Missing database tables on Multisite

[hupe13]

I have Plugin Check installed on a multisite installation and activated it on site 19. I see many errors in debug log about non existing tables in the database.

WordPress database error Table 'database.wp_19_pc_blogs' doesn't exist for query
WordPress database error Table 'database.wp_19_pc_sitemeta' doesn't exist for query
WordPress database error Table 'database.wp_19_pc_usermeta' doesn't exist for query
WordPress database error Table 'database.wp_19_pc_users' doesn't exist for query

Apparently these tables are not created.

[swissspidy]

These are actually standard tables created by WordPress itself. There seems to be something wrong with your Multisite installation.

Also note that PCP doesn't have full Multisite support at the moment, see #64.

[hupe13]

The tables wp_blogs, wp_sitemeta, wp_usermeta and wp_users exist, but not with "_19_pc" in the name.

[dd32]

This sounds like PCP not setting the base_prefix correctly during it's table_prefix switching for runtime tests;

plugin-check/includes/Checker/Runtime_Environment_Setup.php

Lines 43 to 44 in a1ecb29

	// Set the new prefix.
	$old_prefix = $wpdb->set_prefix( $table_prefix . 'pc_' );

[davidperezgar]

Yes! It seems that's the problem.

[swissspidy]

This sounds like PCP not setting the base_prefix correctly during it's table_prefix switching for runtime tests;

plugin-check/includes/Checker/Runtime_Environment_Setup.php

Lines 43 to 44 in a1ecb29

// Set the new prefix.
$old_prefix = $wpdb->set_prefix( $table_prefix . 'pc_' );

@felixarntz maybe that's one for your to look into? #860 looks like a start

[felixarntz]

@dd32 I'm looking into what's wrong here for Multisite. Maybe you can double check?

• In ms-settings.php, the $table_prefix global (as defined in e.g. wp-config.php) is first passed to wpdb::set_prefix(), which then sets the wpdb::$base_prefix property to it.
• Then wpdb::set_blog_id() is called, correctly setting the table names based on the base prefix.
• Afterwards, the $table_prefix global is overwritten to be the table prefix for the current blog.
• The current bug happens because the blog specific prefix in the $table_prefix global is now used even for the global tables, as seen in the bug report: These tables should be using wp_pc_users etc. instead of wp_19_pc_users etc.

It feels a bit confusing to me that in Multisite $table_prefix is first the value that's defined in wp-config.php (effectively wpdb::$base_prefix, but later becomes the value of wpdb::get_blog_prefix(). So the global is used for two different things. But anyway, we obviously cannot change that without breaking backward compatibility.

So if I understand the code correctly, what we need to do here is to call $wpdb->set_prefix( $wpdb->base_prefix . 'pc_' ) instead of $wpdb->set_prefix( $table_prefix . 'pc_' ) , since otherwise (currently) it would append pc_ to the current blog's prefix rather than the overall base prefix.