What is the purpose of publishing value each t to t in .u.pub?

[Mannix]

if[system"t";
	.z.ts:{pub'[t;value each t];@[`.;t;@[;`sym;`g#]0#];i::j;ts .z.D};
	upd:{[t;x]
	if[not -16=type first first x;if[d<"d"$a:.z.P;.z.ts[]];a:"n"$a;x:$[0>type first x;a,x;(enlist(count first x)#a),x]];
	t insert x;if[l;l enlist (`upd;t;x);j+:1];}];

What do we use .z.ts to publish "value each t" to the "t" itself, I thought we just added updates to the table, not the whole table itself?

Why is this?

[leades]

Hello,

Thank you for sharing your query with us, we're working on feedback for you. 

Many Thanks,

Luke

[rocuinneagain · Accepted solution]

This is batching mode when the timer t is set. https://code.kx.com/q/basics/syscmds/#t-timer 

In this mode the TP will cache data and only publish it when the timer triggers .z.ts https://code.kx.com/q/ref/dotz/#zts-timer 

In this case t is a list of tables and it calls pub on each of them (' form)  https://code.kx.com/q/ref/maps/#each 

value is called so that the cached data from the TP is populated in pub to send to subscribers (RDB etc.)

Some more information on batch mode: https://code.kx.com/q/wp/tick-profiling/ 

q)upd'[t;value each t] //A demo 'upd' which prints the parameters sent to it
q)a:([] c1:1 2 3)
q)b:([] c2:4 5 6)
q)t:tables[] //Create list of tables
q)t
`s#`a`b
q)upd'[t;value each t]
(`a;+(,`c1)!,1 2 3)
(`b;+(,`c2)!,4 5 6)