{"id":513,"date":"2012-01-18T13:01:00","date_gmt":"2012-01-18T13:01:00","guid":{"rendered":"\/blogs\/joe\/post\/A-small-scale-test-measuring-the-impact-of-data-compression-on-the-transaction-log.aspx"},"modified":"2012-01-18T13:01:00","modified_gmt":"2012-01-18T13:01:00","slug":"a-small-scale-test-measuring-the-impact-of-data-compression-on-the-transaction-log","status":"publish","type":"post","link":"https:\/\/www.sqlskills.com\/blogs\/joe\/a-small-scale-test-measuring-the-impact-of-data-compression-on-the-transaction-log\/","title":{"rendered":"A small-scale test measuring the impact of data compression on the transaction log"},"content":{"rendered":"<p style=\"line-height: 13pt; margin: 0in 0in 10pt\" class=\"MsoNormal\">\n<font face=\"Calibri\"><font style=\"font-size: 11pt\">I received a question today about the impact of data compression on the transaction log.<span>&nbsp; <\/span>While most of the time we talk about data compression from a data page and memory utilization perspective, I hadn&rsquo;t actually directly tested the impact to transaction logging and I wanted to see it for myself.<\/font><span><font style=\"font-size: 11pt\">&nbsp; <\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt\" class=\"MsoNormal\">\n<font face=\"Calibri\"><font style=\"font-size: 11pt\">Here is just a very small scale test using data from AdventureWorks.HumanResources.Employee into two tables &ndash; one with a clustered index that is not using compression and one that is using page compression (I used a separate database just to keep things clean):<\/font><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">USE<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> [CompressionTest]<\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">;<\/font><\/span><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#0000ff\" style=\"font-size: 10pt\">GO<\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#0000ff\" style=\"font-size: 10pt\"><\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">CREATE<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> <span><font color=\"#0000ff\">TABLE<\/font><\/span> [dbo]<span><font color=\"#808080\">.<\/font><\/span>[Employee]<\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">(<\/font><\/span><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[EmployeeID] [int] <span><font color=\"#0000ff\">IDENTITY<\/font><\/span><span><font color=\"#808080\">(<\/font><\/span>1<span><font color=\"#808080\">,<\/font><\/span>1<span><font color=\"#808080\">)<\/font><\/span> <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[NationalIDNumber] [nvarchar]<span><font color=\"#808080\">(<\/font><\/span>15<span><font color=\"#808080\">)<\/font><\/span> <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[ContactID] [int] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[LoginID] [nvarchar]<span><font color=\"#808080\">(<\/font><\/span>256<span><font color=\"#808080\">)<\/font><\/span> <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[ManagerID] [int] <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[Title] [nvarchar]<span><font color=\"#808080\">(<\/font><\/span>50<span><font color=\"#808080\">)<\/font><\/span> <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[BirthDate] [datetime] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[MaritalStatus] [nchar]<span><font color=\"#808080\">(<\/font><\/span>1<span><font color=\"#808080\">)<\/font><\/span> <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[Gender] [nchar]<span><font color=\"#808080\">(<\/font><\/span>1<span><font color=\"#808080\">)<\/font><\/span> <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[HireDate] [datetime] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[SalariedFlag] [bit] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[VacationHours] [smallint] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[SickLeaveHours] [smallint] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[CurrentFlag] [bit] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[rowguid] [uniqueidentifier] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[ModifiedDate] [datetime] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[EncryptedNationalIDNumber2] [varbinary]<span><font color=\"#808080\">(<\/font><\/span>128<span><font