Re: Declarative partitioning - another take

On 28 October 2016 at 02:53, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp> wrote:
>
> Please find attached the latest version of the patches

Hi,

I started to review the functionality of this patch, so i applied all
9 patches. After that i found this warning, which i guess is because
it needs a cast.

After that, i tried a case that i think is important: to partition an
already existing table. Because there is no ALTER TABL SET PARTITION
or something similar (which i think makes sense because such a command
would need to create the partitions and move the rows to follow the
rule that there is no rows in a parent table).

So, what i tried was:

1) rename original table
2) create a new partitioned table with old name
3) attach old table as a partition with bounds outside normal bounds
and no validate

the idea is to start attaching valid partitions and delete and insert
rows from the invalid one (is there a better way of doing that?), that
will allow to partition a table easily.
So far so good, until i decided points 1 to 3 should happen inside a
transaction to make things transparent to the user.

Attached is script that shows the failure when trying it:

script 1 (failing_test_1.sql) fails the assert
"Assert(RelationGetPartitionKey(parentRel) != NULL);" in
transformAttachPartition() at src/backend/parser/parse_utilcmd.c:3164

After that i tried the same but with an already partitioned (via
inheritance) table and got this (i did this first without a
transaction, doing it with a transaction will show the same failure as
before):

script 2 (failing_test_2.sql) fails the assert
"Assert(childrte->relkind == RELKIND_PARTITIONED_TABLE);" in
expand_inherited_rte_internal() at
src/backend/optimizer/prep/prepunion.c:1551

PS: i don't like the START END syntax but i don't have any ideas
there... except, there was a reason not to use expressions (like a
CHECK constraint?)

--
Jaime Casanova                      www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services