don't store trail blank in varchar column.
You should recompile postgresql
There is only tiny change in "src/backend/utils/adt/varchar.c"
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Datum
varcharin(PG_FUNCTION_ARGS)
{
char *s = PG_GETARG_CSTRING(0);
#ifdef NOT_USED
Oid typelem = PG_GETARG_OID(1);
#endif
int32 atttypmod = PG_GETARG_INT32(2);
VarChar *result;
size_t len,
maxlen;
char *ermsg;
len = strlen(s);
if ((ermsg = pg_verifymbstr(s, len)))
elog(ERROR, "%s", ermsg);
maxlen = atttypmod - VARHDRSZ;
if (atttypmod >= (int32) VARHDRSZ && len > maxlen)
{
/* Verify that extra characters are spaces, and clip them off */
size_t mbmaxlen = pg_mbcharcliplen(s, len, maxlen);
if (strspn(s + mbmaxlen, " ") == len - mbmaxlen)
len = mbmaxlen;
else
elog(ERROR, "value too long for type character varying(%d)",
(int) maxlen);
}
/* **** don't save trail space char */
while (len > 0)
{
if (*(s + len - 1) != ' ')
break;
len--;
}
/* **** end */
result = palloc(len + VARHDRSZ);
VARATT_SIZEP(result) = len + VARHDRSZ;
memcpy(VARDATA(result), s, len);
#ifdef CYR_RECODE
convertstr(VARDATA(result), len, 0);
#endif
PG_RETURN_VARCHAR_P(result);
}