Upon instantiating, a connection is created and maintained for the life of
the object until the close method is called.
It is recommended to use this block as a context manager, which will automatically
close the engine and its connections when the context is exited.
It is also recommended that this block is loaded and consumed within a single task
or flow because if the block is passed across separate tasks and flows,
the state of the block's connection and cursor will be lost.
Parameters:
Name
Type
Description
Default
credentials
The credentials to authenticate with Snowflake.
required
database
The name of the default database to use.
required
warehouse
The name of the default warehouse to use.
required
schema
The name of the default schema to use;
this attribute is accessible through SnowflakeConnector(...).schema_.
required
fetch_size
The number of rows to fetch at a time.
required
poll_frequency_s
The number of seconds before checking query.
required
Examples:
Load stored Snowflake connector as a context manager:
classSnowflakeConnector(DatabaseBlock):""" Block used to manage connections with Snowflake. Upon instantiating, a connection is created and maintained for the life of the object until the close method is called. It is recommended to use this block as a context manager, which will automatically close the engine and its connections when the context is exited. It is also recommended that this block is loaded and consumed within a single task or flow because if the block is passed across separate tasks and flows, the state of the block's connection and cursor will be lost. Args: credentials: The credentials to authenticate with Snowflake. database: The name of the default database to use. warehouse: The name of the default warehouse to use. schema: The name of the default schema to use; this attribute is accessible through `SnowflakeConnector(...).schema_`. fetch_size: The number of rows to fetch at a time. poll_frequency_s: The number of seconds before checking query. Examples: Load stored Snowflake connector as a context manager: ```python from prefect_snowflake.database import SnowflakeConnector snowflake_connector = SnowflakeConnector.load("BLOCK_NAME") ``` Insert data into database and fetch results. ```python from prefect_snowflake.database import SnowflakeConnector with SnowflakeConnector.load("BLOCK_NAME") as conn: conn.execute( "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);" ) conn.execute_many( "INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);", seq_of_parameters=[ {"name": "Ford", "address": "Highway 42"}, {"name": "Unknown", "address": "Space"}, {"name": "Me", "address": "Myway 88"}, ], ) results = conn.fetch_all( "SELECT * FROM customers WHERE address = %(address)s", parameters={"address": "Space"} ) print(results) ``` """# noqa_block_type_name="Snowflake Connector"_logo_url="https://cdn.sanity.io/images/3ugk85nk/production/bd359de0b4be76c2254bd329fe3a267a1a3879c2-250x250.png"# noqa_documentation_url="https://prefecthq.github.io/prefect-snowflake/database/#prefect_snowflake.database.SnowflakeConnector"# noqa_description="Perform data operations against a Snowflake database."credentials:SnowflakeCredentials=Field(default=...,description="The credentials to authenticate with Snowflake.")database:str=Field(default=...,description="The name of the default database to use.")warehouse:str=Field(default=...,description="The name of the default warehouse to use.")schema_:str=Field(default=...,alias="schema",description="The name of the default schema to use.",)fetch_size:int=Field(default=1,description="The default number of rows to fetch at a time.")poll_frequency_s:int=Field(default=1,title="Poll Frequency [seconds]",description=("The number of seconds between checking query ""status for long running queries."),)_connection:Optional[SnowflakeConnection]=None_unique_cursors:Dict[str,SnowflakeCursor]=Nonedefget_connection(self,**connect_kwargs:Any)->SnowflakeConnection:""" Returns an authenticated connection that can be used to query from Snowflake databases. Args: **connect_kwargs: Additional arguments to pass to `snowflake.connector.connect`. Returns: The authenticated SnowflakeConnection. Examples: ```python from prefect_snowflake.credentials import SnowflakeCredentials from prefect_snowflake.database import SnowflakeConnector snowflake_credentials = SnowflakeCredentials( account="account", user="user", password="password", ) snowflake_connector = SnowflakeConnector( database="database", warehouse="warehouse", schema="schema", credentials=snowflake_credentials ) with snowflake_connector.get_connection() as connection: ... ``` """ifself._connectionisnotNone:returnself._connectionconnect_params={"database":self.database,"warehouse":self.warehouse,"schema":self.schema_,}connection=self.credentials.get_client(**connect_kwargs,**connect_params)self._connection=connectionself.logger.info("Started a new connection to Snowflake.")returnconnectiondef_start_connection(self):""" Starts Snowflake database connection. """self.get_connection()ifself._unique_cursorsisNone:self._unique_cursors={}def_get_cursor(self,inputs:Dict[str,Any],cursor_type:Type[SnowflakeCursor]=SnowflakeCursor,)->Tuple[bool,SnowflakeCursor]:""" Get a Snowflake cursor. Args: inputs: The inputs to generate a unique hash, used to decide whether a new cursor should be used. cursor_type: The class of the cursor to use when creating a Snowflake cursor. Returns: Whether a cursor is new and a Snowflake cursor. """self._start_connection()input_hash=hash_objects(inputs)ifinput_hashisNone:raiseRuntimeError("We were not able to hash your inputs, ""which resulted in