Tuesday, October 31, 2006


Sometimes the NDBAPI is not perhaps the most straightforward. This might be useful if you are struggling with scan filters (filtering tuples in the ndbd kernel, like engine-condition-pushdown) in combination with strings. Please have a look at my previous blog about how to use strings in the NDBAPI.

If you are using string daratypes with the NdbScanFilter::COND_EQ then the following rules applies:
  • VARCHAR and VARBINARY strings must have their length prepended (1 or 2 bytes)
  • CHAR must be space padded
  • BINARY must be null byte padded
However, for NdbScanFilter::COND_LIKE the following applies:
  • VARCHAR and VARBINARY must NOThave the lenght prepended!
  • CHAR must NOT be space padded
  • BINARY must NOT be null byte padded
Many thanks to Pekka (MySQL) and Jim Dowling (MySQL) on this subject.

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