color=\"#808080\">)<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#808080\"><font style=\"font-size: 10pt\">)<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> <span><font color=\"#0000ff\">ON<\/font><\/span> [PRIMARY]<\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">;<\/font><\/span><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#0000ff\" style=\"font-size: 10pt\">GO<\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#0000ff\" style=\"font-size: 10pt\"><\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">CREATE<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> <span><font color=\"#0000ff\">CLUSTERED<\/font><\/span> <span><font color=\"#0000ff\">INDEX<\/font><\/span> [IX_Employee] <\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">ON<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> [dbo]<span><font color=\"#808080\">.<\/font><\/span>[Employee] <\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#808080\" style=\"font-size: 10pt\">(<\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[EmployeeID] <\/font><span><font color=\"#0000ff\" style=\"font-size: 10pt\">ASC<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#808080\" style=\"font-size: 10pt\">)<\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">ON<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> [PRIMARY]<\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">;<\/font><\/span><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#0000ff\" style=\"font-size: 10pt\">GO<\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#0000ff\" style=\"font-size: 10pt\"><\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">CREATE<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> <span><font color=\"#0000ff\">TABLE<\/font><\/span> [dbo]<span><font color=\"#808080\">.<\/font><\/span>[Employee_Compressed]<\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">(<\/font><\/span><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[EmployeeID] [int] <span><font color=\"#0000ff\">IDENTITY<\/font><\/span><span><font color=\"#808080\">(<\/font><\/span>1<span><font color=\"#808080\">,<\/font><\/span>1<span><font color=\"#808080\">)<\/font><\/span> <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[NationalIDNumber] [nvarchar]<span><font color=\"#808080\">(<\/font><\/span>15<span><font color=\"#808080\">)<\/font><\/span> <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[ContactID] [int] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[LoginID] [nvarchar]<span><font color=\"#808080\">(<\/font><\/span>256<span><font color=\"#808080\">)<\/font><\/span> <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[ManagerID] [int] <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[Title] [nvarchar]<span><font color=\"#808080\">(<\/font><\/span>50<span><font color=\"#808080\">)<\/font><\/span> <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[BirthDate] [datetime] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[MaritalStatus] [nchar]<span><font color=\"#808080\">(<\/font><\/span>1<span><font color=\"#808080\">)<\/font><\/span> <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[Gender] [nchar]<span><font color=\"#808080\">(<\/font><\/span>1<span><font color=\"#808080\">)<\/font><\/span> <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[HireDate] [datetime] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[SalariedFlag] [bit] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[VacationHours] [smallint] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[SickLeaveHours] [smallint] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[CurrentFlag] [bit] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[rowguid] [uniqueidentifier] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[ModifiedDate] [datetime] <span><font color=\"#808080\">NOT<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL,<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[EncryptedNationalIDNumber2] [varbinary]<span><font color=\"#808080\">(<\/font><\/span>128<span><font color=\"#808080\">)<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#808080\"><font style=\"font-size: 10pt\">)<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> <span><font color=\"#0000ff\">ON<\/font><\/span> [PRIMARY]<\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">;<\/font><\/span><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#0000ff\" style=\"font-size: 10pt\">GO<\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#0000ff\" style=\"font-size: 10pt\"><\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">CREATE<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> <span><font color=\"#0000ff\">CLUSTERED<\/font><\/span> <span><font color=\"#0000ff\">INDEX<\/font><\/span> [IX_Employee_Compressed] <\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">ON<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> [dbo]<span><font color=\"#808080\">.