TEXT vs BLOB in SQLite: Best Practices for Base64 Storage

#webdev #sqlite

When working with SQLite, you often need to decide how to store data efficiently. One common scenario is storing Base64-encoded content, such as images, files, or other binary data. SQLite gives you two main options: storing it as a TEXT or as a BLOB. Understanding the differences can help you make the right choice for performance, storage, and convenience.

Base64 and SQLite

Base64 is a way to represent binary data as text. It uses only ASCII characters, which means you can store it in a text field without worrying about special encoding. However, it is larger than the original binary by roughly 33 percent.

SQLite supports two relevant storage types:

TEXT: For storing strings. It works perfectly for Base64 since Base64 is text.
BLOB: For storing raw binary data. SQLite stores it as-is without any conversion.

Storing Base64 in TEXT

Using TEXT is simple and straightforward. You can insert Base64 strings directly into a column. For example:

CREATE TABLE files (
    id INTEGER PRIMARY KEY,
    name TEXT,
    data TEXT
);

INSERT INTO files (name, data) VALUES ('example.png', 'iVBORw0KGgoAAAANSUhEUgAA...');

Advantages:

Easy to read and debug. You can query the column directly and see the Base64 string.
Works with text functions in SQLite, like LIKE or SUBSTR.

Disadvantages:

Slightly more storage because Base64 is larger than raw binary.
Converting back to binary in your application adds an extra step.

Storing Base64 in BLOB

Even if your data is Base64, you can convert it back to binary before storing it in a BLOB column. Example:

CREATE TABLE files_blob (
    id INTEGER PRIMARY KEY,
    name TEXT,
    data BLOB
);

In your application, decode the Base64 string before inserting it:

import sqlite3
import base64

conn = sqlite3.connect('example.db')
cursor = conn.cursor()

with open('example.png', 'rb') as f:
    binary_data = f.read()

encoded = base64.b64encode(binary_data)
decoded = base64.b64decode(encoded)  # You would store this in BLOB

cursor.execute("INSERT INTO files_blob (name, data) VALUES (?, ?)", ('example.png', decoded))
conn.commit()

Advantages:

Storage is more efficient because the data is stored as raw binary.
Faster read and write operations for large files.
No need to decode Base64 in the application for processing binary data.

Disadvantages:

Not human-readable. You cannot query the content directly in SQLite CLI.
Some text-based operations are unavailable.

Key Takeaways

TEXT is convenient for Base64 strings and small files where human readability or debugging is useful.
BLOB is better for performance and storage efficiency especially when dealing with large files or many rows.
Base64 in TEXT increases storage size by a third compared to storing binary in BLOB.

Recommendation

If you are storing images, documents, or any sizable binary data, decode the Base64 and use BLOB. Use TEXT only when the data is naturally text or small enough that performance and storage are not critical.

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