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From Ildar Absalyamov <ildar.absalya...@gmail.com>
Subject Re: Question about open indexes
Date Fri, 25 Sep 2015 23:23:26 GMT
It did not really occur to me during today during the meeting, but Preston pointed out that
the secondary index delete fix, that I proposed, spans both Hyracks & Asterix codebase.
Thus we will either have to release Hyracks once again, or bite the bullet, sign the RC without
this fixing this issue and create bug-fix releases for both Hyracks&Asterix right after.

> On Sep 22, 2015, at 22:27, Mike Carey <dtabass@gmail.com> wrote:
> 
> Ah - that makes sense now.  Thx.  (And welcome back. :-))
> 
> On 9/22/15 10:02 PM, Ildar Absalyamov wrote:
>> Sorry for confusion, my initial answer was not correct enough, probably should have
waited sometime after I drove 1500 miles form Seattle :)
>> The casting in the insert pipeline, which Abdullah mentioned, is needed only for
secondary index insert. The reasoning behind this casting is to ensure that the record is
equivalent, thus it is safe to create an open index. It is true that we can get <Pk, Sk>
pairs out of original record using get-field-by-name\index, but the cast operator is introduced
merely to kill the pipeline if the dataset input is not correct.
>> Thus the records in primary are never touched of modified, not matter what indexes
were created.
>> I am not sure however what is the second cast in Abdullah’s plan, and where is
comes from.
>> 
>> @Taewoo, so scan-delete-btree-secondary-index-open test does not actually delete
data from the secondary index? I have checked the plan and it has the delete operator. Maybe
it is initialized with wrong parameters, I’ll have a close look.
>> 
>>> On Sep 22, 2015, at 18:33, Mike Carey <dtabass@gmail.com> wrote:
>>> 
>>> Sounds kinda bad!  Also, I wonder what happens when the compiler encounters records
in the dataset - whose type in the catalog doesn't claim to have a given (but now indexed)
open field - e.g., during a data scan or an access via some other path?  Can Bad Things Happen
due to the compiler not properly anticipating the casted form of the records?  (Maybe I am
misunderstanding something, but we should probably take a careful look at the test cases -
and make sure we do things like add a bunch of records, then add such an index, then add some
more records, then stress-test type-related things that come at the dataset (i) thru the index,
(ii) thru a primary dataset scan, and (iii) thru some other index.)
>>> 
>>> On 9/22/15 4:06 PM, Taewoo Kim wrote:
>>>> I think this issue:https://issues.apache.org/jira/browse/ASTERIXDB-1109 is
>>>> related. Currently, index entries (SK, PK) are not deleted on an open-type
>>>> secondary index during a deletion. This issue was not surfaced due to the
>>>> fact that every search after a secondary index search had to go through the
>>>> primary index lookup.
>>>> 
>>>> Best,
>>>> Taewoo
>>>> 
>>>> On Tue, Sep 22, 2015 at 12:04 AM, Ildar Absalyamov <
>>>> ildar.absalyamov@gmail.com> wrote:
>>>> 
>>>>> Abdullah,
>>>>> 
>>>>> If I remember correctly whenever a secondary open index is created all
>>>>> existing records would be casted to a proper type to ensure that the
index
>>>>> creation is valid.
>>>>> As for the overall correctness of casting operation, semantically creating
>>>>> an open index is the same thing as altering the dataset type. The current
>>>>> implementation allows only one open index of particular type created
on a
>>>>> single field. If we would have had “alter datatype” functionality
the open
>>>>> indexing would not be required at all.
>>>>> 
>>>>>> On Sep 21, 2015, at 23:25, abdullah alamoudi <amoudi@apache.org>
wrote:
>>>>>> 
>>>>>> More thoughts:
>>>>>> I assume the intention of the cast was just to make sure if the open
>>>>> field
>>>>>> exists, it is of the specified type. Moreover, the un-casted record
>>>>> should
>>>>>> be inserted into the index.
>>>>>> If my assumptions are not correct, please, let me know ASAP.
>>>>>> 
>>>>>> I have two thoughts on this:
>>>>>> 1. Actually, insert plans show that the records being inserted into
the
>>>>>> primary index is actually the casted record creating the issue described
>>>>>> above.
>>>>>> 
>>>>>> 2. I don't believe this is the right way to ensure that the open
field if
>>>>>> exists is of the right type. why not extract the field using field
access
>>>>>> by name function and then verify the type using the field tag?
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> On Tue, Sep 22, 2015 at 9:11 AM, abdullah alamoudi <amoudi@apache.org>
>>>>>> wrote:
>>>>>> 
>>>>>>> Hi Dev, @Ildar,
>>>>>>> 
>>>>>>> In the insert pipeline for datasets with open indexes, we introduce
a
>>>>> cast
>>>>>>> function before the insert and so one would expect the records
to look
>>>>> like
>>>>>>> the casted record type which I assume has {{the closed fields
+ a
>>>>> nullable
>>>>>>> field}}.
>>>>>>> 
>>>>>>> The question is, what happens to the previously existing records?,
since
>>>>>>> now the index has both, records of the original type and records
of the
>>>>>>> casted type.
>>>>>>> 
>>>>>>> Thanks,
>>>>>>> Abdullah.
>>>>>>> 
>>>>> Best regards,
>>>>> Ildar
>>>>> 
>>>>> 
>> Best regards,
>> Ildar
>> 
>> 
> 

Best regards,
Ildar


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