SnowFlake Integration for EvaDB (#1289)

Please suggest if this feature needs more test cases

---------

Co-authored-by: Lohith K S <lohithks@Lohiths-MacBook-Pro-2.local>

docs/_toc.yml

@@ -71,6 +71,7 @@ parts:
           - file: source/reference/databases/mariadb
           - file: source/reference/databases/clickhouse
           - file: source/reference/databases/github
+          - file: source/reference/databases/snowflake
 
       - file: source/reference/vector_databases/index
         title: Vector Databases

docs/source/reference/databases/snowflake.rst

@@ -0,0 +1,47 @@
+Snowflake
+==========
+
+The connection to Snowflake is based on the `snowflake-connector-python <https://pypi.org/project/snowflake-connector-python/>`_ library.
+
+Dependency
+----------
+
+* snowflake-connector-python
+
+Parameters
+----------
+
+Required:
+
+* `user` is the database user.
+* `password` is the snowflake account password.
+* `database` is the database name.
+* `warehouse` is the snowflake warehouse name.
+* `account` is the snowflake account number ( can be found in the url ).
+* `schema` is the schema name.
+
+
+.. warning:: 
+
+     Provide the parameters of an already running ``Snowflake`` Data Warehouse. EvaDB only connects to an existing ``Snowflake`` Data Warehouse.
+
+Create Connection
+-----------------
+
+.. code-block:: text
+
+   CREATE DATABASE snowflake_data WITH ENGINE = 'snowflake', PARAMETERS = {
+        "user": "<username>",
+        "password": "<my_password>"
+        "account": "<account_number>",
+        "database": "EVADB",
+        "warehouse":  "COMPUTE_WH",
+        "schema": "SAMPLE_DATA"
+   };
+
+.. warning::
+
+    | In Snowflake Terminology, ``Database`` and ``Schema`` refer to the following.
+    | A database is a logical grouping of schemas. Each database belongs to a single Snowflake account.
+    | A schema is a logical grouping of database objects (tables, views, etc.). Each schema belongs to a single database.
+

evadb/third_party/databases/interface.py

@@ -44,6 +44,8 @@ def _get_database_handler(engine: str, **kwargs):
         return mod.MariaDbHandler(engine, **kwargs)
     elif engine == "clickhouse":
         return mod.ClickHouseHandler(engine, **kwargs)
+    elif engine == "snowflake":
+        return mod.SnowFlakeDbHandler(engine, **kwargs)
     elif engine == "github":
         return mod.GithubHandler(engine, **kwargs)
     else:

evadb/third_party/databases/snowflake/__init__.py

@@ -0,0 +1,15 @@
+# coding=utf-8
+# Copyright 2018-2023 EvaDB
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""snowflake integrations"""

