Column Database¶
A column database (or column-oriented / columnar database) stores data by column rather than by row. In a traditional row-oriented database, all the fields of a record are stored together. In a columnar database, each column’s values are stored contiguously.
This layout is particularly efficient for analytical queries that read only a few columns across a large number of rows (OLAP workloads), because:
Only the columns needed for a query need to be read from disk.
Columnar storage compresses well (similar values are adjacent).
Aggregate functions (SUM, AVG, COUNT) operate on contiguous memory.
Popular columnar databases used with PHP include ClickHouse, Apache Parquet (file format), Amazon Redshift, and Google BigQuery.
Row-oriented databases (MySQL, PostgreSQL) remain better for OLTP workloads that access full records.
<?php
// Example: querying ClickHouse (columnar DB) via HTTP
$ch = curl_init('http://localhost:8123/?query=SELECT+sum(price)+FROM+orders+FORMAT+JSON');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$result = curl_exec($ch);
curl_close($ch);
$data = json_decode($result, true);
echo $data['data'][0]['sum(price)'];
?>
See also Column-oriented DBMS - Wikipedia.
Related : Database, SQL Database, Graph Database, Nosql Database, Parquet
