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
>>
>
>
