Hello, Tom. I tried to reproduce the situation from the very beginning (created a new DB, created the datatype in it) but the effect did not reproduce. I continued the investigation and found that it is just suffictient to re-create a datatype in an existing DB for the effect to disappear. Thus, I think that the reason was in some accidental combination of circumstances. Unfortunately, I cannot recall the order of my actions, which lead to this strange situation. But I still feel curious about this fact. If you also do, and if you think that my sources can help you in analyzing the situation, here is the code I used to build my datatype: 1. Here's the code of the four "C" functions, used serve my "int1" datatype: ------------------------8<------------------------ #include "postgres.h" #include <stdio.h> typedef unsigned char int1; // IN - OUT functions int1 *int1_in(char *str); char *int1_out(int1 *i); // Convertion functions int1 *i4toi1(int4 i); int4 i1toi4(int1 *i); /*************************************************************************** ** * Input/Output functions **************************************************************************** */ int1 *int1_in(char *str) { unsigned int i; int1 *result; if ( sscanf( str, "%u", &i ) != 1 ) { elog(ERROR, "int1_in: error in parsing \"%s\"", str); return NULL; } if ( ( i < 0 ) || ( i > 255 ) ) { elog(ERROR, "int1_in: error in parsing \"%s\"", str); return NULL; } result = (int1*)palloc(sizeof(int1)); (*result) = i; return result; } char *int1_out(int1 * i) { char *result; if ( i == NULL ) return NULL; result = (char *) palloc( 60); sprintf(result, "%u", (*i)); return result; } /*************************************************************************** ** * Type conversion functions **************************************************************************** */ int1 *i4toi1(int4 i) { int1 *result; if ( ( i < 0 ) || ( i > 255 ) ) { elog(ERROR, "i4toi1: %d is out of bounds (0...255)", i); return NULL; } result = (int1*)palloc(sizeof(int1)); (*result) = i; return result; } int4 i1toi4(int1 *i) { return (*i); } ------------------------8<------------------------ 2. That's how I built the library: cc -I /usr/local/pgsql/include -I /usr/local/include -fpic -DPIC -shared -o int1.so int1.c 3. Here are the sql statements I used to create the datatype: create function int1_in(opaque) returns int1 as '/usr/local/pgsql/data/int1.so' language 'C'; create function int1_out(opaque) returns opaque as '/usr/local/pgsql/data/int1.so' language 'C'; create type int1 ( input = int1_in, output = int1_out, internallength = 1, externallength = 3, default = "" ); create function int1(int4) returns int1 as '/usr/local/pgsql/data/int1.so', 'i4toi1' language 'C'; create function int4(int1) returns int4 as '/usr/local/pgsql/data/int1.so', 'i1toi4' language 'C'; Hope, this will help you. Best Regards, Konstantin Solodovnikov. > -----Original Message----- > From: Tom Lane [mailto:[EMAIL PROTECTED]] > To: Солодовников Константин > Subject: Re: [BUGS] Strangeness/bug when working with my own datatype in PostgreSQL > > > When I insert a new row into this table without providing a > value for the > > "i1" column, I get a value of "45" in it. > > Seems odd to me too; it should default to NULL if no value is > specified > or available from a DEFAULT clause. Can't guess why you're seeing a > problem without more details, though. Could you show us the code you > used to define your datatype? > > regards, tom lane >