pre_schema_upgrade()

Compatibility

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

Performance profile

How much work a call to pre_schema_upgrade() 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

Heavy

Reaches the database via ->get_var().

Scaling

Constant

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

Instructions

11–149

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 149.

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_var()called directly
• hookthird-party callbacksapply_filters()one call below pre_schema_upgrade()

What one call costs · 160 distinct outcomes

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

Uses · 3

• is_multisite()Determines whether Multisite is enabled.
• wp_should_upgrade_global_tables()Determine if global tables should be upgraded.
• maybe_convert_table_to_utf8mb4()If a table only contains utf8 or utf8mb4 columns, convert it to utf8mb4.

Used by · 1

• wp_upgrade()Runs WordPress Upgrade functions.

Source code

View on Trac ↗View on GitHub ↗

3698function pre_schema_upgrade() {3699	global $wp_current_db_version, $wpdb;3700 3701	// Upgrade versions prior to 2.9.3702	if ( $wp_current_db_version < 11557 ) {3703		// Delete duplicate options. Keep the option with the highest option_id.3704		$wpdb->query( "DELETE o1 FROM $wpdb->options AS o1 JOIN $wpdb->options AS o2 USING (`option_name`) WHERE o2.option_id > o1.option_id" );3705 3706		// Drop the old primary key and add the new.3707		$wpdb->query( "ALTER TABLE $wpdb->options DROP PRIMARY KEY, ADD PRIMARY KEY(option_id)" );3708 3709		// Drop the old option_name index. dbDelta() doesn't do the drop.3710		$wpdb->query( "ALTER TABLE $wpdb->options DROP INDEX option_name" );3711	}3712 3713	// Multisite schema upgrades.3714	if ( $wp_current_db_version < 25448 && is_multisite() && wp_should_upgrade_global_tables() ) {3715 3716		// Upgrade versions prior to 3.7.3717		if ( $wp_current_db_version < 25179 ) {3718			// New primary key for signups.3719			$wpdb->query( "ALTER TABLE $wpdb->signups ADD signup_id BIGINT(20) NOT NULL AUTO_INCREMENT PRIMARY KEY FIRST" );3720			$wpdb->query( "ALTER TABLE $wpdb->signups DROP INDEX domain" );3721		}3722 3723		if ( $wp_current_db_version < 25448 ) {3724			// Convert archived from enum to tinyint.3725			$wpdb->query( "ALTER TABLE $wpdb->blogs CHANGE COLUMN archived archived varchar(1) NOT NULL default '0'" );3726			$wpdb->query( "ALTER TABLE $wpdb->blogs CHANGE COLUMN archived archived tinyint(2) NOT NULL default 0" );3727		}3728	}3729 3730	// Upgrade versions prior to 4.2.3731	if ( $wp_current_db_version < 31351 ) {3732		if ( ! is_multisite() && wp_should_upgrade_global_tables() ) {3733			$wpdb->query( "ALTER TABLE $wpdb->usermeta DROP INDEX meta_key, ADD INDEX meta_key(meta_key(191))" );3734		}3735		$wpdb->query( "ALTER TABLE $wpdb->terms DROP INDEX slug, ADD INDEX slug(slug(191))" );3736		$wpdb->query( "ALTER TABLE $wpdb->terms DROP INDEX name, ADD INDEX name(name(191))" );3737		$wpdb->query( "ALTER TABLE $wpdb->commentmeta DROP INDEX meta_key, ADD INDEX meta_key(meta_key(191))" );3738		$wpdb->query( "ALTER TABLE $wpdb->postmeta DROP INDEX meta_key, ADD INDEX meta_key(meta_key(191))" );3739		$wpdb->query( "ALTER TABLE $wpdb->posts DROP INDEX post_name, ADD INDEX post_name(post_name(191))" );3740	}3741 3742	// Upgrade versions prior to 4.4.3743	if ( $wp_current_db_version < 34978 ) {3744		// If compatible termmeta table is found, use it, but enforce a proper index and update collation.3745		if ( $wpdb->get_var( "SHOW TABLES LIKE '{$wpdb->termmeta}'" ) && $wpdb->get_results( "SHOW INDEX FROM {$wpdb->termmeta} WHERE Column_name = 'meta_key'" ) ) {3746			$wpdb->query( "ALTER TABLE $wpdb->termmeta DROP INDEX meta_key, ADD INDEX meta_key(meta_key(191))" );3747			maybe_convert_table_to_utf8mb4( $wpdb->termmeta );3748		}3749	}3750}

Changelog

Introduced in 2.9.0. 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/upgrade.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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