[pgpointcloud] pg pointcloud with Postgres-XL?

[Jo Walsh]

Paul suggested offlist that I try dropping the pointcloud_formats table and
re-creating it adding a DISTRIBUTE BY REPLICATION clause. I wasn't able to
do this from the console but managed to kludge it into a working state by
editing pgsql/sql/pointcloud.sql and rebuilding and reloading the
pointcloud extension.

The thing is, that tables in Postgres-XL do (usually) get distributed by
default, by one mechanism or another, if no DISTRIBUTE BY clause is
specified:

"If DISTRIBUTE BY is not specified, columns with UNIQUE constraint will be
chosen as the distribution key. If no such column is specified,
distribution column is the first eligible column in the definition. If no
such column is found, then the table will be distributed by ROUNDROBIN."

http://files.postgres-xl.org/documentation/sql-createtable.html

So i can create tables via ogr2ogr for example, and that works as expected
as with regular postgres and i see the records being distributed around the
data nodes. When I CREATE EXTENSION postgis on a coordinator node the
tables and functions get propagated to the data nodes.

I am still getting to grips with Postgres-XL, my understanding is weak and
I and still do not see why this particular table wasnt getting distributed,
something to do with the order of the CHECK constraint and the function
which it is calling?

Anyway, at least with this kludge I am now able to test out PDAL :) If I
arrive at a better understanding or a solution I will certainly let you
know.


cheers,


Jo


On Mon, May 30, 2016 at 3:02 PM, Rémi Cura <remi.cura at gmail.com> wrote:

> Hey,
> I often wondered if pgpointcloud would work with postgresXL.
>
> I don't have any knwoledge of postgresxl,
> but I would be very gratefull if you could keep us posted!
>
> Cheers,
> Rémi-C
>
> 2016-05-30 11:49 GMT+02:00 Jo Walsh <metazool at gmail.com>:
>
>> I wonder if anyone has tried out and had success with the PG Point Cloud
>> extension with Postgres-XL, the clustering version of Postgres? I am running through the basic
>> exercises and see it all almost, but not quite, working. I tried the Postgres-XL general list without any luck in response, so thought it worth re-posting here to see if it's something people have given thought to.
>>
>> http://www.postgres-xl.org/overview/
>>
>> I am able to CREATE EXTENSION pointcloud on a Postgres-XL coordinator node
>> just as straightforwardly as with PostGIS, which works well.
>>
>> However, the pgpointcloud creates a table pointcloud_formats which does not appear to be getting distributed.
>> The table looks like this:
>>
>> testdb=# \d++ pointcloud_formats;
>>                   Table "public.pointcloud_formats"
>>  Column |  Type   | Modifiers | Storage  | Stats target | Description
>> --------+---------+-----------+----------+--------------+-------------
>>  pcid   | integer | not null  | plain    |              |
>>  srid   | integer |           | plain    |              |
>>  schema | text    |           | extended |              |
>> Indexes:
>>     "pointcloud_formats_pkey" PRIMARY KEY, btree (pcid)
>> Check constraints:
>>     "pointcloud_formats_pcid_check" CHECK (pcid > 0 AND pcid < 65536)
>>     "pointcloud_formats_schema_check" CHECK (pc_schemaisvalid(schema))
>>
>> When I INSERT into it, data does not end up stored in the datanodes, and
>> when I subsequently try to INSERT into the points table,
>>
>> ERROR:  no entry in "pointcloud_formats" for pcid = 1
>>
>> Despite the fact that on the coordinator node I can SELECT from
>> pointcloud_formats and see a row with pcid=1.
>>
>> There's more context including log entries in my original post to the Postgres-XL list here:
>>
>> https://sourceforge.net/p/postgres-xl/mailman/message/35119267/
>>
>> I know this is a long shot but any illumination would be appreciated,
>>
>>
>> Jo
>>
>>
>>
>> _______________________________________________
>> pgpointcloud mailing list
>> pgpointcloud at lists.osgeo.org
>> http://lists.osgeo.org/mailman/listinfo/pgpointcloud
>>
>
>
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