A PDO monolog handler implementation. Almost done (it needs tests). It also works with Postgres' json data type.

Monolog\Handler\PDOHandler.php

<?php

namespace AK\Monolog\Handler;

use Monolog\Handler\AbstractProcessingHandler;
use Monolog\Logger;
use Monolog\Formatter\JsonFormatter;

class PDOHandler extends AbstractProcessingHandler
{
    private $dbh;
    private $table;
    private $column;
    private $sth = null;

    public function __construct(\PDO $dbh, $table = null, $column = null, $level = Logger::DEBUG, $bubble = true)
    {
        if ($table === null || $column === null) {
            throw new \InvalidArgumentException('$table and $column are required');
        } else {
            $this->dbh = $dbh;
            $this->table = $table;
            $this->column = $column;
            parent::__construct($level, $bubble);
        }
    }

    public function __destruct()
    {
        if ($this->sth !== null) {
            $this->sth->closeCursor();
        }
        unset($this->sth, $this->dbh, $this->table, $this->column);
    }

    protected function write(array $record)
    {
        try {
            if ($this->sth === null) {
                $sth = $this->dbh->prepare("INSERT INTO $this->table($this->column) VALUES (?)");
                $this->sth = $sth;
            }
            $this->sth->bindParam(1, $record['formatted']);
            $result = $this->sth->execute();
        } catch (PDOException $e) {
            //Throwing Standard Exception in case private data in PDOException
            //Might want to change this to something more reasonable?
            throw new Exception("Problem with PDO Connection.");
        }
        if (!$result) {
            throw new Exception("Problem adding log entry to database.");
        }
    }

    protected function getDefaultFormatter()
    {
        return new JsonFormatter(JsonFormatter::BATCH_MODE_JSON, false);
    }
}