Merge pull request #54 from LuckySting/deletion-of-index

Add support of DROP INDEX statement

Author: vgvoleg

test/test_core.py

@@ -1100,6 +1100,25 @@ def test_index_with_join_usage(self, connection: sa.Connection, metadata: sa.Met
         cursor = connection.execute(select_stmt)
         assert cursor.one() == ("Sarah Connor", "wanted")
 
+    def test_index_deletion(self, connection: sa.Connection, metadata: sa.MetaData):
+        persons = Table(
+            "test_index_deletion/persons",
+            metadata,
+            sa.Column("id", sa.Integer(), primary_key=True),
+            sa.Column("tax_number", sa.Integer()),
+            sa.Column("full_name", sa.Unicode()),
+        )
+        persons.create(connection)
+        index = sa.Index("ix_tax_number", "tax_number", _table=persons)
+        index.create(connection)
+        indexes = sa.inspect(connection).get_indexes(persons.name)
+        assert len(indexes) == 1
+
+        index.drop(connection)
+
+        indexes = sa.inspect(connection).get_indexes(persons.name)
+        assert len(indexes) == 0
+
 
 class TestTablePathPrefix(TablesTest):
     __backend__ = True

ydb_sqlalchemy/sqlalchemy/__init__.py

@@ -13,7 +13,7 @@
 from sqlalchemy.engine import characteristics, reflection
 from sqlalchemy.engine.default import DefaultExecutionContext, StrCompileDialect
 from sqlalchemy.exc import CompileError, NoSuchTableError
-from sqlalchemy.sql import functions, literal_column
+from sqlalchemy.sql import ddl, functions, literal_column
 from sqlalchemy.sql.compiler import (
     DDLCompiler,
     IdentifierPreparer,
@@ -462,7 +462,7 @@ def visit_upsert(self, insert_stmt, visited_bindparam=None, **kw):
 
 
 class YqlDDLCompiler(DDLCompiler):
-    def visit_create_index(self, create, include_schema=False, include_table_schema=True, **kw):
+    def visit_create_index(self, create: ddl.CreateIndex, **kw) -> str:
         index: sa.Index = create.element
         ydb_opts = index.dialect_options.get("ydb", {})
 
@@ -491,6 +491,16 @@ def visit_create_index(self, create, include_schema=False, include_table_schema=
 
         return text
 
+    def visit_drop_index(self, drop: ddl.DropIndex, **kw) -> str:
+        index: sa.Index = drop.element
+
+        self._verify_index_table(index)
+
+        table_name = self.preparer.format_table(index.table)
+        index_name = self._prepared_index_name(index)
+
+        return f"ALTER TABLE {table_name} DROP INDEX {index_name}"
+
     def post_create_table(self, table: sa.Table) -> str:
         ydb_opts = table.dialect_options["ydb"]
         with_clause_list = self._render_table_partitioning_settings(ydb_opts)