From: Jorma O. Tähtinen <jotahtin@alpha.hut.fi>
To: pgsql-interfaces@postgresql.org
Subject: ecpg: how select/insert n rows (array) in one query
Date: Sat, 10 Jun 2000 17:49:42 +0300
Message-ID: <39425586.2E418BAC@alpha.hut.fi> (raw)
Hello
I'm new postgres user (currenly converting db application with quite
large database from mysql to postgres, hopefully pg is not too slow but
I really need triggers and views).
Anyway could somebody please explain how multiple row select/insert
should be used in embedded sql (ecpg)
1) select - this is simple (well documented)
EXEC SQL BEGIN DECLARE SECTION;
struct data_t {
char md5[100][32];
int size[100];
} data;
struct ind_t { short md5,size } ind;
EXEC SQL END DECLARE SECTION;
EXEC SQL BEGIN TRANSACTION;
EXEC SQL DECLARE cur CURSOR FOR
select md5,size FROM filetable;
EXEC SQL OPEN cur;
EXEC SQL WHENEVER NOT FOUND DO break;
while(1) {
EXEC SQL FETCH 1000 FROM cur INTO :data:ind;
for(n=0;n<sqlca.sqlerrd[2];++n) { /*do something*/
}
EXEC SQL CLOSE cur;
EXEC SQL COMMIT;
This is fine, speed on my hardware about (magnitude) 10.000 rows/per
sec.
(mostly limited by disk i/o)
Only question here is: why can't I declare that data struct like
struct data_t {
char md5[32];
int size;
} data[100];
Is this possible and how to use it.
.
2) insert - Now this is my real problem
if I have understod docs correctly : use of insert like select in
about example is NOT possible
please somebody say that I'm wrong - small example would be nice to
see ;-)
And yes I have tried to insert multiple rows in one transaction
block like
EXEC SQL BEGIN TRANSACTION
for(....) {
insert .....
}
EXEC SQL COMMIT
but this is still way to slow at max 50-100 insert per sec. I
understand that inserting is slow operation
but 10.000/sec in select and 50/sec in insert - can't be THAT
slow??? (inserting 12-13M rows is a bit pain...;-)
And yes, I really want to use c+embedded sql code to do inserting
(real app/table struct of course more complex)
-jt-
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-interfaces@postgresql.org
Cc: jotahtin@alpha.hut.fi
Subject: Re: ecpg: how select/insert n rows (array) in one query
In-Reply-To: <39425586.2E418BAC@alpha.hut.fi>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox