How to set statement timeout for query execution in python

How to set statement timeout for query execution in python

To set a statement timeout for query execution in Python, you can use the psycopg2 library if you are working with PostgreSQL, or the mysql-connector-python library if you are working with MySQL. Both libraries allow you to set a timeout for SQL queries. Here's how to do it for both databases:

For PostgreSQL (using psycopg2):

import psycopg2 # Establish a connection to your PostgreSQL database conn = psycopg2.connect( dbname="your_database", user="your_username", password="your_password", host="your_host", port="your_port" ) # Create a cursor object cursor = conn.cursor() # Set a statement_timeout for the query (in milliseconds) timeout_milliseconds = 5000 # 5 seconds cursor.execute("SET statement_timeout TO %s", (timeout_milliseconds,)) # Execute your SQL query try: cursor.execute("SELECT * FROM your_table") result = cursor.fetchall() except psycopg2.extensions.QueryCanceledError: print("Query execution was canceled due to statement timeout.") # Close the cursor and connection cursor.close() conn.close()

In this example, we use the SET statement_timeout command to set a timeout for the query in milliseconds. If the query takes longer than the specified timeout, it will be canceled, and a QueryCanceledError exception will be raised.

For MySQL (using mysql-connector-python):

import mysql.connector # Establish a connection to your MySQL database conn = mysql.connector.connect( host="your_host", user="your_username", password="your_password", database="your_database" ) # Create a cursor object cursor = conn.cursor() # Set a statement_timeout for the query (in seconds) timeout_seconds = 5 # 5 seconds cursor.execute("SET max_execution_time = %s", (timeout_seconds,)) # Execute your SQL query try: cursor.execute("SELECT * FROM your_table") result = cursor.fetchall() except mysql.connector.errors.DatabaseError as e: if "Max execution time" in str(e): print("Query execution was canceled due to statement timeout.") # Close the cursor and connection cursor.close() conn.close()

In this MySQL example, we use the SET max_execution_time command to set a timeout for the query in seconds. If the query takes longer than the specified timeout, it will be canceled, and a DatabaseError exception with a message indicating the timeout will be raised.

Make sure to replace "your_database", "your_username", "your_password", "your_host", "your_port", "your_table", and the timeout values with your specific database and query information.

Examples

  1. "Python psycopg2 set statement timeout example" Description: This query aims to set a statement timeout for query execution using psycopg2, a PostgreSQL adapter for Python.

    import psycopg2 conn = psycopg2.connect("dbname=mydatabase user=myuser password=mypassword") cursor = conn.cursor() cursor.execute("SET statement_timeout TO 5000") # Timeout set to 5 seconds (5000 milliseconds)

  2. "Python SQLAlchemy statement timeout" Description: Users may seek to implement statement timeouts using SQLAlchemy, a Python SQL toolkit and ORM library.

    from sqlalchemy import create_engine engine = create_engine('postgresql://user:password@localhost:5432/mydatabase') with engine.connect() as connection: connection.execute("SET statement_timeout TO 5000") # Timeout set to 5 seconds (5000 milliseconds)

  3. "Python psycopg2 query timeout setting" Description: This query focuses on setting a timeout for individual queries executed with psycopg2, providing control over query execution time.

    import psycopg2 conn = psycopg2.connect("dbname=mydatabase user=myuser password=mypassword") cursor = conn.cursor() cursor.execute("SET LOCAL statement_timeout TO 5000") # Timeout set to 5 seconds (5000 milliseconds) for this session only

  4. "Python PostgreSQL execute timeout" Description: Users may want to enforce query execution timeouts directly within PostgreSQL from Python scripts.

    import psycopg2 conn = psycopg2.connect("dbname=mydatabase user=myuser password=mypassword") cursor = conn.cursor() cursor.execute("SELECT pg_sleep(10)") # Execute a query that sleeps for 10 seconds, but will be terminated after the timeout

  5. "Python psycopg2 query execution time limit" Description: This query targets limiting the execution time of queries using psycopg2, allowing developers to manage resource allocation efficiently.

    import psycopg2 conn = psycopg2.connect("dbname=mydatabase user=myuser password=mypassword") cursor = conn.cursor() cursor.execute("SET LOCAL statement_timeout TO 5000") # Timeout set to 5 seconds (5000 milliseconds) for this session only

  6. "Python psycopg2 timeout error handling" Description: Users may want to handle timeout errors gracefully when using psycopg2 in their Python applications.

    import psycopg2 from psycopg2 import OperationalError try: conn = psycopg2.connect("dbname=mydatabase user=myuser password=mypassword") cursor = conn.cursor() cursor.execute("SET LOCAL statement_timeout TO 5000") # Timeout set to 5 seconds (5000 milliseconds) for this session only except OperationalError as e: print("Timeout error:", e)

  7. "Python PostgreSQL statement timeout decorator" Description: This query focuses on using decorators to enforce statement timeouts in Python, offering a reusable solution.

    import psycopg2 def with_statement_timeout(timeout_ms): def decorator(func): def wrapper(*args, **kwargs): conn = psycopg2.connect("dbname=mydatabase user=myuser password=mypassword") cursor = conn.cursor() cursor.execute(f"SET LOCAL statement_timeout TO {timeout_ms}") result = func(cursor, *args, **kwargs) conn.commit() conn.close() return result return wrapper return decorator @with_statement_timeout(5000) # Timeout set to 5 seconds (5000 milliseconds) for the decorated function def execute_query(cursor): cursor.execute("SELECT * FROM table_name")

  8. "Python psycopg2 query timeout context manager" Description: This query aims to learn about using context managers to enforce query timeouts in Python, simplifying resource management.

    import psycopg2 class QueryTimeoutContextManager: def __init__(self, connection, timeout_ms): self.connection = connection self.timeout_ms = timeout_ms def __enter__(self): self.cursor = self.connection.cursor() self.cursor.execute(f"SET LOCAL statement_timeout TO {self.timeout_ms}") def __exit__(self, exc_type, exc_val, exc_tb): self.connection.rollback() self.cursor.close() conn = psycopg2.connect("dbname=mydatabase user=myuser password=mypassword") with QueryTimeoutContextManager(conn, 5000): # Timeout set to 5 seconds (5000 milliseconds) for queries within this context cursor.execute("SELECT * FROM table_name")

  9. "Python psycopg2 set query timeout milliseconds" Description: This query specifically focuses on setting query timeouts in milliseconds using psycopg2.

    import psycopg2 conn = psycopg2.connect("dbname=mydatabase user=myuser password=mypassword") cursor = conn.cursor() cursor.execute("SET LOCAL statement_timeout TO 5000") # Timeout set to 5 seconds (5000 milliseconds) for this session only

  10. "Python psycopg2 cancel query after timeout" Description: Users may want to automatically cancel queries after a timeout occurs to prevent excessive resource consumption.

    import psycopg2 conn = psycopg2.connect("dbname=mydatabase user=myuser password=mypassword") cursor = conn.cursor() cursor.execute("SET LOCAL statement_timeout TO 5000") # Timeout set to 5 seconds (5000 milliseconds) for this session only conn.set_session(autocommit=True) # Set autocommit mode to ensure immediate query cancellation on timeout

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