Re: the attribute order in sql 'select * from...'

[Timo Walther]

Especially, as it might also change the serialized binary format.


Am 13/01/17 um 11:24 schrieb Fabian Hueske:

I think the sorting is done for consistency reasons, i.e., that all PojoTypeInfos for the same class behave the same. Since this code is used in many parts of Flink and many jobs (DataSet, DataStream, etc.) I would be very careful to change the default behavior here.

Maybe we can add a constructor that does not sort the fields.

2017-01-13 10:46 GMT+01:00 Hongyuhong <hongyuh...@huawei.com <mailto:hongyuh...@huawei.com>>:

    Hi Fabian,

    Yes, OrderA is a table of POJO.

    But what I consume is that in construct func PojoTypeInfo

    The input param (fields)’s order is right, it ‘s change after the
    sort operation, and I’m wonder if the sort operation can be removed?

    public PojoTypeInfo(Class<T> typeClass, List<PojoField> fields) {

    super(typeClass);

     checkArgument(Modifier.isPublic(typeClass.getModifiers()),"POJO
    %s is not public", typeClass);

     this.fields = fields.toArray(new PojoField[fields.size()]);

    *Arrays.sort(this.fields, new Comparator<PojoField>() {*

    * @Override*

    * public int compare(PojoField o1, PojoField o2) {*

    *  return o1.getField().getName().compareTo(o2.getField().getName());*

    * }*

    });

    *发件人:*Fabian Hueske [mailto:fhue...@gmail.com
    <mailto:fhue...@gmail.com>]
    *发送时间:*2017年1月13日17:23
    *收件人:*user@flink.apache.org <mailto:user@flink.apache.org>
    *主题:*Re: the attribute order in sql 'select * from...'

    Hi Yuhong,

    I assume that OrderA is a table of POJO objects and you are
    expecting the order of the attribute to be as the order in which
    the fields of the POJO are defined in the source code.

    Flink accepts fields which are either public members or accessible
    via a getter and setter.

    This makes it difficult to automatically define an order, esp. if
    some fields use getter and setter or public fields. Would the
    order depend on the field (which might not exist in case of
    getter/setter) or setter or getter methods (which might also not
    exist).

    I'm also not sure if it is possible to extract the line number of
    a method or field via reflection.

    Best, Fabian

    2017-01-13 9:54 GMT+01:00 Hongyuhong <hongyuh...@huawei.com
    <mailto:hongyuh...@huawei.com>>:

    Hi,

    I’m now using streaming sql, And I have the sql like

    select *  FROM OrderA where user > 2

    the OrderA has 3 attr (user, product, amount)

    and I expect the result is as the order like input, but it has
    been sorted by attr name,

    and I found the order has already been sorted when call addSource,

    What is the purpose of doing so?cause it’s a little not meet our
    requirements.

    Thanks very much.

    public PojoTypeInfo(Class<T> typeClass, List<PojoField> fields) {

    super(typeClass);

    checkArgument(Modifier.isPublic(typeClass.getModifiers()),

    "POJO %s is not public", typeClass);

    this.fields = fields.toArray(new PojoField[fields.size()]);

    Arrays.sort(this.fields, new Comparator<PojoField>() {

    @Override

    public int compare(PojoField o1, PojoField o2) {

    return o1.getField().getName().compareTo(o2.getField().getName());

    }

    });

    Best,

    Yuhong