Re: jsonb status

Alexander will take a look on TriConsistent function.

On Mon, Mar 17, 2014 at 9:48 PM, Andrew Dunstan <andrew@dunslane.net> wrote:
>
> On 03/16/2014 04:10 AM, Peter Geoghegan wrote:
>>
>> On Thu, Mar 13, 2014 at 2:00 PM, Andrew Dunstan <andrew@dunslane.net>
>> wrote:
>>>
>>> I'll be travelling a good bit of tomorrow (Friday), but I hope Peter has
>>> finished by the time I am back on deck late tomorrow and that I am able
>>> to
>>> commit this on Saturday.
>>
>> I asked Andrew to hold off on committing this today. It was agreed
>> that we weren't quite ready, because there were one or two remaining
>> bugs (since fixed), but also because I felt that it would be useful to
>> first hear the opinions of more people before proceeding. I think that
>> we're not that far from having something committed. Obviously I hope
>> to get this into 9.4, and attach a lot of strategic importance to
>> having the feature, which is why I made a large effort to help land
>> it.
>>
>> Attached patch has a number of notable revisions. Throughout, it has
>> been possible for anyone to follow our progress here:
>> https://github.com/feodor/postgres/commits/jsonb_and_hstore
>>
>> * In general, the file jsonb_support.c (renamed to jsonb_utils.c) is
>> vastly better commented, and has a much clearer structure. This was
>> not something I did much with in the previous revision, and so it has
>> been a definite focus of this one.
>>
>> * Hashing is refactored to not use CRC32 anymore. I felt this was a
>> questionable method of hashing, both within jsonb_hash(), as well as
>> the jsonb_hash_ops GIN operator class.
>>
>> * Dead code elimination.
>>
>> * I got around to fixing the memory leaks in B-Tree support function one.
>>
>> * Andrew added hstore_to_jsonb, hstore_to_jsonb_loose functions and a
>> cast. One goal of this effort is to preserve a parallel set of
>> facilities for the json and jsonb types, and that includes
>> hstore-related features.
>>
>> * A fix from Alexander for the jsonb_hash_ops @>operator issue I
>> complained about during the last submission was merged.
>>
>> * There is no longer any GiST opclass. That just leaves B-Tree, hash,
>> GIN (default) and GIN jsonb_hash_ops opclasses.
>>
>> My outstanding concerns are:
>>
>> * Have we got things right with GIN indexing, containment semantics,
>> etc? See my remarks in the patch, by grepping "contain" within
>> jsonb_util.c. Is the GIN text storage serialization format appropriate
>> and correct?
>>
>> * General design concerns. By far the largest source of these is the
>> file jsonb_util.c.
>>
>> * Is the on-disk format that we propose to tie Postgres to as good as
>> it could be?
>>
>
>
>
> I've been working through all the changes and fixes that Peter and others
> have made, and they look pretty good to me. There are a few mostly cosmetic
> changes I want to make, but nothing that would be worth holding up
> committing this for. I'm fairly keen to get this committed, get some
> buildfarm coverage and get more people playing with it and testing it.
>
> Like Peter, I would like to see more comments from people on the GIN
> support, especially.
>
> The one outstanding significant question of substance I have is this: given
> the commit 5 days ago of provision for triConsistent functions for GIN
> opclasses, should be be adding these to the two GIN opclasses we are
> providing, and what should they look like? Again, this isn't an issue that I
> think needs to hold up committing what we have now.
>
> Regarding Peter's last question, if we're not satisfied with the on-disk
> format proposed it would mean throwing the whole effort out and starting
> again. The only thing I have thought of as an alternative would be to store
> the structure and values separately rather than with values inline with the
> structure. That way you could have a hash of values more or less, which
> would eliminate redundancy of storage of things like object field names. But
> such a structure might well involve at least as much computational overhead
> as the current structure. And nobody's been saying all along "hold on, we
> can do better than this." So I'm pretty inclined to go with what we have.
>
>
> cheers
>
> andrew
>
>
>
>
>
>
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