<\/font><\/span>[Employee_Compressed] <\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#808080\" style=\"font-size: 10pt\">(<\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><span><font style=\"font-size: 10pt\">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <\/font><\/span><font style=\"font-size: 10pt\">[EmployeeID] <\/font><span><font color=\"#0000ff\" style=\"font-size: 10pt\">ASC<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#808080\"><font style=\"font-size: 10pt\">)<\/font><\/font><\/span><font style=\"font-size: 10pt\"><span><font color=\"#0000ff\">WITH <\/font><\/span><span><font color=\"#808080\">(<\/font><\/span><span><font color=\"#0000ff\">DATA_COMPRESSION<\/font><\/span><span><font color=\"#808080\">=<\/font><\/span><\/font><span><font style=\"font-size: 10pt\">PAGE<span><font color=\"#808080\">)<\/font><\/span> <span><font color=\"#0000ff\">ON<\/font><\/span> [PRIMARY]<\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#0000ff\" style=\"font-size: 10pt\">GO<\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#0000ff\" style=\"font-size: 12pt\"><\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt\" class=\"MsoNormal\">\n<font face=\"Calibri\"><font style=\"font-size: 11pt\">Now the test is very simple.<span>&nbsp; <\/span>I perform a full backup, and an initial transaction log backup:<\/font><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">BACKUP<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> <span><font color=\"#0000ff\">DATABASE<\/font><\/span> CompressionTest <span><font color=\"#0000ff\">TO<\/font><\/span> <span><font color=\"#0000ff\">DISK<\/font><\/span> <span><font color=\"#808080\">=<\/font><\/span> <span><font color=\"#ff0000\">&#39;c:\\temp\\CompressionTest.bak&#39;<\/font><\/span><\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">;<\/font><\/span><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#808080\" style=\"font-size: 10pt\"><\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span style=\"line-height: 12pt\"><font color=\"#0000ff\"><font style=\"font-size: 10pt\">BACKUP<\/font><\/font><\/span><span style=\"line-height: 12pt\"><font style=\"font-size: 10pt\"> <span><font color=\"#ff00ff\">LOG<\/font><\/span> CompressionTest <span><font color=\"#0000ff\">TO<\/font><\/span> <span><font color=\"#0000ff\">DISK<\/font><\/span> <span><font color=\"#808080\">=<\/font><\/span> <span><font color=\"#ff0000\">&#39;c:\\temp\\throwaway.trn&#39;<\/font><\/span><\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">;<\/font><\/span><\/span><\/font><span style=\"line-height: 12pt\"><\/span>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt\" class=\"MsoNormal\">\n<font face=\"Calibri\"><font style=\"font-size: 11pt\">Next, I insert 290,000 rows into the uncompressed table:<\/font><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">SET<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> <span><font color=\"#0000ff\">NOCOUNT<\/font><\/span> <span><font color=\"#0000ff\">ON<\/font><\/span><\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">;<\/font><\/span><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font color=\"#808080\" style=\"font-size: 10pt\"><\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">INSERT<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> dbo<span><font color=\"#808080\">.