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Thread: execute table query in backend

execute table query in backend

From
Anh Pham
Date:
Hi,
I am trying to extend the server backend by writing a new module.
Basically, it tries to retrieve tuples from a specific table using some predefined qualifications (equivalent to "SELECT FROM WHERE" client sql statement ).
Is there any quick or efficient way to do this?

Many thanks :)

Re: execute table query in backend

From
Amit Langote
Date:
On Tue, Mar 4, 2014 at 12:38 AM, Anh Pham <atpham.wpi@gmail.com> wrote:
> Hi,
> I am trying to extend the server backend by writing a new module.
> Basically, it tries to retrieve tuples from a specific table using some
> predefined qualifications (equivalent to "SELECT FROM WHERE" client sql
> statement ).
> Is there any quick or efficient way to do this?


Assuming you're trying to write a server extension (and NOT a client
application), this is where you can start:

http://www.postgresql.org/docs/9.3/static/server-programming.html

Specifically, an interface called "server programming interface"
(chapter 44 on the above page) can be used to issue SQLs from a server
extension module. Read more about it here (documentation also includes
few examples to get started with):

http://www.postgresql.org/docs/9.3/static/spi.html

--
Amit

Re: execute table query in backend

From
Anh Pham
Date:
Thank you for you suggestion.
I actually took a look at SPI_ functions before. However, I believe using this will bring quite an overhead.
I am trying to modify the Sequence scan node such that: each time the scan returns a tuple,
we'll take some information from this tuple. And finally issue another scan operation on a different table based on these information


On Thu, Mar 6, 2014 at 12:36 AM, Amit Langote <amitlangote09@gmail.com> wrote:
On Tue, Mar 4, 2014 at 12:38 AM, Anh Pham <atpham.wpi@gmail.com> wrote:
> Hi,
> I am trying to extend the server backend by writing a new module.
> Basically, it tries to retrieve tuples from a specific table using some
> predefined qualifications (equivalent to "SELECT FROM WHERE" client sql
> statement ).
> Is there any quick or efficient way to do this?


Assuming you're trying to write a server extension (and NOT a client
application), this is where you can start:

http://www.postgresql.org/docs/9.3/static/server-programming.html

Specifically, an interface called "server programming interface"
(chapter 44 on the above page) can be used to issue SQLs from a server
extension module. Read more about it here (documentation also includes
few examples to get started with):

http://www.postgresql.org/docs/9.3/static/spi.html

--
Amit



--
Anh T Pham
Computer Science
Worcester Polytechnic Institute