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

[Hongyuhong]

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]
发送时间: 2017年1月13日 17:23
收件人: 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