From zxbzswxr at gmail.com  Thu Nov  1 07:31:56 2018
From: zxbzswxr at gmail.com (Music samal)
Date: Fri Nov  2 06:58:45 2018
Subject: [odb-users] Questions about accessing database in parrallel(PPL
	library) using odb
Message-ID: <CAD9VYp=F=c3UJGcVxY0Y-V3rPfPcExAHUOAo-6mZ1-W11Rj5Rw@mail.gmail.com>

I want to read data from database , and using Microsoft PPL  for parallel
support,

I write an class A, it has an id name which has string type and an Integer
menber

#pragma db object pointer(std::tr1::shared_ptr)
class A
{
public:
A(const string name_):name(name_) {}
~A() {}

friend class odb::access;
A() {}
#pragma db id
string name;

int  number;

};

I just test three scenes
the serial scene,
the parrallel scene using parrallel_for_each from PPL
the parrallel scene using task from PPL
they all do the same thing, persisting 100 objects to database



template <class Function>
__int64 time_call(Function&& f)
{
__int64 begin = GetTickCount();
f();
return GetTickCount() - begin;
}




//  Parrallel test; create
void ParrallelFun(std::vector<int> & vAlist, shared_ptr<database> & db)
{
parallel_for_each(begin(vAlist), end(vAlist), [&](int i)
{
transaction t(db->begin());
string newName = "Parallel_A" + to_string(i);
shared_ptr<A>  tempA(new A(newName));
tempA->number = i;
db->persist(tempA);
// wait(10);
t.commit();
// wait(4);
});
}

//  serialize test
void SerializeFun(std::vector<int> & vAlist , shared_ptr<database> & db)
{

for (auto iter : vAlist)
{
transaction t(db->begin());
string newName = "Serial_A" + to_string(iter);
shared_ptr<A>  tempA(new A(newName));
tempA->number = iter;
db->persist(tempA);
// wait(10);
t.commit();
}

}


//  two task test

void TaskParallel_1();
void TaskParallel_2();



int main(int argc, char* argv[])
{
try
{
//  PPLtest
shared_ptr<database> db(new
odb::pgsql::database("postgres","123456","postgres","localhost",5432));
std::vector<int >  vList(100);
for (int i = 0; i < 100; i++)
{
vList[i] = i;
}
__int64 elapseSerial = time_call([&vList, &db] {

SerializeFun(vList, db);
});

__int64 elapseParallel = time_call([&vList, &db] {
ParrallelFun(vList, db);
});


__int64 elapseParallelTask = time_call([]{
array<task<void>, 2> tasks =
{
create_task([] { TaskParallel_1(); }),
create_task([] { TaskParallel_2(); })
};

auto joinTask = when_all(begin(tasks), end(tasks));

joinTask.wait();
});



cout << "serial time: " << elapseSerial << " ms" << endl;
cout << "parrallel time : " << elapseParallel << " ms" << endl;
cout << "two Task time : " << elapseParallelTask << "ms" << endl;

}
catch (const odb::exception& odberr)
{
cerr << odberr.what() << endl;


}

system("pause");
return 0;
}


void TaskParallel_1()
{
shared_ptr<database> db1(new
odb::pgsql::database("postgres","123456","postgres","localhost",5432));


for (unsigned int i = 0; i < 50; i++)
{
transaction t(db1->begin());
string newName = "TaskParallel_1_" + to_string(i);
shared_ptr<A> temp(new A(newName));
temp->number = i;
db1->persist(temp);
t.commit();
}


}


void TaskParallel_2()
{
shared_ptr<database> db2(new odb::pgsql::database("postgres", "123456",
"postgres", "localhost", 5432));

for (unsigned int i = 0; i < 50; i++)
{
transaction t(db2->begin());
string newName = "TaskParallel_2_" + to_string(i);
shared_ptr<A> temp(new A(newName));
temp->number = i;
db2->persist(temp);
t.commit();

}

}

the ouput is somewhat puzzle to me,
let me list the output here
serial time : 406ms
parrallel time : 2610ms
two Task time: 359ms

  parrallel_for_each  presents   terriblely unacceptable result .Something
must limit its performance. I  tended to  my friends for help , he told  me
may be it's the database connection ,not  transaction that impacts the
parrallel access performance..
so I just tried the third scene, I use two database variable for connection
independently in
task, the performace really improved.
Really is the database connection the main factor impose the parrallel
accessing perfomance?
Can anyone supply more advices about parrallel accessing using odb?

