wordpress custom archive hooks

wp-custom-archives.php

<?php

/**
 * archive list join clause
 */
function myArchiveJoin($join)
{
    global $wpdb;

    $join .= "
        INNER JOIN {$wpdb->prefix}term_relationships
            ON ({$wpdb->prefix}posts.ID = {$wpdb->prefix}term_relationships.object_id)
        INNER JOIN {$wpdb->prefix}term_taxonomy
            ON ({$wpdb->prefix}term_relationships.term_taxonomy_id = {$wpdb->prefix}term_taxonomy.term_taxonomy_id)
        INNER JOIN {$wpdb->prefix}terms
            ON {$wpdb->prefix}term_taxonomy.term_id = {$wpdb->prefix}terms.term_id
        ";

    return $join;
}
add_filter('getarchives_join', 'myArchiveJoin' );

/**
 * archive list where clause
 */
function myArchiveWhere($where)
{
    global $wpdb;

    $parameters = array( 'some-category', 'some-other-category' );

    // escape happens later
    $where .= " AND {$wpdb->prefix}term_taxonomy.taxonomy = 'category' AND {$wpdb->prefix}terms.slug IN ('"
           . implode("','", $parameters) . "')";

    return $where;
}
add_filter('getarchives_where', 'myArchiveWhere');

/**
 * archive page query
 */
function myArchiveTemplateQuery(WP_Query $query)
{
    $terms = array('some-category', 'some-other-category');

    if ( $query->is_main_query() && $query->is_archive() ) {
        $query->set( 'tax_query', array(array(
            'taxonomy' => 'category',
            'field' => 'slug',
            'terms' => $terms
        )));
    }

    return $query;
}
add_action( 'pre_get_posts', 'myArchiveTemplateQuery' );