Question

I have to write a SQL script to compare the differences between the indices of two tables on SQL Server. How can I get the structure of the indices on a table through a SQL query?

Answer 1

If the two databases are on the same server then you can do a series of queries that outer joins the sys.indexes and sys.index_columns tables on both databases. You will also need to look at sys.index_columns to check that the columns are the same (also check for the same order – this will affect query plans).

If both databases are on different servers you will need to copy the contents of sys.indexes and sys.index_columns onto the other server and do a similar query against your copies of the tables.

An example of such a query might look like (substitute appropriate databases for FOO and BAR and add appropriate filters to the individual queries if you want to look at individual tables):

select *
  from
       (select s1.name           as SchemaName
              ,t1.name           as TableName
              ,c1.name           as ColumnName
              ,i1.name           as IndexName
              ,i1.index_id
              ,c1.column_id
              ,c1.system_type_id
              ,c1.user_type_id
              ,ty1.name          as ColumnType
              ,c1.collation_name  -- Note this is nullable
              ,c1.is_nullable
              ,c1.max_length
              ,c1.[precision]
              ,c1.scale
              ,ic1.index_column_id
              ,ic1.key_ordinal
              ,ic1.partition_ordinal
              ,ic1.is_descending_key
              ,ic1.is_included_column
          from [FOO].sys.schemas s1
          join [FOO].sys.tables t1
            on t1.schema_id = s1.schema_id
          join [FOO].sys.columns c1
            on t1.object_id = c1.object_id
          join [FOO].sys.types ty1
            on ty1.system_type_id = c1.system_type_id
           and ty1.user_type_id = c1.user_type_id
          join [FOO].sys.index_columns ic1
            on ic1.object_id = c1.object_id
           and ic1.column_id = c1.column_id
          join [FOO].sys.indexes i1
            on i1.object_id = ic1.object_id
           and i1.index_id = ic1.index_id) r1
  full outer join
       (select s1.name           as SchemaName
              ,t1.name           as TableName
              ,c1.name           as ColumnName
              ,i1.name           as IndexName
              ,i1.index_id
              ,c1.column_id
              ,c1.system_type_id
              ,c1.user_type_id
              ,ty1.name          as ColumnType
              ,c1.collation_name  -- Note this is nullable
              ,c1.is_nullable
              ,c1.max_length
              ,c1.[precision]
              ,c1.scale
              ,ic1.index_column_id
              ,ic1.key_ordinal
              ,ic1.partition_ordinal
              ,ic1.is_descending_key
              ,ic1.is_included_column
          from [BAR].sys.schemas s1
          join [BAR].sys.tables t1
            on t1.schema_id = s1.schema_id
          join [BAR].sys.columns c1
            on t1.object_id = c1.object_id
          join [BAR].sys.types ty1
            on ty1.system_type_id = c1.system_type_id
           and ty1.user_type_id = c1.user_type_id
          join [BAR].sys.index_columns ic1
            on ic1.object_id = c1.object_id
           and ic1.column_id = c1.column_id
          join [BAR].sys.indexes i1
            on i1.object_id = ic1.object_id
           and i1.index_id = ic1.index_id) r2 
    on r1.SchemaName = r2.SchemaName
   and r1.TableName = r2.TableName
   and r1.ColumnName = r2.ColumnName
   and r1.IndexName = r2.IndexName