Hello,
I think that the only way to do what you need is by using a function:
I wrote this javascript:
parameters: rid, list_name, key_name, key_value
var g=orient.getGraph();
var sel=g.command("sql","select expand("+list_name+"."+key_name+") from "+
rid+" where '"+key_name+"' in "+list_name+".keys()");
if(sel.length > 0){
return sel[0]
} else {
var upd=g.command("sql","update "+rid+" put "+list_name+"='"+key_name+"',"
+key_value+" return after @this."+list_name+"['"+key_name+"']");
return upd[0];
}
then here's an example of usage:
select
expand(function_name('#23:0','lista','key7',"{'Action':'Test22a','Enabled':false,
'@type':'d', '@class':'Test'}"))
Il giorno mercoledì 1 giugno 2016 06:38:14 UTC+2, Eric24 ha scritto:
>
> I'm trying to determine the most efficient and least contentious way to do
> a sort of UPSERT on a LINKMAP property. Specifically, if I try to PUT a new
> item with a key value that already exists, I want the PUT to fail and leave
> the existing item in place (and instead return that item to the caller). By
> default, a PUT overwrites the key-matching item. I can prevent that with a
> WHERE clause, but I can't get RETURN to work (no syntax I've tried works).
> I can accomplish this doing a SELECT first, followed by a conditional
> UPDATE, but I'm hoping there's a more efficient way.
>
> Also, this is a very high-frequency operation (many potential update or
> update attempts to a given record per second). What happens to a single
> record with a LINKMAP (or EMBEDDEDMAP) property if one operation adds a new
> key/record and a concurrent operation adds a new different key/record? Are
> both keys/records retained or does the most recent update "win",
> effectively loosing the key/record added in the first operation or are both
> retained? If so, would locking the record during the operation solve that
> issue?
>
>
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