FIX: WP All Export - slow export when using OR filters on postmeta (custom fields)

README.md

If you are experiencing high CPU usage using WP All Export with OR filters on post meta (custom fields) you may find it useful to apply this patch. We went down from exporting ~8000 records in 2 hours to exporting them in 5 minutes.

in src/Pro/Filtering/FilteringCPT.php change line 214 and 215

before:

                        $joinString = " INNER JOIN {$this->wpdb->postmeta} AS $table_alias ON ({$this->wpdb->posts}.ID = $table_alias.post_id) ";
                        $whereString = "$table_alias.meta_key = '$meta_key' AND $table_alias.meta_value " . $this->parse_condition($rule, false, $table_alias);

after:

                        $joinString = " INNER JOIN {$this->wpdb->postmeta} AS $table_alias ON ({$this->wpdb->posts}.ID = $table_alias.post_id AND $table_alias.meta_key = '$meta_key') ";
                        $whereString = "$table_alias.meta_value " . $this->parse_condition($rule, false, $table_alias);

FilteringCPT.patch

--- src/Pro/Filtering/FilteringCPT.php    2023-12-16 13:44:38.817294704 +0000
+++ src/Pro/Filtering/FilteringCPT.php    2023-12-16 13:44:19.792826943 +0000
@@ -211,8 +211,8 @@
                             self::$variationWhere = $this->queryWhere;
                         }
 
-                        $joinString = " INNER JOIN {$this->wpdb->postmeta} AS $table_alias ON ({$this->wpdb->posts}.ID = $table_alias.post_id) ";
-                        $whereString = "$table_alias.meta_key = '$meta_key' AND $table_alias.meta_value " . $this->parse_condition($rule, false, $table_alias);
+                        $joinString = " INNER JOIN {$this->wpdb->postmeta} AS $table_alias ON ({$this->wpdb->posts}.ID = $table_alias.post_id AND $table_alias.meta_key = '$meta_key') ";
+                        $whereString = "$table_alias.meta_value " . $this->parse_condition($rule, false, $table_alias);
 
                         $this->queryJoin[] = $joinString;
                         $this->queryWhere .= $whereString;