Re: NdbScanFilter with strings - Monty Taylor - com.mysql.lists.ndb-connectors

11 messages in com.mysql.lists.ndb-connectorsRe: NdbScanFilter with strings

From	Sent On	Attachments
John David Duncan	18 Aug 2007 23:38
Monty Taylor	19 Aug 2007 14:35
John David Duncan	19 Aug 2007 18:01
Frazer Clement	20 Aug 2007 07:09
John David Duncan	22 Aug 2007 10:21
Monty Taylor	22 Aug 2007 10:24
John David Duncan	22 Aug 2007 10:26
Monty Taylor	22 Aug 2007 10:32
Monty Taylor	29 Aug 2007 22:41
John David Duncan	29 Aug 2007 22:52
Monty Taylor	29 Aug 2007 23:47

Subject:	Re: NdbScanFilter with strings
From:	Monty Taylor (mtay...@mysql.com)
Date:	08/22/2007 10:24:30 AM
List:	com.mysql.lists.ndb-connectors

Nice.

What version of MySQL is this with?

John David Duncan wrote:

Hi guys,

I finally got it to work, at least with COND_EQ filters.

The length parameter in NdbScanFilter::cmp() is important.

For CHAR, length needs to be set to col::getLength(). For VARCHAR, it needs to be set to col::getLength() + 1. For LONGVARCHAR, I assume (but haven't tested), it needs to be col::getLength() + 2.

I'll work on LIKE filters next...

On Aug 20, 2007, at 7:09 AM, Frazer Clement wrote:

I seem to recall that the passing-convention depends on the comparison used. If I remember correctly, LIKE filters don't require the preceding length byte stuff in the passed buffer, but equality does. Not sure about the other inequalities. Keep trying all the combinations.... :)

John David Duncan <jd...@mysql.com> 20/08/2007 02:02

To Monty Taylor <mtay...@mysql.com> cc ndb-...@lists.mysql.com Subject Re: NdbScanFilter with strings

int cmpString(NdbOperation * op, BinaryCondition cond, int ColId, const char * anInputString, size_t len ) { const NdbDictionary::Column * theColumn = op->getTable()->getColumn(ColId); char * stringVal = ndbFormatString(theColumn,anInputString,len); if (stringVal == NULL) return -1; int retval = self->cmp(cond,ColId,(void *)stringVal); free(stringVal); return retval; };

where ndbFormatString returns the whole length-byte-string thing.

I'm not 100% I've tested this, though. But I think I remember talking to Johan about it at the time...

Yeah, I try essentially the same thing (with either CHAR or VARCHAR), but I always get an empty result, as if the filter does not match anything.

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