CREATE TABLE customer

(

cust_id smallint NULL,

cust_name varchar(50) NULL,

cust_addr1 varchar(50) NULL,

cust_addr2 varchar(50) NULL,

cust_city varchar(50) NULL,

cust_state char(2) NULL,

cust_postal_code varchar(10) NULL,

cust_phone varchar(20) NULL,

cust_fax varchar(20) NULL,

cust_email varchar(30) NULL,

cust_web_url varchar(100) NULL

)

Avec 1000 lignes dans la table voici le résultat fournit par POWER AMC 9.5

–POWER AMC 9.5

Estimation de la taille de la base de donnes "ModeleConceptuelDonnees_1"…

Nombre Taille estime Objet

————————- ———————– —————————————————-

1.000 405 Ko Table "customer"

————————- ———————– —————————————————-

405 Ko Espace total estimé

Nous allons maintenant utiliser la procédure de Tim Laqua. cette procédure est détaillée ici

–> La table de définition des types : les types Geography et Geometry ne sont pas pris en compte

CREATE TYPE TableColumnDefinition AS TABLE
  ([DataType] VARCHAR(16) NOT NULL
  ,[Length] INT
  ,[IsKey] BIT
  ,[DataLength] AS
    CASE  
      WHEN [DataType] = 'BIT' THEN 0.125
      WHEN [DataType] = 'TINYINT' THEN 1
      WHEN [DataType] = 'SMALLINT' THEN 2
      WHEN [DataType] IN ('INT', 'SMALLMONEY', 'REAL', 'SMALLDATETIME') THEN 4
      WHEN [DataType] IN ('BIGINT', 'DATETIME', 'MONEY') THEN 8
      WHEN [DataType] = 'UNIQUEIDENTIFIER' THEN 16
      WHEN [DataType] = 'NVARCHAR' THEN [Length] * 2 + 2
      WHEN [DataType] = 'VARCHAR' THEN [Length] + 2  -- DOESN'T SUPPORT MAX
      WHEN [Datatype] = 'DATE' THEN 3  
      WHEN [Datatype] = 'TIME' THEN 5 -- Worst case
      WHEN [Datatype] = 'DATETIME2' THEN 8 -- Worst case
      WHEN [Datatype] = 'DATETIMEOFFSET' THEN 10 -- Worst case
      WHEN [DataType] = 'CHAR' THEN [Length]
      WHEN [DataType] = 'NCHAR' THEN [Length] * 2 + 2
      WHEN [DataType] = 'BINARY' THEN [Length]
      WHEN [DataType] = 'VARBINARY' THEN [Length] + 2
      WHEN [Datatype] = 'TIMESTAMP' THEN 8
      WHEN [DataType] = 'XML' THEN [Length]  -- Estimate an average size in bytes, 2GB max
      WHEN [DataType] IN ('DECIMAL', 'NUMERIC') THEN  
        CASE  
          WHEN [Length] BETWEEN 1 AND 9  THEN 5
          WHEN [Length] BETWEEN 10 AND 19 THEN 9
          WHEN [Length] BETWEEN 20 AND 28 THEN 13
          WHEN [Length] BETWEEN 29 AND 38 THEN 17
        END
      WHEN [DataType] = 'FLOAT' THEN
        CASE
          WHEN [Length] BETWEEN 1 AND 24 THEN 4
          WHEN [Length] BETWEEN 25 AND 53 THEN 8
          WHEN [Length] IS NULL THEN 8  -- Default n is 53
        END
      ELSE 0
    END
  ,[IsVariableLength] AS
    CASE  
      WHEN [DataType] IN ('VARCHAR', 'NVARCHAR', 'VARBINARY') THEN 1
      ELSE 0
    END)

–> La procédure stockée de calcul

/*************************************************************************************
***
*** Procedure:      [Utility_EstimateClusteredIndexSize]
*** Purpose:        Estimates the amount of space needed for a given clustered index
*** Methodology:    http://msdn.microsoft.com/en-us/library/ms178085.aspx
***      
***      
*** Author:          Tim Laqua
*** Date Created:    2009-10-15  
***  
*** Revision History
*** Date    Author      Description
*** 2009-10-15  tl        Created
*************************************************************************************/
ALTER PROCEDURE [dbo].[Utility_EstimateClusteredIndexSize]
(
   @Num_Rows FLOAT
  ,@ClusteredIndexIsUnique BIT
  ,@Fill_Factor FLOAT
  ,@TableColumn TableColumnDefinition READONLY
)
AS  
 
SET NOCOUNT ON
 
DECLARE
   @Num_Cols FLOAT = 0          -- total number of columns (fixed-length and variable-length)
  ,@Fixed_Data_Size FLOAT = 0      -- total byte size of all fixed-length columns
  ,@Num_Variable_Cols FLOAT  = 0      -- number of variable-length columns
  ,@Max_Var_Size FLOAT  = 0        -- maximum byte size of all variable-length columns
  ,@Variable_Data_Size FLOAT = 0
 
