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Todd Lipcon resolved KUDU-483. ------------------------------ Resolution: Won't Fix Fix Version/s: n/a Doesn't seem like this would really be worth it > Non-ordered MRS scanning for better performance > ----------------------------------------------- > > Key: KUDU-483 > URL: https://issues.apache.org/jira/browse/KUDU-483 > Project: Kudu > Issue Type: Improvement > Components: perf, tablet > Affects Versions: Backlog > Reporter: Todd Lipcon > Priority: Minor > Fix For: n/a > > > Here's a performance improvement I was thinking about recently: > Currently, scanning the MRS is fairly expensive due to cache misses and the > per-leaf iteration code. Each leaf node has a pointer to its adjacent leaf, > but that may be somewhere fairly random in memory. Despite our best effort to > prefetch, we see a lot of cache misses in this code. > For short (non fault-tolerant) scans, we don't need to yield rows in key > order. So, we could reorganize the memory layout of the MRS such that all > leaf nodes were allocated from a single arena-like structure. Then, iterating > could proceed in memory order rather than key order, and likely be a lot > faster. For fault tolerant (ordered) scans, we'd still have to use the btree > traversal. -- This message was sent by Atlassian JIRA (v7.6.3#76005)