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What is index in sql?

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Anonymous

13y ago
Updated: 8/17/2019

Index is a data structure that improve the performance of data.

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13y ago

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Related Questions

Which command is used to remove an index from the database in SQL?

It may depend on what flavor of SQL, but whenever you want to get rid of something, DROP is generally your friend. DROP INDEX <indexname>; is likely to be the command needed, with various options depending on, again, exactly what flavor of SQL you're talking about.


Can you explain the process of how to drop an index in a database?

To drop an index in a database, you need to use a specific SQL command. First, you identify the name of the index you want to drop. Then, you use the DROP INDEX statement followed by the name of the index. This command removes the index from the database, making the associated data searchable without the index.


What is a composite index?

You can create an index for a table to improve the performance of queries issued against the corresponding table. You can also create an index for a cluster. You can create a compositeindex on multiple columns up to a maximum of 32 columns. A composite index key cannot exceed roughly one-half (minus some overhead) of the available space in the data block.Use the SQL command CREATE INDEX to create an index. CREATE INDEX emp_ename ON emp_tab(ename);


Difference between table and index in sql?

A table is a collection of data that is organized into rows and columns. An index is a data structure that improves the performance of data fetch operations on a table. A table can exist as a standalone component but an index cannot. Indexes are built on top of tables and cannot exist without tables.


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What is an index in database?

Oracle includes numerous data structures to improve the speed of Oracle SQL queries. Oracle includes many new indexing algorithms that dramatically increase the speed with which Oracle queries are serviced like b-tree index, bitmap indexes, function-based indexes, and index-only tables (IOTsOracle uses indexes to avoid the need for large-table, full-table scans and disk sorts, which are required when the SQL optimizer cannot find an efficient way to service the SQL query. I begin our look at Oracle indexing with a review of standard Oracle b-tree index methodologies.


Forms of sub queries in ms sql?

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