Some important views of SQL Server 1

The first one:

Sys.indexs Each heap has a row with the index on it.

The second one:

Sys.partitions returns one row per heap with each partition of the index. Each table can have a maximum of 1000 extents.

The third one:

Sys. Allocation_units a set of special types of pages in a partition is called an allocation unit. (Inline data page, row overflow page, large object data page)

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There can be more than one table in a partition, so Sys.partitions has a one-to-many relationship with Sys.indexs. So you can put two unions on a object_id,index_id column.

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A partition can contain multiple (three) allocation units so sys.partitions has a one-to-many relationship with Sys.allocation_units.

SYS.ALLOCATION_UNITS.CONTAINER_ID refers to sys.partitions.partition_id, which means they can be combined with these two columns.

Some important views of SQL Server 1