The Problem With UUIDs

Tutorial: The Problems with Using UUIDs as Primary Keys in Databases

Step 1: Understand What UUIDs Are

• UUIDs stand for Universally Unique Identifiers and are used as primary keys in databases.
• They are designed to be unique across different systems and time.

Step 2: Learn about the Two Problems with Using UUIDs as Primary Keys

1. Insert Performance Issue:

   • When a new record is inserted into a table with a UUID as the primary key, the associated index needs to be updated.
   • This can lead to performance issues, especially in high-volume databases, as MySQL may take longer to rebalance the tree structure.

2. Higher Storage Utilization:

   • Using UUIDs as primary keys can lead to higher storage utilization compared to using auto-incrementing integers.
   • UUIDs consume more storage space due to their larger size, which can impact the overall database size.

Step 3: Understand the Storage Comparison between Integer, Collision-Resistant Unique Identifier, and UUID

• A comparison was made between tables with 1 million rows each using different types of identifiers:
  • Integer-based table: Consumed 32 bits per entry.
  • Collision-resistant unique identifier: Consumed more space than integers.
  • UUID: Consumed significantly more space compared to integers and other identifiers.

Step 4: Analyze the Storage Size Differences

• The total table size for 1 million entries was compared between integers, collision-resistant unique identifiers, and UUIDs.
• The results showed a significant difference in storage size, with UUIDs consuming the most space per entry.

Step 5: Consider Query Times and Readability

• Despite the differences in storage size, the query times for different types of identifiers were not affected significantly.
• The main considerations are storage size and insert performance rather than query times.

Step 6: Evaluate the Impact of Using UUIDs in Databases

• While UUIDs offer uniqueness, they can lead to performance and storage issues in databases, especially as the database scales.
• Consider the trade-offs between uniqueness and performance when choosing primary keys for your database tables.

By following these steps, you can understand the challenges associated with using UUIDs as primary keys in databases and make informed decisions when designing database schemas.