RENAME TABLE: 'preserve foreign key' behavior depends on existence of…

… Vitess internal tables in statement (mysql#94)

* RENAME TABLE: 'preserve foreign key' behavior depends on existence of Vitess internal tables in statement

Signed-off-by: Shlomi Noach <2607934+shlomi-noach@users.noreply.github.com>

mysql-test/r/rename_preserve_foreign_key_child.result

@@ -27,9 +27,7 @@ CONSTRAINT `new_child_parent_fk` FOREIGN KEY (parent_id) REFERENCES parent_table
 );
 insert into _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl select * from child_table;
 SET FOREIGN_KEY_CHECKS=1;
-SET rename_table_preserve_foreign_key=1;
 rename table child_table to _vt_HOLD_6ace8bcef73211ea87e9f875a4d24e90_20200915120410, _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl to child_table, _vt_HOLD_6ace8bcef73211ea87e9f875a4d24e90_20200915120410 to _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl;
-SET rename_table_preserve_foreign_key=0;
 show create table child_table;
 Table	Create Table
 child_table	CREATE TABLE `child_table` (

mysql-test/r/rename_preserve_foreign_key_parent.result

@@ -25,9 +25,47 @@ PRIMARY KEY (id)
 );
 insert into parent_table_new values (1, 7), (2, 7), (55, 7);
 SET FOREIGN_KEY_CHECKS=1;
-SET rename_table_preserve_foreign_key=1;
 rename table parent_table to parent_table_old, parent_table_new to parent_table;
-SET rename_table_preserve_foreign_key=0;
+show create table child_table;
+Table	Create Table
+child_table	CREATE TABLE `child_table` (
+  `id` int NOT NULL,
+  `parent_id` int DEFAULT NULL,
+  PRIMARY KEY (`id`),
+  KEY `parent_id_idx` (`parent_id`),
+  CONSTRAINT `child_parent_fk` FOREIGN KEY (`parent_id`) REFERENCES `parent_table_old` (`id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
+rename table parent_table to parent_table_new, parent_table_old to parent_table;
+show create table child_table;
+Table	Create Table
+child_table	CREATE TABLE `child_table` (
+  `id` int NOT NULL,
+  `parent_id` int DEFAULT NULL,
+  PRIMARY KEY (`id`),
+  KEY `parent_id_idx` (`parent_id`),
+  CONSTRAINT `child_parent_fk` FOREIGN KEY (`parent_id`) REFERENCES `parent_table` (`id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
+rename table parent_table to _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl;
+show create table child_table;
+Table	Create Table
+child_table	CREATE TABLE `child_table` (
+  `id` int NOT NULL,
+  `parent_id` int DEFAULT NULL,
+  PRIMARY KEY (`id`),
+  KEY `parent_id_idx` (`parent_id`),
+  CONSTRAINT `child_parent_fk` FOREIGN KEY (`parent_id`) REFERENCES `_84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl` (`id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
+rename table _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl to parent_table;
+show create table child_table;
+Table	Create Table
+child_table	CREATE TABLE `child_table` (
+  `id` int NOT NULL,
+  `parent_id` int DEFAULT NULL,
+  PRIMARY KEY (`id`),
+  KEY `parent_id_idx` (`parent_id`),
+  CONSTRAINT `child_parent_fk` FOREIGN KEY (`parent_id`) REFERENCES `parent_table` (`id`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci
+rename table parent_table to _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl, parent_table_new to parent_table;
 show create table child_table;
 Table	Create Table
 child_table	CREATE TABLE `child_table` (
@@ -44,15 +82,15 @@ id	hint
 55	7
 delete from parent_table where id=1;
 ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails (`test`.`child_table`, CONSTRAINT `child_parent_fk` FOREIGN KEY (`parent_id`) REFERENCES `parent_table` (`id`))
-delete from parent_table_old where id=1;
+delete from _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl where id=1;
 insert into child_table values (14, 55);
 alter table child_table force;
 select id, hint from parent_table;
 id	hint
 1	7
 2	7
 55	7
-delete from parent_table_old;
+delete from _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl;
 delete from parent_table where id=2;
 ERROR 23000: Cannot delete or update a parent row: a foreign key constraint fails (`test`.`child_table`, CONSTRAINT `child_parent_fk` FOREIGN KEY (`parent_id`) REFERENCES `parent_table` (`id`))
 drop table if exists _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl, _vt_HOLD_6ace8bcef73211ea87e9f875a4d24e90_20200915120410, child_table, child_table_old, child_table_new;

mysql-test/t/rename_preserve_foreign_key_child.test

@@ -40,9 +40,7 @@ CREATE TABLE _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl (
 insert into _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl select * from child_table;
 # rename, preserving foreign key
 SET FOREIGN_KEY_CHECKS=1;
-SET rename_table_preserve_foreign_key=1;
 rename table child_table to _vt_HOLD_6ace8bcef73211ea87e9f875a4d24e90_20200915120410, _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl to child_table, _vt_HOLD_6ace8bcef73211ea87e9f875a4d24e90_20200915120410 to _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl;
-SET rename_table_preserve_foreign_key=0;
 # child_table's foreign key definition should point to parent_table
 show create table child_table;
 select * from child_table;

