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

Posted by mannix on March 17, 2022 at 12:00 am

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?

mannix replied 8 months, 1 week ago 2 Members · 1 Reply

1 Reply

rocuinneagain

Member
March 21, 2022 at 12:00 am
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)
```

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