Question

我正在运行以下查询以获取索引外部碎片：

SELECT SCH.[name] as 'Schema' 
      ,TBL.[name] as 'Table' 
      ,IX.[name] as 'Index'
      ,IXStats.[avg_fragmentation_in_percent]
      ,IXStats.[page_count]
FROM [sys].[dm_db_index_physical_stats] (DB_ID(), NULL, NULL, NULL, NULL) AS IXStats
INNER JOIN [sys].[tables] AS TBL 
    on TBL.[object_id] = IXStats.[object_id]
INNER JOIN [sys].[schemas] SCH 
    on TBL.[schema_id] = SCH.[schema_id]
INNER JOIN [sys].[indexes] AS IX 
    ON IX.[object_id] = IXStats.[object_id]
    AND IXStats.[index_id] = IX.[index_id]
WHERE IXStats.database_id = DB_ID()
ORDER BY IXStats.[avg_fragmentation_in_percent] DESC

对于几个表（没有索引或主键），查询返回碎片。

这怎么可能？ SQL Server是否创建了一些内部索引？

Answer 1

因此，如果您运行查询并抓住index_id列，那么：

SELECT SCH.[name] as 'Schema' 
      ,TBL.[name] as 'Table' 
      ,IX.[name] as 'Index'
      ,IX.index_id
      ,IXStats.[avg_fragmentation_in_percent]
      ,IXStats.[page_count]
FROM [sys].[dm_db_index_physical_stats] (DB_ID(), NULL, NULL, NULL, NULL) AS IXStats
INNER JOIN [sys].[tables] AS TBL 
    on TBL.[object_id] = IXStats.[object_id]
INNER JOIN [sys].[schemas] SCH 
    on TBL.[schema_id] = SCH.[schema_id]
INNER JOIN [sys].[indexes] AS IX 
    ON IX.[object_id] = IXStats.[object_id]
    AND IXStats.[index_id] = IX.[index_id]
WHERE IXStats.database_id = DB_ID()
ORDER BY IXStats.[avg_fragmentation_in_percent] DESC

您应该看到没有为它们定义索引的表的ID为0，这意味着该表是一个堆（即没有聚簇索引的表）。如果您看到索引ID为1，则表示该表是聚簇索引。

有关堆的更多信息，请参阅此处：

Heaps (Tables without Clustered Indexes)

可用于不存在索引的索引统计信息？

1 个答案: