Re: How to apply Bulk Copy hints when using ctlib ?

On Thu, Mar 03, 2011 at 05:45:39PM +0200, Mark Songhurst wrote:
> You wrote:
> 
> > As long as blkdesc->bcpinfo.hint points to a valid string
> 
> I'm using 0.82 of FreeTDS and my BLKDESC structure boils down to this,
> in ctlib.h:
> 
> struct _cs_blkdesc
> {
> 	CS_CONNECTION *con;
> 	CS_CHAR *tablename;
> 	CS_CHAR *insert_stmt;
> 	CS_INT direction;
> 	CS_INT identity_insert_on;
> 	CS_INT bind_count;
> 	CS_INT xfer_init;
> 	CS_INT var_cols;
> 	TDSRESULTINFO *bindinfo;
> };
> 
> I don't have a bcpinfo member.
> Please can you tell me if you are referring to a newer version of
> FreeTDS, or perhaps I have misunderstood your suggestion?

You understood correctly; I had just checked CVS HEAD.  :-/  

It will be easier to change a recent snapshot, because Frediano unified the
bcp structures.  If you want to modify 0.82, you'll have to add your own hint
member.  

In case it matters, we're actively working on a new release Real Soon Now.  I
would be happy to incorporate your patch if you want to contribute one.  

In ctlib.h we currently have:

struct _cs_blkdesc
{
	CS_CONNECTION *con;
	TDSBCPINFO bcpinfo;
};

and in tds.h:

typedef struct tds_bcpinfo
{
	const char *hint;
	void *parent;
	TDS_CHAR *tablename;
	TDS_CHAR *insert_stmt;
	TDS_INT direction;
	TDS_INT identity_insert_on;
	TDS_INT xfer_init;
	TDS_INT var_cols;
	TDS_INT bind_count;
	TDSRESULTINFO *bindinfo;
} TDSBCPINFO;

This is used in src/tds/bulk.c::tds_bcp_start_insert_stmt()

	if (bcpinfo->hint) {
		if (asprintf(&hint, " with (%s)", bcpinfo->hint) < 0)
			hint = NULL;
	} else {
		hint = strdup("");
	}

As you can see, it's important that the hint text be carefully controlled, which
is why it's checked against a static list in db-lib.  

HTH.

--jkl