Question

我使用Visual Studio 2015 Professional与Sql Server 2016和EntityFramework 6。在想知道模型生成的缓慢性能后，我在类 EntityStoreSchemaGeneratorDatabaseSchemaLoader 中找到了方法IEnumerable<DataRow> LoadDataTable。

命令的执行有时需要超过2分钟，而使用旧版本的sql server则需要几毫秒。

using (EntityCommand command = CreateFilteredCommand(_connection, sql, null, queryTypes, new List<EntityStoreSchemaFilterEntry>(filters), filterAliases))
{
    using (DbDataReader reader = command.ExecuteReader(CommandBehavior.SequentialAccess))
...

有谁知道，为什么ExecuteReader非常慢？这不是CPU或内存的问题。 也许重要的是，SQL-Server 2016在VM-Ware中运行！

更新

这些语句在SQL-Server 2016中运行几分钟，在2012年需要几毫秒。

exec sp_executesql N'SELECT 
[UnionAll1].[Ordinal] AS [C1], 
[Extent1].[CatalogName] AS [CatalogName], 
[Extent1].[SchemaName] AS [SchemaName], 
[Extent1].[Name] AS [Name], 
[UnionAll1].[Name] AS [C2], 
[UnionAll1].[IsNullable] AS [C3], 
[UnionAll1].[TypeName] AS [C4], 
[UnionAll1].[MaxLength] AS [C5], 
[UnionAll1].[Precision] AS [C6], 
[UnionAll1].[DateTimePrecision] AS [C7], 
[UnionAll1].[Scale] AS [C8], 
[UnionAll1].[IsIdentity] AS [C9], 
[UnionAll1].[IsStoreGenerated] AS [C10], 
CASE WHEN ([Project5].[C2] IS NULL) THEN cast(0 as bit) ELSE [Project5].[C2] END AS [C11]
FROM   (
        SELECT
        quotename(TABLE_SCHEMA) + quotename(TABLE_NAME) [Id]
        ,   TABLE_CATALOG [CatalogName]
        ,   TABLE_SCHEMA [SchemaName]
        ,   TABLE_NAME    [Name]
        FROM
        INFORMATION_SCHEMA.TABLES
        WHERE
        TABLE_TYPE = ''BASE TABLE''
      ) AS [Extent1]
INNER JOIN  (SELECT 
    [Extent2].[Id] AS [Id], 
    [Extent2].[Name] AS [Name], 
    [Extent2].[Ordinal] AS [Ordinal], 
    [Extent2].[IsNullable] AS [IsNullable], 
    [Extent2].[TypeName] AS [TypeName], 
    [Extent2].[MaxLength] AS [MaxLength], 
    [Extent2].[Precision] AS [Precision], 
    [Extent2].[DateTimePrecision] AS [DateTimePrecision], 
    [Extent2].[Scale] AS [Scale], 
    [Extent2].[IsIdentity] AS [IsIdentity], 
    [Extent2].[IsStoreGenerated] AS [IsStoreGenerated], 
    0 AS [C1], 
    [Extent2].[ParentId] AS [ParentId]
    FROM (
          SELECT
          quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME) + quotename(c.COLUMN_NAME) [Id]
          ,   quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME)                             [ParentId]
          ,   c.COLUMN_NAME   [Name]
          ,   c.ORDINAL_POSITION [Ordinal]
          ,   CAST( CASE c.IS_NULLABLE WHEN ''YES'' THEN 1 WHEN ''NO'' THEN 0 ELSE 0 END as bit) [IsNullable]
          ,   CASE
          WHEN c.DATA_TYPE in (''varchar'', ''nvarchar'', ''varbinary'') and
          c.CHARACTER_MAXIMUM_LENGTH = -1 THEN
          c.DATA_TYPE + ''(max)''
          ELSE
          c.DATA_TYPE
          END
          as [TypeName]
          ,   c.CHARACTER_MAXIMUM_LENGTH [MaxLength]
          ,   CAST(c.NUMERIC_PRECISION as integer) [Precision]
          ,   CAST(c.DATETIME_PRECISION as integer)[DateTimePrecision]
          ,   CAST(c.NUMERIC_SCALE as integer) [Scale]
          ,   c.COLLATION_CATALOG [CollationCatalog]
          ,   c.COLLATION_SCHEMA [CollationSchema]
          ,   c.COLLATION_NAME [CollationName]
          ,   c.CHARACTER_SET_CATALOG [CharacterSetCatalog]
          ,   c.CHARACTER_SET_SCHEMA [CharacterSetSchema]
          ,   c.CHARACTER_SET_NAME [CharacterSetName]
          ,   CAST(0 as bit) as [IsMultiSet]
          ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsIdentity'' ) as bit) as [IsIdentity]
          ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsComputed'' ) | CASE WHEN c.DATA_TYPE = ''timestamp'' THEN 1 ELSE 0 END as bit) as [IsStoreGenerated]
          , c.COLUMN_DEFAULT as [Default]
          FROM
          INFORMATION_SCHEMA.COLUMNS c
          INNER JOIN
          INFORMATION_SCHEMA.TABLES t ON
          c.TABLE_CATALOG = t.TABLE_CATALOG AND
          c.TABLE_SCHEMA = t.TABLE_SCHEMA   AND
          c.TABLE_NAME = t.TABLE_NAME       AND
          t.TABLE_TYPE = ''BASE TABLE''
      ) AS [Extent2]
UNION ALL
    SELECT 
    [Extent3].[Id] AS [Id], 
    [Extent3].[Name] AS [Name], 
    [Extent3].[Ordinal] AS [Ordinal], 
    [Extent3].[IsNullable] AS [IsNullable], 
    [Extent3].[TypeName] AS [TypeName], 
    [Extent3].[MaxLength] AS [MaxLength], 
    [Extent3].[Precision] AS [Precision], 
    [Extent3].[DateTimePrecision] AS [DateTimePrecision], 
    [Extent3].[Scale] AS [Scale], 
    [Extent3].[IsIdentity] AS [IsIdentity], 
    [Extent3].[IsStoreGenerated] AS [IsStoreGenerated], 
    6 AS [C1], 
    [Extent3].[ParentId] AS [ParentId]
    FROM (
          SELECT
          quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME) + quotename(c.COLUMN_NAME) [Id]
          ,   quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME)                             [ParentId]
          ,   c.COLUMN_NAME   [Name]
          ,   c.ORDINAL_POSITION [Ordinal]
          ,   CAST( CASE c.IS_NULLABLE WHEN ''YES'' THEN 1 WHEN ''NO'' THEN 0 ELSE 0 END as bit) [IsNullable]
          ,   CASE
          WHEN c.DATA_TYPE in (''varchar'', ''nvarchar'', ''varbinary'') and
          c.CHARACTER_MAXIMUM_LENGTH = -1 THEN
          c.DATA_TYPE + ''(max)''
          ELSE
          c.DATA_TYPE
          END
          as [TypeName]
          ,   c.CHARACTER_MAXIMUM_LENGTH [MaxLength]
          ,   CAST(c.NUMERIC_PRECISION as integer) [Precision]
          ,   CAST(c.DATETIME_PRECISION as integer) as [DateTimePrecision]
          ,   CAST(c.NUMERIC_SCALE as integer) [Scale]
          ,   c.COLLATION_CATALOG [CollationCatalog]
          ,   c.COLLATION_SCHEMA [CollationSchema]
          ,   c.COLLATION_NAME [CollationName]
          ,   c.CHARACTER_SET_CATALOG [CharacterSetCatalog]
          ,   c.CHARACTER_SET_SCHEMA [CharacterSetSchema]
          ,   c.CHARACTER_SET_NAME [CharacterSetName]
          ,   CAST(0 as bit) as [IsMultiSet]
          ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsIdentity'' ) as bit) as [IsIdentity]
          ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsComputed'' ) | CASE WHEN c.DATA_TYPE = ''timestamp'' THEN 1 ELSE 0 END as bit) as [IsStoreGenerated]
          ,   c.COLUMN_DEFAULT [Default]
          FROM
          INFORMATION_SCHEMA.COLUMNS c
          INNER JOIN
          INFORMATION_SCHEMA.VIEWS v ON
          c.TABLE_CATALOG = v.TABLE_CATALOG AND
          c.TABLE_SCHEMA = v.TABLE_SCHEMA AND
          c.TABLE_NAME = v.TABLE_NAME
          WHERE
          NOT (v.TABLE_SCHEMA = ''dbo''
          AND v.TABLE_NAME in(''syssegments'', ''sysconstraints'')
