在 Apache Ignite 中使用 linq 进行左连接时如何解决“意外查询源：在 CacheQueryable 中加入 ICacheEntry”异常？

Question

我正在尝试使用 linq 在存储在 Apache Ignite 中的两个表之间进行左连接。它是一个 C# 控制台应用程序。我正在使用 .NET 6 以及 Apache.Ignite 2.16.0 和 Apache.Ignite.Linq 2.16.0 作为 NuGet 包。我正在运行 Windows 10 AMD64 和 Apache Ignite 版本 2.16.0 请找到下面的代码：

static void Main(string[] args)
{
    try
    {
        var cfg = new IgniteClientConfiguration
        {
            Endpoints = new[] { "127.0.0.1:10800" }
        };

        using (var client = Ignition.StartClient(cfg))
        {
            var empQueryEntity = new QueryEntity(typeof(int), typeof(Employee));
            var empCacheConfig = new CacheClientConfiguration("employee-cache", empQueryEntity);
            var empCache = client.GetOrCreateCache<int, Employee>(empCacheConfig);

            empCache.Query(new SqlFieldsQuery("CREATE TABLE IF NOT EXISTS Employee " +
                "(id int primary key, " +
                "name varchar, " +
                "age int, " +
                "departmentId int)")).GetAll();

            empCache.Query(
                new SqlFieldsQuery("INSERT INTO Employee (_key, id, name, age, departmentId) " +
                                                   "VALUES (1, 1, 'john williams', 25, 1), " +
                                                          "(2, 2, 'danny kent', 30, 2), " +
                                                          "(3, 3, 'julian shea', 25, 1), " +
                                                          "(4, 4, 'dave white', 55, 1) ")
            ).GetAll();

            empCache.Query(
                new SqlFieldsQuery("INSERT INTO Employee (_key, id, name, age) " +
                                                   "VALUES (5, 5, 'robin harrison', 26)")
            ).GetAll();

            var deptQueryEntity = new QueryEntity(typeof(int), typeof(Department));
            var deptCacheConfig = new CacheClientConfiguration("department-cache", deptQueryEntity);
            var deptCache = client.GetOrCreateCache<int, Department>(deptCacheConfig);

            deptCache.Query(new SqlFieldsQuery("CREATE TABLE IF NOT EXISTS DEPARTMENT (" +
                "id int primary key, " +
                "name varchar, " +
                "city varchar)")
            ).GetAll();

            deptCache.Query(
                new SqlFieldsQuery("INSERT INTO DEPARTMENT (_key, id, name, city) " +
                                                    " VALUES (1, 1, 'engineering', 'new jersey')," +
                                                            "(2, 2, 'operations', 'new york') ")
            ).GetAll(); 

            IQueryable<ICacheEntry<int, Employee>> employees = empCache.AsCacheQueryable();
            IQueryable<ICacheEntry<int, Department>> departments = deptCache.AsCacheQueryable();
            
            //left join - not working
            var query1 =
                from employee in employees
                join department in departments on employee.Value.DepartmentId equals department.Value.Id into jt
                from record in jt.DefaultIfEmpty()
                select new
                {
                    empName = employee.Value.Name,
                    deptName = record==null ? "" : record.Value.Name 
                };

            //left join - not working
            var query2 = employees.GroupJoin(departments, employee => employee.Value.DepartmentId, department => department.Value.Id,
                        (employee, department) => new { employee, subgroup = department.DefaultIfEmpty() })
                        .Select(gj => new
                        {
                            empName = gj.employee.Value.Name,
                            deptName = gj.subgroup.FirstOrDefault().Value.Name ?? string.Empty
                        });
            
            //left join - not working
            var query3 =
                from employee in employees
                from department in departments
                     .Where(d => employee.Value.DepartmentId == d.Value.Id)
                     .DefaultIfEmpty()
                select new { 
                    empName = employee.Value.Name, 
                    deptName = department.Value.Name };
            
            
            //left join - not working
            // https://stackoverflow.com/questions/6662887/how-to-achieve-left-excluding-join-using-linq 
            var query4 =
               from employee in employees
               join department in departments on employee.Value.DepartmentId equals department.Value.Id into jt
               from b in jt.DefaultIfEmpty()
               where b == null
               select new { empName = employee.Value.Name,
                            deptName = b.Value.Name };


            //inner join - working
            var query5 =
                from employee in employees
                join department in departments on employee.Value.DepartmentId equals department.Value.Id
                select new
                {
                    empName = employee.Value.Name,
                    deptName = department.Value.Name
                };

            //left join - working
            var query6 = empCache.Query(new SqlFieldsQuery("select t1.name, t2.name from \"employee-cache\".Employee as t1 left join \"department-cache\".Department t2 on t1.departmentId = t2.id")).GetAll();

            foreach (var rec in query1)
            {
                Console.WriteLine(rec.empName + ": " + rec.deptName);
            }
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.ToString());
    }
}

class Employee
{
    [QuerySqlField]
    public int Id { get; set; }

    [QuerySqlField]
    public string Name { get; set; }

    [QuerySqlField]
    public int Age { get; set; }

    [QuerySqlField]
    public int DepartmentId { get; set; }
    public Employee()
    {
        Random random = new Random();
        Id = random.Next();
    }
}
class Department
{
    [QuerySqlField]
    public int Id { get; set; }

    [QuerySqlField]
    public string Name { get; set; }

    [QuerySqlField]
    public string City { get; set; }
    public Department()
    {
        Random random = new Random();
        Id = random.Next();
    }
}

我尝试了 linq 查询和方法语法。他们没有工作。怀疑我的设置可能有一些错误，我尝试使用 linq 进行内部联接，并使用 sql 进行外部联接。他们都工作了。然而，通过 linq 的左连接给出了一个例外：

System.NotSupportedException: Unexpected query source: join ICacheEntry`2 department in CacheQueryable [CacheName=department-cache, TableName=DEPARTMENT, Query=SqlFieldsQuery [Sql=select _T0._KEY, _T0._VAL from "department-cache".DEPARTMENT as _T0, Arguments=[], Local=False, PageSize=1024, EnableDistributedJoins=False, EnforceJoinOrder=False, Timeout=00:00:00, Partitions=[], UpdateBatchSize=1, Colocated=False, Schema=, Lazy=False]] on [employee].Value.DepartmentId equals [department].Value.Id into IEnumerable`1 jt
   at Apache.Ignite.Linq.Impl.ExpressionWalker.GetQuerySource(Expression expression, MemberExpression memberHint)
   at Apache.Ignite.Linq.Impl.ExpressionWalker.GetQuerySource(Expression expression, MemberExpression memberHint)
   at Apache.Ignite.Linq.Impl.ExpressionWalker.GetQuerySource(Expression expression, MemberExpression memberHint)
   at Apache.Ignite.Linq.Impl.ExpressionWalker.GetQuerySource(Expression expression, MemberExpression memberHint)
   at Apache.Ignite.Linq.Impl.AliasDictionary.GetTableAlias(Expression expression)
   at Apache.Ignite.Linq.Impl.CacheQueryExpressionVisitor.VisitQuerySourceReference(QuerySourceReferenceExpression expression)
   at Remotion.Linq.Clauses.Expressions.QuerySourceReferenceExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Remotion.Linq.Parsing.ThrowingExpressionVisitor.Visit(Expression expression)
   at Apache.Ignite.Linq.Impl.CacheQueryExpressionVisitor.Visit(Expression expression)
   at Apache.Ignite.Linq.Impl.CacheQueryExpressionVisitor.VisitBinary(BinaryExpression expression)
   at System.Linq.Expressions.BinaryExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Remotion.Linq.Parsing.ThrowingExpressionVisitor.Visit(Expression expression)
   at Apache.Ignite.Linq.Impl.CacheQueryExpressionVisitor.Visit(Expression expression)
   at Apache.Ignite.Linq.Impl.CacheQueryExpressionVisitor.VisitConditional(ConditionalExpression expression)
   at System.Linq.Expressions.ConditionalExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Remotion.Linq.Parsing.ThrowingExpressionVisitor.Visit(Expression expression)
   at Apache.Ignite.Linq.Impl.CacheQueryExpressionVisitor.Visit(Expression expression)
   at Apache.Ignite.Linq.Impl.CacheQueryExpressionVisitor.VisitArguments(IEnumerable`1 arguments)
   at Apache.Ignite.Linq.Impl.CacheQueryExpressionVisitor.VisitNew(NewExpression expression)
   at System.Linq.Expressions.NewExpression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Remotion.Linq.Parsing.ThrowingExpressionVisitor.Visit(Expression expression)
   at Apache.Ignite.Linq.Impl.CacheQueryExpressionVisitor.Visit(Expression expression)
   at Apache.Ignite.Linq.Impl.CacheQueryModelVisitor.BuildSqlExpression(Expression expression, Boolean useStar, Boolean includeAllFields, Boolean visitSubqueryModel)
   at Apache.Ignite.Linq.Impl.CacheQueryModelVisitor.VisitSelectors(QueryModel queryModel, Boolean includeAllFields)
   at Apache.Ignite.Linq.Impl.CacheQueryModelVisitor.VisitQueryModel(QueryModel queryModel, Boolean includeAllFields, Boolean copyAliases)
   at Apache.Ignite.Linq.Impl.CacheQueryModelVisitor.VisitQueryModel(QueryModel queryModel)
   at Apache.Ignite.Linq.Impl.CacheQueryModelVisitor.GenerateQuery(QueryModel queryModel)
   at Apache.Ignite.Linq.Impl.CacheFieldsQueryExecutor.GetQueryData(QueryModel queryModel)
   at Apache.Ignite.Linq.Impl.CacheFieldsQueryExecutor.ExecuteCollection[T](QueryModel queryModel)
   at Remotion.Linq.Clauses.StreamedData.StreamedSequenceInfo.ExecuteCollectionQueryModel[T](QueryModel queryModel, IQueryExecutor executor)
   at Remotion.Linq.Clauses.StreamedData.StreamedSequenceInfo.ExecuteQueryModel(QueryModel queryModel, IQueryExecutor executor)
   at Remotion.Linq.QueryModel.Execute(IQueryExecutor executor)
   at Apache.Ignite.Linq.Impl.CacheFieldsQueryProvider.Execute(Expression expression)
   at Apache.Ignite.Linq.Impl.CacheFieldsQueryProvider.Execute[TResult](Expression expression)
   at Remotion.Linq.QueryableBase`1.GetEnumerator()

Apache Ignite 按照 [1] 支持 LEFT OUTER JOIN

请让我知道我在哪里犯了错误，或者我这边提供更多信息。

[1] - https://ignite.apache.org/docs/latest/sql-reference/sql-conformance

谢谢你。

我已经尝试过：

工作过

在 C# 中的 sql 中运行相同的查询
在 linq 中运行内连接查询
在 linqpad 中的演示数据库上运行左连接查询
对 C# 中存储为对象的数据进行左连接查询

失败 5）使用 linq 的方法语法运行相同的查询 6) 尝试了如何使用 LINQ 实现 Left Exclusion JOIN？中给出的代码出现错误：

System.NotSupportedException
  HResult=0x80131515
  Message=FROM clause must be IQueryable: from ICacheEntry`2 b in {[jt] => DefaultIfEmpty()}
  Source=Apache.Ignite.Linq
  StackTrace:
   at Apache.Ignite.Linq.Impl.CacheQueryModelVisitor.ValidateFromClause(IFromClause clause)
   at Apache.Ignite.Linq.Impl.CacheQueryModelVisitor.VisitMainFromClause(MainFromClause fromClause, QueryModel queryModel)
   at Remotion.Linq.QueryModelVisitorBase.VisitQueryModel(QueryModel queryModel)
   at Apache.Ignite.Linq.Impl.CacheQueryModelVisitor.VisitQueryModel(QueryModel queryModel, Boolean includeAllFields, Boolean copyAliases)
   at Apache.Ignite.Linq.Impl.CacheQueryModelVisitor.GenerateQuery(QueryModel queryModel)
   at Apache.Ignite.Linq.Impl.CacheFieldsQueryExecutor.ExecuteCollection[T](QueryModel queryModel)
   at Remotion.Linq.Clauses.StreamedData.StreamedSequenceInfo.ExecuteQueryModel(QueryModel queryModel, IQueryExecutor executor)
   at Apache.Ignite.Linq.Impl.CacheFieldsQueryProvider.Execute[TResult](Expression expression)
   at Remotion.Linq.QueryableBase`1.GetEnumerator()
   at IgniteTest.Program.Main(String[] args) in C:\Users\vince\source\repos\ApacheIgniteExample\ApacheIgniteExample\Program.cs:line 202

  This exception was originally thrown at this call stack:
    [External Code]
    IgniteTest.Program.Main(string[]) in Program.cs

Answer 1

使用
```
Join
```
代替
```
GroupJoin
```
在第二个表上使用
```
DefaultIfEmpty
```
执行
```
left outer
```
join

这适用于您的示例：

var linqLeftJoin = employees.Join(
    departments.DefaultIfEmpty(),
    employee => employee.Value.DepartmentId,
    department => department.Value.Id,
    (employee, jt) => new { empName = employee.Value.Name, deptName = jt.Value.Name });

foreach (var rec in linqLeftJoin)
{
    Console.WriteLine(rec.empName + ": " + rec.deptName);
}

在 Apache Ignite 中使用 linq 进行左连接时如何解决“意外查询源：在 CacheQueryable 中加入 ICacheEntry”异常？

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最新问题

在 Apache Ignite 中使用 linq 进行左连接时如何解决“意外查询源：在 CacheQueryable 中加入 ICacheEntry”异常？

问题描述 投票：0回答：1

1个回答

最新问题

问题描述投票：0回答：1