PHP - RRD rrd_first() Function

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The PHP RRD rrd_first() function is used to gets the timestamp of the first sample from rrd file. This function helps in the analysis of the data recorded in the RRD's start time.

Syntax

Below is the syntax of the PHP RRD rrd_first() function −

int rrd_first(string $file, int $raaindex = 0)

Parameters

Below are the parameters of the rrd_first() function −

• $file − It is the path to the RRD file.

• $raaindex − It is the index of the archive to get the timestamp from. Default value is 0.

Return Value

The rrd_first() function returns the timestamp of the first data point in the given RRD file on success or FALSE on failure.

PHP Version

The rrd_first() function is available from version 0.9.0 of the PECL rrd extension.

Example 1

First we will show you the basic example of the PHP RRD rrd_first() function to get the timestamp of the first data point from a given RRD file.

<?php
   // Path to the rrd file
   $filename = '/PHP/PhpProjects/example.rrd';
   $first = rrd_first($filename);
   
   if ($first !== FALSE) {
       echo "The first data point timestamp is: " . date('Y-m-d H:i:s', $first);
   } else {
       echo "Failed to retrieve the timestamp.";
   }
?>

Output

The above code will result something like this −

The first data point timestamp is: 2024-08-05 00:00:00

Example 2

In the below PHP code we will try to use the rrd_first() function and see how the function handles a RRD file which does not exist.

<?php
   // Path to the rrd file
   $filename = '/PHP/PhpProjects/myrrd.rrd';
   $first = rrd_first($filename);
   
   if ($first !== FALSE) {
       echo "The first data point timestamp is: " . date('Y-m-d H:i:s', $first);
   } else {
       echo "File does not exist or could not be read.";
   }
?> 

Output

After running the above program, it generates the following output −

File does not exist or could not be read.

Example 3

The following example explains what happens if an RRD file has a defective or incorrect format while using the rrd_first() function.

<?php
   // Path to the invalid rrd file
   $filename = 'invalid_format.rrd';
   $first = rrd_first($filename);
   
   if ($first !== FALSE) {
       echo "The first data point timestamp is: " . date('Y-m-d H:i:s', $first);
   } else {
       echo "Invalid RRD file format.";
   }
?> 

Output

This will create the below output −

Invalid RRD file format.