simonw/vacuum-sqlite.md Secret

## vacuum-sqlite.md

      
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              vacuum-sqlite.md
            
          
    2024-03-08T12:36:01    conversation: 01hrf11gesvvx0pec8wnxrr6zk

Model: claude-3-opus-20240229
Prompt:

Write me a Python function which accepts a path to a SQLite database
Then it spawns a new subprocess to run the following command:
python -c "import sqlite3; sqlite3...."
The code in that string will connect to the SQLite database path and then use vacuum into to create a brand new SQLite database copy of it in the /tmp directory
The function should return the path to the new SQLite database
I want to be able to call this from with an async def Python function, so it should use the asyncio mechanism for running subprocesses.
Response:

Here's a Python function that accomplishes what you described:
import asyncio
import os
import tempfile

async def vacuum_sqlite_database(db_path):
    # Generate a unique filename for the new SQLite database in the /tmp directory
    with tempfile.NamedTemporaryFile(suffix='.db', delete=False, dir='/tmp') as tmp_file:
        new_db_path = tmp_file.name

    # Create the Python command to execute in a subprocess
    command = f"python -c \"import sqlite3; conn = sqlite3.connect('{db_path}'); conn.execute('VACUUM INTO \\\"{new_db_path}\\\"'); conn.close()\""

    # Run the command in a subprocess using asyncio
    proc = await asyncio.create_subprocess_shell(
        command,
        stdout=asyncio.subprocess.PIPE,
        stderr=asyncio.subprocess.PIPE
    )

    # Wait for the subprocess to complete
    stdout, stderr = await proc.communicate()

    # Check if the subprocess completed successfully
    if proc.returncode == 0:
        return new_db_path
    else:
        # Handle any errors that occurred during the subprocess execution
        error_message = stderr.decode().strip()
        raise RuntimeError(f"Failed to vacuum SQLite database: {error_message}")
This function, named vacuum_sqlite_database, accepts a db_path parameter which represents the path to the SQLite database file.
Inside the function:


It generates a unique filename for the new SQLite database in the /tmp directory using tempfile.NamedTemporaryFile(). The delete=False argument ensures that the temporary file is not automatically deleted when closed, and the dir='/tmp' argument specifies the directory where the file should be created.


It constructs the Python command to execute in a subprocess. The command uses sqlite3 to connect to the specified database, execute the VACUUM INTO command to create a new copy of the database at the generated temporary file path, and then closes the connection.


It uses asyncio.create_subprocess_shell() to run the command in a subprocess asynchronously. The stdout and stderr arguments are set to asyncio.subprocess.PIPE to capture the output and error streams of the subprocess.


It waits for the subprocess to complete using await proc.communicate(), which returns the captured stdout and stderr outputs.


It checks the return code of the subprocess. If the return code is 0 (indicating success), it returns the path to the newly created SQLite database. If an error occurred, it raises a RuntimeError with the error message obtained from the stderr output.


You can call this function from within an async def Python function using the await keyword. For example:
async def main():
    original_db_path = '/path/to/original/database.db'
    new_db_path = await vacuum_sqlite_database(original_db_path)
    print(f"New SQLite database created at: {new_db_path}")
Make sure to run the main() function using an event loop, such as asyncio.run(main()).
Note: This function assumes that the required Python dependencies (sqlite3) are available in the environment where the subprocess is executed.