On Thu, Aug 15, 2019 at 06:58:07AM +0000, Yonatan Misgan wrote:
Hello, I am trying to develop calendar extension for PostgreSQL but
there is a difficulties on how to get day, month and year from
PostgreSQL source code because when am read the PostgreSQL source code
it uses DateADT as a data type and this DateADT returns the total
numbers of day. So how can I get day, month or year only. For example
the below code is PostgreSQL source code to return current date.
/*
* GetSQLCurrentDate -- implements CURRENT_DATE
*/
DateADT
GetSQLCurrentDate(void)
{
TimestampTz ts;
struct pg_tm tt,
*tm = &tt;
fsec_t fsec;
int tz;
ts = GetCurrentTransactionStartTimestamp();
if (timestamp2tm(ts, &tz, tm, &fsec, NULL, NULL) != 0)
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("timestamp out
of range")));
return date2j(tm->tm_year, tm->tm_mon, tm->tm_mday) -
POSTGRES_EPOCH_JDATE;
}
From this source code how can I get only the year to convert my own
calendar year. I need this because Ethiopian calendar is totally
differ from GC in terms of day, month and year.
I think you might want to look at timestamptz_part() function, in
timestamp.c. That's what's behind date_part() SQL function, which seems
doing the sort of stuff you need.
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
