Updating multiple rows at a time in sql server
Disk I/O path errors can be the cause of database corruption problems and are generally caused by power failures or disk hardware failures that occur at the time the page is being written to disk.TORN PAGE DETECTION: Works by saving a specific bit for each 512-byte sector in the 8-kilobyte (KB) database page and is stored in the database page header when the page is written to disk. During an index reorganization operation, if the index spans multiple files, will pages be allowed to migrate between files Ans: No – pages will not migrate between files during an index reorganization. If you need to REBUILD a non-clustered index that is 10GB in size and have 5GB of free data-file space available with no room to grow the data file(s), how can you accomplish the task?Ans: When rebuilding an existing non-clustered index, you typically require free space that is approximately equivalent to 2.2 times the size of the existing index, since during a rebuild operation, the existing index is kept until the rebuilt structure is complete and an additional approximately 20% free space for temporary sorting structures used during the rebuild operation Q. Ans: If you know that your application will be performing the same query over and over on the same table, consider creating a covering index on the table.
CHECKSUM: Works by calculating a checksum over the contents of the whole page and stores the value in the page header when a page is written to disk.During these offline operations, the indexing operations hold exclusive locks on the underlying table and associated indexes.During online index operations, SQL Server 2005 eliminates the need of exclusive locks The Online indexing feature is very helpful for environments that run 24 hours a day, seven days a week. Ans: The online index operation can be divided into three phases: The Build phase is a longest phase of all.When the page is read from disk, the torn bits stored in the page header are compared to the actual page sector information.