an unexpected data return; ""please open an issue with a reproducible example.")ifinput_hashnotinself._unique_cursors.keys():new_cursor=self._connection.cursor(cursor_type)self._unique_cursors[input_hash]=new_cursorreturnTrue,new_cursorelse:existing_cursor=self._unique_cursors[input_hash]returnFalse,existing_cursorasyncdef_execute_async(self,cursor:SnowflakeCursor,inputs:Dict[str,Any]):"""Helper method to execute operations asynchronously."""response=awaitrun_sync_in_worker_thread(cursor.execute_async,**inputs)self.logger.info(f"Executing the operation, {inputs['command']!r}, asynchronously; "f"polling for the result every {self.poll_frequency_s} seconds.")query_id=response["queryId"]whileself._connection.is_still_running(awaitrun_sync_in_worker_thread(self._connection.get_query_status_throw_if_error,query_id)):awaitasyncio.sleep(self.poll_frequency_s)awaitrun_sync_in_worker_thread(cursor.get_results_from_sfqid,query_id)defreset_cursors(self)->None:""" Tries to close all opened cursors. Examples: Reset the cursors to refresh cursor position. ```python from prefect_snowflake.database import SnowflakeConnector with SnowflakeConnector.load("BLOCK_NAME") as conn: conn.execute( "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);" ) conn.execute_many( "INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);", seq_of_parameters=[ {"name": "Ford", "address": "Highway 42"}, {"name": "Unknown", "address": "Space"}, {"name": "Me", "address": "Myway 88"}, ], ) print(conn.fetch_one("SELECT * FROM customers")) # Ford conn.reset_cursors() print(conn.fetch_one("SELECT * FROM customers")) # should be Ford again ``` """# noqaifnotself._unique_cursors:self.logger.info("There were no cursors to reset.")returninput_hashes=tuple(self._unique_cursors.keys())forinput_hashininput_hashes:cursor=self._unique_cursors.pop(input_hash)try:cursor.close()exceptExceptionasexc:self.logger.warning(f"Failed to close cursor for input hash {input_hash!r}: {exc}")self.logger.info("Successfully reset the cursors.")@sync_compatibleasyncdeffetch_one(self,operation:str,parameters:Optional[Dict[str,Any]]=None,cursor_type:Type[SnowflakeCursor]=SnowflakeCursor,**execute_kwargs:Any,)->Tuple[Any]:""" Fetch a single result from the database. Repeated calls using the same inputs to *any* of the fetch methods of this block will skip executing the operation again, and instead, return the next set of results from the previous execution, until the reset_cursors method is called. Args: operation: The SQL query or other operation to be executed. parameters: The parameters for the operation. cursor_type: The class of the cursor to use when creating a Snowflake cursor. **execute_kwargs: Additional options to pass to `cursor.execute_async`. Returns: A tuple containing the data returned by the database, where each row is a tuple and each column is a value in the tuple. Examples: Fetch one row from the database where address is Space. ```python from prefect_snowflake.database import SnowflakeConnector with SnowflakeConnector.load("BLOCK_NAME") as conn: conn.execute( "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);" ) conn.execute_many( "INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);", seq_of_parameters=[ {"name": "Ford", "address": "Highway 42"}, {"name": "Unknown", "address": "Space"}, {"name": "Me", "address": "Myway 88"}, ], ) result = conn.fetch_one( "SELECT * FROM customers WHERE address = %(address)s", parameters={"address": "Space"} ) print(result) ``` """# noqainputs=dict(command=operation,params=parameters,**execute_kwargs,)new,cursor=self._get_cursor(inputs,cursor_type=cursor_type)ifnew:awaitself._execute_async(cursor,inputs)self.logger.debug("Preparing to fetch a row.")result=awaitrun_sync_in_worker_thread(cursor.fetchone)returnresult@sync_compatibleasyncdeffetch_many(self,operation:str,parameters:Optional[Dict[str,Any]]=None,size:Optional[int]=None,cursor_type:Type[SnowflakeCursor]=SnowflakeCursor,**execute_kwargs:Any,)->List[Tuple[Any]]:""" Fetch a limited number of results from the database. Repeated calls using the same inputs to *any* of the fetch methods of this block will skip executing the operation again, and instead, return the next set of results from the previous execution, until the reset_cursors method is called. Args: operation: The SQL query or other operation to be executed. parameters: The parameters for the operation. size: The number of results to return; if None or 0, uses the value of `fetch_size` configured on the block. cursor_type: The class of the cursor to use when creating a Snowflake cursor. **execute_kwargs: Additional options to pass to `cursor.execute_async`. Returns: A list of tuples containing the data returned by the database, where each row is a tuple and each column is a value in the tuple. Examples: Repeatedly fetch two rows from the database where address is Highway 42. ```python from prefect_snowflake.database import SnowflakeConnector with SnowflakeConnector.load("BLOCK_NAME") as conn: conn.execute( "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);" ) conn.execute_many( "INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);", seq_of_parameters=[ {"name": "Marvin", "address": "Highway 42"}, {"name": "Ford", "address": "Highway 42"}, {"name": "Unknown", "address": "Highway 42"}, {"name": "Me", "address": "Highway 42"}, ], ) result = conn.fetch_many( "SELECT * FROM customers WHERE address = %(address)s", parameters={"address": "Highway 42"}, size=2 ) print(result) # Marvin, Ford result = conn.fetch_many( "SELECT * FROM customers WHERE address = %(address)s", parameters={"address": "Highway 42"}, size=2 ) print(result) # Unknown, Me ``` """# noqainputs=dict(command=operation,params=parameters,**execute_kwargs,)new,cursor=self._get_cursor(inputs,cursor_type)ifnew:awaitself._execute_async(cursor,inputs)size=sizeorself.fetch_sizeself.logger.debug(f"Preparing to fetch {size} rows.")result=awaitrun_sync_in_worker_thread(cursor.fetchmany,size=size)returnresult@sync_compatibleasyncdeffetch_all(self,operation:str,parameters:Optional[Dict[str,Any]]=None,cursor_type:Type[SnowflakeCursor]=SnowflakeCursor,**execute_kwargs:Any,)->List[Tuple[Any]]:""" Fetch all results from the database. Repeated calls using the same inputs to *any* of the fetch methods of this block will skip executing the operation again, and instead, return the next set of results from the previous execution, until the reset_cursors method is called. Args: operation: The SQL query or other operation to be executed. parameters: The parameters for the operation. cursor_type: The class of the cursor to use when creating a Snowflake cursor. **execute_kwargs: Additional options to pass to `cursor.execute_async`. Returns: A list of tuples containing the data returned by the database, where each row is a tuple and each column is a value in the tuple. Examples: Fetch all rows from the database where address is Highway 42. ```python from prefect_snowflake.database import SnowflakeConnector with SnowflakeConnector.load("BLOCK_NAME") as conn: conn.execute( "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);" ) conn.execute_many( "INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);", seq_of_parameters=[ {"name": "Marvin", "address": "Highway 42"}, {"name": "Ford", "address": "Highway 42"}, {"name": "Unknown", "address": "Highway 42"}, {"name": "Me", "address": "Myway 88"}, ], ) result = conn.fetch_all( "SELECT * FROM customers WHERE address = %(address)s", parameters={"address": "Highway 42"}, ) print(result) # Marvin, Ford, Unknown ``` """# noqainputs=dict(command=operation,params=parameters,**execute_kwargs,)new,cursor=self._get_cursor(inputs,cursor_type)ifnew:awaitself._execute_async(cursor,inputs)self.logger.debug("Preparing to fetch all rows.")result=awaitrun_sync_in_worker_thread(cursor.fetchall)returnresult@sync_compatibleasyncdefexecute(self,operation:str,parameters:Optional[Dict[str,Any]]=None,cursor_type:Type[SnowflakeCursor]=SnowflakeCursor,**execute_kwargs:Any,)->None:""" Executes an operation on the database. This method is intended to be used for operations that do not return data, such as INSERT, UPDATE, or DELETE. Unlike the fetch methods, this method will always execute the operation upon calling. Args: operation: The SQL query or other operation to be executed. parameters: The parameters for the operation. cursor_type: The class of the cursor to use when creating a Snowflake cursor. **execute_kwargs: Additional options to pass to `cursor.execute_async`. Examples: Create table named customers with two columns, name and address. ```python from prefect_snowflake.database import SnowflakeConnector with SnowflakeConnector.load("BLOCK_NAME") as conn: conn.execute( "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);" ) ``` """# noqaself._start_connection()inputs=dict(command=operation,params=parameters,**execute_kwargs,)withself._connection.cursor(cursor_type)ascursor:awaitrun_sync_in_worker_thread(cursor.execute,**inputs)self.logger.info(f"Executed the operation, {operation!r}.")@sync_compatibleasyncdefexecute_many(self,operation:str,seq_of_parameters:List[Dict[str,Any]],)->None:""" Executes many operations on the database. This method is intended to be used for operations that do not return data, such as INSERT, UPDATE, or DELETE. Unlike the fetch methods, this method will always execute the operations upon calling. Args: operation: The SQL query or other operation to be executed. seq_of_parameters: The sequence of parameters for the operation. Examples: Create table and insert three rows into it. ```python from prefect_snowflake.database import SnowflakeConnector with SnowflakeConnector.load("BLOCK_NAME") as conn: conn.execute( "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);" ) conn.execute_many( "INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);", seq_of_parameters=[ {"name": "Marvin", "address": "Highway 42"}, {"name": "Ford", "address": "Highway 42"}, {"name": "Unknown", "address": "Space"}, ], ) ``` """# noqaself._start_connection()inputs=dict(command=operation,seqparams=seq_of_parameters,)withself._connection.cursor()ascursor:awaitrun_sync_in_worker_thread(cursor.executemany,**inputs)self.logger.info(f"Executed {len(seq_of_parameters)} operations off {operation!r}.")defclose(self):""" Closes connection and its cursors. """try:self.reset_cursors()finally:ifself._connectionisNone:self.logger.info("There was no connection open to be closed.")returnself._connection.close()self._connection=Noneself.logger.info("Successfully closed the Snowflake connection.")def__enter__(self):""" Start a connection upon entry. """returnselfdef__exit__(self,*args):""" Closes connection and its cursors upon exit. """self.close()def__getstate__(self):"""Allows block to be pickled and dumped."""data=self.__dict__.copy()data.update({k:Noneforkin{"_connection","_unique_cursors"}})returndatadef__setstate__(self,data:dict):"""Reset connection and cursors upon loading."""self.__dict__.update(data)self._start_connection()
defclose(self):""" Closes connection and its cursors. """try:self.reset_cursors()finally:ifself._connectionisNone:self.logger.info("There was no connection open to be closed.")returnself._connection.close()self._connection=Noneself.logger.info("Successfully closed the Snowflake connection.")
