SQL Server - Difference between a table and index scan - Feb
27, 2010 at 11:50 AM by Shuchi Gauri
What is the difference between a table and index scan in an execution plan?
An index scan is in which SQL Server reads the complete index for matches. Time
taken is directly proportional to size of the index. It loads the index in
memory and then reads it from top to bottom looking for records that match.
A table scan is in which SQL Server reads a complete table itself from top to
bottom. It reads all the rows present in the table for matches. This might take
a lot of time if the table is huge. However, in a scenario where table is not
huge and the number of rows is not many, a table scan is faster than an index
scan.
SQL Server - Difference between a table and index scan - May
05, 2009 at 22:00 PM by Rajmeet Ghai
What is the difference between a table and index scan in an execution plan?
When a query needs to be optimized, an execution plan is created by the query
optimizer. A table scan examines all records of a table to meet the requirement
of a query. This works well for small tables. However, can be time consuming
for large tables. For large tables, an index scan is used. In an index scan,
instead of scanning the table itself, the rows of the index are examined.
SQL Server - Difference between a table and index scan - June
21, 2009 at 09:00 PM by Amit Satpute
What is the difference between a table and index scan in an execution plan?
Table Scan:
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Every single record is scanned in a Table Scan.
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Efficient for smaller sized tables.
Index Scan:
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The rows at the leaf level of the index are scanned.
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Therefore the table is not scanned directly.
Also read
SQL Server uses different ways to execute SQL statements which are listed
below................
SQL Server caches the plan of execution of query or stored procedure which it
uses in subsequent call. This is a very important feature with regards to
performance enhancement. You can view execution plan of data retrieval
graphically or textually................
Answer - Index can be thought as index of the book that is used
for fast retrieval of information. Index uses one or more column index keys and
pointers to the record to locate record.........
Answer - The column or columns of the table whose value
uniquely identifies each row in the table is called primary key. You can define
column as primary key using primary key constraint while you create table.....
Answer - The Bulk Copy is a command utility that transfer SQL
data to or from a data file. This utility mostly used to transfer huge data to
SQL server from other database....
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