Beginner LevelPostgreSQL
How do RESTART IDENTITY and CASCADE flags modify TRUNCATE execution?
❓ Interview Prompt: Explain TRUNCATE command, table page de-allocation, RESTART IDENTITY (reset sequences), and CASCADE (truncate child tables).
'TRUNCATE' quickly removes all rows from a table by de-allocating underlying data pages rather than deleting rows individually:
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'RESTART IDENTITY': Automatically resets sequence counters associated with table identity columns back to 1.
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'CASCADE': Recursively truncates all child tables that reference the target table via foreign keys.
Code Implementation Example
sql
-- Remove all rows, reset sequence counter, and cascade to child tables
TRUNCATE TABLE orders RESTART IDENTITY CASCADE;💡Executing TRUNCATE with RESTART IDENTITY and CASCADE flags.
🎯 Interview Key Takeaway
Use TRUNCATE ... RESTART IDENTITY CASCADE for fast table resets during testing or staging data re-loads.
#TRUNCATE#RESTART IDENTITY#CASCADE#Beginner
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