Re: Fix pgstattuple/pgstatindex to use regclass-type as the argument

On Thu, Jun 20, 2013 at 11:43 AM, Satoshi Nagayasu <snaga(at)uptime(dot)jp> wrote:
> (2013/06/17 4:02), Fujii Masao wrote:
>>
>> On Sat, Mar 9, 2013 at 3:23 PM, Satoshi Nagayasu <snaga(at)uptime(dot)jp> wrote:
>>>
>>> It is obviously easy to keep two types of function interfaces,
>>> one with regclass-type and another with text-type, in the next
>>> release for backward-compatibility like below:
>>>
>>> pgstattuple(regclass) -- safer interface.
>>> pgstattuple(text) -- will be depreciated in the future release.
>>
>>
>> So you're thinking to remove pgstattuple(oid) soon?
>
>
> AFAIK, a regclass type argument would accept an OID value,
> which means regclass type has upper-compatibility against
> oid type.
>
> So, even if the declaration is changed, compatibility could
> be kept actually. This test case (in sql/pgstattuple.sql)
> confirms that.
>
> ----------------------------------------------------------------
> select * from pgstatindex('myschema.test_pkey'::regclass::oid);
> version | tree_level | index_size | root_block_no | internal_pages |
> leaf_pages | empty_pages | deleted_pages | avg_leaf_density |
> leaf_fragmentation
> ---------+------------+------------+---------------+----------------+------------+-------------+---------------+------------------+--------------------
> 2 | 0 | 8192 | 1 | 0 |
> 1 | 0 | 0 | 0.79 | 0
> (1 row)
> ----------------------------------------------------------------
>
>
>>> Having both interfaces for a while would allow users to have enough
>>> time to rewrite their applications.
>>>
>>> Then, we will be able to obsolete (or just drop) old interfaces
>>> in the future release, maybe 9.4 or 9.5. I think this approach
>>> would minimize an impact of such interface change.
>>>
>>> So, I think we can clean up function arguments in the pgstattuple
>>> module, and also we can have two interfaces, both regclass and text,
>>> for the next release.
>>>
>>> Any comments?
>>
>>
>> In the document, you should mark old functions as deprecated.
>
>
> I'm still considering changing the function name as Tom pointed
> out. How about "pgstatbtindex"?

Or just adding pgstatindex(regclass)?

> In fact, pgstatindex does support only BTree index.
> So, "pgstatbtindex" seems to be more appropriate for this function.

Can most ordinary users realize "bt" means "btree"?

> We can keep having both (old) pgstatindex and (new) pgstatbtindex
> during next 2-3 major releases, and the old one will be deprecated
> after that.

Since pg_relpages(oid) doesn't exist, pg_relpages() is in the same
situation as pgstatindex(), i.e., we cannot just replace pg_relpages(text)
with pg_relpages(regclass) for the backward-compatibility. How do you
think we should solve the pg_relpages() problem? Rename? Just
add pg_relpages(regclass)?

Regards,

--
Fujii Masao