Hey there! Let's tackle your questions one by one, since you're looking for a temporary in-memory database that only your Python program can write to, with no external modifications allowed.

First: Can other parties access the database via conn when using sqlite3.connect(':memory:')? #

Short answer: Absolutely not. The :memory: SQLite database is 100% private to your Python process. Here's why:

• This database lives entirely within your process's private memory space. Operating systems strictly isolate memory between processes, so no external program, user, or even another Python process can peek into or modify this memory.
• The conn variable is an internal object within your program's runtime—there's no way for external code to get a reference to it unless you explicitly expose it (which you won't, if you're following good practice).
• By default, each :memory: connection creates a brand-new, independent in-memory database. Even if you spawn another thread in your own process, a new :memory: connection won't share data with the original unless you use shared mode (more on that below).

Second: Alternative implementations to meet your requirements #

If you want options beyond the basic :memory: setup, here are a few solid choices that still enforce your "write-only by creator" rule:

1. Shared in-memory database (for multi-connection use within your process) #

If you need multiple connections in the same Python process to share the in-memory data, use the shared cache URI:

import sqlite3
conn = sqlite3.connect('file::memory:?cache=shared', uri=True)

Important note: This only shares data within your single Python process. External programs still can't touch it—this is just for intra-process connection sharing.

2. Temporary file database (disk-backed, auto-cleaned) #

SQLite supports temporary on-disk databases that are automatically deleted when your process exits. These are harder for external actors to access than regular disk databases, and still enforce your write restrictions:

conn = sqlite3.connect('')  # Empty string triggers a temporary file database

This is a good middle ground if you want the stability of disk storage (in case of unexpected crashes) without leaving behind persistent files. The temporary file is usually restricted to your user account, so others can't modify it.

3. Encapsulated database class (strict access control) #

For maximum control, wrap the database in a class that hides the raw connection and only exposes approved write/read methods. This way, you can completely block unauthorized modifications:

import sqlite3

class PrivateTempDB:
    def __init__(self):
        # Hide the connection as a private attribute
        self._conn = sqlite3.connect(':memory:')
        self._cursor = self._conn.cursor()
        # Initialize your table structure here
        self._cursor.execute('CREATE TABLE IF NOT EXISTS records (id INTEGER PRIMARY KEY, content TEXT)')
        self._conn.commit()

    def add_record(self, content):
        # Only allow writes through this method (add validation if needed)
        self._cursor.execute('INSERT INTO records (content) VALUES (?)', (content,))
        self._conn.commit()

    def get_all_records(self):
        self._cursor.execute('SELECT * FROM records')
        return self._cursor.fetchall()

# Usage example
db = PrivateTempDB()
db.add_record("Only my program can write this!")
print(db.get_all_records())
# External code can't access db._conn, so no rogue modifications

This approach locks down access completely—only the methods you define can interact with the database, so you don't have to worry about accidental or malicious changes.

Quick Recap #

• The default :memory: database is already perfect for your core needs—it's 100% private to your process.
• Use shared in-memory mode if you need multi-connection access within your program.
• Temporary file databases offer a disk-backed, auto-cleaned alternative.
• Encapsulating the database in a class gives you the strictest control over who can write data.

内容的提问来源于stack exchange，提问作者Scalextrix