Fix wrong migrations

For Postgres migrations are failed.
More then we can get for mysql an error
"Specified key was too long; max key length is 1000 bytes" in b6ae66d05e3
migration in some versions of dialect.

Fixes-Bug: #1219776

Change-Id: Id9b0e1eb0e685053291367f7eb62fef68b6b2f84

ceilometer/storage/sqlalchemy/alembic/versions/2c3ccda5a3ad_fix_uniq_name.py

@@ -32,13 +32,13 @@ from alembic import op
 
 
 TABLE_NAME = 'sourceassoc'
-OLD_NAME = 'uniq_sourceassoc0meter_id'
-NEW_NAME = 'uniq_sourceassoc0meter_id0user_id'
+UNIQ_NAME = 'uniq_sourceassoc0meter_id0user_id'
 COLUMNS = ('meter_id', 'user_id')
 
 
-def change_uniq(table_name, old_name, new_name, columns):
-    engine = op.get_bind().engine
+def change_uniq(table_name, uniq_name, columns, downgrade=False):
+    bind = op.get_bind()
+    engine = bind.engine
     if engine.name == 'sqlite':
         return
     if engine.name == 'mysql':
@@ -50,12 +50,10 @@ def change_uniq(table_name, old_name, new_name, columns):
         op.drop_constraint('fk_sourceassoc_user_id',
                            table_name,
                            type_='foreignkey')
-    try:
-        # For some versions of dialects constraint can be skipped.
-        op.drop_constraint(old_name, table_name=table_name, type_='unique')
-    except Exception:
-        pass
-    op.create_unique_constraint(new_name, table_name, columns)
+    if downgrade:
+        op.drop_constraint(uniq_name, table_name=table_name, type_='unique')
+    else:
+        op.create_unique_constraint(uniq_name, table_name, columns)
     if engine.name == 'mysql':
         op.create_foreign_key('fk_sourceassoc_meter_id', table_name, 'meter',
                               ['meter_id'], ['id'])
@@ -64,8 +62,8 @@ def change_uniq(table_name, old_name, new_name, columns):
 
 
 def upgrade():
-    change_uniq(TABLE_NAME, OLD_NAME, NEW_NAME, COLUMNS)
+    change_uniq(TABLE_NAME, UNIQ_NAME, COLUMNS)
 
 
 def downgrade():
-    change_uniq(TABLE_NAME, NEW_NAME, OLD_NAME, COLUMNS)
+    change_uniq(TABLE_NAME, UNIQ_NAME, COLUMNS, downgrade=True)

ceilometer/storage/sqlalchemy/alembic/versions/b6ae66d05e3_remove_extra_indexes.py

@@ -29,53 +29,66 @@ revision = 'b6ae66d05e3'
 down_revision = '17738166b91'
 
 from alembic import op
+import sqlalchemy as sa
 
 
 INDEXES = (
-    # ([dialects], table_name, index_name, create/delete, uniq/not uniq)
+    # ([dialects], table_name, index_name, create/delete, uniq/not_uniq,
+    # length_limited)
     (['mysql', 'sqlite', 'postgresql'],
      'resource',
      'resource_user_id_project_id_key',
-    ('user_id', 'project_id'), True, False),
-    (['mysql'], 'source', 'id', ('id',), False, True))
+     ('user_id', 'project_id'), True, False, True),
+    (['mysql'], 'source', 'id', ('id',), False, True, False))
 
 
-def index_cleanup(engine_names, table_name, uniq_name, columns, create=True,
-                  unique=False):
-    engine = op.get_bind().engine
+def index_cleanup(engine_names, table_name, uniq_name, columns, create,
+                  unique, limited):
+    bind = op.get_bind()
+    engine = bind.engine
     if engine.name not in engine_names:
         return
     if create:
-        # We have unique constraint in postgres for `resource` table.
-        # But it should be a simple index. So, we should delete unique key
-        # before index creation.
-        if engine.name == 'postgresql':
-            op.drop_constraint(uniq_name, table_name, type_='unique')
-        op.create_index(uniq_name, table_name, columns, unique=unique)
+        if limited and engine.name == 'mysql':
+            # For some versions of mysql we can get an error
+            # "Specified key was too long; max key length is 1000 bytes".
+            # We should create an index by hand in this case with limited
+            # length of columns.
+            meta = sa.MetaData()
+            meta.bind = engine
+            table = sa.Table(table_name, meta, autoload=True)
+            columns_mysql = ",".join((c + "(100)" for c in columns))
+            sql = ("create index %s ON %s (%s)" % (uniq_name, table,
+                                                   columns_mysql))
+            engine.execute(sql)
+        else:
+            op.create_index(uniq_name, table_name, columns, unique=unique)
     else:
         if unique:
             op.drop_constraint(uniq_name, table_name, type_='unique')
         else:
             op.drop_index(uniq_name, table_name=table_name)
-        if engine.name == 'postgresql':
-            op.create_unique_constraint(uniq_name, table_name, columns)
 
 
 def upgrade():
-    for engine_names, table_name, uniq_name, columns, create, uniq in INDEXES:
+    for (engine_names, table_name, uniq_name, columns, create, uniq,
+         limited) in INDEXES:
         index_cleanup(engine_names,
                       table_name,
                       uniq_name,
                       columns,
                       create,
-                      uniq)
+                      uniq,
+                      limited)
 
 
 def downgrade():
-    for engine_names, table_name, uniq_name, columns, create, uniq in INDEXES:
+    for (engine_names, table_name, uniq_name, columns, create, uniq,
+         limited) in INDEXES:
         index_cleanup(engine_names,
                       table_name,
                       uniq_name,
                       columns,
                       not create,
-                      uniq)
+                      uniq,
+                      limited)