[MariaDB] Extended support for MariaDB's ALTER KEY|INDEX (#4427)

Author: jcechace

sql/mariadb/MariaDBParser.g4

@@ -743,6 +743,7 @@ alterSpecification
     | DROP indexFormat = (INDEX | KEY) ifExists? uid                      # alterByDropIndex // here ifExists is MariaDB-specific only
     | RENAME indexFormat = (INDEX | KEY) uid TO uid                       # alterByRenameIndex
     | ALTER INDEX uid (VISIBLE | INVISIBLE)                               # alterByAlterIndexVisibility
+    | ALTER (KEY | INDEX) ifExists? uid NOT? IGNORED                      # alterByAlterIndexIgnore
     | DROP FOREIGN KEY ifExists? uid dottedId?                            # alterByDropForeignKey // here ifExists is MariaDB-specific only
     | DISABLE KEYS                                                        # alterByDisableKeys
     | ENABLE KEYS                                                         # alterByEnableKeys

sql/mariadb/examples/fast/ddl_alter.sql

@@ -32,6 +32,11 @@ alter table add_test add index if not exists ix_add_test_col1 using btree (col1)
 alter table add_test add index if not exists ix_add_test_col4 using btree (col4) comment 'test index';
 alter table add_test alter index ix_add_test_col1 invisible;
 alter table add_test alter index ix_add_test_col1 visible;
+alter table add_test alter index if exists ix_add_test_col1 ignored;
+alter table add_test alter index ix_add_test_col1 ignored;
+alter table add_test alter index ix_add_test_col1 not ignored;
+alter table add_test alter key if exists fk ignored;
+alter table add_test alter key if exists fk not ignored;
 alter table add_test change column if exists col8 col9 tinyint;
 alter table add_test change column if exists col3 col5 tinyint;
 alter table add_test modify column if exists col9 tinyint;