Re: [GENERAL] gsoc ideas

2008-03-11 Thread longlong
your words are a great encouragement to me!

i am embarrassed by my English and i will improve it.

maybe i missed something that makes you a little misunderstand in point 3.
what i want is data-copys between databases automatically processed by
program. and databases may be not in the same host. i feel that this is hard
to implement now. so i'll try 1 and 2 in [HACKERS].

thanks for you advice.


Re: [GENERAL] gsoc ideas

2008-03-11 Thread Richard Huxton

longlong wrote:

your words are a great encouragement to me!

i am embarrassed by my English and i will improve it.

maybe i missed something that makes you a little misunderstand in point 3.
what i want is data-copys between databases automatically processed by
program. and databases may be not in the same host. i feel that this is hard
to implement now. so i'll try 1 and 2 in [HACKERS].


You can do it with different hosts too:

psql -h host1 -c copy x to stdout | psql -h host2 -c copy y from stdin


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Re: [GENERAL] gsoc ideas

2008-03-11 Thread longlong
i see.
now i know that COPY with STDIN/OUT can do what i mentioned before exactly.


2008/3/11, Richard Huxton [EMAIL PROTECTED]:

 longlong wrote:
  your words are a great encouragement to me!
 
  i am embarrassed by my English and i will improve it.
 
  maybe i missed something that makes you a little misunderstand in point
 3.
  what i want is data-copys between databases automatically processed by
  program. and databases may be not in the same host. i feel that this is
 hard
  to implement now. so i'll try 1 and 2 in [HACKERS].

 You can do it with different hosts too:

 psql -h host1 -c copy x to stdout | psql -h host2 -c copy y from stdin


 --
   Richard Huxton
   Archonet Ltd



Re: [GENERAL] gsoc ideas

2008-03-10 Thread Devrim GÜNDÜZ
Hi,

On Mon, 2008-03-10 at 13:10 +0800, longlong wrote:
 i want some advice about ideas for gsoc. i don't konw if it is
 appropriate that i send a email here, so if you feel uncomfortable,
 please accept my apology.

Use pgsql-hackers list. Development discussions are done on that list.

Regards,
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Re: [GENERAL] gsoc ideas

2008-03-10 Thread Alvaro Herrera
longlong escribió:

 3.sometimes, i want to copy data from one database to another. i think using
 COPY will simple the code. i want the content from COPY TO not store in the
 file, but in the memory, and i can COPY FROM the memory(i don't kown COPY
 with STDIN and STDOUT can do this or not.).

I don't think this is very interesting because you can do 

pg_dump -t foo | psql

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Re: [GENERAL] gsoc ideas

2008-03-10 Thread Greg Smith

On Mon, 10 Mar 2008, longlong wrote:


1.release8.2 make COPY TO can copy the output of an arbitrary SELECT
statement. so i think maybe COPY FROM can get data from output and 'insert
into' some column that designated. the format of the command will be
discussed.


This would be a nice feature.  Right now there are often applications 
where there is a data loading or staging table that ends up being merged 
with a larger table after some cleanup.  Moving that data from the 
preperation area into the final table right now is most easily done with 
INSERT INTO X (SELECT A,B FROM C) type actions.  This is slow because 
INSERT takes much longer than COPY.  Adding support for COPY X FROM 
(SELECT A,B FROM C) would make this problem go away.


It is possible to do this right now with some clever use of STDIN/OUT like 
the below, but having a pure SQL solution would be more widely applicable. 
The overhead of having to pass everything through the client (as STDIN/OUT 
do) is certainly not zero.



2.this come from TODO list: COPY always behaviors like a unit of work thar
consists of some insert commands, if any error, it rollback. but sometimes
we only care the data should be inserted. in that situation, i used to use
trycatch insert row by row to skip the error, because it will take
much time to examine every row. so:
   Allow COPY to report error lines and continue.  this is a good idea.


This is a long standing request and many people would be happy to see it 
implemented.  You do want to make sure the implementation easily allows 
pushing all the lines that didn't commit into what's commonly called a 
reject file.



3.sometimes, i want to copy data from one database to another. i think using
COPY will simple the code. i want the content from COPY TO not store in the
file, but in the memory, and i can COPY FROM the memory(i don't kown COPY
with STDIN and STDOUT can do this or not.).


It can:

create table x(a int);
insert into x(select generate_series(1,10));
create table y(b int);

psql -c copy x to stdout | psql -c copy y from stdout

Try it out, table y will have the same thing when it's all done.

I think you've got the basics of some useful features to add here.  What 
you probably want to do is write a slightly longer description of your 
plan and submit it to the pgsql-hackers list where the developers are at 
to get feedback on the feasibility of doing this as a GSOC project.  From 
your message, I get the impression that English writing is tough for you. 
That will make it a little harder for you to get through the process of 
getting a patch designed and then accepted, as this community likes to 
talk through that sort of thing.  If you've got another language you're 
more comfortable with, you might also want to see if there's an existing 
community member who speaks it you might work with to make that easier.


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