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SQL Optimization Tips and Index Optimization tips

 

  1. Have you ever used DBCC command? Give an example for it.
    The Transact-SQL programming language provides DBCC statements that act as Database Console Commands for Microsoft® SQL Serve 2000. These statements check the physical and logical consistency of a database. Many DBCC statements can fix detected problems. Database Console Command statements are grouped into these categories.

Statement category

Perform

Maintenance statements

Maintenance tasks on a database, index, or filegroup.

Miscellaneous statements

Miscellaneous tasks such as enabling row-level locking or removing a dynamic-link library (DLL) from memory.

Status statements

Status checks.

Validation statements

Validation operations on a database, table, index, catalog, filegroup, system tables, or allocation of database pages.

DBCC CHECKDB, DBCC CHECKTABLE, DBCC CHECKCATALOG, DBCC CHECKALLOC, DBCC SHOWCONTIG, DBCC SHRINKDATABASE, DBCC SHRINKFILE etc.

  1.  
  2. How do you use DBCC statements to monitor various aspects of a SQL server installation?
    **
  3. What is the output of DBCC Showcontig statement?
    Displays fragmentation information for the data and indexes of the specified table.
  4. How do I reset the identity column?
    You can use the DBCC CHECKIDENT statement, if you want to reset or reseed the identity column. For example, if you need to force the current identity value in the jobs table to a value of 100, you can use the following:
    USE pubs
    GO
    DBCC CHECKIDENT (jobs, RESEED, 100)
    GO
  5. About SQL Command line executables

Utilities

bcp
console
isql
sqlagent
sqldiag
sqlmaint
sqlservr
vswitch

dtsrun
dtswiz
isqlw
itwiz
odbccmpt
osql
rebuildm
sqlftwiz

distrib
logread
replmerg
snapshot

scm

regxmlss

  1. What is DTC?
    The Microsoft Distributed Transaction Coordinator (MS DTC) is a transaction manager that allows client applications to include several different sources of data in one transaction. MS DTC coordinates committing the distributed transaction across all the servers enlisted in the transaction.
  2. What is DTS? Any drawbacks in using DTS?
    Microsoft® SQL Server™ 2000 Data Transformation Services (DTS) is a set of graphical tools and programmable objects that lets you extract, transform, and consolidate data from disparate sources into single or multiple destinations.
  3. What is BCP?
    The bcp utility copies data between an instance of Microsoft® SQL Server™ 2000 and a data file in a user-specified format.
    C:Documents and Settingssthomas>bcp
    usage: bcp {dbtable | query} {in | out | queryout | format} datafile
    [-m maxerrors] [-f formatfile] [-e errfile]
    [-F firstrow] [-L lastrow] [-b batchsize]
    [-n native type] [-c character type] [-w wide character type]
    [-N keep non-text native] [-V file format version] [-q quoted identifier]
    [-C code page specifier] [-t field terminator] [-r row terminator]
    [-i inputfile] [-o outfile] [-a packetsize]
    [-S server name] [-U username] [-P password]
    [-T trusted connection] [-v version] [-R regional enable]
    [-k keep null values] [-E keep identity values]
    [-h "load hints"]
  4. How can I create a plain-text flat file from SQL Server as input to another application?
    One of the purposes of Extensible Markup Language (XML) is to solve challenges like this, but until all applications become XML-enabled, consider using our faithful standby, the bulk copy program (bcp) utility. This utility can do more than just dump a table; bcp also can take its input from a view instead of from a table. After you specify a view as the input source, you can limit the output to a subset of columns or to a subset of rows by selecting appropriate filtering (WHERE and HAVING) clauses.
    More important, by using a view, you can export data from multiple joined tables. The only thing you cannot do is specify the sequence in which the rows are written to the flat file, because a view does not let you include an ORDER BY clause in it unless you also use the TOP keyword.
    If you want to generate the data in a particular sequence or if you cannot predict the content of the data you want to export, be aware that in addition to a view, bcp also supports using an actual query. The only "gotcha" about using a query instead of a table or view is that you must specify queryout in place of out in the bcp command line.
    For example, you can use bcp to generate from the pubs database a list of authors who reside in California by writing the following code:
    bcp "SELECT * FROM pubs..authors WHERE state = 'CA'" queryout c:CAauthors.txt -c -T -S
  5. What are the different ways of moving data/databases between servers and databases in SQL Server?
    There are lots of options available, you have to choose your option depending upon your requirements. Some of the options you have are: BACKUP/RESTORE, detaching and attaching databases, replication, DTS, BCP, logshipping, INSERT…SELECT, SELECT…INTO, creating INSERT scripts to generate data.
  6. How will I export database?
    Through DTS – Import/Export wizard
    Backup – through Complete/Differential/Transaction Log
  7. How to export database at a particular time, every week?
    Backup – Schedule
    DTS – Schedule
    Jobs – create a new job
  8. How do you load large data to the SQL server database?
    bcp
  9. How do you transfer data from text file to database (other than DTS)?
    bcp
  10. What is OSQL and ISQL utility?
    The osql utility allows you to enter Transact-SQL statements, system procedures, and script files. This utility uses ODBC to communicate with the server.
    The isql utility allows you to enter Transact-SQL statements, system procedures, and script files; and uses DB-Library to communicate with Microsoft® SQL Server™ 2000.
    All DB-Library applications, such as isql, work as SQL Server 6.5–level clients when connected to SQL Server 2000. They do not support some SQL Server 2000 features.
    The osql utility is based on ODBC and does support all SQL Server 2000 features. Use osql to run scripts that isql cannot run.
  11. What Tool you have used for checking Query Optimization? What is the use of profiler in sql server? What is the first thing u look at in a SQL Profiler?
    SQL Profiler is a graphical tool that allows system administrators to monitor events in an instance of Microsoft® SQL Server™. You can capture and save data about each event to a file or SQL Server table to analyze later. For example, you can monitor a production environment to see which stored procedures is hampering performance by executing too slowly.
    Use SQL Profiler to:
    • Monitor the performance of an instance of SQL Server.
    • Debug Transact-SQL statements and stored procedures.
    • Identify slow-executing queries.
    • Test SQL statements and stored procedures in the development phase of a project by single-stepping through statements to confirm that the code works as expected.
    • Troubleshoot problems in SQL Server by capturing events on a production system and replaying them on a test system. This is useful for testing or debugging purposes and allows users to continue using the production system without interference.

Audit and review activity that occurred on an instance of SQL Server. This allows a security administrator to review any of the auditing events, including the success and failure of a login attempt and the success and failure of permissions in accessing statements and objects.

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