irap/multi-query

Wrapper object around mysqli to combine queries into one.

MultiQuery Package

This is a package for simplifying the sending multiple PHP Mysqli queries in a single request and handling the responses. This often greatly improve performance by removing the round-trip-time, which is most noticeable when the database is on a remote host., _(*1)

Example Usage

Basic Example

$db = new mysqli($host, $user, $password, $db_name);

$queries = array(
    "DROP TABLE `table1`",
    "DROP TABLE `table2`",
    "DROP TABLE `table3`"
);

$multiQuery = new iRAP\MultiQuery\MultiQuery($db, $queries);

Full Example

In the example below we run lots of different queries and use the index we get when we added the query in order to get it's result from the multiQuery object later. We also demonstrate how to check that nothing went wrong by checking the status of the object after having run it., _(*2)

$connection = new mysqli('host', 'user', 'password', 'db_name');

$queries = array(
    'SELECT * FROM `table1`',
    'SHOW TABLES`',
    'SELECT * FROM `table2`'
);

$select1QueryIndex = 0;
$showTablesQueryIndex = 1;
$select2QueryIndex = 2;

$multiQuery = new iRAP\MultiQuery\MultiQuery($connection, $queries);


if ($multiQuery->hasErrors())
{
    $errors = $multiQuery->getErrors();
    // do something with the errors array such as use them in an
    // exception message....
}
else
{
    $tablesResult = $multiQuery->getResult($showTablesQueryIndex);

    if ($tablesResult === FALSE)
    {
        throw new Exception("Failed to fetch tables");
    }
    else
    {
        $tables = array();

        while (($row = $tablesResult->fetch_array()) !== null)
        {
            $tables[] = $row[0];
        }

        print "tables: " . implode(", ", $tables);
    }
}

Merged Result Example

If you have partitioned your data using separate tables (e.g. the tables all have the same structure), then you may want to make use of the get_merged_result() method to just stitch all the query results into one, _(*3)

# // Example 2 - Fetch data from two tables that have exactly the same structure
# // e.g. a case of partitioning data using table names like "dataset1", "dataset2"

$queries = array(
    'SELECT * FROM `table1`',
    'SELECT * FROM `table2`'
);

$multiQuery2 = new iRAP\MultiQuery\MultiQuery($connection, $queries);
$mergedResult = $multiQuery2->getMergedResult();
print "merged result: " . print_r($mergedResult, true) . PHP_EOL;

Transactions

This package also has a class to help with making MySQL transactions. Below is an example of using this class:, _(*4)

$queries = array(
    'DELETE FROM `myTable` WHERE id = ' . $id,
    'INSERT INTO `myTable` SELECT * FROM `myTable2` WHERE id = ' . $id
);

$transaction = new iRAP\MultiQuery\Transaction($mysqli, $queries);

if (!$transaction->wasSuccessful())
{
    throw new Exception("Failed to reset the record in xyz");
}

The transaction will automatically detect and rollback if any of the queries within the transaction object fail. By default, if the transaction fails the object will not retry, but you can configure it to do so. Below is the same example, but this time we have set it to retry up to 5 times when the transaction is run, and to wait 3 seconds between each attempt. The default for the sleep period if you do not set it, is 1 second., _(*5)

$queries = array(
    'DELETE FROM `myTable` WHERE id = ' . $id,
    ... # more quries here.
);

$transaction = new iRAP\MultiQuery\Transaction(
    $mysqli,
    $queries,
    $attempts=5,
    $sleepPeriod=3
);
...