#69 run create unique index with MDL shared no write (not hot WRT writes)

mysql-test/suite/tokudb.add_index/r/hot_create_unique_index.result

+drop table if exists t;
+create table t (id int auto_increment primary key, x int);
+create unique index x on t (x);
+drop table t;

mysql-test/suite/tokudb.add_index/t/hot_create_unique_index.test

+# verify that create unique index is not a hot operation.  
+# in tokudb_add_index assert that the table MDL >= shared no write.
+
+source include/have_tokudb.inc;
+source include/have_debug.inc;
+
+disable_warnings;
+drop table if exists t;
+enable_warnings;
+
+create table t (id int auto_increment primary key, x int);
+
+create unique index x on t (x);
+
+drop table t;

storage/tokudb/ha_tokudb.cc

@@ -3470,6 +3470,8 @@ int ha_tokudb::end_bulk_insert() {
     return end_bulk_insert( false );
 }
 
+volatile int ha_tokudb_is_index_unique_wait = 0; // debug
+
 int ha_tokudb::is_index_unique(bool* is_unique, DB_TXN* txn, DB* db, KEY* key_info) {
     int error;
     DBC* tmp_cursor1 = NULL;
@@ -3614,6 +3616,7 @@ int ha_tokudb::is_index_unique(bool* is_unique, DB_TXN* txn, DB* db, KEY* key_in
     error = 0;
 
 cleanup:
+    while (ha_tokudb_is_index_unique_wait) sleep(1); // debug
     if (tmp_cursor1) {
         tmp_cursor1->c_close(tmp_cursor1);
         tmp_cursor1 = NULL;
@@ -7813,6 +7816,7 @@ int ha_tokudb::tokudb_add_index(
         indexer = NULL;
     }
     else {
+        DBUG_ASSERT(table->mdl_ticket->get_type() >= MDL_SHARED_NO_WRITE);
         rw_unlock(&share->num_DBs_lock);
         rw_lock_taken = false;
         prelocked_right_range_size = 0;

storage/tokudb/ha_tokudb_alter_56.cc

@@ -312,8 +312,10 @@ enum_alter_inplace_result ha_tokudb::check_if_supported_inplace_alter(TABLE *alt
 
                 // someday, allow multiple hot indexes via alter table add key. don't forget to change the store_lock function.
                 // for now, hot indexing is only supported via session variable with the create index sql command
-                if (ha_alter_info->index_add_count == 1 && ha_alter_info->index_drop_count == 0 && 
-                    get_create_index_online(thd) && thd_sql_command(thd) == SQLCOM_CREATE_INDEX) {
+                if (ha_alter_info->index_add_count == 1 && ha_alter_info->index_drop_count == 0 &&  // only one add or drop
+                    ctx->handler_flags == Alter_inplace_info::ADD_INDEX &&                          // must be add index not add unique index
+                    thd_sql_command(thd) == SQLCOM_CREATE_INDEX &&                                  // must be a create index command
+                    get_create_index_online(thd)) {                                                 // must be enabled
                     // external_lock set WRITE_ALLOW_WRITE which allows writes concurrent with the index creation
                     result = HA_ALTER_INPLACE_NO_LOCK_AFTER_PREPARE; 
                 }