Horton

Re: Allowing extensions to supply operator-/function-specific info

Simon Riggs <simon@2ndquadrant.com>

View thread
From: Simon Riggs <simon@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-01-27T08:00:31Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Allow extensions to generate lossy index conditions.

  2. Build out the planner support function infrastructure.

  3. Create the infrastructure for planner support functions.

  4. Disable transforms that replaced AT TIME ZONE with RelabelType.

On Sun, 20 Jan 2019 at 23:48, Tom Lane <tgl@sss.pgh.pa.us> wrote:


> What I'm envisioning therefore is that we allow an auxiliary function to
> be attached to any operator or function that can provide functionality
> like this, and that we set things up so that the set of tasks that
> such functions can perform can be extended over time without SQL-level
> changes.  For example, we could say that the function takes a single
> Node* argument, and that the type of Node tells it what to do, and if it
> doesn't recognize the type of Node it should just return NULL indicating
> "use default handling".  We'd start out with two relevant Node types,
> one for the selectivity-estimation case and one for the extract-a-lossy-
> index-qual case, and we could add more over time.
>

Does this help with these cases?

* Allow a set returning function to specify number of output rows, in cases
where that is variable and dependent upon the input params?

* Allow a normal term to match a functional index, e.g. WHERE x =
'abcdefgh' => WHERE substr(x, 1 , 5) = 'abcde' AND x = 'abcdefgh'

* Allow us to realise that ORDER BY f(x) => ORDER BY x so we can use
ordered paths from indexes, or avoid sorts.

-- 
Simon Riggs                http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/>
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services