[GORA-411] Add exists(key) to DataStore interface

• Type: New Feature
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.8
• Fix Version/s: 0.9
• Component/s: gora-core, storage
• Assignee: John Mora
• Reporter: Alfonso Nishikawa Muñumer
• Created: 19/Feb/15 14:22
• Updated: 03/Mar/22 14:27
• Resolved: 03/May/19 05:01

Description

NUTCH-1679 need to check if there exists some rows and they are proposing to use store.get(TableUtil.reverseUrl(url))).
This will have a considerably impact on performance since every column will be fetched.

Some datastores implements a call to just check if a row exists (like HBase) so no data is transfered by network.
If a datastore can't handle an "exists" call, can default to a get.

Issue Links

• relates to: NUTCH-1679 UpdateDb using batchId, link may override crawled page.