Executes an operation on the database. This method is intended to be used
for operations that do not return data, such as INSERT, UPDATE, or DELETE.
Unlike the fetch methods, this method will always execute the operation
upon calling.
Parameters:
Name
Type
Description
Default
operation
str
The SQL query or other operation to be executed.
required
parameters
Optional[Dict[str, Any]]
The parameters for the operation.
None
cursor_type
Type[SnowflakeCursor]
The class of the cursor to use when creating a Snowflake cursor.
SnowflakeCursor
**execute_kwargs
Any
Additional options to pass to cursor.execute_async.
{}
Examples:
Create table named customers with two columns, name and address.
fromprefect_snowflake.databaseimportSnowflakeConnectorwithSnowflakeConnector.load("BLOCK_NAME")asconn:conn.execute("CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);")
@sync_compatibleasyncdefexecute(self,operation:str,parameters:Optional[Dict[str,Any]]=None,cursor_type:Type[SnowflakeCursor]=SnowflakeCursor,**execute_kwargs:Any,)->None:""" Executes an operation on the database. This method is intended to be used for operations that do not return data, such as INSERT, UPDATE, or DELETE. Unlike the fetch methods, this method will always execute the operation upon calling. Args: operation: The SQL query or other operation to be executed. parameters: The parameters for the operation. cursor_type: The class of the cursor to use when creating a Snowflake cursor. **execute_kwargs: Additional options to pass to `cursor.execute_async`. Examples: Create table named customers with two columns, name and address. ```python from prefect_snowflake.database import SnowflakeConnector with SnowflakeConnector.load("BLOCK_NAME") as conn: conn.execute( "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);" ) ``` """# noqaself._start_connection()inputs=dict(command=operation,params=parameters,**execute_kwargs,)withself._connection.cursor(cursor_type)ascursor:awaitrun_sync_in_worker_thread(cursor.execute,**inputs)self.logger.info(f"Executed the operation, {operation!r}.")
Executes many operations on the database. This method is intended to be used
for operations that do not return data, such as INSERT, UPDATE, or DELETE.
Unlike the fetch methods, this method will always execute the operations
upon calling.
Parameters:
Name
Type
Description
Default
operation
str
The SQL query or other operation to be executed.
required
seq_of_parameters
List[Dict[str, Any]]
The sequence of parameters for the operation.
required
Examples:
Create table and insert three rows into it.
fromprefect_snowflake.databaseimportSnowflakeConnectorwithSnowflakeConnector.load("BLOCK_NAME")asconn:conn.execute("CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);")conn.execute_many("INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);",seq_of_parameters=[{"name":"Marvin","address":"Highway 42"},{"name":"Ford","address":"Highway 42"},{"name":"Unknown","address":"Space"},],)
@sync_compatibleasyncdefexecute_many(self,operation:str,seq_of_parameters:List[Dict[str,Any]],)->None:""" Executes many operations on the database. This method is intended to be used for operations that do not return data, such as INSERT, UPDATE, or DELETE. Unlike the fetch methods, this method will always execute the operations upon calling. Args: operation: The SQL query or other operation to be executed. seq_of_parameters: The sequence of parameters for the operation. Examples: Create table and insert three rows into it. ```python from prefect_snowflake.database import SnowflakeConnector with SnowflakeConnector.load("BLOCK_NAME") as conn: conn.execute( "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);" ) conn.execute_many( "INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);", seq_of_parameters=[ {"name": "Marvin", "address": "Highway 42"}, {"name": "Ford", "address": "Highway 42"}, {"name": "Unknown", "address": "Space"}, ], ) ``` """# noqaself._start_connection()inputs=dict(command=operation,seqparams=seq_of_parameters,)withself._connection.cursor()ascursor:awaitrun_sync_in_worker_thread(cursor.executemany,**inputs)self.logger.info(f"Executed {len(seq_of_parameters)} operations off {operation!r}.")
Fetch all results from the database.
