Re: ECPG mass retrieval?

Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA

-----Original Message-----
From: Edmund Bacon [mailto:ebacon@onesystem.com]
Sent: Monday, March 29, 2004 9:51 AM
To: Stergios Zissakis
Cc: pgsql-interfaces
Subject: Re: [INTERFACES] ECPG mass retrieval?

How about:

EXEC SQL BEGIN DECLARE SECTION;
   int *num = NULL
   char **string = NULL;
   int low, high;
   char *context = "some context";
EXEC SQL END DECLARE SECTION;

EXEC SQL SELECT  number, string  INTO :num, string
    WHERE number BETWEEN :low AND :hi AND string = :context;

num_rec_returned = sqlca.sqlerrd[2];

for(i = 0; i < num_rec_returned; ++i)
    printf("%d %s", num, string);

free(num);
free(string);

ECPG will alloc the memory it needs, you just need to remember to free()
it.  And yes, free(string) frees all of string and string[0], string[1], ... string[n].

Just remember to pass in NULL pointers to your SELECT statement.


On Mon, 2004-03-29 at 06:13, Stergios Zissakis wrote:

Hi there,

It is possible to do bulk retrievals using ECPG?

What I mean is that I want to be able to delcare a host array variable, of
size 100 for example, and get
to retrive my data in batches of 100 rows.

To be more specific the following piece of code, using a cursor, results in
the databse being accessed at every fetch statement degrading performance:
		sprintf(stmt, "select * from test where number between %d and %d and
string = \'%s\'", lower, upper, context);
		EXEC SQL PREPARE S FROM :stmt;		EXEC SQL AT :ctx DECLARE curs CURSOR FOR S;		EXEC SQL AT :ctx OPEN curs;
		EXEC SQL WHENEVER NOT FOUND DO break;
		while( true )		{			EXEC SQL AT :ctx FETCH NEXT FROM curs INTO :num, :str;		}


What alternatives do I have to fetch things in bulk?

Thanks for your help.

Regards,

Stergios Zissakis


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Edmund Bacon <ebacon@onesystem.com>