Re: [GENERAL] How does postgresql jdbc driver implement prepared batch?

You will get considerably more response if you use the jdbc list.

The driver does not change it to a "final statement" it creates the
prepared statement then sets the parameters many times and executes it,

Although the most recent code does it a bit differently now

Dave Cramer

davec(at)postgresintl(dot)com
www.postgresintl.com

On 20 April 2016 at 07:08, Jinhua Luo <luajit(dot)io(at)gmail(dot)com> wrote:

> Hi,
>
> As document said, in the extended query protocol, "The query string
> contained in a Parse message cannot include more than one SQL
> statement".
>
> So to support batch in prepared statement, I think the only way is to
> determine the batch size in advance and then create the appropriate
> prepared statement, e.g.
>
> Given the batch size is fixed to 3, then prepare below statement:
> -- create table foobar(a int, b text);
> insert into foobar values($1, $2), ($3, $4), ($5, $6);
>
> Then this prepared statement must be bound with 3 set of arguments.
>
> The limitation is obvious: the batch size is fixed, so if you need to
> do batch with size of 4, the previous prepared statement is useless
> and you need to recreate it.
>
> On the other hand, in JDBC, it seems that you just need to prepare
> below statement:
>
> insert into foobar values($1, $2);
>
> And then calls addBatch() repeatedly until you think the batch size is
> enough.
>
> What's the final statement does postgresql jdbc driver convert to? I'm
> so curious.
>
> I'm not familiar with jdbc, and although I check the driver source
> codes, but I still cannot understand it.
>
> Anybody knows the answer? Thanks.
>
>
> Regards,
> Jinhua Luo
>
>
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