@Override
    public boolean equals(Object o) {

        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        if (!super.equals(o)) {
            return false;
        }

        UpdateOrInsertStream that = (UpdateOrInsertStream) o;

        if (onUpdateExpression != null ? !onUpdateExpression.equals(that.onUpdateExpression) :
                that.onUpdateExpression != null) {
            return false;
        }
        return updateSetter != null ? updateSetter.equals(that.updateSetter) : that.updateSetter == null;
    }
Query output stream try to update table else insert into it
modules/siddhi-query-api/src/main/java/io/siddhi/query/api/execution/query/output/stream/UpdateOrInsertStream.java