Repeated calls using the same inputs to any of the fetch methods of this
block will skip executing the operation again, and instead,
return the next set of results from the previous execution,
until the reset_cursors method is called.
Parameters:
Name
Type
Description
Default
operation
str
The SQL query or other operation to be executed.
required
parameters
Optional[Dict[str, Any]]
The parameters for the operation.
None
cursor_type
Type[SnowflakeCursor]
The class of the cursor to use when creating a Snowflake cursor.
SnowflakeCursor
**execute_kwargs
Any
Additional options to pass to cursor.execute_async.
{}
Returns:
Type
Description
List[Tuple[Any]]
A list of tuples containing the data returned by the database,
where each row is a tuple and each column is a value in the tuple.
Examples:
Fetch all rows from the database where address is Highway 42.
fromprefect_snowflake.databaseimportSnowflakeConnectorwithSnowflakeConnector.load("BLOCK_NAME")asconn:conn.execute("CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);")conn.execute_many("INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);",seq_of_parameters=[{"name":"Marvin","address":"Highway 42"},{"name":"Ford","address":"Highway 42"},{"name":"Unknown","address":"Highway 42"},{"name":"Me","address":"Myway 88"},],)result=conn.fetch_all("SELECT * FROM customers WHERE address = %(address)s",parameters={"address":"Highway 42"},)print(result)# Marvin, Ford, Unknown
@sync_compatibleasyncdeffetch_all(self,operation:str,parameters:Optional[Dict[str,Any]]=None,cursor_type:Type[SnowflakeCursor]=SnowflakeCursor,**execute_kwargs:Any,)->List[Tuple[Any]]:""" Fetch all results from the database. Repeated calls using the same inputs to *any* of the fetch methods of this block will skip executing the operation again, and instead, return the next set of results from the previous execution, until the reset_cursors method is called. Args: operation: The SQL query or other operation to be executed. parameters: The parameters for the operation. cursor_type: The class of the cursor to use when creating a Snowflake cursor. **execute_kwargs: Additional options to pass to `cursor.execute_async`. Returns: A list of tuples containing the data returned by the database, where each row is a tuple and each column is a value in the tuple. Examples: Fetch all rows from the database where address is Highway 42. ```python from prefect_snowflake.database import SnowflakeConnector with SnowflakeConnector.load("BLOCK_NAME") as conn: conn.execute( "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);" ) conn.execute_many( "INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);", seq_of_parameters=[ {"name": "Marvin", "address": "Highway 42"}, {"name": "Ford", "address": "Highway 42"}, {"name": "Unknown", "address": "Highway 42"}, {"name": "Me", "address": "Myway 88"}, ], ) result = conn.fetch_all( "SELECT * FROM customers WHERE address = %(address)s", parameters={"address": "Highway 42"}, ) print(result) # Marvin, Ford, Unknown ``` """# noqainputs=dict(command=operation,params=parameters,**execute_kwargs,)new,cursor=self._get_cursor(inputs,cursor_type)ifnew:awaitself._execute_async(cursor,inputs)self.logger.debug("Preparing to fetch all rows.")result=awaitrun_sync_in_worker_thread(cursor.fetchall)returnresult
Fetch a limited number of results from the database.
Repeated calls using the same inputs to any of the fetch methods of this
block will skip executing the operation again, and instead,
return the next set of results from the previous execution,
until the reset_cursors method is called.
Parameters:
Name
Type
Description
Default
operation
str
The SQL query or other operation to be executed.
required
parameters
Optional[Dict[str, Any]]
The parameters for the operation.
None
size
Optional[int]
The number of results to return; if None or 0, uses the value of
fetch_size configured on the block.
None
cursor_type
Type[SnowflakeCursor]
The class of the cursor to use when creating a Snowflake cursor.
SnowflakeCursor
**execute_kwargs
Any
Additional options to pass to cursor.execute_async.
{}
Returns:
Type
Description
List[Tuple[Any]]
A list of tuples containing the data returned by the database,
where each row is a tuple and each column is a value in the tuple.
Examples:
Repeatedly fetch two rows from the database where address is Highway 42.
