Replication
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- based on publish-subscribe model\
- Standard Edition
- near real time replication
- manual fail-over, need to use VIP or ask the application to change database IP
- is probably the most complex, specifically when it comes down to troubleshooting or management
There are some limitations we have to consider:- cannot truncate table. otherwise need to re-create the replication
- all tables should have Primary keys
- no transitional in triggers
- special steps should be taken for text, ntext and image data type
- schema change is complex, need some steps from the replication side whenever we do below changes
add/drop objects
alter table
Alter view
Alter procedure
Alter function
Alter triggers
- replication is often broken, we need to investigate the reason and resolve it manually.
Log Shipping
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- based on backup/restore model
- supported by Standard Edition
- replication lag is the biggest
- manual fail-over, need to use VIP or ask the application to change database IP
- simple and stable, very easy for maintenance
Database Mirror===============================================
- Based on transaction, no transactional data losing
- Standard Edition only offers high-safety mode(synchronous replication) and Enterprise Edition supports high-performance mode(asynchronously)
- real time replication
- automatic fail-over, the standby database becomes active and clients are redirected without any data loss or downtime
- complex and stable
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