[HBASE-21462] Add note for CopyTable section explained it does not perform a diff, but a full write from source to target

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.0.0-alpha-1, 2.1.5
• Fix Version/s: 3.0.0-alpha-1
• Component/s: documentation
• Assignee: Wellington Chevreuil
• Reporter: Wellington Chevreuil
• Created: 09/Nov/18 14:34
• Updated: 16/Jul/19 22:52
• Resolved: 16/Jul/19 17:41

Description

Performance is a common issue with CopyTable is when the key/time range for the data to be copied is large because it basically scans all rows on the specified range, in the source and perform related puts on the source. We should add extra note explaining that on the reference guide, to help users/admins understand when to choose between the different tools/approaches for syncing clusters.