<\/font><\/span>Employee<\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#808080\"><font style=\"font-size: 10pt\">(<\/font><\/font><\/span><span><font style=\"font-size: 10pt\">NationalIDNumber<span><font color=\"#808080\">,<\/font><\/span> ContactID<span><font color=\"#808080\">,<\/font><\/span> LoginID<span><font color=\"#808080\">,<\/font><\/span> ManagerID<span><font color=\"#808080\">,<\/font><\/span> Title<span><font color=\"#808080\">,<\/font><\/span> BirthDate<span><font color=\"#808080\">,<\/font><\/span> <\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font style=\"font-size: 10pt\">MaritalStatus<span><font color=\"#808080\">,<\/font><\/span> Gender<span><font color=\"#808080\">,<\/font><\/span> HireDate<span><font color=\"#808080\">,<\/font><\/span> SalariedFlag<span><font color=\"#808080\">,<\/font><\/span> VacationHours<span><font color=\"#808080\">,<\/font><\/span> <\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font style=\"font-size: 10pt\">SickLeaveHours<span><font color=\"#808080\">,<\/font><\/span> CurrentFlag<span><font color=\"#808080\">,<\/font><\/span> rowguid<span><font color=\"#808080\">,<\/font><\/span> ModifiedDate<span><font color=\"#808080\">,<\/font><\/span> EncryptedNationalIDNumber2<\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">)<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">SELECT<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> NationalIDNumber<span><font color=\"#808080\">,<\/font><\/span> ContactID<span><font color=\"#808080\">,<\/font><\/span> LoginID<span><font color=\"#808080\">,<\/font><\/span> ManagerID<span><font color=\"#808080\">,<\/font><\/span> Title<span><font color=\"#808080\">,<\/font><\/span> BirthDate<span><font color=\"#808080\">,<\/font><\/span> <\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font style=\"font-size: 10pt\">MaritalStatus<span><font color=\"#808080\">,<\/font><\/span> Gender<span><font color=\"#808080\">,<\/font><\/span> HireDate<span><font color=\"#808080\">,<\/font><\/span> SalariedFlag<span><font color=\"#808080\">,<\/font><\/span> VacationHours<span><font color=\"#808080\">,<\/font><\/span> <\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font style=\"font-size: 10pt\">SickLeaveHours<span><font color=\"#808080\">,<\/font><\/span> CurrentFlag<span><font color=\"#808080\">,<\/font><\/span> rowguid<span><font color=\"#808080\">,<\/font><\/span> ModifiedDate<span><font color=\"#808080\">,<\/font><\/span> EncryptedNationalIDNumber2<\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">FROM<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> AdventureWorks<span><font color=\"#808080\">.<\/font><\/span>HumanResources<span><font color=\"#808080\">.<\/font><\/span>Employee<\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">;<\/font><\/span><\/span><\/font>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span style=\"line-height: 12pt\"><font color=\"#0000ff\"><font style=\"font-size: 10pt\">GO<\/font><\/font><\/span><span style=\"line-height: 12pt\"><font style=\"font-size: 10pt\"> 1000<\/font><\/span><\/font><span style=\"line-height: 12pt\"><\/span>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt\" class=\"MsoNormal\">\n<font face=\"Calibri\"><font style=\"font-size: 11pt\">Data used is 74,288 KB:<\/font><\/font>\n<\/p>\n<p style=\"line-height: 13pt; text-indent: 0.5in; margin: 0in 0in 10pt\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span style=\"line-height: 12pt\"><font color=\"#0000ff\"><font style=\"font-size: 10pt\">EXEC<\/font><\/font><\/span><span style=\"line-height: 12pt\"><font style=\"font-size: 10pt\"> <span><font color=\"#800000\">sp_spaceused<\/font><\/span><span><font color=\"#0000ff\"> <\/font><\/span><span><font color=\"#ff0000\">&#39;dbo.Employee&#39;<\/font><\/span><\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">;<\/font><\/span><span><\/span><\/span><\/font>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt\" class=\"MsoNormal\">\n<font face=\"Calibri\"><font style=\"font-size: 11pt\">Querying the log record length from fn_dblog shows 120,503,216 bytes:<\/font><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">SELECT<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> <span><font color=\"#ff00ff\">SUM<\/font><\/span><span><font color=\"#808080\">(<\/font><\/span>[log record length]<span><font color=\"#808080\">)<\/font><\/span> <\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span style=\"line-height: 12pt\"><font color=\"#0000ff\"><font style=\"font-size: 10pt\">FROM<\/font><\/font><\/span><span style=\"line-height: 12pt\"><font style=\"font-size: 