Re: [Postgres-xc-developers] prepare statement bug

[Mason S. <mas...@en...>]

Sent from my IPhone

On Dec 3, 2010, at 5:31 PM, "Andrei.Martsinchyk" <and...@en...> wrote:

> Mason,
> 
> 2010/12/3 Mason Sharp <mas...@en...>:
>> On 12/1/10 1:53 PM, Andrei.Martsinchyk wrote:
>>> 
>>> Hi Benny,
>>> 
>>> Thanks for pointing this out. I tested with a program using Postgres C
>>> library and extended query protocol.
>>> For you and anyone else who want to test I am attaching the test
>>> program and simple Makefile.
>>> I fixed the segmentation fault (updated patch is attached), but
>>> anyway, PREPARE / EXECUTE commands do not work properly.
>>> 
>> 
>> It looks like it is still not quite right:
>> 
>> 
>> mds1=# create table mytab (col1 int, col2 int);
>> CREATE TABLE
>> mds1=# prepare p (int, int) AS INSERT INTO mytab VALUES ($1, $2);
>> PREPARE
>> mds1=# execute p (1,2);
>> INSERT 0 1
>> mds1=# select * from mytab;
>>  col1 | col2
>> ------+------
>> (0 rows)
>> 
>> It does not find the row that should have been inserted.
>> 
> 
> Yes, I mentioned the PREPARE command does not work properly.
> In this particular case it is inserting row into Coordinator database
> and not visible for select.
> 

Oh. So, only SELECT is currently handled?

>> Also, one other question- the session seems to retain the fact that there
>> are associated prepared statements. Does that mean that the pooler will not
>> put these back in the pool until all are deallocated?
>> 
> 
> Coordinator does not prepare statements on datanodes, so connection
> can be released at the transaction end.

It converts it into a simple statement? I think we need to support prepare and execute on the data nodes for performance.

> 
>> On a related note, for the WITH HOLD cursors you implemented, did you also
>> do something to hold on to the connections?
>> 
> 
> I did not implement WITH HOLD.

Let me retest this, and look at old emails later when back at my laptop.

Mason
> 
>> Thanks,
>> 
>> Mason
>> 
>> 
>> 
>> 
>> Mason Sharp
>> EnterpriseDB Corporation
>> The Enterprise Postgres Company
>> 
>> 
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> 
> 
> 
> -- 
> Andrei Martsinchyk
> 
> EntepriseDB Corporation
> The Enterprise Postgres Company
> 
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