json datatype and table bloat? - Mailing list pgsql-general

From Adam Jelinek
Subject json datatype and table bloat?
Date
Msg-id CAMwTJE6qLvY9Te1nifXXjNVw34JxG1SRFK2e2+jrCB8vTOH3Vw@mail.gmail.com
Whole thread Raw
In response to Re: json datatype and table bloat?  (Merlin Moncure <mmoncure@gmail.com>)
Responses Re: json datatype and table bloat?
List pgsql-general
Along the lines of the equality operator; I have ran into issues trying to pivot a table/result set with a json type due what seemed to be no equality operator.
 
 

On Nov 4, 2013 10:14 AM, "Merlin Moncure" <mmoncure@gmail.com> wrote:
On Fri, Nov 1, 2013 at 1:50 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Gregory Haase <haaseg@onefreevoice.com> writes:
>> The json_data column is not accounted for in pg_stats:
>
> Ah!  I hadn't twigged to the fact that your bloat measurement approach
> assumed you had pg_stats entries for all the columns.
>
>> So I'm not sure if I'd actually qualify this as a "bug", but it appears
>> that there is no way to currently get stats on a json data type.
>
> ANALYZE currently punts on columns that don't have an equality operator,
> which json does not.  There isn't that much in the way of stats that we
> could collect, though I suppose we could still compute average datum width
> and null fraction.
>
> I'm not sure whether there are plans to invent an equality operator for
> json.

IMNSO, this may not be a bug, but it's pretty close.  All base types
should have equality operator as well as other supporting
infrastructure that the database itself depends on (in/out and
send/receive for example).  This is a pretty good example of why.

merlin


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