Re: PL/Python adding support for multi-dimensional arrays

From: Heikki Linnakangas <hlinnaka(at)iki(dot)fi>
To: Dave Cramer <pg(at)fastcrypt(dot)com>
Cc: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, Alexey Grishchenko <programmerag(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: PL/Python adding support for multi-dimensional arrays
Date: 2016-09-27 18:58:06
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On 09/27/2016 02:04 PM, Dave Cramer wrote:
> On 26 September 2016 at 14:52, Dave Cramer <pg(at)fastcrypt(dot)com> wrote:
>>> This crashes with arrays with non-default lower bounds:
>>> postgres=# SELECT * FROM test_type_conversion_array_int
>>> 4('[2:4]={1,2,3}');
>>> INFO: ([1, 2, <NULL>], <type 'list'>)
>>> server closed the connection unexpectedly
>>> This probably means the server terminated abnormally
>>> before or while processing the request.
>>> Attached patch fixes this bug, and adds a test for it.

I spent some more time massaging this:

* Changed the loops from iterative to recursive style. I think this
indeed is slightly easier to understand.

* Fixed another segfault, with too deeply nested lists:

CREATE or replace FUNCTION test_type_conversion_mdarray_toodeep()
RETURNS int[] AS $$
return [[[[[[[[[[[[[[[[[[1]]]]]]]]]]]]]]]]]]
$$ LANGUAGE plpythonu;

* Also, in PLySequence_ToArray(), we must check that the 'len' of the
array doesn't overflow.

* Fixed reference leak in the loop in PLySequence_ToArray() to count the
number of dimensions.

>>> I'd like to see some updates to the docs for this. The manual doesn't
>>> currently say anything about multi-dimensional arrays in pl/python, but it
>>> should've mentioned that they're not supported. Now that it is supported,
>>> should mention that, and explain briefly that a multi-dimensional array is
>>> mapped to a python list of lists.
>> If the code passes I'll fix the docs

Please do, thanks!

- Heikki

Attachment Content-Type Size
0001-WIP-Multi-dimensional-arrays-in-PL-python.patch text/x-patch 48.7 KB

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