WordPress get_terms replace INNER JOIN with STRAIGHT_JOIN using filters

wp-get-terms-straight-join.php

<?php
// Step 1. Add the filters surrounding the get_terms (which should be used in your code)
add_filter( 'terms_clauses', 'rs_replace_inner_with_straight_joins', 20 );
$terms = get_terms( $args );
remove_filter( 'terms_clauses', 'rs_replace_inner_with_straight_joins', 20 );

// Step 2. Add to functions.php or similar:
function rs_replace_inner_with_straight_joins( $pieces, $taxonomies = null, $args = null ) {
	global $wpdb;
	
	$s = 'INNER JOIN ' . $wpdb->prefix;
	$r = 'STRAIGHT_JOIN ' . $wpdb->prefix;
	$pieces['join'] = str_replace( $s, $r, $pieces['join'] );
	
	return $pieces;
}

Hi,
Thank you for that code, please can you tell me where to put it, in functions.php of my wordpress theme right?

The function (line 7-16) should go in your functions.php. The add/remove filters (line 3 & 5) need to wrap around a get_terms function like I used for #4 as an example.

If you want to affect ALL term queries you will probably run into problems so don't jump straight to that solution.

One important thing to note with STRAIGHT_JOINS is that the joined table is REQUIRED so it must have a value. So if you add a new custom field for example, you need to add a value to all your existing terms or else they won't show up in the query. Even if that query allows the value to be false / blank / not exist.

thanks for this, btw the function name doesn't match the one used in the add/remove filter

@rtpHarry oops! Thanks for catching that