SQL server Interview Questions & Answers
Q: – Can you explain about buffer cash and log Cache in sql server?
Buffer Cache: Buffer cache is a memory pool in which data pages are read. It performance of the buffer cache is indicated as follows: 95% indicates that pages that were found in the memory are 95% of time. Another 5% is needed for physical disk access.
If the value falls below 90%, it is the indication of more physical memory requirement on the server. Log Caches: Log cache is a memory pool used to read and write the log pages. A set of cache pages are available in each log cache. The synchronization is reduced between log and data buffers by managing log caches separately from the buffer cache.
Q: – What is a Trace frag? Where do we use it?
Temporary setting of specific server characteristics is done by trace tags. DBCC TRACEON is the command to set the trace flags. Once activated, trace flag will be in effect until the server is restarted. Trace frags are frequently used for diagnosing performance issues. For example, the trace flag 3205 is used for disabling hard compression for tape drives, when an instance of SQL Server starts.
Q: – Explain how to make remote connection in database?
The following is the process to make a remote connection in database:
Use SQL Server Surface Area Configuration Tool for enabling the remote connection in database.
Click on Surface Area Configuration for Services and Connections.
Click on SQLEXPRESS/Database Engine/RemoteConnections
Select the radio button: Local and Remote Connections and select ‘Using TCP/IP only’ under Local and Remote Connections.
Click on OK button / Apply button
Q: – Difference between cross join and Full outer join?
Cross Join : No join conditions are specified. Results in pairs of rows. Results in Cartesian product of two tables. Full Outer Join: A combination of both left and right outer joins. Results in every row from both of the tables , at least once. Assigns NULL for unmatched fields.
Q: – Explain how to store pdf file in sql server
reate a column as type ‘blob’ in a table. Read the content of the file and save in ‘blob’ type column in a table. Or store them in a folder and establish the pointer to link them in the database.
Q: – What is index segmentation?
A segment is a part of relational data base and consists of one or more extents. Each extent is further divided into blocks. Every segment has an index for holding all of its data for quick data retrieval. Index segments can be created explicitly by using the CREATE INDEX command. Storage parameters for the extents of the index segment can be specified along with this command.
Q: – What are backup Types?
Transaction Log Architecture Backups
File and Filegroup Backups
Q: – Define Differential Backups
Differential backup backups up files that have been changed since the last backup. This reduces the time to backup since only changed files need to be restored. Restoring differential back up is faster and storage requirements are less. The list of files changed since the last back up is recorded in a catalogue file with .bkc extension.
Q: – What are the advantages and disadvantages of merge replication?
It provides built-in and custom conflict resolution capabilities.
It allows for the synchronization of data from multiple tables at one time.
It provides rich data replication options like selection of article types and filtering and identity range management.
Merge replication requires more configuration and maintenance at the server