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Subject: Re: foreign data wrappers
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From: Zheng Yang <zhengyang4k@gmail.com>
In-Reply-To: <4D8AF8C2.3000007@lelarge.info>
Date: Thu, 24 Mar 2011 16:49:19 +0800
Cc: Selena Deckelmann <selena@chesnok.com>,
	Andrew Dunstan <andrew@dunslane.net>, pgsql-students@postgresql.org
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To: Guillaume Lelarge <guillaume@lelarge.info>

Hi Guillaume,

Thanks very much! Your answers help a lot!

>=20
> Le 24/03/2011 06:39, Zheng Yang a =E9crit :
>=20
>> 4) Is theFDW something similar to the Mysql storage engine =
architecture?
>>=20
>=20
> Not really.

AFAIK,there is a CSV storage engine in MySql that serves as a wrapper, =
enable executing SQL queries directly on the file.
This makes me think that the CSV FDW was doing similar things.=20

>=20
>> 5) for the datalink, the doc has mentioned about it's going to be OS =
dependent. but i dun quite understand how does the kernel module and =
LD_PRELOAD will work in this case, esp.LD_PRELOAD.
>>=20
>=20
> No idea.
>=20
I am quite new to postgresql, but slowly picking up :)  In general =
context, storing images directly inside DBMS fields as BLOBs was not =
considered as a good practice.=20
However, storing file directories  or links may cause inconsistency. So =
I am quite interested in how this datalink concept can be implemented!=20=


> Writing some FDWs would make a really good GSoC project.
Haha, agree!  I believe that's also a great starting point for learning =
pgsql internals.


cheers

ZY