fromprefect_snowflake.databaseimportSnowflakeConnectorwithSnowflakeConnector.load("BLOCK_NAME")asconn:conn.execute("CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);")conn.execute_many("INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);",seq_of_parameters=[{"name":"Marvin","address":"Highway 42"},{"name":"Ford","address":"Highway 42"},{"name":"Unknown","address":"Highway 42"},{"name":"Me","address":"Highway 42"},],)result=conn.fetch_many("SELECT * FROM customers WHERE address = %(address)s",parameters={"address":"Highway 42"},size=2)print(result)# Marvin, Fordresult=conn.fetch_many("SELECT * FROM customers WHERE address = %(address)s",parameters={"address":"Highway 42"},size=2)print(result)# Unknown, Me
@sync_compatibleasyncdeffetch_many(self,operation:str,parameters:Optional[Dict[str,Any]]=None,size:Optional[int]=None,cursor_type:Type[SnowflakeCursor]=SnowflakeCursor,**execute_kwargs:Any,)->List[Tuple[Any]]:""" Fetch a limited number of results from the database. Repeated calls using the same inputs to *any* of the fetch methods of this block will skip executing the operation again, and instead, return the next set of results from the previous execution, until the reset_cursors method is called. Args: operation: The SQL query or other operation to be executed. parameters: The parameters for the operation. size: The number of results to return; if None or 0, uses the value of `fetch_size` configured on the block. cursor_type: The class of the cursor to use when creating a Snowflake cursor. **execute_kwargs: Additional options to pass to `cursor.execute_async`. Returns: A list of tuples containing the data returned by the database, where each row is a tuple and each column is a value in the tuple. Examples: Repeatedly fetch two rows from the database where address is Highway 42. ```python from prefect_snowflake.database import SnowflakeConnector with SnowflakeConnector.load("BLOCK_NAME") as conn: conn.execute( "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);" ) conn.execute_many( "INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);", seq_of_parameters=[ {"name": "Marvin", "address": "Highway 42"}, {"name": "Ford", "address": "Highway 42"}, {"name": "Unknown", "address": "Highway 42"}, {"name": "Me", "address": "Highway 42"}, ], ) result = conn.fetch_many( "SELECT * FROM customers WHERE address = %(address)s", parameters={"address": "Highway 42"}, size=2 ) print(result) # Marvin, Ford result = conn.fetch_many( "SELECT * FROM customers WHERE address = %(address)s", parameters={"address": "Highway 42"}, size=2 ) print(result) # Unknown, Me ``` """# noqainputs=dict(command=operation,params=parameters,**execute_kwargs,)new,cursor=self._get_cursor(inputs,cursor_type)ifnew:awaitself._execute_async(cursor,inputs)size=sizeorself.fetch_sizeself.logger.debug(f"Preparing to fetch {size} rows.")result=awaitrun_sync_in_worker_thread(cursor.fetchmany,size=size)returnresult
Fetch a single result from the database.
Repeated calls using the same inputs to any of the fetch methods of this
block will skip executing the operation again, and instead,
return the next set of results from the previous execution,
until the reset_cursors method is called.
Parameters:
Name
Type
Description
Default
operation
str
The SQL query or other operation to be executed.
required
parameters
Optional[Dict[str, Any]]
The parameters for the operation.
None
cursor_type
Type[SnowflakeCursor]
The class of the cursor to use when creating a Snowflake cursor.
SnowflakeCursor
**execute_kwargs
Any
Additional options to pass to cursor.execute_async.
{}
Returns:
Type
Description
Tuple[Any]
A tuple containing the data returned by the database,
where each row is a tuple and each column is a value in the tuple.
Examples:
Fetch one row from the database where address is Space.
fromprefect_snowflake.databaseimportSnowflakeConnectorwithSnowflakeConnector.load("BLOCK_NAME")asconn:conn.execute("CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);")conn.execute_many("INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);",seq_of_parameters=[{"name":"Ford","address":"Highway 42"},{"name":"Unknown","address":"Space"},{"name":"Me","address":"Myway 88"},],)result=conn.fetch_one("SELECT * FROM customers WHERE address = %(address)s",parameters={"address":"Space"})print(result)
@sync_compatibleasyncdeffetch_one(self,operation:str,parameters:Optional[Dict[str,Any]]=None,cursor_type:Type[SnowflakeCursor]=SnowflakeCursor,**execute_kwargs:Any,)->Tuple[Any]:""" Fetch a single result from the database. Repeated calls using the same inputs to *any* of the fetch methods of this block will skip executing the operation again, and instead, return the next set of results from the previous execution, until the reset_cursors method is called. Args: operation: The SQL query or other operation to be executed. parameters: The parameters for the operation. cursor_type: The class of the cursor to use when creating a Snowflake cursor. **execute_kwargs: Additional options to pass to `cursor.execute_async`. Returns: A tuple containing the data returned by the database, where each row is a tuple and each column is a value in the tuple. Examples: Fetch one row from the database where address is Space. ```python from prefect_snowflake.database import SnowflakeConnector with SnowflakeConnector.load("BLOCK_NAME") as conn: conn.execute( "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);" ) conn.execute_many( "INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);", seq_of_parameters=[ {"name": "Ford", "address": "Highway 42"}, {"name": "Unknown", "address": "Space"}, {"name": "Me", "address": "Myway 88"}, ], ) result = conn.fetch_one( "SELECT * FROM customers WHERE address = %(address)s", parameters={"address": "Space"} ) print(result) ``` """# noqainputs=dict(command=operation,params=parameters,**execute_kwargs,)new,cursor=self._get_cursor(inputs,cursor_type=cursor_type)ifnew:awaitself._execute_async(cursor,inputs)self.logger.debug("Preparing to fetch a row.")result=awaitrun_sync_in_worker_thread(cursor.fetchone)returnresult