mysql-test/t/rename_preserve_foreign_key_parent.test

@@ -36,26 +36,34 @@ CREATE TABLE parent_table_new (
   PRIMARY KEY (id)
 );
 insert into parent_table_new values (1, 7), (2, 7), (55, 7);
-# rename, preserving foreign key
+# rename, using non-vitess names, expecting standard RENAME behavior
 SET FOREIGN_KEY_CHECKS=1;
-SET rename_table_preserve_foreign_key=1;
 rename table parent_table to parent_table_old, parent_table_new to parent_table;
-SET rename_table_preserve_foreign_key=0;
+show create table child_table;
+rename table parent_table to parent_table_new, parent_table_old to parent_table;
+show create table child_table;
+# rename, but only a single table named, expecting standard RENAME behavior
+rename table parent_table to _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl;
+show create table child_table;
+rename table _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl to parent_table;
+show create table child_table;
+# rename, preserving foreign key
+rename table parent_table to _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl, parent_table_new to parent_table;
 # child_table's foreign key definition should point to parent_table (formerly parent_table_new)
 show create table child_table;
 select id, hint from parent_table;
 # Verify that child's FK is now associated with the newly instated `parent_table`:
 --error ER_ROW_IS_REFERENCED_2
 delete from parent_table where id=1;
-# This should work, this table is no longer the parent of child_table
-delete from parent_table_old where id=1;
+# This should work, this table is no longer the parent of child_table, and also it is an internal table
+delete from _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl where id=1;
 # insert rows matching data only available in the new `parent_table`
 insert into child_table values (14, 55);
 # Rebuild child table. Foreign key should point to parent_table (the new one)
 alter table child_table force;
 select id, hint from parent_table;
 # This should work:
-delete from parent_table_old;
+delete from _84371a37_6153_11eb_9917_f875a4d24e90_20210128122816_vrepl;
 # This should error because of ON DELETE NO ACTION:
 --error ER_ROW_IS_REFERENCED_2
 delete from parent_table where id=2;

sql/sql_rename.cc

@@ -553,7 +553,7 @@ static bool do_rename(THD *thd, Table_ref *ren_table, const char *new_db,
                       const char *new_table_name, const char *new_table_alias,
                       bool *int_commit_done,
                       std::set<handlerton *> *post_ddl_htons,
-                      Foreign_key_parents_invalidator *fk_invalidator) {
+                      Foreign_key_parents_invalidator *fk_invalidator, bool preserve_foreign_key) {
   const char *new_alias = new_table_name;
   const char *old_alias = ren_table->table_name;
 
@@ -795,10 +795,10 @@ static bool do_rename(THD *thd, Table_ref *ren_table, const char *new_db,
       } else {
         // rename successful
         if (hton->flags & HTON_SUPPORTS_FOREIGN_KEYS) {
-          // If 'OPTION_RENAME_TABLE_PRESERVE_FOREIGN_KEY' is set, then we explicitly don't want to run `adjust_fks_for_rename_table`,
+          // If 'preserve_foreign_key' is set, then we explicitly don't want to run `adjust_fks_for_rename_table`,
           // because we want the foreign key child to point to the newly instated table, rather than follow
           // the old, renamed table.
-          if (thd_test_options(thd, OPTION_RENAME_TABLE_PRESERVE_FOREIGN_KEY)) {
+          if (preserve_foreign_key) {
             if (adjust_fks_for_rename_table_with_preserve_fk(thd, ren_table->db, old_alias, new_db, new_alias, hton)) {
               // adjust FKs failed
               cleanup_required = true;
@@ -953,11 +953,39 @@ static Table_ref *rename_tables(THD *thd, Table_ref *table_list,
 
   DBUG_TRACE;
 
+  // PlanetScale patch: if _any_ table at all in this `RENAME` TABLE statement is an
+  // internal Vitess table, then apply a "preserve foreign key" logic to the `RENAME`.
+  // Also, there must be at least two renamed tables in this clause. Otherwise, again
+  // this is treated just as a normal MySQL `RENAME`.
+  // What we want to catch here are Vitess-specific `RENAME TABLE` statements that
+  // should preserve the foreign key.
+  bool preserve_foreign_key = false;
+  int count_renames = 0;
+  for (ren_table = table_list; ren_table; ren_table = new_table->next_local) {
+    new_table = ren_table->next_local;
+    {
+      Table_name_inspector table_inspector(ren_table->table_name);
+      if (table_inspector.skip_fk_checks()) {
+        preserve_foreign_key = true;
+      }
+    }
+    {
+      Table_name_inspector table_inspector(new_table->table_name);
+      if (table_inspector.skip_fk_checks()) {
+        preserve_foreign_key = true;
+      }
+    }
+    count_renames++;
+  }
+  if (count_renames < 2) {
+    preserve_foreign_key = false;
+  }
+
   for (ren_table = table_list; ren_table; ren_table = new_table->next_local) {
     new_table = ren_table->next_local;
     if (do_rename(thd, ren_table, new_table->db, new_table->table_name,
                   new_table->alias, int_commit_done, post_ddl_htons,
-                  fk_invalidator))
+                  fk_invalidator, preserve_foreign_key))
       return ren_table;
   }
   return nullptr;