10pt\"> <span><font color=\"#008000\">fn_dblog<\/font><\/span><span><font color=\"#0000ff\"> <\/font><\/span><span><font color=\"#808080\">(NULL,<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL);<\/font><\/span><\/span><\/font><span style=\"line-height: 14pt\"><\/span>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt\" class=\"MsoNormal\">\n<font face=\"Calibri\"><font style=\"font-size: 11pt\">Backing up the transaction log produces a file that is 121,964 KB in size:<\/font><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">SELECT<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> <span><font color=\"#ff00ff\">SUM<\/font><\/span><span><font color=\"#808080\">(<\/font><\/span>[log record length]<span><font color=\"#808080\">)<\/font><\/span> <\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span style=\"line-height: 12pt\"><font color=\"#0000ff\"><font style=\"font-size: 10pt\">FROM<\/font><\/font><\/span><span style=\"line-height: 12pt\"><font style=\"font-size: 10pt\"> <span><font color=\"#008000\">fn_dblog<\/font><\/span><span><font color=\"#0000ff\"> <\/font><\/span><span><font color=\"#808080\">(NULL,<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL);<\/font><\/span><\/span><\/font><span style=\"line-height: 14pt\"><\/span>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt\" class=\"MsoNormal\">\n<font face=\"Calibri\"><font style=\"font-size: 11pt\">Now to insert rows into the table with data compression:<\/font><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">INSERT<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> dbo<span><font color=\"#808080\">.<\/font><\/span>Employee_Compressed<\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#808080\"><font style=\"font-size: 10pt\">(<\/font><\/font><\/span><span><font style=\"font-size: 10pt\">NationalIDNumber<span><font color=\"#808080\">,<\/font><\/span> ContactID<span><font color=\"#808080\">,<\/font><\/span> LoginID<span><font color=\"#808080\">,<\/font><\/span> ManagerID<span><font color=\"#808080\">,<\/font><\/span> Title<span><font color=\"#808080\">,<\/font><\/span> BirthDate<span><font color=\"#808080\">,<\/font><\/span> <\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font style=\"font-size: 10pt\">MaritalStatus<span><font color=\"#808080\">,<\/font><\/span> Gender<span><font color=\"#808080\">,<\/font><\/span> HireDate<span><font color=\"#808080\">,<\/font><\/span> SalariedFlag<span><font color=\"#808080\">,<\/font><\/span> VacationHours<span><font color=\"#808080\">,<\/font><\/span> <\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font style=\"font-size: 10pt\">SickLeaveHours<span><font color=\"#808080\">,<\/font><\/span> CurrentFlag<span><font color=\"#808080\">,<\/font><\/span> rowguid<span><font color=\"#808080\">,<\/font><\/span> ModifiedDate<span><font color=\"#808080\">,<\/font><\/span> EncryptedNationalIDNumber2<\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">)<\/font><\/span><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">SELECT<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> NationalIDNumber<span><font color=\"#808080\">,<\/font><\/span> ContactID<span><font color=\"#808080\">,<\/font><\/span> LoginID<span><font color=\"#808080\">,<\/font><\/span> ManagerID<span><font color=\"#808080\">,<\/font><\/span> Title<span><font color=\"#808080\">,<\/font><\/span> BirthDate<span><font color=\"#808080\">,<\/font><\/span> <\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font style=\"font-size: 10pt\">MaritalStatus<span><font color=\"#808080\">,<\/font><\/span> Gender<span><font color=\"#808080\">,<\/font><\/span> HireDate<span><font color=\"#808080\">,<\/font><\/span> SalariedFlag<span><font color=\"#808080\">,<\/font><\/span> VacationHours<span><font color=\"#808080\">,<\/font><\/span> <\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<span><font face=\"Lucida Console\"><font style=\"font-size: 10pt\">SickLeaveHours<span><font color=\"#808080\">,<\/font><\/span> CurrentFlag<span><font color=\"#808080\">,<\/font><\/span> rowguid<span><font color=\"#808080\">,<\/font><\/span> ModifiedDate<span><font color=\"#808080\">,<\/font><\/span> EncryptedNationalIDNumber2<\/font><\/font><\/span>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">FROM<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> AdventureWorks<span><font color=\"#808080\">.