defget_connection(self,**connect_kwargs:Any)->SnowflakeConnection:""" Returns an authenticated connection that can be used to query from Snowflake databases. Args: **connect_kwargs: Additional arguments to pass to `snowflake.connector.connect`. Returns: The authenticated SnowflakeConnection. Examples: ```python from prefect_snowflake.credentials import SnowflakeCredentials from prefect_snowflake.database import SnowflakeConnector snowflake_credentials = SnowflakeCredentials( account="account", user="user", password="password", ) snowflake_connector = SnowflakeConnector( database="database", warehouse="warehouse", schema="schema", credentials=snowflake_credentials ) with snowflake_connector.get_connection() as connection: ... ``` """ifself._connectionisnotNone:returnself._connectionconnect_params={"database":self.database,"warehouse":self.warehouse,"schema":self.schema_,}connection=self.credentials.get_client(**connect_kwargs,**connect_params)self._connection=connectionself.logger.info("Started a new connection to Snowflake.")returnconnection
fromprefect_snowflake.databaseimportSnowflakeConnectorwithSnowflakeConnector.load("BLOCK_NAME")asconn:conn.execute("CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);")conn.execute_many("INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);",seq_of_parameters=[{"name":"Ford","address":"Highway 42"},{"name":"Unknown","address":"Space"},{"name":"Me","address":"Myway 88"},],)print(conn.fetch_one("SELECT * FROM customers"))# Fordconn.reset_cursors()print(conn.fetch_one("SELECT * FROM customers"))# should be Ford again
defreset_cursors(self)->None:""" Tries to close all opened cursors. Examples: Reset the cursors to refresh cursor position. ```python from prefect_snowflake.database import SnowflakeConnector with SnowflakeConnector.load("BLOCK_NAME") as conn: conn.execute( "CREATE TABLE IF NOT EXISTS customers (name varchar, address varchar);" ) conn.execute_many( "INSERT INTO customers (name, address) VALUES (%(name)s, %(address)s);", seq_of_parameters=[ {"name": "Ford", "address": "Highway 42"}, {"name": "Unknown", "address": "Space"}, {"name": "Me", "address": "Myway 88"}, ], ) print(conn.fetch_one("SELECT * FROM customers")) # Ford conn.reset_cursors() print(conn.fetch_one("SELECT * FROM customers")) # should be Ford again ``` """# noqaifnotself._unique_cursors:self.logger.info("There were no cursors to reset.")returninput_hashes=tuple(self._unique_cursors.keys())forinput_hashininput_hashes:cursor=self._unique_cursors.pop(input_hash)try:cursor.close()exceptExceptionasexc:self.logger.warning(f"Failed to close cursor for input hash {input_hash!r}: {exc}")self.logger.info("Successfully reset the cursors.")
Determines if the results of queries
controlling the transaction (BEGIN/COMMIT) should be returned.
False
poll_frequency_seconds
int
Number of seconds to wait in between checks for
run completion.
1
Returns:
Type
Description
List[List[Tuple[Any]]]
List of the outputs of response.fetchall() for each query.
Examples:
Query Snowflake table with the ID value parameterized.
fromprefectimportflowfromprefect_snowflake.credentialsimportSnowflakeCredentialsfromprefect_snowflake.databaseimportSnowflakeConnector,snowflake_multiquery@flowdefsnowflake_multiquery_flow():snowflake_credentials=SnowflakeCredentials(account="account",user="user",password="password",)snowflake_connector=SnowflakeConnector(database="database",warehouse="warehouse",schema="schema",credentials=snowflake_credentials)result=snowflake_multiquery(["SELECT * FROM table WHERE id=%{id_param}s LIMIT 8;","SELECT 1,2"],snowflake_connector,params={"id_param":1},as_transaction=True)returnresultsnowflake_multiquery_flow()
@taskasyncdefsnowflake_multiquery(queries:List[str],snowflake_connector:SnowflakeConnector,params:Union[Tuple[Any],Dict[str,Any]]=None,cursor_type:Type[SnowflakeCursor]=SnowflakeCursor,as_transaction:bool=False,return_transaction_control_results:bool=False,poll_frequency_seconds:int=1,)->List[List[Tuple[Any]]]:""" Executes multiple queries against a Snowflake database in a shared session. Allows execution in a transaction. Args: queries: The list of queries to execute against the database. params: The params to replace the placeholders in the query. snowflake_connector: The credentials to use to authenticate. cursor_type: The type of database cursor to use for the query. as_transaction: If True, queries are executed in a transaction. return_transaction_control_results: Determines if the results of queries controlling the transaction (BEGIN/COMMIT) should be returned. poll_frequency_seconds: Number of seconds to wait in between checks for run completion. Returns: List of the outputs of `response.fetchall()` for each query. Examples: Query Snowflake table with the ID value parameterized. ```python from prefect import flow from prefect_snowflake.credentials import SnowflakeCredentials from prefect_snowflake.database import SnowflakeConnector, snowflake_multiquery @flow def snowflake_multiquery_flow(): snowflake_credentials = SnowflakeCredentials( account="account", user="user", password="password", ) snowflake_connector = SnowflakeConnector( database="database", warehouse="warehouse", schema="schema", credentials=snowflake_credentials ) result = snowflake_multiquery( ["SELECT * FROM table WHERE id=%{id_param}s LIMIT 8;", "SELECT 1,2"], snowflake_connector, params={"id_param": 1}, as_transaction=True ) return result snowflake_multiquery_flow() ``` """withsnowflake_connector.get_connection()asconnection:ifas_transaction:queries.insert(0,BEGIN_TRANSACTION_STATEMENT)queries.append(END_TRANSACTION_STATEMENT)withconnection.cursor(cursor_type)ascursor:results=[]forqueryinqueries:response=cursor.execute_async(query,params=params)query_id=response["queryId"]whileconnection.is_still_running(connection.get_query_status_throw_if_error(query_id)):awaitasyncio.sleep(poll_frequency_seconds)cursor.get_results_from_sfqid(query_id)result=cursor.fetchall()results.append(result)# cut off results from BEGIN/COMMIT queriesifas_transactionandnotreturn_transaction_control_results:returnresults[1:-1]else:returnresults
Number of seconds to wait in between checks for
run completion.
