
- Size: 207 KB
- Stars: 7
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: readme.md
- License: LICENSE
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README
**Note:** PostgreSQL version 14 introduced their own [`bit_count`](https://www.postgresql.org/docs/14/functions-bitstring.html). You may find [their implementation here](https://github.com/postgres/postgres/blob/master/src/port/pg_bitutils.c) (or [here](https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/port/pg_bitutils.c;hb=HEAD)) for comparison. It is therefore recommended to only use this repository for postgres versions <14. More information in [this blog post](https://eschmann.dev/2023/04/revisiting-popcount-on-postgres-14).
# PostgreSQL population count function for data type bit(n).
Provides `popcount`, `popcount32`, `popcount64`, `popcountAsm`, `popcountAsm64` and `popcount256` functions to PostgreSQL. The extension was elected to provide all algorithms to enable a conscious choice on runtime. Statistical benchmark data suggests that `popcountAsm64` should be chosen in most cases.
## Usage
The extension is [available on PGXN](https://pgxn.org/dist/popcount/).
```sh
pgxn install popcount
```
If you want to compile it yourself, `pg_config` is required.
```sh
make install
make installcheck
```
## Benchmarks 2018
The test bench was running an Intel(R) Xeon(R) Platinum 8168 CPU @ 2.70GHz on Ubuntu 18.04 and PostgreSQL 10.3.
## Benchmarks 2023
More information in [this blog post](https://eschmann.dev/2023/04/revisiting-popcount-on-postgres-14).
The test bench was running an Intel(R) Xeon(R) Platinum 8358 CPU @ 2.60GHz on Ubuntu 22.04 and PostgreSQL 14.7. It can be reproduced the following way.
```sh
./helper/generate_db_postgres.sh -d 500000 -a "2048 4096 8192"
./benchmark/postgres.sh -s popcountAsm64 -t 50 -d 500000 -a "2048 4096 8192"
```
option | values | comment
--- | --- | ---
-s | `popcount`, `popcount32`, `popcount64`, `popcountAsm`, `popcountAsm64`, `popcount256` | 8bit lookup table, 32bit hamming weight, 64bit hamming weight, 32 bit intrinsic function, 64 bit intrinsic function, unrolled assembly instruction.
-t | *integer* | Number of trials.
-d | *integer* | Number of rows in domain.
-a | *integer* | Bit alignments to test.
--units | - | Whether time units should be printed or not.
## Setup
Setup instructions on Ubuntu 22.04 LTS for convenience.
```sh
# install dependencies
sudo apt update
sudo apt install build-essential postgresql postgresql-contrib libpq-dev postgresql-server-dev-14 make
sudo systemctl start postgresql.service
# install extension...
sudo -i -u postgres
git clone https://github.com/eschmar/postgresql-popcount.git
cd postgresql-popcount
make install
make installcheck
# .. and enable it
psql
CREATE EXTENSION popcount;
\q
```