DECLARE @VAR TABLE
  ([Name] VARCHAR(64)
  ,[VALUE] FLOAT
  ,[DisplayValue] AS
    CASE
      WHEN LOWER([Name]) LIKE '%size%' OR LOWER([Name]) LIKE '%space%' THEN
        CASE  
          WHEN [VALUE] < 1024 THEN CAST(CAST(ROUND([VALUE], 3) AS NUMERIC(16,0)) AS VARCHAR(16)) + ' B'
          WHEN [VALUE] < 1024*1024 THEN CAST(CAST(ROUND([VALUE]/1024, 3) AS NUMERIC(16,3)) AS VARCHAR(16)) + ' KB'
          WHEN [VALUE] < 1024*1024*1024 THEN CAST(CAST(ROUND([VALUE]/1024/1024, 3) AS NUMERIC(16,3)) AS VARCHAR(16)) + ' MB'
          ELSE CAST(CAST(ROUND([VALUE]/1024/1024/1024, 3) AS NUMERIC(16,3)) AS VARCHAR(16)) + ' GB'
        END
      ELSE CAST(FLOOR([VALUE]) AS VARCHAR(16))
    END)
 
 
-- Leaf level data
SELECT  
   @Num_Variable_Cols = COUNT(1)
  ,@Max_Var_Size = ISNULL(SUM([DataLength]), 0)
FROM @TableColumn WHERE [IsVariableLength] = 1
 
SELECT  
   @Num_Cols = COUNT(1) + @Num_Variable_Cols
  ,@Fixed_Data_Size = CEILING(ISNULL(SUM([DataLength]), 0))
FROM @TableColumn WHERE [IsVariableLength] = 0
 
 
INSERT INTO @VAR VALUES ('@Fixed_Data_Size', @Fixed_Data_Size)
 
IF @ClusteredIndexIsUnique <> 0
BEGIN
  SET @Num_Cols += 1
  IF @Num_Variable_Cols > 0
    SET @Num_Variable_Cols += 1
  IF @Max_Var_Size > 0
    SET @Max_Var_Size += 4
END
 
DECLARE @Null_Bitmap INT = CEILING(2 + ((@Num_Cols + 7) / 8))
INSERT INTO @VAR VALUES ('@Null_Bitmap', @Null_Bitmap)
 
-- if there are variable columns
IF @Num_Variable_Cols > 0
  SET @Variable_Data_Size = 2 + (@Num_Variable_Cols * 2) + @Max_Var_Size  
INSERT INTO @VAR VALUES ('@Num_Cols', @Num_Cols)
INSERT INTO @VAR VALUES ('@Num_Variable_Cols', @Num_Variable_Cols)
INSERT INTO @VAR VALUES ('@Max_Var_Size', @Max_Var_Size)
 
DECLARE @Row_Size FLOAT = CEILING(@Fixed_Data_Size + @Variable_Data_Size + @Null_Bitmap + 4 )
INSERT INTO @VAR VALUES ('@Row_Size', @Row_Size)
 
DECLARE @Rows_Per_Page FLOAT = FLOOR(8096 / (@Row_Size + 2))
INSERT INTO @VAR VALUES ('@Rows_Per_Page', @Rows_Per_Page)
 
DECLARE @Free_Rows_Per_Page FLOAT = FLOOR(8096 * ((100 - @Fill_Factor) / 100) / (@Row_Size + 2) )
INSERT INTO @VAR VALUES ('@Free_Rows_Per_Page', @Free_Rows_Per_Page)
 
DECLARE @Num_Leaf_Pages FLOAT = CEILING(@Num_Rows / (@Rows_Per_Page - @Free_Rows_Per_Page) )
INSERT INTO @VAR VALUES ('@Num_Leaf_Pages', @Num_Leaf_Pages)
 
DECLARE @Leaf_space_used FLOAT = 8192 * @Num_Leaf_Pages
INSERT INTO @VAR VALUES ('@Leaf_space_used', @Leaf_space_used)
 
-- Index Information
DECLARE
   @Num_Key_Cols FLOAT = 0      -- total number of key columns (fixed-length and variable-length)
  ,@Fixed_Key_Size FLOAT = 0      -- total byte size of all fixed-length key columns
  ,@Num_Variable_Key_Cols FLOAT = 0  -- number of variable-length key columns
  ,@Max_Var_Key_Size FLOAT = 0    -- maximum byte size of all variable-length key columns
 
 
SELECT  
   @Num_Variable_Key_Cols = COUNT(1)
  ,@Max_Var_Key_Size = ISNULL(SUM([DataLength]), 0)
FROM @TableColumn  
WHERE  
  [IsVariableLength] = 1  
  AND [IsKey] = 1
 
