[CASSANDRA-1337] parallelize fetching rows for low-cardinality indexes and range scans of small tables

• Type: Improvement
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 2.1 beta1
• Assignee: Tom Hobbs
• Reporter: Jonathan Ellis

Authors

Tom Hobbs

Reviewers

Jonathan Ellis

• Created: 29/Jul/10 21:51
• Updated: 16/Apr/19 09:33
• Resolved: 04/Oct/13 21:49

Description

currently, we read the indexed rows (and rows for a range scan) from the first node (in partitioner order); if that does not have enough matching rows, we read the rows from the next, and so forth.

we should use the statistics fom CASSANDRA-1155 to query multiple nodes in parallel, such that we have a high chance of getting enough rows w/o having to do another round of queries (but, if our estimate is incorrect, we do need to loop and do more rounds until we have enough data or we have fetched from each node).

Issue Links

• is related to: CASSANDRA-4858 Coverage analysis for low-CL queries