Re: Plans for partitioning of inheriting tables

Thiemo,

it looks to me like you are using inheritance just to make sure your
SOURCES and TOPO_FILES tables have some common columns. If you are not
actually querying the TEMPLATE_TECH table and expect to see all the rows
from the other 2 tables in that one table combined, then you could use
CREATE TABLE (LIKE ...) instead of inheritance. That way your "child"
tables would become normal tables and you could use declarative
partitioning on them.

Even if you are querying the TEMPLATE_TECH table, you could still do that
by turning the TEMPLATE_TECH table into a view which performs a UNION ALL
over the other tables.

Just my 2 cents

--
Torsten

On Fri, Nov 1, 2024 at 7:01 PM Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>
wrote:

>
>
> On 11/1/24 10:21 AM, thiemo(at)gelassene-pferde(dot)biz wrote:
> >
> > Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com> escribió:
> >
> >> Changing that would count as a major change. Even if you where to
> >> convince the developers to make the change the earliest it would
> >> released would be with the next major release in Fall of 2025. That
> >> assumes you can convince then early enough or at all.
> >
> > I was not trying to convince anyone to do anything about the
> > implementation of declarative partitioning. I have been just curious if
> > there were plans. If I have raised the impression of the former, I am
> > sorry.
> Even if there where plans, any changes would happen in the future and
> would not be help the now problem.
>
>
> >>> Is there experience on the efficiency/speed comparing partitioning
> >>> with inheritance using triggers/rules and using the declarative way?
> >>> I don't think that partition speed is an issue in my case, as I have
> >>> fairly few records that are in themselves rather big.
> >>
> >> Hard to say without some firm numbers and/or testing.
> >
> > Sure, I was hoping those test would have been done some day. But in the
> > end, to me, it is not important.
>
> That is contradicted by your statement below:
>
> "I mean to say that I believe that loading that much data into one field
> will take much more time than runtime difference of
> trigger/rules/declarative partitioning solutions would to sort the data
> into the correct partition."
>
> Either performance is important or it is not.
>
> If TILE is referring to the same thing you are dealing with in related
> question on psycopg list then you are talking about bytea storage. You
> should take a look at:
>
> https://www.postgresql.org/docs/current/storage-toast.html
>
> In any case assuming you are not entering/reading/updating all the bytea
> data at one time then you are looking at fetching only that bytea data
> that are filtered by other attributes of the rows. I would strongly
> suggest running some tests on a single table with the data and see if
> you can live with the performance results before complicating things
> with partitioning.
>
> >
> >> Also this "... I have fairly few records that are in themselves rather
> >> big" could use some explanation. In other words what makes you think
> >> that partitioning is the answer to this issue?
> >
> > I was not thinking that partitioning was the answer to a performance
> > problem. Partitioning might be an answer to the maintenance of records,
> > specifically if entire sources are affected. The size of the tif files
> > to get loaded into the raster attribute TILE range from 112 kB to 32 MB.
> > I am complete unaware of the inner storing mechanisms of raster in
> > PostGIS, but on first sight, it seems that the rest of a records of
> > TOPO_FILES is negligible compared to the TILE. The total number of files
> > to be loaded in my case are 3273, even though that only encompasses a
> > small part of the world, I do not think, the latter would surpass 100000
> > records. Not much for a database table, afaik. I mean to say that I
> > believe that loading that much data into one field will take much more
> > time than runtime difference of trigger/rules/declarative partitioning
> > solutions would to sort the data into the correct partition.
> >
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com
>
>
>