<\/font><\/span>HumanResources<span><font color=\"#808080\">.<\/font><\/span>Employee<\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">;<\/font><\/span><\/span><\/font>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span style=\"line-height: 12pt\"><font color=\"#0000ff\"><font style=\"font-size: 10pt\">GO<\/font><\/font><\/span><span style=\"line-height: 12pt\"><font style=\"font-size: 10pt\"> 1000<\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt\" class=\"MsoNormal\">\n<font face=\"Calibri\"><font style=\"font-size: 11pt\">Data used is 36,800 KB (versus 74,288 KB):<\/font><\/font>\n<\/p>\n<p style=\"line-height: 13pt; text-indent: 0.5in; margin: 0in 0in 10pt\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span style=\"line-height: 12pt\"><font color=\"#0000ff\"><font style=\"font-size: 10pt\">EXEC<\/font><\/font><\/span><span style=\"line-height: 12pt\"><font style=\"font-size: 10pt\"> <span><font color=\"#800000\">sp_spaceused<\/font><\/span><span><font color=\"#0000ff\"> <\/font><\/span><span><font color=\"#ff0000\">&#39;dbo.Employee_Compressed&#39;<\/font><\/span><\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">;<\/font><\/span><span><\/span><\/span><\/font>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt\" class=\"MsoNormal\">\n<font face=\"Calibri\"><font style=\"font-size: 11pt\">Querying the log record length from fn_dblog shows 100,677,612 bytes versus the uncompressed 120,503,216 bytes:<\/font><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">SELECT<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> <span><font color=\"#ff00ff\">SUM<\/font><\/span><span><font color=\"#808080\">(<\/font><\/span>[log record length]<span><font color=\"#808080\">)<\/font><\/span> <\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span style=\"line-height: 12pt\"><font color=\"#0000ff\"><font style=\"font-size: 10pt\">FROM<\/font><\/font><\/span><span style=\"line-height: 12pt\"><font style=\"font-size: 10pt\"> <span><font color=\"#008000\">fn_dblog<\/font><\/span><span><font color=\"#0000ff\"> <\/font><\/span><span><font color=\"#808080\">(NULL,<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL);<\/font><\/span><span><\/span><\/span><\/font>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt\" class=\"MsoNormal\">\n<font face=\"Calibri\"><font style=\"font-size: 11pt\">Backing up the transaction log produces a file that is 102,158 KB in size (versus 121,964 KB):<\/font><\/font>\n<\/p>\n<p style=\"line-height: normal; margin: 0in 0in 0pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span><font color=\"#0000ff\"><font style=\"font-size: 10pt\">SELECT<\/font><\/font><\/span><span><font style=\"font-size: 10pt\"> <span><font color=\"#ff00ff\">SUM<\/font><\/span><span><font color=\"#808080\">(<\/font><\/span>[log record length]<span><font color=\"#808080\">)<\/font><\/span> <\/font><\/span><\/font>\n<\/p>\n<p style=\"line-height: 13pt; margin: 0in 0in 10pt 0.5in\" class=\"MsoNormal\">\n<font face=\"Lucida Console\"><span style=\"line-height: 12pt\"><font color=\"#0000ff\"><font style=\"font-size: 10pt\">FROM<\/font><\/font><\/span><span style=\"line-height: 12pt\"><font style=\"font-size: 10pt\"> <span><font color=\"#008000\">fn_dblog<\/font><\/span><span><font color=\"#0000ff\"> <\/font><\/span><span><font color=\"#808080\">(NULL,<\/font><\/span> <\/font><span><font color=\"#808080\" style=\"font-size: 10pt\">NULL);<\/font><\/span><\/span><\/font>\n<\/p>\n<p><span style=\"line-height: 13pt\"><font face=\"Calibri\"><font style=\"font-size: 11pt\">So on a much larger scale &ndash; you can imagine the transaction log size reduction could be non-trivial.<span>&nbsp; <\/span>Mileage will vary on the overall compression you can get from specific tables and data &ndash; but this is just another potential benefit to be aware of.<span>&nbsp; <\/span>And as an aside, compressed rows <em>are<\/em> written to the transaction log in the ROW compression format and not the PAGE type. <\/font><\/font><\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>I received a question today about the impact of data compression on the transaction log.