Union all in View Performance issue in SQL Server - sql-server

Question

I have 40 Tables - Table1, Table2 , Table3 ... Table40, all having same columns .
These tables contains distinct data and to identify each table's data , I have a column Reporting_Type which have different value for each table.
For example: column Reporting_Type of Table1 has value Reportin_Type1 and so on.
Please note that each table contains 2-3 million records.
I need to create a view which combines the data from all the tables.
I have simply applied UNION ALL and put the following query :
CREATE VIEW ALL DATA
AS
SELECT
COLUMN1, COLUMN2, COLUMN3, REPORTING_TYPE ..., COLUMN 40
FROM
TABLE1
UNION ALL
SELECT
COLUMN1, COLUMN2, COLUMN3, REPORTING_TYPE ..., COLUMN 40
FROM
TABLE2
UNION ALL
SELECT
COLUMN1, COLUMN2, COLUMN3, REPORTING_TYPE ..., COLUMN 40
FROM
TABLE3
....
SELECT
COLUMN1, COLUMN2, COLUMN3, REPORTING_TYPE ..., COLUMN 40
FROM
TABLE40
The above query takes a lot of time to fetch the data from all the tables.
Could any please suggest any performance tuned query or any other way to create this view in SQL Server 2012?
Apologies if any one find this question too Naive. I am new to database. Kindly let me know if more information is required.

Answer 1

I kindly recommend Clustered Indexes on those table, so should have primary key in all of the tables, if there is a primary key with those tables, try to rebuild or reorganize indexes,to rebuild and reorganize you could also refer below script. Without any cluster index and where condition it would be scan but with Clustered index you would get better performance.
-- Make Sure you have write USE <databasename> statement before executing statement.
-- USE <databasename>
SET NOCOUNT ON;
DECLARE #objectid int;
DECLARE #indexid int;
DECLARE #partitioncount bigint;
DECLARE #schemaname nvarchar(500);
DECLARE #objectname nvarchar(500);
DECLARE #indexname nvarchar(500);
DECLARE #partitionnum bigint;
DECLARE #partitions bigint;
DECLARE #frag float;
DECLARE #command nvarchar(4000);
-- Conditionally select tables and indexes from the sys.dm_db_index_physical_stats function
-- and convert object and index IDs to names.
SELECT
object_id AS objectid,
index_id AS indexid,
partition_number AS partitionnum,
avg_fragmentation_in_percent AS frag
INTO #work_to_do
FROM sys.dm_db_index_physical_stats (DB_ID(), NULL, NULL , NULL, 'LIMITED')
WHERE index_id > 0;
-- Declare the cursor for the list of partitions to be processed.
DECLARE partitions CURSOR FOR SELECT * FROM #work_to_do;
-- Open the cursor.
OPEN partitions;
-- Loop through the partitions.
WHILE (1=1)
BEGIN;
FETCH NEXT
FROM partitions
INTO #objectid, #indexid, #partitionnum, #frag;
IF ##FETCH_STATUS < 0 BREAK;
SELECT #objectname = QUOTENAME(o.name), #schemaname = QUOTENAME(s.name)
FROM sys.objects AS o
JOIN sys.schemas as s ON s.schema_id = o.schema_id
WHERE o.object_id = #objectid;
SELECT #indexname = QUOTENAME(name)
FROM sys.indexes
WHERE object_id = #objectid AND index_id = #indexid;
SELECT #partitioncount = count (*)
FROM sys.partitions
WHERE object_id = #objectid AND index_id = #indexid;
-- 30 is an arbitrary decision point at which to switch between reorganizing and rebuilding.
IF #frag < 30.0 OR #frag >= 5.0
SET #command = N'ALTER INDEX ' + #indexname + N' ON ' + #schemaname + N'.' + #objectname + N' REORGANIZE';
IF #frag >= 30.0 OR #frag < 5.0
SET #command = N'ALTER INDEX ' + #indexname + N' ON ' + #schemaname + N'.' + #objectname + N' REBUILD';
IF #partitioncount > 1
SET #command = #command + N' PARTITION=' + CAST(#partitionnum AS nvarchar(10));
EXEC (#command);
PRINT N'Executed: ' + #command;
END;
-- Close and deallocate the cursor.
CLOSE partitions;
DEALLOCATE partitions;
-- Drop the temporary table.
DROP TABLE #work_to_do;
GO
I also recommend to use cross apply, which is explained in StackOverflow's another thread