</>
sqlintermediate

Optimistic Locking with Version Column

Prevent lost updates in concurrent environments using a version column for optimistic concurrency control.

sql
-- Add version column
ALTER TABLE products ADD COLUMN version INT NOT NULL DEFAULT 1;

-- Update with optimistic lock check
UPDATE products
SET
  price = 29.99,
  version = version + 1
WHERE
  id = 42
  AND version = 3;  -- Expected version

-- Check if update succeeded (0 rows = conflict)
-- In application code:
-- if (result.rowCount === 0) throw new Error('Concurrent modification detected');

Use Cases

  • Multi-user editing
  • Cart checkout
  • Inventory management

Tags

#concurrency#locking#transactions#data-integrity

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sqladvanced

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Best for: Preventing race conditions in financial transactions

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Best for: Circular references

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typescriptadvanced

Node.js In-Memory Task Queue

A simple in-memory task queue with concurrency control, retries, and priority support.

Best for: Rate-limited API call processing

#nodejs#queue
typescriptintermediate

Promise Concurrency Patterns

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Best for: Parallel API calls with error handling

#nodejs#promise