[Pgpool-hackers] First try at rephrasing the documentation

[Guillaume Lelarge]

Le 20/12/2010 11:44, Marc Cousin a écrit :
> The Monday 20 December 2010 10:13:01, Tatsuo Ishii wrote :
>>> I will try to answer your TODO items one by one following emals...
> Ok. Here is a patch with corrections corresponding to your answers, to be 
> applied to the file provided in the previous email.
> 
>>
>> TODO : what does this refer to, there is no 3 in the array ?
>> A: It referes to "row mode".
> Ok, added.
> 
>>
>> TODO : is that true ? It seems to me the JDBC driver starts a
>> transaction only on first DDL query (in read committed mode at least).
>>
>> A: Really? I do not observe what you said with
>> postgresql-8.4-701.jdbc4.jar.
> I've just checked, and I was mistaken :)
> 
>>
>> TODO: Are DDL queries accounted for in the load balancing algorithm ?
>> A: Yes.
> Corrected
>>
>> TODO: can a table be non-distributed and non-replicated, and still be
>> used in parallel mode ?
>> A: Not sure. will check.
> Ok
>>
>> TODO: should we define 'pool' in this context ? I find it a bit confusing
>> A: The reason why we use 'pool' is just for a historical reason...
> Ok, so I've put a definition, tell me if I'm wrong
> 
>>
>> TODO: Should be explained in more detail. I guess it's only for the
>> 'rsync' method, not PITR…
>> A: You are correct.
> Modified
>>
>> TODO: What is the point of 'flushing the sequences' ? Don't we trust
>> WAL recovery ?
>> A: PostgreSQL does not log sequence value whenever it counts
>> up. Instead it logs 'discretely'. So just redoing from WAL, it's
>> possible that slave loses upto 32 sequences. See
>> src/backend/commands/sequence.c.
> I still don't get it. The purpose of this is just to avoid having a hole of 32 
> values in the sequence ? Or is it useful in replication mode and not in 
> master-slave? Because having a hole in a sequence is something that happens 
> all the time.
> 
>>
>> TODO: contradiction in the previous sentence md5 is supported by using
>> "pool_passwd".
>> A: You are correct.
> Yes, but is clear text password supported or not ? :)
> 
>>
>> TODO: what happens then ? Is it rejected ?
>> A: No. Inconsistent values will be inserted.
> Ok, corrected
> 
>>
>> TODO: I don't really get this one. Can somebody explain ?
>> A: Me neither:-) Let me check...
>>
>> <p>The USING CLAUSE is converted to an ON CLAUSE by the query rewrite
>> process. Therefore, when "*" is used at target list, the row of the same
>> column name appears.</p> TODO: What does it mean ?
>> A: I don't know neither:-) Let me check...
>>
>> TODO: This following section may be completely false. I tried to
>> understand the general meaning of the original text, and look into
>> pgpool's code to understand.
>> A: Let me check...
> Ok, I'll wait on these 3 ones too.
> 

I proofreaded Marc's rewrite. It's mostly really good, but there are a
few mistakes. Patch attached fixes them. The whole new file is also
attached (with Marc's patch and mine).

So I think all is need is to put the last bit of informations Tatsuo
gave you, to have a complete file.

Thanks for your work.


-- 
Guillaume
 http://www.postgresql.fr
 http://dalibo.com
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