This example is very illustrative. Many discussions and tickets will benefit a lot from such good examples.
Chen On Thu, Jan 14, 2016 at 12:15 PM, abdullah alamoudi <[email protected]> wrote: > Example: > > data type: [int(pk),int]. > existing data: > {1,5} > > (case 1) > upsert {1,5} > > This means that in the secondary index update the old secondary key == the > new secondary key. Hence, it will be no op. > > (case 2 and 3) > upsert{1,2} > this means the secondary keys are not equal hence in the secondary upsert, > this will happen: > old key != new key > (previous value exists which was {5,1}, so we delete it) > (new value is {2,1} so we insert it). > > (case 3 only) > upsert {2,2} > since there is no old value, we will only insert the key {2,2} in secondary > index. > > I hope this made it clearer. If you still need more clarification, let me > know. > Cheers, > Abdullah. > > > Amoudi, Abdullah. > > On Thu, Jan 14, 2016 at 11:05 PM, Young-Seok Kim <[email protected]> > wrote: > > > I'm still not clear. > > (Probably, I'm not clear about the terms used in those cases such as > > existing secondary key, a different old secondary key, and a different > new > > secondary key.) > > Could you explain the case with an example? :) > > > > Thanks, > > Young-Seok > > > > > > > > > > On Thu, Jan 14, 2016 at 11:49 AM, abdullah alamoudi <[email protected]> > > wrote: > > > >> Young Seok, > >> In the documentation, 2 and 3 are not mutually exclusive. So you can > >> think of it as follows: > >> if we hit 1, we will not hit 2 and 3. > >> if we don't hit 1, we will definitely do 3. but whether we hit case 2 > >> depends on whether there was a previous value. > >> > >> In another way: > >> if(case 1){ > >> return; > >> } else{ > >> // case 3 > >> if (case 2){ > >> -- do something(case 2) > >> } > >> -- do something(case 3) > >> } > >> > >> Does that make sense? > >> > >> Amoudi, Abdullah. > >> > >> On Thu, Jan 14, 2016 at 10:41 PM, Young-Seok Kim <[email protected]> > >> wrote: > >> > >>> Can someone help me understanding the following part in the upsert > >>> design document ( > >>> https://cwiki.apache.org/confluence/display/ASTERIXDB/Upsert) ? > >>> > >>> - The secondary Upsert operator perform the following tasks: > >>> > >>> > >>> 1. If the existing secondary key equals to the new secondary key, it > >>> is a NO OP. > >>> 2. If a different old secondary key exists, it deletes the existing > >>> secondary key-primary key pair from the secondary index. > >>> 3. If a different new secondary key exists, it inserts the new > >>> secondary key-primary key pair from the secondary index. > >>> > >>> > >>> How can the third case happen? > >>> > >>> Was there another upsert transaction T1 (upserting record R1 but not > >>> committed yet) when this transaction T2 reached the secondary index, > for > >>> instance? Is this possible? > >>> I think this example is not valid due to the guarantee of the primary > >>> key locking in the primary index. T1 must be holding a exclusive lock > on > >>> the primary key of R1, so when T2 reached the primary index and read > the > >>> R1, it must either be waiting the T1 is over to get a lock on R1 or > see the > >>> new record upserted by T1. Thus, when T2 reads from the secondary > index, it > >>> must see the value upserted by T2. This is the second case. > >>> > >>> Again, how can the third case happen? > >>> > >>> Thanks, > >>> Young-Seok > >>> > >>> On Thu, Jan 14, 2016 at 9:37 AM, Jenkins (Code Review) < > >>> [email protected]> wrote: > >>> > >>>> Jenkins has posted comments on this change. > >>>> > >>>> Change subject: Add Support for Upsert Operation > >>>> ...................................................................... > >>>> > >>>> > >>>> Patch Set 13: Verified-1 > >>>> > >>>> Build Unstable > >>>> > >>>> https://asterix-jenkins.ics.uci.edu/job/asterix-gerrit-topic/570/ : > >>>> UNSTABLE > >>>> > >>>> -- > >>>> To view, visit https://asterix-gerrit.ics.uci.edu/477 > >>>> To unsubscribe, visit https://asterix-gerrit.ics.uci.edu/settings > >>>> > >>>> Gerrit-MessageType: comment > >>>> Gerrit-Change-Id: I8999000331795a5949d621d2dd003903e057a521 > >>>> Gerrit-PatchSet: 13 > >>>> Gerrit-Project: asterixdb > >>>> Gerrit-Branch: master > >>>> Gerrit-Owner: abdullah alamoudi <[email protected]> > >>>> Gerrit-Reviewer: Jenkins <[email protected]> > >>>> Gerrit-Reviewer: Taewoo Kim <[email protected]> > >>>> Gerrit-Reviewer: Till Westmann <[email protected]> > >>>> Gerrit-Reviewer: Young-Seok Kim <[email protected]> > >>>> Gerrit-Reviewer: abdullah alamoudi <[email protected]> > >>>> Gerrit-HasComments: No > >>>> > >>> > >>> > >> > > >