          AND SUBSTRING(CAST(SERVERPROPERTY(''productversion'') as varchar(20)),1,1) = 8)
      ) AS [Extent3]) AS [UnionAll1] ON (0 = [UnionAll1].[C1]) AND ([Extent1].[Id] = [UnionAll1].[ParentId])
LEFT OUTER JOIN  (SELECT 
    [UnionAll2].[Id] AS [C1], 
    cast(1 as bit) AS [C2]
    FROM  (
        SELECT
        quotename(tc.CONSTRAINT_SCHEMA) + quotename(tc.CONSTRAINT_NAME) [Id]
        , quotename(tc.TABLE_SCHEMA) + quotename(tc.TABLE_NAME) [ParentId]
        ,   tc.CONSTRAINT_NAME [Name]
        ,   tc.CONSTRAINT_TYPE [ConstraintType]
        ,   CAST(CASE tc.IS_DEFERRABLE WHEN ''NO'' THEN 0 ELSE 1 END as bit) [IsDeferrable]
        ,   CAST(CASE tc.INITIALLY_DEFERRED WHEN ''NO'' THEN 0 ELSE 1 END as bit) [IsInitiallyDeferred]
        FROM
        INFORMATION_SCHEMA.TABLE_CONSTRAINTS tc
        WHERE tc.TABLE_NAME IS NOT NULL
      ) AS [Extent4]
    INNER JOIN  (SELECT 
        7 AS [C1], 
        [Extent5].[ConstraintId] AS [ConstraintId], 
        [Extent6].[Id] AS [Id]
        FROM  (
        SELECT
        quotename(CONSTRAINT_SCHEMA) + quotename(CONSTRAINT_NAME) [ConstraintId]
        ,   quotename(TABLE_SCHEMA) + quotename(TABLE_NAME) + quotename(COLUMN_NAME) [ColumnId]
        FROM
        INFORMATION_SCHEMA.KEY_COLUMN_USAGE
      ) AS [Extent5]
        INNER JOIN (
          SELECT
          quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME) + quotename(c.COLUMN_NAME) [Id]
          ,   quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME)                             [ParentId]
          ,   c.COLUMN_NAME   [Name]
          ,   c.ORDINAL_POSITION [Ordinal]
          ,   CAST( CASE c.IS_NULLABLE WHEN ''YES'' THEN 1 WHEN ''NO'' THEN 0 ELSE 0 END as bit) [IsNullable]
          ,   CASE
          WHEN c.DATA_TYPE in (''varchar'', ''nvarchar'', ''varbinary'') and
          c.CHARACTER_MAXIMUM_LENGTH = -1 THEN
          c.DATA_TYPE + ''(max)''
          ELSE
          c.DATA_TYPE
          END
          as [TypeName]
          ,   c.CHARACTER_MAXIMUM_LENGTH [MaxLength]
          ,   CAST(c.NUMERIC_PRECISION as integer) [Precision]
          ,   CAST(c.DATETIME_PRECISION as integer)[DateTimePrecision]
          ,   CAST(c.NUMERIC_SCALE as integer) [Scale]
          ,   c.COLLATION_CATALOG [CollationCatalog]
          ,   c.COLLATION_SCHEMA [CollationSchema]
          ,   c.COLLATION_NAME [CollationName]
          ,   c.CHARACTER_SET_CATALOG [CharacterSetCatalog]
          ,   c.CHARACTER_SET_SCHEMA [CharacterSetSchema]
          ,   c.CHARACTER_SET_NAME [CharacterSetName]
          ,   CAST(0 as bit) as [IsMultiSet]
          ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsIdentity'' ) as bit) as [IsIdentity]
          ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsComputed'' ) | CASE WHEN c.DATA_TYPE = ''timestamp'' THEN 1 ELSE 0 END as bit) as [IsStoreGenerated]
          , c.COLUMN_DEFAULT as [Default]
          FROM
          INFORMATION_SCHEMA.COLUMNS c
          INNER JOIN
          INFORMATION_SCHEMA.TABLES t ON
          c.TABLE_CATALOG = t.TABLE_CATALOG AND
          c.TABLE_SCHEMA = t.TABLE_SCHEMA   AND
          c.TABLE_NAME = t.TABLE_NAME       AND
          t.TABLE_TYPE = ''BASE TABLE''
      ) AS [Extent6] ON [Extent6].[Id] = [Extent5].[ColumnId]
    UNION ALL
        SELECT 
        11 AS [C1], 
        [Extent7].[ConstraintId] AS [ConstraintId], 
        [Extent8].[Id] AS [Id]
        FROM  (
        SELECT
        CAST(NULL as nvarchar(1))     [ConstraintId]
        , CAST(NULL as nvarchar(max)) [ColumnId]  
        WHERE 1=2
      ) AS [Extent7]
        INNER JOIN (
          SELECT
          quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME) + quotename(c.COLUMN_NAME) [Id]
          ,   quotename(c.TABLE_SCHEMA) + quotename(c.TABLE_NAME)                             [ParentId]
          ,   c.COLUMN_NAME   [Name]
          ,   c.ORDINAL_POSITION [Ordinal]
          ,   CAST( CASE c.IS_NULLABLE WHEN ''YES'' THEN 1 WHEN ''NO'' THEN 0 ELSE 0 END as bit) [IsNullable]
          ,   CASE
          WHEN c.DATA_TYPE in (''varchar'', ''nvarchar'', ''varbinary'') and
          c.CHARACTER_MAXIMUM_LENGTH = -1 THEN
          c.DATA_TYPE + ''(max)''
          ELSE
          c.DATA_TYPE
          END
          as [TypeName]
          ,   c.CHARACTER_MAXIMUM_LENGTH [MaxLength]
          ,   CAST(c.NUMERIC_PRECISION as integer) [Precision]
          ,   CAST(c.DATETIME_PRECISION as integer) as [DateTimePrecision]
          ,   CAST(c.NUMERIC_SCALE as integer) [Scale]
          ,   c.COLLATION_CATALOG [CollationCatalog]
          ,   c.COLLATION_SCHEMA [CollationSchema]
          ,   c.COLLATION_NAME [CollationName]
          ,   c.CHARACTER_SET_CATALOG [CharacterSetCatalog]
          ,   c.CHARACTER_SET_SCHEMA [CharacterSetSchema]
          ,   c.CHARACTER_SET_NAME [CharacterSetName]
          ,   CAST(0 as bit) as [IsMultiSet]
          ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsIdentity'' ) as bit) as [IsIdentity]
          ,   CAST(columnproperty( object_id(quotename(c.TABLE_SCHEMA) + ''.'' + quotename(c.TABLE_NAME)), c.COLUMN_NAME, ''IsComputed'' ) | CASE WHEN c.DATA_TYPE = ''timestamp'' THEN 1 ELSE 0 END as bit) as [IsStoreGenerated]
          ,   c.COLUMN_DEFAULT [Default]
          FROM
          INFORMATION_SCHEMA.COLUMNS c
          INNER JOIN
          INFORMATION_SCHEMA.VIEWS v ON
          c.TABLE_CATALOG = v.TABLE_CATALOG AND
          c.TABLE_SCHEMA = v.TABLE_SCHEMA AND
          c.TABLE_NAME = v.TABLE_NAME
          WHERE
          NOT (v.TABLE_SCHEMA = ''dbo''
          AND v.TABLE_NAME in(''syssegments'', ''sysconstraints'')
          AND SUBSTRING(CAST(SERVERPROPERTY(''productversion'') as varchar(20)),1,1) = 8)
      ) AS [Extent8] ON [Extent8].[Id] = [Extent7].[ColumnId]) AS [UnionAll2] ON (7 = [UnionAll2].[C1]) AND ([Extent4].[Id] = [UnionAll2].[ConstraintId])
    WHERE [Extent4].[ConstraintType] = N''PRIMARY KEY'' ) AS [Project5] ON [UnionAll1].[Id] = [Project5].[C1]
WHERE  NOT ([Extent1].[Name] LIKE @p0)',N'@p0 nvarchar(4000)',@p0=N'__RefactorLog'

Answer 1

与user1666620预期的一样，这是SQL-Server 2014或更高版本的基数估算的问题。对于给定的查询，它会导致问题，即查询结果的估计被解释为错误。有两种方法可以解决这个问题：

在where子句中为查询提供以下参数：
OPTION(QUERYTRACEON 9481)

用法：
WHERE NOT ([Extent1].[Name] LIKE @p0) OPTION(QUERYTRACEON 9481)',N'@p0 nvarchar(4000)',@p0=N'__RefactorLog'
停用＆＃34;遗产基数估算＆＃34;在数据库上。

数据库 - ＆gt;属性 - ＆gt;选项 - ＆gt;旧版基数估算=开启

使用SQL-Server 2016，EntityFramework 6模型生成速度非常慢

1 个答案: