Should All Temp Files Be Deleted

Should All Temp Files Be Deleted' title='Should All Temp Files Be Deleted' />SQL Server ShrinkCheck out our Pluralsight online training course SQL Server Understanding and Using DBCC Commands. One of my biggest hot buttons is around shrinking data files. Although I used to own the shrink code while I was at Microsoft, I didnt write it so dont blame meBut I really dont like the data file shrink process. Now, dont confuse shrinking the transaction log with shrinking data files. Shrinking the log may be necessary if your log has grown out of control, or as part of a process to remove excessive VLF fragmentation see Kimberlys excellent posts on this here and here. However, shrinking the log should be a rare operation and should not be part of any regular maintenance you perform. In either case, Im not talking about using the TRUNCATEONLY option all that does is lop off any unused space at the end of the files thats perfectly fine. Drunk Man Walk Home Game more. Im talking about actually running the shrink algorithm. Shrinking of data files should be performed even more rarely, if at all. Heres why data file shrink can cause massiveindex fragmentation of the out of order pages kind, not the wasted space kind and it is very expensive in terms of IO, locking, transaction log generation. Let me demonstrate with a simple script you can run. The script below will create a data file, create a 1. Experts Exchange Questions Is it safe to delete DismHost. AppDataLocalTemp folder. I have a diectory where I need to delete all files and folders except a small list of files and folders. I can already exclude a list of files, but dont see a way to. Did you know files never actually get deleted Thats why they can be recovered by you or someone else. If this makes you feel uncomfortable, learn how to securely. I had a reader write me a few days ago. Im in a school environment and a student has deleted some files and I would like to know how I can do this in Win2k. These temporary files are created automatically in your computer and should be removed from your computer automatically as well. The software which generates the Temp. Should All Temp Files Be Deleted In 24' title='Should All Temp Files Be Deleted In 24' />MB filler table at the start of the data file, create a 1. MB production clustered index, and then analyze the fragmentation of the new clustered index. IF DATABASEPROPERTYEX NDBMaint. NVersion IS NOT NULL. DROP DATABASE DBMaint. CREATE DATABASE DBMaint. USE DBMaint. 20. SET NOCOUNT ON. Create the 1. MB filler table at the front of the data file. CREATE TABLE Filler. Lost or deleted excel files in Windows 10 before clicking. Why cant restore temporary excel worksheets from temp folder immediatelyTable. INT IDENTITY. CHAR 8. DEFAULT filler. Fill up the filler table. INSERT INTO Filler. Table DEFAULT VALUES. Create the production table, which will be after the filler table in the data file. CREATE TABLE Prod. Table. c. 1 INT IDENTITY. CHAR 8. 00. 0 DEFAULT production. CREATE CLUSTERED INDEX prodcl ON Prod. Table c. 1. INSERT INTO Prod. Table DEFAULT VALUES. Check the fragmentation of the production table. FROM sys. dmdbindexphysicalstats. DBID NDBMaint. OBJECTID NProd. Table, 1, NULL, LIMITED. The logical fragmentation of the clustered index before the shrink is a near perfect 0. Now Ill drop the filler table, run a shrink to reclaim the space, and re analyze the fragmentation of the clustered index. Drop the filler table, creating 1. MB of free space at the front of the data file. DROP TABLE Filler. Table. Shrink the database. DBCC SHRINKDATABASE DBMaint. Check the index fragmentation again. FROM sys. dmdbindexphysicalstats. DBID NDBMaint. OBJECTID NProd. Table, 1, NULL, LIMITED. Db. Id File. Id Current. Renesas Electronics Usb 3.0 Host Controller Driver Windows 7 there. Size Minimum. Size Used. Pages Estimated. Pages. DBCC execution completed. If DBCC printed error messages, contact your system administrator. Wow After the shrink, the logical fragmentation out of order pages is almost 1. The shrink operation ompletelyfragmented the index. Now, will that have any effect on your workload performance If the index is larger than a few thousand pages, is typically not all in the buffer pool, and is scanned a lot, then possibly. Otherwise, probably not. Why does this happen A data file shrink operation works on a single file at a time, and uses the GAM bitmaps see Inside The Storage Engine GAM, SGAM, PFS and other allocation maps to find the highest page allocated in the file. It then moves it as far towards the front of the file as it can, and so on, and so on. In the case above, it completely reversed the order of the clustered index, taking it from perfectly defragmented to perfectly fragmented. The same code is used for DBCC SHRINKFILE, DBCC SHRINKDATABASE, and auto shrink theyre equally as bad. As well as introducing index fragmentation, data file shrink also generates a lot of IO, uses a lot of CPU, and generates oadsof transaction log as everything it does is fully logged. Data file shrink should never be part of regular maintenance, and you should NEVER, NEVER have auto shrink enabled. I tried to have it removed from the product for SQL 2. SQL 2. 00. 8 when I was in a position to do so the only reason its still there is for backwards compatibility. Dont fall into the trap of having a maintenance plan that rebuilds all indexes and then tries to reclaim the space required to rebuild the indexes by running a shrink thats a zero sum game where all you do is generate a log of transaction log for no actual gain. So what if you oneed to run a shrinkFor instance, if youve deleted a large proportion of a very large database and the database isnt likely to grow, or you need to empty a file before removing it The method I like to recommend is as follows Create a new filegroup. Move all affected tables and indexes into the new filegroup using the CREATE INDEX WITH DROPEXISTING ON ON syntax, to move the tables and remove fragmentation from them at the same time. Drop the old filegroup that you were going to shrink anyway or shrink it way down if its the primary filegroupBasically you need to provision some more space before you can shrink the old files, but its a much cleaner mechanism. If you absolutely have no choice and have to run a data file shrink operation, be aware that youre going to cause index fragmentation and you might need to take steps to remove it afterwards if its going to cause performance problems. The only way to remove index fragmentation without causing data file growth again is to use DBCC INDEXDEFRAG or ALTER INDEX REORGANIZE. These commands only require a single 8. KB page of extra space, instead of needing to build a whole new index in the case of an index rebuild operation which will likely cause the file to grow. Bottom line try to avoid running data file shrink at all costsIm often misquoted as saying never run data file shrink thats not true. I say never run a regular shrink operation of any kind, and if you absolutely must run a data file shrink, be aware of the problems it can cause.