Ticket #34870: fix.34870.diff

wp-admin/includes/upgrade.php

@@ -2168 +2168 @@
                         continue;
 
                 // Clear the field and index arrays.
-                $cfields = $indices = array();
+                $cfields = $indices = $change_indices = array();
 
                 // Get all of the field names in the query from between the parentheses.
                 preg_match("|\((.*)\)|ms", $qry, $match2);
@@ -2307 +2307 @@
                                         "$index_string ($alt_index_columns)",
                                 );
 
+                                // Find the index key so we know what already exists and needs to be dropped first.
+                                if ( preg_match( "/KEY ([^ ]*)/", $index_string, $matches ) || preg_match( "/INDEX ([^ ]*)/", $index_string, $matches ) ) {
+                                        if ( ! empty( $matches[1] ) ) {
+                                                foreach ( $indices as $key => $value ) {
+                                                        if ( false !== stripos( $value, 'KEY ' . $matches[1] . ' ' ) || false !== stripos( $value, 'INDEX ' . $matches[1] . ' ' ) ) {
+
+                                                                // We found an existing key, but need to determine if the index actually is changing.
+                                                                if ( ! in_array( $value, $index_strings ) ) {
+                                                                        // If we reach this point, an existing index exists and is changing.
+                                                                        $change_indices[ $matches[1] ] = $value;
+                                                                }
+
+                                                                unset( $indices[ $key ] );
+                                                                break;
+                                                        }
+                                                }
+                                        }
+                                }
+
                                 foreach ( $index_strings as $index_string ) {
                                         if ( ! ( ( $aindex = array_search( $index_string, $indices ) ) === false ) ) {
                                                 unset( $indices[ $aindex ] );
@@ -2320 +2339 @@
                         }
                 }
 
+                /**
+                 * Handle indexes that are changing.
+                 */
+                foreach ( $change_indices as $existing_index => $index ) {
+                        $cqueries[]   = "ALTER TABLE {$table} DROP INDEX $existing_index, ADD $index";
+                        $for_update[] = 'Changed index ' . $table . ' ' . $existing_index . ' to ' . $index;
+                }
+
                 // For every remaining index specified for the table.
                 foreach ( (array) $indices as $index ) {
                         // Push a query line into $cqueries that adds the index to that table.