Re: proposal: ignore null fields in not relation type composite type based constructors

From: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
To: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Cc: Andrew Dunstan <andrew(at)dunslane(dot)net>
Subject: Re: proposal: ignore null fields in not relation type composite type based constructors
Date: 2014-06-28 15:42:58
Message-ID: CAFj8pRCizZwv2yFMCQs6bVGofaELPY7tQx4sZs_WT1FVwj+Q3A@mail.gmail.com
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Hello

I am sending small patch, that allows ignore nulls in row_to_json function.
It allow significant size reduction of generated JSON documents.

Regards

Pavel

2014-05-25 7:53 GMT+02:00 Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>:

> Hello
>
> In Czech Postgres mailing list was user request for serialization to json
> without null values.
>
> He needs a similar behave like XMLFOREST has - it ignores NULLs
>
> In some situations and conversions, when your table is +/- sparse matrix,
> this request is valid
>
> postgres=# select hstore(omega) from omega;
> hstore
> ─────────────────────────────────
> "a"=>"10", "b"=>"20", "c"=>NULL
> "a"=>NULL, "b"=>"20", "c"=>"30"
> (2 rows)
>
> Proposed function
>
> postgres=# select hstore(omega, ignore_nulls := true) from omega;
> hstore
> ─────────────────────────────────
> "a"=>"10", "b"=>"20"
> "b"=>"20", "c"=>"30"
> (2 rows)
>
> What do you thinking about this proposal?
>
> Regards
>
> Pavel
>
>

Attachment Content-Type Size
row_to_json_choosy.patch text/x-patch 7.5 KB

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