secondo/Algebras/PartitionedStream/opt_correl.sec

let OrteP = plz feed sortby[Ort asc] groupby[Ort; Anzahl: . count] consume;

let OrteP2 = plz feed project[Ort] consume;

let OrteP2_Ort = OrteP2 createbtree[Ort];

let plz_Ort = plz createbtree[Ort];