evadb/third_party/databases/snowflake/requirements.txt

@@ -0,0 +1,3 @@
+snowflake-connector-python
+pyarrow                   
+pandas                    

evadb/third_party/databases/snowflake/snowflake_handler.py

@@ -0,0 +1,184 @@
+# coding=utf-8
+# Copyright 2018-2023 EvaDB
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import datetime
+
+import pandas as pd
+import snowflake.connector
+
+from evadb.third_party.databases.types import (
+    DBHandler,
+    DBHandlerResponse,
+    DBHandlerStatus,
+)
+
+
+class SnowFlakeDbHandler(DBHandler):
+
+    """
+    Class for implementing the SnowFlake DB handler as a backend store for
+    EvaDB.
+    """
+
+    def __init__(self, name: str, **kwargs):
+        """
+        Initialize the handler.
+        Args:
+            name (str): name of the DB handler instance
+            **kwargs: arbitrary keyword arguments for establishing the connection.
+        """
+        super().__init__(name)
+        self.user = kwargs.get("user")
+        self.password = kwargs.get("password")
+        self.database = kwargs.get("database")
+        self.warehouse = kwargs.get("warehouse")
+        self.account = kwargs.get("account")
+        self.schema = kwargs.get("schema")
+
+    def connect(self):
+        """
+        Establish connection to the database.
+        Returns:
+          DBHandlerStatus
+        """
+        try:
+            self.connection = snowflake.connector.connect(
+                user=self.user,
+                password=self.password,
+                database=self.database,
+                warehouse=self.warehouse,
+                schema=self.schema,
+                account=self.account,
+            )
+            # Auto commit is off by default.
+            self.connection.autocommit = True
+            return DBHandlerStatus(status=True)
+        except snowflake.connector.errors.Error as e:
+            return DBHandlerStatus(status=False, error=str(e))
+
+    def disconnect(self):
+        """
+        Disconnect from the database.
+        """
+        if self.connection:
+            self.connection.close()
+
+    def check_connection(self) -> DBHandlerStatus:
+        """
+        Method for checking the status of database connection.
+        Returns:
+          DBHandlerStatus
+        """
+        if self.connection:
+            return DBHandlerStatus(status=True)
+        else:
+            return DBHandlerStatus(status=False, error="Not connected to the database.")
+
+    def get_tables(self) -> DBHandlerResponse:
+        """
+        Method to get the list of tables from database.
+        Returns:
+          DBHandlerStatus
+        """
+        if not self.connection:
+            return DBHandlerResponse(data=None, error="Not connected to the database.")
+
+        try:
+            query = f"SELECT table_name as table_name FROM information_schema.tables WHERE table_schema='{self.schema}'"
+            cursor = self.connection.cursor()
+            cursor.execute(query)
+            tables_df = self._fetch_results_as_df(cursor)
+            return DBHandlerResponse(data=tables_df)
+        except snowflake.connector.errors.Error as e:
+            return DBHandlerResponse(data=None, error=str(e))
+
+    def get_columns(self, table_name: str) -> DBHandlerResponse:
+        """
+        Method to retrieve the columns of the specified table from the database.
+        Args:
+          table_name (str): name of the table whose columns are to be retrieved.
+        Returns:
+          DBHandlerStatus
+        """
+        if not self.connection:
+            return DBHandlerResponse(data=None, error="Not connected to the database.")
+
+        try:
+            query = f"SELECT column_name as name, data_type as dtype FROM information_schema.columns WHERE table_name='{table_name}'"
+            cursor = self.connection.cursor()
+            cursor.execute(query)
+            columns_df = self._fetch_results_as_df(cursor)
+            columns_df["dtype"] = columns_df["dtype"].apply(
+                self._snowflake_to_python_types
+            )
+            return DBHandlerResponse(data=columns_df)
+        except snowflake.connector.errors.Error as e:
+            return DBHandlerResponse(data=None, error=str(e))
+
+    def _fetch_results_as_df(self, cursor):
+        """
+        Fetch results from the cursor for the executed query and return the
+        query results as dataframe.
+        """
+        try:
+            res = cursor.fetchall()
+            res_df = pd.DataFrame(
+                res, columns=[desc[0].lower() for desc in cursor.description]
+            )
+            return res_df
+        except snowflake.connector.errors.ProgrammingError as e:
+            if str(e) == "no results to fetch":
+                return pd.DataFrame({"status": ["success"]})
+            raise e
+
+    def execute_native_query(self, query_string: str) -> DBHandlerResponse:
+        """
+        Executes the native query on the database.
+        Args:
+            query_string (str): query in native format
+        Returns:
+            DBHandlerResponse
+        """
+        if not self.connection:
+            return DBHandlerResponse(data=None, error="Not connected to the database.")
+
+        try:
+            cursor = self.connection.cursor()
+            cursor.execute(query_string)
+            return DBHandlerResponse(data=self._fetch_results_as_df(cursor))
+        except snowflake.connector.errors.Error as e:
+            return DBHandlerResponse(data=None, error=str(e))
+
+    def _snowflake_to_python_types(self, snowflake_type: str):
+        mapping = {
+            "TEXT": str,
+            "NUMBER": int,
+            "INT": int,
+            "DECIMAL": float,
+            "STRING": str,
+            "CHAR": str,
+            "BOOLEAN": bool,
+            "BINARY": bytes,
+            "DATE": datetime.date,
+            "TIME": datetime.time,
+            "TIMESTAMP": datetime.datetime
+            # Add more mappings as needed
+        }
+
+        if snowflake_type in mapping:
+            return mapping[snowflake_type]
+        else:
+            raise Exception(
+                f"Unsupported column {snowflake_type} encountered in the snowflake. Please raise a feature request!"
+            )

test/third_party_tests/test_native_executor.py

@@ -228,6 +228,28 @@ def test_should_run_query_in_clickhouse(self):
         self._execute_native_query()
         self._execute_evadb_query()
 
+    @pytest.mark.skip(
+        reason="Snowflake does not come with a free version of account, so integration test is not feasible"
+    )
+    def test_should_run_query_in_snowflake(self):
+        # Create database.
+        params = {
+            "user": "eva",
+            "password": "password",
+            "account": "account_number",
+            "database": "EVADB",
+            "schema": "SAMPLE_DATA",
+            "warehouse": "warehouse",
+        }
+        query = f"""CREATE DATABASE test_data_source
+                    WITH ENGINE = "snowflake",
+                    PARAMETERS = {params};"""
+        execute_query_fetch_all(self.evadb, query)
+
+        # Test executions.
+        self._execute_native_query()
+        self._execute_evadb_query()
+
     def test_should_run_query_in_sqlite(self):
         # Create database.
         import os