/*
* lag
* returns the value of VE evaluated on a row that is 1
* row before the current row within a partition,
* per spec.
*/
Datum
window_lag(PG_FUNCTION_ARGS)
{
return leadlag_common(fcinfo, false, false, false);
}
/*
* lag_with_offset
* returns the value of VE evelulated on a row that is OFFSET
* rows before the current row within a partition,
* per spec.
*/
Datum
window_lag_with_offset(PG_FUNCTION_ARGS)
{
return leadlag_common(fcinfo, false, true, false);
}
/*
* lead_with_offset_and_default
* same as lead_with_offset but accepts default value
* as its third argument.
*/
Datum
window_lead_with_offset_and_default(PG_FUNCTION_ARGS)
{
return leadlag_common(fcinfo, true, true, true);
}