SELECT  
   @Num_Key_Cols = COUNT(1) + @Num_Variable_Key_Cols
  ,@Fixed_Key_Size = ISNULL(SUM([DataLength]), 0)
FROM @TableColumn  
WHERE  
  [IsVariableLength] = 0
  AND [IsKey] = 1
 
IF @ClusteredIndexIsUnique <> 0
BEGIN
  SET @Num_Key_Cols += 1
  IF @Num_Variable_Key_Cols > 0
    SET @Num_Variable_Key_Cols += 1
  IF @Max_Var_Key_Size > 0
    SET @Max_Var_Key_Size += 4
END
INSERT INTO @VAR VALUES ('@Num_Variable_Key_Cols', @Num_Variable_Key_Cols)
INSERT INTO @VAR VALUES ('@Max_Var_Key_Size', @Max_Var_Key_Size)
INSERT INTO @VAR VALUES ('@Num_Key_Cols', @Num_Key_Cols)
 
-- Who would seriously have a nullable key column?  ridiculous.
DECLARE @Index_Null_Bitmap FLOAT = 2 + ((@Num_Key_Cols + 7) / 8)  
INSERT INTO @VAR VALUES ('@Index_Null_Bitmap', @Index_Null_Bitmap)
 
DECLARE @Variable_Key_Size FLOAT = 0
 
IF @Max_Var_Key_Size > 0
  SET @Variable_Key_Size = 2 + (@Num_Variable_Key_Cols * 2) + @Max_Var_Key_Size  
INSERT INTO @VAR VALUES ('@Variable_Key_Size', @Variable_Key_Size)
 
DECLARE @Index_Row_Size FLOAT = @Fixed_Key_Size + @Variable_Key_Size + @Index_Null_Bitmap + 1 + 6
INSERT INTO @VAR VALUES ('@Index_Row_Size',@Index_Row_Size )
 
DECLARE @Index_Rows_Per_Page  FLOAT = FLOOR(8096 / (@Index_Row_Size + 2))
INSERT INTO @VAR VALUES ('@Index_Rows_Per_Page', @Index_Rows_Per_Page)
 
DECLARE @Non_Leaf_Levels FLOAT = 1
 
-- Log base @Non_Leaf_Levels hack
WHILE (@Num_Leaf_Pages / @Index_Rows_Per_Page) > POWER(@Index_Rows_Per_Page,@Non_Leaf_Levels)
  SET @Non_Leaf_Levels += 1
 
SET @Non_Leaf_Levels += 1
INSERT INTO @VAR VALUES ('@Non_Leaf_Levels', @Non_Leaf_Levels)
 
-- Summation hack
DECLARE  
   @Num_Index_Pages FLOAT = 0
  ,@Summand INT = @Non_Leaf_Levels
 
WHILE @Summand > 0
BEGIN
  SET @Num_Index_Pages += CEILING(@Num_Leaf_Pages/POWER(@Index_Rows_Per_Page, @Summand))
  SET @Summand -= 1
END
INSERT INTO @VAR VALUES ('@Num_Index_Pages', @Num_Index_Pages)
 
DECLARE @Index_Space_Used FLOAT = 8192 * @Num_Index_Pages  
INSERT INTO @VAR VALUES ('@Index_Space_Used', @Index_Space_Used)
 
DECLARE @Clustered_Index_Size FLOAT = @Leaf_Space_Used + @Index_Space_used
INSERT INTO @VAR VALUES ('@Clustered_Index_Size', @Clustered_Index_Size)
 
SELECT * FROM @VAR

–> Test de la procédure en utilisant la définition (DDL) de la table customer

DECLARE @TableColumn TableColumnDefinition

INSERT INTO @TableColumn

VALUES

('smallint',NULL,0)

,('VARCHAR',50,0)

,('VARCHAR',50,0)

,('VARCHAR',50,0)

,('VARCHAR',50,0)

,('CHAR',2,0)

,('VARCHAR',10,0)

,('VARCHAR',20,0)

,('VARCHAR',20,0)

,('VARCHAR',30,0)

,('VARCHAR',100,0)

EXEC [dbo].[Utility_EstimateClusteredIndexSize]

@Num_Rows = 1 – number of rows in the table

,@ClusteredIndexIsUnique = 0 – is it?

,@Fill_Factor = 90 – page fill factor

,@TableColumn = @TableColumn – definition of table columns

Résultat

——————————

@Row_Size 431 octets

@Rows_Per_Page 18

Pour les 1000 lignes, l'estimation de la taille de la base = 431 octets X 1000 = 421 Ko

–> Que peut-on dire ?

POWER AMC estime la taille de la base à 405 Ko et la procédure basée sur la méthodologie Microsoft affiche 421 Ko. à mon humble avis ces résultats sont proches.

Qu’en pensez-vous ?

————————————————————————-
Auteur : Etienne ZINZINDOHOUE
————————————————————————-