Add Find_SQL_Server_Integer_Columns_to_Make_Skinnier script

Author: ktaranov

Scripts/Find_SQL_Server_Integer_Columns_to_Make_Skinnier.sql

@@ -0,0 +1,99 @@
+/*
+<documentation>
+  <summary>Find SQL Server Integer Columns to Make Skinnier</summary>
+  <returns>1 data set: temp table #errlog.</returns>
+  <issues>No</issues>
+  <author>Konstantin Taranov</author>
+  <created>2019-07-25</created>
+  <modified>2019-08-14 by Konstantin Taranov</modified>
+  <version>1.0</version>
+  <sourceLink>https://github.com/ktaranov/sqlserver-kit/blob/master/Scripts/Find_SQL_Server_Integer_Columns_to_Make_Skinnier.sql</sourceLink>
+  <originalLink>https://www.mssqltips.com/sqlservertip/6107/find-sql-server-integer-columns-to-make-skinnier/</originalLink>
+</documentation>
+*/
+
+SET NOCOUNT ON;
+
+IF OBJECT_ID(N'dbo.floob', 'U') IS NOT NULL DROP TABLE dbo.floob;
+IF OBJECT_ID(N'dbo.mort', 'U')  IS NOT NULL DROP TABLE dbo.mort;
+
+CREATE TABLE dbo.floob(x bigint, y int, z smallint);
+INSERT dbo.floob(x,y,z) VALUES(1,1,1),(32766,32766,254);
+CREATE TABLE dbo.mort(a int, b tinyint);
+INSERT dbo.mort(a,b) VALUES(1,1),(32768,254);	
+
+IF OBJECT_ID(N'tempdb..#cols', 'U') IS NOT NULL DROP TABLE #cols;
+
+DECLARE @src bigint = 2;
+;WITH types AS 
+(
+  SELECT * FROM 
+  (VALUES
+    (1,0,1, 104, N'bit',      1, 0, 1),
+    (2,1,1, 48,  N'tinyint',  1, 0, 255),
+    (3,1,1, 52,  N'smallint', 2, -(POWER(@src,15)),       (POWER(@src,15)-1)),
+    (4,1,1, 56,  N'int',      4, -(POWER(@src,31)),       (POWER(@src,31)-1)),
+    (5,1,0, 127, N'bigint',   8, -(POWER(@src,62)-1)*2-2, (POWER(@src,62)-1)*2+1)
+  ) AS v(seq,src,trg,type_id,[type],bytes,minval,maxval)
+),
+cols AS
+(
+  SELECT t.[object_id],
+         [schema] = s.name, 
+         [table]  = t.name, 
+         [column] = QUOTENAME(c.name), 
+         [type]   = styp.name + COALESCE(' (alias: ' + utyp.name + ')', ''),
+         c.is_nullable, 
+         trgtyp.seq,
+         trgtyp.type_id, 
+         trgtype = trgtyp.[type],
+         savings = srctyp.bytes - trgtyp.bytes, 
+         trgtyp.minval,
+         trgtyp.maxval,
+         [rowcount] = (SELECT SUM([rows]) FROM sys.partitions
+           WHERE object_id = t.object_id AND index_id IN (0,1))
+  FROM sys.tables AS t
+  INNER JOIN sys.schemas AS s
+  ON s.[schema_id] = t.[schema_id]
+  INNER JOIN sys.columns AS c
+  ON t.[object_id] = c.[object_id]
+  INNER JOIN sys.types AS styp
+  ON c.system_type_id = styp.system_type_id
+  AND c.system_type_id = styp.user_type_id
+  LEFT OUTER JOIN sys.types AS utyp
+  ON c.user_type_id = utyp.user_type_id
+  AND utyp.user_type_id <> utyp.system_type_id
+  INNER JOIN types AS srctyp
+  ON srctyp.type_id = c.system_type_id
+  INNER JOIN types AS trgtyp
+  ON trgtyp.seq < srctyp.seq
+  WHERE srctyp.src = 1
+  AND trgtyp.trg = 1
+)
+SELECT * INTO #cols FROM cols;
+
+DECLARE @sql nvarchar(max) = N';WITH x([object_id], [column], minval, maxval)
+AS (',
+        @core nvarchar(max) = N'
+    SELECT $oid, ''$c'', MIN($c), MAX($c) FROM $obj UNION ALL';
+SELECT @sql += REPLACE(REPLACE(REPLACE(@core, '$oid', RTRIM(object_id)),
+  '$c',[column]),'$obj',QUOTENAME([schema]) + '.' + QUOTENAME([table]))
+  FROM (SELECT [schema],[table],[column],object_id FROM #cols
+  GROUP BY [schema],[table],[column],object_id) AS x;
+SET @sql += N'
+    SELECT NULL,NULL,NULL,NULL
+  ) 
+  SELECT c.[schema], c.[table], c.[column], c.is_nullable,
+    current_type = c.[type], potential_type = c.trgtype,
+    space_savings = c.savings * c.[rowcount], x.minval, x.maxval,
+    range = RTRIM(c.minval) + '' -> '' + RTRIM(c.maxval) 
+  FROM x
+  INNER JOIN #cols AS c 
+  ON x.[object_id] = c.[object_id]
+  AND x.[column] = c.[column]
+  AND x.minval >= c.minval
+  AND x.maxval <= c.maxval;';
+
+--PRINT(@sql);
+
+EXEC sys.sp_executesql @sql;