os : windows 10
compiler:vs2017
From boris at codesynthesis.com  Fri Nov  2 08:01:03 2018
From: boris at codesynthesis.com (Boris Kolpackov)
Date: Fri Nov  2 08:10:49 2018
Subject: [odb-users] Questions about accessing database in parrallel(PPL
	library) using odb
In-Reply-To: <CAD9VYp=F=c3UJGcVxY0Y-V3rPfPcExAHUOAo-6mZ1-W11Rj5Rw@mail.gmail.com>
References: <CAD9VYp=F=c3UJGcVxY0Y-V3rPfPcExAHUOAo-6mZ1-W11Rj5Rw@mail.gmail.com>
Message-ID: <boris.20181102135643@codesynthesis.com>

Music samal <zxbzswxr@gmail.com> writes:

> the ouput is somewhat puzzle to me,
> let me list the output here
> serial time : 406ms
> parrallel time : 2610ms
> two Task time: 359ms
>
> parrallel_for_each presents terriblely unacceptable result .Something must
> limit its performance. I tended to my friends for help , he told me may be
> it's the database connection ,not transaction that impacts the parrallel
> access performance.. so I just tried the third scene, I use two database
> variable for connection independently in task, the performace really
> improved. Really is the database connection the main factor impose the
> parrallel accessing perfomance?

The database instance in ODB by default uses a connection pool so it
should not matter whether you have one or two.

I think the reason for poor parrallel_for_each performance lies in
the way it is implemented, which is unclear. For example, if it
tries to execute all 100 transactions simultaneously (e.g., from
100 different threads), then that would probably explain the result
you are getting (due to high contention).

From zxbzswxr at gmail.com  Sun Nov  4 20:13:59 2018
From: zxbzswxr at gmail.com (Music samal)
Date: Mon Nov  5 08:44:04 2018
Subject: [odb-users] Questions about accessing database in parrallel(PPL
	library) using odb
In-Reply-To: <boris.20181102135643@codesynthesis.com>
References: <CAD9VYp=F=c3UJGcVxY0Y-V3rPfPcExAHUOAo-6mZ1-W11Rj5Rw@mail.gmail.com>
	<boris.20181102135643@codesynthesis.com>
Message-ID: <CAD9VYpneVe3arPXHm-R6_B_vWpOVzyOYVo-vA-QJ05PTs2mc0A@mail.gmail.com>

following your advise , I  have tried another sence ..
I use 20 iterations and plus 200ms in every iteration using "wait(200);"
the parralel scene is better than serial scence ... I used cout to pirnt
commit message and found that  code was been implemented in serial scene
with no delay
while take a little time before the iteration really began in parrallel
scence , It's about 1500ms~ 2000ms delay

I searched in MSDN  and found  parallel_for and parrallel_for_each  which
PPL supplies
will take a short time rearrangging all iterations to work threads before
iteration begin , and different scheduling policy can be
choosen to lead to different  performance influence ..

Another scence, I increase the iteration number to 100'000.,obviously  I
kick out "wait(200)" and "cout" in every iteration
and wait for result.
the serial time 102062ms
the parrallel time 27063ms
It's amazing !!!
From kexuetutu at sina.com  Mon Nov 12 04:18:18 2018
From: kexuetutu at sina.com (Jerry)
Date: Mon Nov 12 04:28:49 2018
Subject: [odb-users] Can I use relationship and polymorphic at the same time?
Message-ID: <20181112091818.B350A5D0009A@webmail.sinamail.sina.com.cn>

Hello ODB
I'm trying use ODB in my program to save a class A that contains a std::map, which value is a pointer to base class B. My code is some what like below:there are 2 *.h to define each class/*----------File1----------*/
#pragma db object polymorphicclass B{......}
#pragma db object no_idclass B1 : B{......}
/*----------File2----------*/
#pragma db objectclass A{......protected:	std::map<unsigned long, std::shared_ptr<B>> m_CheckSectionResultTable;......}
When I compile the File2 with ODB, it tells me this
D:\v1_8_1-New\src\YJKBridge\BridgePostProcess\BridgePostProcess\ElementDesignResult.h:40:68: error: unable to map C++ type '::std::map< long unsigned int, ::std::shared_ptr< ::SectionDesignResultBase > >::mapped_type' used in data member 'm_CheckSectionResultTable' to a SQLite database type

My question are: 1.How to solve this error?Class B is already defined "object abstract", why can't Class A recognise the "std::map<unsigned long, std::shared_ptr<B>>" type in ODB compiler?
2.I'm confuse with the "value" and "object", this are my point:(1).I'll use "value" if one class is another class's member (direct, not by pointer);(2).I'll use "object" if i want to use the features of abstract and polymorphic;Question2: if a class need polymorphic and this class is another class's member(need "value" feature), how to define the ODB type?
3?I'm confuse with the "abstract" useage, this are my point:(1).I'll use "abstract" if i want to save class which contains base class's memeber; (I'm not sure if this is right. I have tried save Class B, which inherit Class A without the "abstract" lable, it seems the Class B can also save members which defined in Class A)(2).I'll use "polymorphic" if i want to save class by it's base class pointer;Question3: In program, class is common use both inherit and polymorphic. For this class, how can i define it's ODB type? (The manual tell me an object can't be both "abstract" and "polymorphic".)
PS:I use VS2013 windowns
Thinks
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From zxbzswxr at gmail.com  Sat Nov 10 03:08:40 2018
From: zxbzswxr at gmail.com (Music samal)
Date: Mon Nov 12 06:58:56 2018
Subject: [odb-users] Questions about enable cross-database access
Message-ID: <CAD9VYp=1d189xGgOSRKifzR8FygUo3BqW4h6_Z9Hbc+P-nW0Pw@mail.gmail.com>

Does odb support cross-database access ?

eg: A member in Table A of database AAA has foreign key constraint with
Table B in database BBB.

If it does, the tutorial is requried. Thank you ,Boris and other helpers

OS : win10
Compiler: vs2017
From zxbzswxr at gmail.com  Sat Nov 10 21:20:37 2018
From: zxbzswxr at gmail.com (Music samal)
Date: Mon Nov 12 06:58:56 2018
Subject: [odb-users] Questions about export view class as DLL
Message-ID: <CAD9VYpmpftx+Yg3WfUaVD1QydOYGpUipv3FN1WknAmSvBD9neQ@mail.gmail.com>

I want to use view structs on occasions.
So I write some sample code to test it.
It works well when I build it as EXE.
But when I export it as dll.
and use it in another project.
VS post link errors LNK2001

let me show the code and error .
my test.hxx
//////    test.hxx
///////
//////
/////   odb compile command
   /*
       odb -I D:\ODB\odbfiles
       -I E:\boost_1_67_0
       -d pgsql
      --profile boost
       --export-symbol  ODB_MODULE_EXPORT
      --generate-query
     --generate-schema
      --schema-format sql
        test.hxx
*/
#pragma once
#ifdef BUILD_EXPORT
#define ODB_MODULE_EXPORT __declspec(dllexport)
#elif defined USE_DLL
#define ODB_MODULE_EXPORT __declspec(dllimport)
#else
#define ODB_MODULE_EXPORT
#endif


#include <string>
//  use boost::uuids::uuid as  object Id
#include <boost/uuid/uuid.hpp>
#include <boost/uuid/uuid_generators.hpp>

#include <odb/tr1/memory.hxx>
#include <odb/tr1/lazy-ptr.hxx>

using boost::uuids::uuid;
using std::tr1::shared_ptr;
using std::tr1::weak_ptr;
using odb::tr1::lazy_weak_ptr;
using odb::tr1::lazy_shared_ptr;
using namespace odb::core;
using namespace std;

class SomeB;
#pragma db object pointer(std::tr1::shared_ptr)
class ODB_MODULE_EXPORT SomeA
{
public:
SomeA() {}
friend class odb::access;
#pragma db id
uuid m_Id;

string m_strNodeId;
#pragma db inverse(m_SupA)
vector<lazy_weak_ptr<SomeB> >  m_vBs;

};
#pragma db object pointer(std::tr1::shared_ptr)
class ODB_MODULE_EXPORT SomeB
{
public:
SomeB() {}
friend class odb::access;
#pragma db id
uuid m_Id;
string m_strNodeId;
#pragma db on_delete(cascade)
lazy_shared_ptr<SomeA> m_SupA;
};

#pragma db view object(SomeB) pointer(std::tr1::shared_ptr)
struct ODB_MODULE_EXPORT B_NodeId
{
string m_strNodeId;
};

///////
///////   here is main.cpp  in another project .
//////   this main.cpp works well when it is builded with
////    test.hxx , test-odb.hxx,test-odb.cxx ......
/////     as an exe
/////  so I just remove main.cpp from project and build remain files
/////  and export them as DLL.
/////
////////  I copy the main.cpp to another project and import previous DLL
///////    LINK error occured
//////    error messages is listed at the bottom

#include "database.hxx"
#include <windows.h>
#include "test.hxx"
#include "test-odb.hxx"
#include <boost/uuid/random_generator.hpp>
using boost::uuids::random_generator;
using namespace odb::core;
// using namespace boost::uuids;

int main()
{

shared_ptr<database> db(new odb::pgsql::database("postgres", "123456",
"postgres", "localhost", 5432));
try
{
transaction t(db->begin());
random_generator rgen;
shared_ptr<SomeA>  SomeA1(new SomeA);
SomeA1->m_Id = rgen();
SomeA1->m_strNodeId = "SomeA1";
uuid SomeA1Id = db->persist(SomeA1);
vector<uuid>  vSomeBs;
for (unsigned int i = 0; i < 5; i++)
{
shared_ptr<SomeB> tempB(new SomeB);
tempB->m_Id = rgen();
tempB->m_strNodeId = "SomeB_" + to_string(i);
tempB->m_SupA = SomeA1;
vSomeBs.emplace_back(db->persist(tempB));
}
t.commit();
t.reset(db->begin());
result<B_NodeId>
resB_NodeIds(db->query<B_NodeId>(odb::query<B_NodeId>::SupA == SomeA1Id));

for (auto iB : resB_NodeIds)
{
cout << "B_NodeId : " << iB.m_strNodeId << endl;

}

db->erase<SomeA>(SomeA1Id);
t.commit();


}
catch (const odb::exception& odberror)
{
cerr << odberror.what() << endl;
}
catch (...)
{


}
system("pause");
return 0;
}
////////
/////// this is link error tips
///////
LNK2001 unsolved external symbol "public: static struct
odb::pgsql::query_column<struct boost::uuids::uuid,14> const
odb::pointer_query_columns<class SomeB,2,class
odb::access::object_traits_impl<class SomeB,2> >::SupA" (?SupA@
?$pointer_query_columns@VSomeB@@$01V?$object_traits_impl@VSomeB@@$01@access
@odb@@@odb@@2U?$query_column@Uuuid@uuids@boost@@$0O@@pgsql@2@B)
structviewDllTest E:\structviewDllTest\main.obj 1

odb  version: 2.4.0 release
OS  : win10
Compiler: VS2017
help!!
From boris at codesynthesis.com  Mon Nov 12 08:24:41 2018
From: boris at codesynthesis.com (Boris Kolpackov)
Date: Mon Nov 12 08:35:01 2018
Subject: [odb-users] Questions about enable cross-database access
In-Reply-To: <CAD9VYp=1d189xGgOSRKifzR8FygUo3BqW4h6_Z9Hbc+P-nW0Pw@mail.gmail.com>
References: <CAD9VYp=1d189xGgOSRKifzR8FygUo3BqW4h6_Z9Hbc+P-nW0Pw@mail.gmail.com>
Message-ID: <boris.20181112152009@codesynthesis.com>

Music samal <zxbzswxr@gmail.com> writes:

> Does odb support cross-database access ?
> 
> eg: A member in Table A of database AAA has foreign key constraint with
> Table B in database BBB.

If/how this works is database-specific with the only mechanism provided
by ODB being support for qualifying the database name with a schema. See
Section 14.1.8 "schema" for details.

From boris at codesynthesis.com  Mon Nov 12 08:31:41 2018
From: boris at codesynthesis.com (Boris Kolpackov)
Date: Mon Nov 12 08:41:59 2018
Subject: [odb-users] Can I use relationship and polymorphic at the same
	time?
In-Reply-To: <20181112091818.B350A5D0009A@webmail.sinamail.sina.com.cn>
References: <20181112091818.B350A5D0009A@webmail.sinamail.sina.com.cn>
Message-ID: <boris.20181112152723@codesynthesis.com>

Jerry <kexuetutu@sina.com> writes:

> std::map<unsigned long, std::shared_ptr<B>> m_CheckSectionResultTable;
>
> When I compile the File2 with ODB, it tells me this
> ElementDesignResult.h:40:68: error: unable to map C++ type '::std::map< long
> unsigned int, ::std::shared_ptr< ::SectionDesignResultBase > >::mapped_type'
> used in data member 'm_CheckSectionResultTable' to a SQLite database type

This is most likely caused by shared_ptr not being the object pointer
of B. See Section 3.3 "Object and View Pointers" for details.


> 2. I'm confuse with the "value" and "object" [...]
> 3. I'm confuse with the "abstract" useage [...]

These are explained in the manual. Make sure you read through Chapter 3,
"Working with Persistent Objects" in its entirety.

From biohazard at hixxy.org  Thu Nov 15 05:47:14 2018
From: biohazard at hixxy.org (Biohazard)
Date: Thu Nov 15 05:58:01 2018
Subject: [odb-users] Fwd: Getting "different libodb-boost interface
 versions" when compiling from source
In-Reply-To: <CAMy2XzDae5uRtagco0R6ERPEe-Q4rE78PDgLxRr4waH5+X-pyw@mail.gmail.com>
References: <CAMy2XzDae5uRtagco0R6ERPEe-Q4rE78PDgLxRr4waH5+X-pyw@mail.gmail.com>
Message-ID: <CAMy2XzCoBDDw0OkWtPCdbYKABt-+qtb5rMH=8kdcw6Hs2M=BaA@mail.gmail.com>

Hello,

I discovered this
<https://www.codesynthesis.com/pipermail/odb-users/2018-March/003972.html>
thread when having trouble using ODB with c++17 and the proceeded to give
compiling the provided beta
<https://www.codesynthesis.com/pipermail/odb-users/2018-March/003974.html>
a try. Now I'm getting version mismatch errors that I can't figure out how
to fix.

These are the offending errors:

src/data-odb.hpp:12:4: error: #error ODB and C++ compilers see different
libodb-boost interface versions


and:


src/data-odb.hpp:22:2: error: #error ODB runtime version mismatch


Are you able to advise me on how to solve this? Also, do you have any idea
when the next stable release of ODB will be?

Cheers,
Troy
From boris at codesynthesis.com  Thu Nov 15 08:10:55 2018
From: boris at codesynthesis.com (Boris Kolpackov)
Date: Thu Nov 15 08:21:23 2018
Subject: [odb-users] Fwd: Getting "different libodb-boost interface
	versions" when compiling from source
In-Reply-To: <CAMy2XzCoBDDw0OkWtPCdbYKABt-+qtb5rMH=8kdcw6Hs2M=BaA@mail.gmail.com>
References: <CAMy2XzDae5uRtagco0R6ERPEe-Q4rE78PDgLxRr4waH5+X-pyw@mail.gmail.com>
	<CAMy2XzCoBDDw0OkWtPCdbYKABt-+qtb5rMH=8kdcw6Hs2M=BaA@mail.gmail.com>
Message-ID: <boris.20181115150620@codesynthesis.com>

Biohazard <biohazard@hixxy.org> writes:

> Now I'm getting version mismatch errors that I can't figure out how to fix.

You need to use matching versions of the ODB compiler and all the
runtime libraries (libodb*). Also, after upgrading make sure that
you have re-generated all the *-odb files with the new ODB compiler.


> Also, do you have any idea when the next stable release of ODB will be?

We are working towards a more continuous delivery and the new recommended
way to acquire ODB is via build2 packages. Here are the instructions:

https://codesynthesis.com/products/odb/doc/install-build2.xhtml

We haven't packages the Boost and Qt profiles yet but can do that
quickly if you would like to give it a try.

From fengzhiwuxing05 at 163.com  Tue Nov 20 20:12:04 2018
From: fengzhiwuxing05 at 163.com (=?gb2312?B?yqK35g==?=)
Date: Wed Nov 21 05:44:23 2018
Subject: [odb-users] How should I use odb on ios,
 and how should I compile static libraries that are available on ios
Message-ID: <C7747ED8-0FA5-4BF7-9321-5BED7D1823DF@163.com>

How should I use odb on ios, and how should I compile static libraries that are available on ios
From lfiedler at informatik.uni-leipzig.de  Wed Nov 21 05:42:30 2018
From: lfiedler at informatik.uni-leipzig.de (Lisa Fiedler)
Date: Wed Nov 21 05:53:26 2018
Subject: [odb-users] Transaction within ODB Object class
Message-ID: <8068af94-4f01-a3e8-61ee-82071b737e4d@informatik.uni-leipzig.de>

Dear ODB community,

I was trying to execute a databank transaction within an ODB Object 
class. That is I wanted to alter some of the attributes and update them 
in the databank within a member function. I therefore provided the 
databank object as parameter to the member function.

However, I did not get this to work out. Is this even possible and if so 
how?


Thanks. Best regards.

From boris at codesynthesis.com  Thu Nov 22 11:11:04 2018
From: boris at codesynthesis.com (Boris Kolpackov)
Date: Thu Nov 22 11:21:58 2018
Subject: [odb-users] Transaction within ODB Object class
In-Reply-To: <8068af94-4f01-a3e8-61ee-82071b737e4d@informatik.uni-leipzig.de>
References: <8068af94-4f01-a3e8-61ee-82071b737e4d@informatik.uni-leipzig.de>
Message-ID: <boris.20181122180830@codesynthesis.com>

Lisa Fiedler <lfiedler@informatik.uni-leipzig.de> writes:

> I was trying to execute a databank transaction within an ODB Object class.
> That is I wanted to alter some of the attributes and update them in the
> databank within a member function. I therefore provided the databank object
> as parameter to the member function.
> 
> However, I did not get this to work out. Is this even possible and if so
> how?

It's hard to answer your question without more details. Specifically,
what exactly you tried to do and what result you got (exceptions, etc).
Showing the relevant code fragment is always helpful.

From hua.wang at attobio.com  Tue Nov 27 23:29:04 2018
From: hua.wang at attobio.com (=?gb2312?B?zfW7qg==?=)
Date: Wed Nov 28 05:24:21 2018
Subject: [odb-users] how to use ODB for paged query
Message-ID: <000001d486d2$e569d740$b03d85c0$@attobio.com>

Hi Sir,

       

       I can?t find the solution for paged query of ODB, could  you give me
some advice for this section, Thanks!

 

       For example: there is a table have 1000 records, I want to get 100
items each time.

 

??   Walker

?????     ???

???????????????

Attogen Biomedical (Suzhou) Inc.Ltd.

TEL?400-828-7399; FAX: 0512-62863009 ;Mobile:15151881025

E-Mail: hua.wang@attobio.com     Website: www.attobio.com

?????????????218??????B3?401??

 

From boris at codesynthesis.com  Thu Nov 29 06:57:26 2018
From: boris at codesynthesis.com (Boris Kolpackov)
Date: Thu Nov 29 07:08:42 2018
Subject: [odb-users] how to use ODB for paged query
In-Reply-To: <000001d486d2$e569d740$b03d85c0$@attobio.com>
References: <000001d486d2$e569d740$b03d85c0$@attobio.com>
Message-ID: <boris.20181129135557@codesynthesis.com>

?? <hua.wang@attobio.com> writes:

> For example: there is a table have 1000 records, I want to get 100
> items each time.

This (the term is "pagination", BWT) is normally done in a database-
specific way. See this earlier post for details:

https://www.codesynthesis.com/pipermail/odb-users/2012-January/000429.html

From zxbzswxr at gmail.com  Thu Nov 29 20:50:24 2018
From: zxbzswxr at gmail.com (Music samal)
Date: Fri Nov 30 05:02:54 2018
Subject: [odb-users] Question about complex query implementing
Message-ID: <CAD9VYpnPDQb6-DxTHiWtVp1KURwWMBGEWLy6yhk+6cTqUpcSNA@mail.gmail.com>

If I have a class which has a std::string menber

and It is stored in database as Name + index form

#pragma db object
class A{
public:
   A(){}
   friend class odb::access;
  #pragma db id
   uuid  m_id;
  #pragma db column("name")
  std::string m_strName;
};

If I want to store A  object in the database, and make them show like that

A1 has name AName_001;
A2 has name  AName_002;
.....
AXX  has name  AName_0XX;
.....
AZZZ has name  AName_ZZZ;

A1,A2.... AXX ....AZZZ  are all A objects.

If I want to query the an A object with this name form  AName_XXX which has
the biggist index, maybe it's AName_657 or other number and I want to
return this number.
what should I do to implement this query