📦 MySQL Binary Types (BLOB) – Store Files, Images & Raw Data Safely

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🧲 Introduction – Why Use Binary Types in MySQL?

While MySQL is primarily used for structured, textual, or numeric data, it also supports binary types like BLOB (Binary Large Object) for storing non-text content such as:

• Images
• Files
• PDFs
• Encrypted data
• Multimedia

The BLOB data type allows you to store and retrieve this raw binary data efficiently, making it ideal for file-based storage needs embedded in the database.

🎯 In this guide, you’ll learn:

• What BLOB types are and when to use them
• Variants and size limits of BLOB
• How to store and retrieve binary data
• Best practices for file and media handling

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📘 What Is a BLOB in MySQL?

• BLOB stands for Binary Large Object
• Stores binary (non-character) data
• Treated differently than TEXT because it is not subject to character set or collation
• Cannot be indexed fully without a prefix
• Often used for storing images, documents, compressed files, etc.

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🔢 Types of BLOB in MySQL

Type	Max Size	Use Case
TINYBLOB	255 bytes	Very small images, config blobs
BLOB	64 KB	Standard images (e.g., PNG, JPEG)
MEDIUMBLOB	16 MB	Medium videos, PDFs, compressed files
LONGBLOB	4 GB	High-res videos, backups, large binaries

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🧪 Example – Store Images in BLOB Field

🔹 Table Structure

CREATE TABLE files (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(255),
  data LONGBLOB,
  uploaded_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

Explanation:

• name: Stores file name or description.
• data: Stores raw file content using LONGBLOB.
• uploaded_at: Timestamp when the file was inserted.

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🔹 Insert Binary Data (Using Prepared Statements)

In your programming language (e.g., PHP, Python), you would:

INSERT INTO files (name, data) VALUES (?, ?);

Where:

• ? placeholders are filled using binary-safe prepared statements.
• Binary content is passed as a blob (e.g., f.read() in Python).

⚠️ Never insert binary data using plain SQL strings—always use parameterized queries.

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🔍 Retrieve BLOB Data

🔹 SQL Query

SELECT id, name, data FROM files WHERE id = 1;

Explanation:

• Retrieves the file row by ID.
• Application logic must handle the data field as binary and convert it (e.g., stream it as a file).

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⚠️ BLOB Limitations & Considerations

Limitation	Explanation
❌ Not indexable without prefix	Requires INDEX (column_name(length))
❌ No default values allowed	You can’t define DEFAULT on BLOB columns
⚠️ Slower than filesystem for large data	Storing big files in DB can increase I/O overhead
🔐 Encoding required	Must encode binary for web delivery (e.g., base64)

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🔐 Best Practices for Using BLOB

✅ Tip	💡 Why It Matters
Use LONGBLOB for large file storage	Avoids size errors
Stream files in/out using app code	Prevents memory overload
Use INDEX(blob_column(length)) if needed	Enables fast filtering by blob prefix
Prefer filesystem + file path in DB	For high-volume, file-heavy systems
Always use binary-safe APIs	Prevents data corruption during insert/retrieve

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🚀 Real-World Use Cases

Use Case	Type	Description
User profile images	BLOB	Small image files for avatars
PDF document storage	MEDIUMBLOB	Store invoices, contracts, reports
Multimedia upload	LONGBLOB	High-res audio/video embedded in the app
Encrypted JSON or config	TINYBLOB	Binary-safe blobs of settings
Offline backup binaries	LONGBLOB	Raw files stored in full as backup in MySQL

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📌 Summary – Recap & Next Steps

MySQL’s BLOB types allow you to store and retrieve binary data like files, media, and documents. While powerful, they must be used carefully due to indexing limits, storage costs, and performance trade-offs.

🔍 Key Takeaways

• Use BLOB, MEDIUMBLOB, LONGBLOB based on file size
• Always use parameterized binary-safe inserts
• Avoid using plain SQL for binary data
• Prefer file paths in DB for large, static files
• Consider caching or CDN for high-frequency binary access

⚙️ Real-World Relevance

BLOBs are frequently used in image upload systems, document archiving, binary analytics, and self-contained mobile/web apps where file access is integrated into the database.

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❓ FAQ – MySQL BLOB Types

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❓ What is the max size for each BLOB type?

• TINYBLOB: 255 bytes
• BLOB: 65,535 bytes (64 KB)
• MEDIUMBLOB: 16,777,215 bytes (16 MB)
• LONGBLOB: 4,294,967,295 bytes (4 GB)

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❓ Can I index a BLOB column?

✅ Yes, but only partially:

CREATE INDEX idx_file_data ON files (data(255));

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❓ Should I store images/files in MySQL?

✅ Yes, for small-scale or secure content
❌ No, for large/public-facing media—use file systems or cloud (S3, etc.)

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❓ Can I define default values for BLOB columns?

❌ No. MySQL does not allow DEFAULT values on BLOB or TEXT fields.

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❓ What’s the difference between TEXT and BLOB?

• TEXT: Character-based with collation and charset
• BLOB: Binary-based with no collation (for raw data)

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