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Generate UUIDs for automatic row identification.

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Problem

You need unique identifiers for rows in your data pipeline. Maybe you’re building an API that returns specific records, tracking processing status across systems, or joining data from multiple sources.

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Solution

What’s in this recipe:
  • Create tables with auto-generated UUID primary keys
  • Add UUID columns to existing tables
  • Generate UUIDs with uuid4()
You use uuid4() to generate UUIDs for each row. Define it in the schema with {'column_name': uuid4()} syntax, or add it to existing tables with add_computed_column().

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Setup

%pip install -qU pixeltable

import pixeltable as pxt
from pixeltable.functions.uuid import uuid4

# Create a fresh directory
pxt.drop_dir('uuid_demo', force=True)
pxt.create_dir('uuid_demo')

Connected to Pixeltable database at: postgresql+psycopg://postgres:@/pixeltable?host=/Users/pjlb/.pixeltable/pgdata
Created directory ‘uuid_demo’.
<pixeltable.catalog.dir.Dir at 0x104e3c810>

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Create a table with a UUID primary key

Use uuid4() in your schema to create a column that auto-generates UUIDs: 
# Create table with auto-generated UUID primary key
products = pxt.create_table(
    'uuid_demo.products',
    {
        'id': uuid4(),  # Auto-generates UUID for each row
        'name': pxt.String,
        'price': pxt.Float
    },
    primary_key=['id']
)

Created table ‘products’.
# Insert data - no need to provide 'id', it's auto-generated
products.insert([
    {'name': 'Laptop', 'price': 999.99},
    {'name': 'Mouse', 'price': 29.99},
    {'name': 'Keyboard', 'price': 79.99}
])

Inserting rows into `products`: 3 rows [00:00, 338.71 rows/s]
Inserted 3 rows with 0 errors.
3 rows inserted, 6 values computed.
# View the data - each row has a unique UUID
products.collect()

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Add a UUID column to an existing table

You can add a UUID column to a table that already exists using add_computed_column(): 
# Create a table without a UUID column
orders = pxt.create_table(
    'uuid_demo.orders',
    {
        'customer': pxt.String,
        'amount': pxt.Float
    }
)

Created table ‘orders’.
# Insert some data
orders.insert([
    {'customer': 'Alice', 'amount': 150.00},
    {'customer': 'Bob', 'amount': 75.50}
])

Inserting rows into `orders`: 2 rows [00:00, 1070.66 rows/s]
Inserted 2 rows with 0 errors.
2 rows inserted, 2 values computed.
# Add a UUID column to existing table
orders.add_computed_column(order_id=uuid4())

Added 2 column values with 0 errors.
2 rows updated, 4 values computed.
# View orders with their UUID column
orders.collect()

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Explanation

Two ways to add UUIDs:
Both use uuid4() which generates UUIDv4 (random) identifiers:
  • 128-bit values
  • Formatted as 32 hex digits with hyphens: 550e8400-e29b-41d4-a716-446655440000
  • Virtually guaranteed unique (collision probability is negligible)

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See also