layout: default title: Progress Function

Progress Function

Monitor query execution progress in real-time via HTTP headers.

Usage

$db->progressFunction(function ($data) {
    echo json_encode($data) . "\n";
});

Works for both SELECT and INSERT/WRITE operations.

SELECT Progress

$db->progressFunction(function ($data) {
    echo sprintf(
        "Read: %s rows, %s bytes\n",
        $data['read_rows'] ?? 0,
        $data['read_bytes'] ?? 0
    );
});

$st = $db->select('SELECT number, sleep(0.1) FROM system.numbers LIMIT 100');

// Output:
// Read: 10 rows, 80 bytes
// Read: 20 rows, 160 bytes
// Read: 30 rows, 240 bytes
// ...

INSERT/WRITE Progress

$db->progressFunction(function ($data) {
    echo sprintf(
        "Written: %s rows, %s bytes\n",
        $data['written_rows'] ?? 0,
        $data['written_bytes'] ?? 0
    );
});

// Insert a large batch
$rows = [];
for ($i = 0; $i < 100000; $i++) {
    $rows[] = [$i, "item_$i"];
}
$db->insert('my_table', $rows, ['id', 'name']);

Progress Data Format

The callback receives an associative array with these fields:

Field	Description
`read_rows`	Number of rows read so far
`read_bytes`	Number of bytes read so far
`written_rows`	Number of rows written (INSERT)
`written_bytes`	Number of bytes written (INSERT)
`total_rows_to_read`	Total rows to read (if known)

Settings

progressFunction() automatically enables:

Setting	Value	Purpose
`send_progress_in_http_headers`	1	Enable progress headers
`http_headers_progress_interval_ms`	100	Update interval (ms)
`wait_end_of_query`	1	Required for write progress

You can customize the interval before calling progressFunction():

$db->settings()->set('http_headers_progress_interval_ms', 500); // every 500ms
$db->progressFunction($callback);

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