1
Returns:
Type
Description
List[Tuple[Any]]
The output of response.fetchall().
Examples:
Query Snowflake table with the ID value parameterized.
fromprefectimportflowfromprefect_snowflake.credentialsimportSnowflakeCredentialsfromprefect_snowflake.databaseimportSnowflakeConnector,snowflake_query@flowdefsnowflake_query_flow():snowflake_credentials=SnowflakeCredentials(account="account",user="user",password="password",)snowflake_connector=SnowflakeConnector(database="database",warehouse="warehouse",schema="schema",credentials=snowflake_credentials)result=snowflake_query("SELECT * FROM table WHERE id=%{id_param}s LIMIT 8;",snowflake_connector,params={"id_param":1})returnresultsnowflake_query_flow()
@taskasyncdefsnowflake_query(query:str,snowflake_connector:SnowflakeConnector,params:Union[Tuple[Any],Dict[str,Any]]=None,cursor_type:Type[SnowflakeCursor]=SnowflakeCursor,poll_frequency_seconds:int=1,)->List[Tuple[Any]]:""" Executes a query against a Snowflake database. Args: query: The query to execute against the database. params: The params to replace the placeholders in the query. snowflake_connector: The credentials to use to authenticate. cursor_type: The type of database cursor to use for the query. poll_frequency_seconds: Number of seconds to wait in between checks for run completion. Returns: The output of `response.fetchall()`. Examples: Query Snowflake table with the ID value parameterized. ```python from prefect import flow from prefect_snowflake.credentials import SnowflakeCredentials from prefect_snowflake.database import SnowflakeConnector, snowflake_query @flow def snowflake_query_flow(): snowflake_credentials = SnowflakeCredentials( account="account", user="user", password="password", ) snowflake_connector = SnowflakeConnector( database="database", warehouse="warehouse", schema="schema", credentials=snowflake_credentials ) result = snowflake_query( "SELECT * FROM table WHERE id=%{id_param}s LIMIT 8;", snowflake_connector, params={"id_param": 1} ) return result snowflake_query_flow() ``` """# context manager automatically rolls back failed transactions and closeswithsnowflake_connector.get_connection()asconnection:withconnection.cursor(cursor_type)ascursor:response=cursor.execute_async(query,params=params)query_id=response["queryId"]whileconnection.is_still_running(connection.get_query_status_throw_if_error(query_id)):awaitasyncio.sleep(poll_frequency_seconds)cursor.get_results_from_sfqid(query_id)result=cursor.fetchall()returnresult
@taskasyncdefsnowflake_query_sync(query:str,snowflake_connector:SnowflakeConnector,params:Union[Tuple[Any],Dict[str,Any]]=None,cursor_type:Type[SnowflakeCursor]=SnowflakeCursor,)->List[Tuple[Any]]:""" Executes a query in sync mode against a Snowflake database. Args: query: The query to execute against the database. params: The params to replace the placeholders in the query. snowflake_connector: The credentials to use to authenticate. cursor_type: The type of database cursor to use for the query. Returns: The output of `response.fetchall()`. Examples: Execute a put statement. ```python from prefect import flow from prefect_snowflake.credentials import SnowflakeCredentials from prefect_snowflake.database import SnowflakeConnector, snowflake_query @flow def snowflake_query_sync_flow(): snowflake_credentials = SnowflakeCredentials( account="account", user="user", password="password", ) snowflake_connector = SnowflakeConnector( database="database", warehouse="warehouse", schema="schema", credentials=snowflake_credentials ) result = snowflake_query_sync( "put file://a_file.csv @mystage;", snowflake_connector, ) return result snowflake_query_sync_flow() ``` """# context manager automatically rolls back failed transactions and closeswithsnowflake_connector.get_connection()asconnection:withconnection.cursor(cursor_type)ascursor:cursor.execute(query,params=params)result=cursor.fetchall()returnresult