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PHP cheatsheet

Materialize is wire-compatible with PostgreSQL, which means that PHP applications can use common PostgreSQL clients to interact with Materialize. In this guide, we’ll use the PDO_PGSQL driver to connect to Materialize and issue SQL commands.

Connect

To connect to Materialize using PDO_PGSQL:

<?php

function connect(string $host, int $port, string $db, string $user, string $password): PDO
{
    try {
        $dsn = "pgsql:host=$host;port=$port;dbname=$db;";

        // make a database connection
        return new PDO(
            $dsn,
            $user,
            $password,
            [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]
        );
    } catch (PDOException $e) {
        die($e->getMessage());
    }
}

$connection = connect('MATERIALIZE_HOST', 6875, 'materialize', 'MATERIALIZE_USERNAME', 'MATERIALIZE_PASSWORD');

You can add the above code to a config.php file and then include it in your application with require 'connect.php';.

Stream

To take full advantage of incrementally updated materialized views from a PHP application, instead of querying Materialize for the state of a view at a point in time, use a SUBSCRIBE statement to request a stream of updates as the view changes.

To read a stream of updates from an existing materialized view, open a long-lived transaction with BEGIN and use SUBSCRIBE with FETCH to repeatedly fetch all changes to the view since the last query:

<?php
// Include the Postgres connection details
require 'connect.php';

// Begin a transaction
$connection->beginTransaction();
// Declare a cursor
$statement = $connection->prepare('DECLARE c CURSOR FOR SUBSCRIBE demo');
// Execute the statement
$statement->execute();

/* Fetch all of the remaining rows in the result set */
while (true) {
    //$result = $statement->fetchAll();
    $subscribe = $connection->prepare('FETCH ALL c');
    $subscribe->execute();
    $result = $subscribe->fetchAll(PDO::FETCH_ASSOC);
    print_r($result);
}

The SUBSCRIBE output format of result is an array of view updates objects. When a row of a subscribed view is updated, two objects will show up in the result array:

    ...
        Array
        (
            [0] => Array
                (
                    [mz_timestamp] => 1646310999683
                    [mz_diff] => 1
                    [my_column_one] => 'value'
                )

        )
        Array
        (
            [0] => Array
                (
                    [mz_timestamp] => 1646311002682
                    [mz_diff] => -1
                    [my_column_one] => 'value'
                )

        )
    ...

An mz_diff value of -1 indicates Materialize is deleting one row with the included values. An update is just a retraction (mz_diff: '-1') and an insertion (mz_diff: '1') with the same timestamp.

Query

Querying Materialize is identical to querying a PostgreSQL database: PHP executes the query, and Materialize returns the state of the view, source, or table at that point in time.

Because Materialize keeps results incrementally updated, response times are much faster than traditional database queries, and polling (repeatedly querying) a view doesn’t impact performance.

To query a view my_view using a SELECT statement:

<?php
// Include the Postgres connection details
require 'connect.php';

$sql = 'SELECT * FROM my_view';
$statement = $connection->query($sql);

while (($row = $statement->fetch(PDO::FETCH_ASSOC)) !== false) {
    var_dump($row);
}

For more details, see the PHP PDOStatement documentation.

Insert data into tables

Most data in Materialize will stream in via an external system, but a TABLE in Materialize can be helpful for supplementary data. For example, you can use a table to join slower-moving reference or lookup data with a stream.

Basic Example: Insert a row of data into a table named countries in Materialize.

<?php
// Include the Postgres connection details
require 'connect.php';

$sql = 'INSERT INTO countries (name, code) VALUES (?, ?)';
$statement = $connection->prepare($sql);
$statement->execute(['United States', 'US']);
$statement->execute(['Canada', 'CA']);
$statement->execute(['Mexico', 'MX']);
$statement->execute(['Germany', 'DE']);

$countStmt = "SELECT COUNT(*) FROM countries";
$count = $connection->query($countStmt);
while (($row = $count->fetch(PDO::FETCH_ASSOC)) !== false) {
    var_dump($row);
}

Manage sources, views, and indexes

Typically, you create sources, views, and indexes when deploying Materialize, although it is possible to use a PHP app to execute common DDL statements.

Create a source from PHP

<?php
// Include the Postgres connection details
require 'connect.php';

$sql = "CREATE SOURCE counter FROM LOAD GENERATOR COUNTER";

$statement = $connection->prepare($sql);
$statement->execute();

$sources = "SHOW SOURCES";
$statement = $connection->query($sources);
$result = $statement->fetchAll(PDO::FETCH_ASSOC);
var_dump($result);

For more information, see CREATE SOURCE.

Create a view from PHP

<?php
// Include the Postgres connection details
require 'connect.php';

$sql = "CREATE VIEW market_orders_2 AS
            SELECT
                val->>'symbol' AS symbol,
                (val->'bid_price')::float AS bid_price
            FROM (SELECT text::jsonb AS val FROM market_orders_raw_2)";

$statement = $connection->prepare($sql);
$statement->execute();

$views = "SHOW VIEWS";
$statement = $connection->query($views);
$result = $statement->fetchAll(PDO::FETCH_ASSOC);
var_dump($result);

For more information, see CREATE VIEW.

PHP ORMs

ORM frameworks like Eloquent tend to run complex introspection queries that may use configuration settings, system tables or features not yet implemented in Materialize. This means that even if a tool is compatible with PostgreSQL, it’s not guaranteed that the same integration will work out-of-the-box.

The level of support for these tools will improve as we extend the coverage of pg_catalog in Materialize (#2157) and join efforts with each community to make the integrations Just Work™️.

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