&nbsp; While most of the time we talk about data compression from a data page and memory utilization perspective, I hadn&rsquo;t actually directly tested the impact to transaction logging and I wanted to see it for myself.&nbsp; Here is just a [&hellip;]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[28],"tags":[],"class_list":["post-513","post","type-post","status-publish","format-standard","hentry","category-performance"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v21.9.1 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>A small-scale test measuring the impact of data compression on the transaction log - Joe Sack<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.sqlskills.com\/blogs\/joe\/a-small-scale-test-measuring-the-impact-of-data-compression-on-the-transaction-log\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"A small-scale test measuring the impact of data compression on the transaction log - Joe Sack\" \/>\n<meta property=\"og:description\" content=\"I received a question today about the impact of data compression on the transaction log.&nbsp; While most of the time we talk about data compression from a data page and memory utilization perspective, I hadn&rsquo;t actually directly tested the impact to transaction logging and I wanted to see it for myself.&nbsp; Here is just a [&hellip;]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.sqlskills.com\/blogs\/joe\/a-small-scale-test-measuring-the-impact-of-data-compression-on-the-transaction-log\/\" \/>\n<meta property=\"og:site_name\" content=\"Joe Sack\" \/>\n<meta property=\"article:published_time\" content=\"2012-01-18T13:01:00+00:00\" \/>\n<meta name=\"author\" content=\"Joseph Sack\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Joseph Sack\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"4 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.sqlskills.com\/blogs\/joe\/a-small-scale-test-measuring-the-impact-of-data-compression-on-the-transaction-log\/\",\"url\":\"https:\/\/www.sqlskills.com\/blogs\/joe\/a-small-scale-test-measuring-the-impact-of-data-compression-on-the-transaction-log\/\",\"name\":\"A small-scale test measuring the impact of data compression on the transaction log - Joe Sack\",\"isPartOf\":{\"@id\":\"https:\/\/www.sqlskills.com\/blogs\/joe\/#website\"},\"datePublished\":\"2012-01-18T13:01:00+00:00\",\"dateModified\":\"2012-01-18T13:01:00+00:00\",\"author\":{\"@id\":\"https:\/\/www.sqlskills.com\/blogs\/joe\/#\/schema\/person\/533eb0113a15fb5a6e8067a49e4ae648\"},\"breadcrumb\":{\"@id\":\"https:\/\/www.sqlskills.com\/blogs\/joe\/a-small-scale-test-measuring-the-impact-of-data-compression-on-the-transaction-log\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.sqlskills.com\/blogs\/joe\/a-small-scale-test-measuring-the-impact-of-data-compression-on-the-transaction-log\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.sqlskills.com\/blogs\/joe\/a-small-scale-test-measuring-the-impact-of-data-compression-on-the-transaction-log\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.sqlskills.com\/blogs\/joe\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Performance\",\"item\":\"https:\/\/www.sqlskills.com\/blogs\/joe\/category\/performance\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"A small-scale test measuring the impact of data compression on the transaction log\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.sqlskills.com\/blogs\/joe\/#website\",\"url\":\"https:\/\/www.sqlskills.com\/blogs\/joe\/\",\"name\":\"Joe Sack\",\"description\":\"SQL Server Performance Tuning, High Availability and Disaster Recovery Blog\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.sqlskills.com\/blogs\/joe\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"en-US\"},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.sqlskills.com\/blogs\/joe\/#\/schema\/person\/533eb0113a15fb5a6e8067a49e4ae648\",\"name\":\"Joseph Sack\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.sqlskills.com\/blogs\/joe\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/a4b39a7719a6bfff1add3ec00527810734579ee114d6d983e8e68f937b77be96?s=96&d=mm&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/a4b39a7719a6bfff1add3ec00527810734579ee114d6d983e8e68f937b77be96?s=96&d=mm&r=g\",\"caption\":\"Joseph Sack\"},\"description\":\"Joe Sack is a Principal Consultant with SQLskills. 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