Hi, I have a question regarding the correlation between the visible timestamp of a KV (denoted as ts) and its memstore timestamp (aka, the write number, denoted as memts). Reading the HRegion.java code it seems that these two are independently assigned. Let's assume two concurrent put: (k, v1) and (k, v2)
Suppose somehow memts(k,v1) < memts(k, v2) then (k,v1) will be committed and visible before (k,v2). If ts(k,v1) < ts(k, v2), then after both KVs commits, (k,v2) becomes the latest version. else, if ts(k,v1) > ts(k, v2), then after a "later"(w.r.t. MVCC) KV commits, it immediately become stale and still not visible. --- Is it a desirable feature? Am I understanding it correctly, that memts(k,v1) < memts(k, v2) does not indicate that ts(k,v1) < ts(k, v2), and vice versa? PS: let's talk about the hbase region server assigned, not user assigned, visible timestamp. Thanks, Wei Best Regards, Wei Wei Tan Research Staff Member IBM T. J. Watson Research Center 19 Skyline Dr, Hawthorne, NY 10532 [email protected]; 914-784-6752
