Data Governance

Data governance features help you manage historical versions, lifecycle, and change tracking for your data. The core capability is Time Travel — based on the MVCC mechanism, every data change retains historical versions, allowing you to query the data state at any point in time, recover accidentally deleted data, or roll back unintended operations.

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This Section

Page	Description
Time Travel Overview	Time Travel feature introduction, retention period configuration, supported operations
Time Travel	Quick examples: query historical data, roll back a table, recover a dropped table
Time Travel Concept	MVCC working mechanism, three core capabilities (query/recover/rollback), typical scenarios
Data Lifecycle Management	Automatically reclaim expired data to control storage costs

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Quick Reference

What I want to do	Method	Reference
Query historical data at a specific point in time	SELECT ... TIMESTAMP AS OF '...'	TIME TRAVEL
View the version history of a table	DESC HISTORY table_name	DESC HISTORY
Recover an accidentally dropped table	UNDROP TABLE table_name	UNDROP TABLE
Roll back table data to a historical version	RESTORE TABLE ... TO TIMESTAMP AS OF '...'	RESTORE TABLE
Set the number of days to retain historical data	ALTER TABLE ... SET PROPERTIES ('data_retention_days'='7')	Time Travel Overview
Automatically clean up expired data	ALTER TABLE ... SET PROPERTIES ('data_lifecycle'='30')	Data Lifecycle Management

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Two Easily Confused Concepts

Concept	Purpose	Parameter	Default
data_retention_days	Controls how long Time Travel can access historical versions; versions older than this are physically deleted	0–90 days	1 day
data_lifecycle	Controls how long table data survives from its last modification time; data is automatically reclaimed after expiry	Positive integer (days)	Disabled (-1)

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Common Scenarios

Recovering after accidental data deletion

-- Check the row count before the accidental deletion SELECT COUNT(*) FROM orders TIMESTAMP AS OF '2024-01-15 09:59:00'; -- Roll the table back to before the deletion RESTORE TABLE orders TO TIMESTAMP AS OF '2024-01-15 09:59:00';

Recovering after an accidental DROP TABLE

-- View deleted tables SHOW TABLES HISTORY LIKE 'orders%'; -- Recover the table UNDROP TABLE orders;

Tracing data change history

-- View the version history of a table (operator, time, row count) DESC HISTORY orders;