KDB Find first date with data in each table of a process

Question

I am trying to find first date where we have data available per process over IPC. I tried below but it isn't efficient. Is there a better way to find this?

select min date from ({select date from x where date=first date }each tables[])

I came across another way but that requires loading par.txt or hdb location which cannot be done over IPC.

(first date where@)each 0<.Q.pn

My ultimate goal is to open connection to HDB of each process from the list of processes, get the first available date where we have data for at least one table.

Answer 1

You can use .Q.pv to display a list of the partition values found in the hdb, then first to get the earliest date:

first .Q.pv

Answer 2

If your HDB is partitioned by date, a variable called date will exist in memory of the process. It will contain a list of dates in the HDB, you can pick up the first entry of this list via IPC:

`:host:port "first date"