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WP_Debug_Data::get_mysql_var( string $mysql_var ): string|null

Since
5.9.0
Source
wp-admin/includes/class-wp-debug-data.php:1750
Returns the value of a MySQL system variable.

Compatibility

WordPress
since 5.9.0
PHP
7.4–8.6-dev
  • 6.7.7
  • 6.8.8
  • 6.9.7
  • 7.0.4
  • 7.1.0

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$mysql_varstring
Name of the MySQL system variable.

Return value

string|null
The variable value on success. Null if the variable does not exist.

Performance profile

How much work a call to WP_Debug_Data::get_mysql_var() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class
Trivial

Reaches the database via ->get_row().

Scaling
Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions
15–18

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 19.

Plugin surface
None

Nothing here hands control to plugin code.

Called by
1

1 place in core call this, so the cost is paid more often than your own code shows.

What it touches

  • sqldatabase query->get_row()called directly

What one call costs · 1 distinct outcome

One number would be a lie: the work depends on which branch runs. These are every distinct cost WP_Debug_Data::get_mysql_var() can have, taken from its control-flow graph on PHP 8.5.

WhenInstructionsCalls it makes
always15–18->prepare(), ->get_row()

Across PHP versions

Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 19 instructions, 15–18 executed per call, 2 branches. The work does not change between versions.

An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.

Used by · 1

Source code

View on Trac View on GitHub 

	public static function get_mysql_var( $mysql_var ) {		global $wpdb; 		$result = $wpdb->get_row(			$wpdb->prepare( 'SHOW VARIABLES LIKE %s', $mysql_var ),			ARRAY_A		); 		if ( ! empty( $result ) && array_key_exists( 'Value', $result ) ) {			return $result['Value'];		} 		return null;	}

Changelog

Introduced in 5.9.0. Unchanged from 6.7.7 through 7.1.0.

  1. 6.7.7
  2. 6.8.8
  3. 6.9.7
  4. 7.0.4
  5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data
Generated from the wordpress-develop 6.8.8 tag, from src/wp-admin/includes/class-wp-debug-data.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
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