Forum OpenACS Q&A: Response to Pg driver: undefined symbol: Ns_DbAddColumnInfo

You're right.  The version you're using is based on postgres.c version 1.15, whereas I'm using postgres.c version 1.20, which is the latest from cvs.  There were some changes in between the two versions which resulted in the build process changing slightly.  version 1.15 depends on the variable NS_AOLSERVER_3_PLUS being defined.  Check the ns.h file in your include path and make sure that it has NS_AOLSERVER_3_PLUS defined.  It's possible you're building against the old 2.3 include file.