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Questions tagged [covering-index]

56 questions
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How MSSql covering indexes should be configured in Oracle Sql Developer (Data Modeller) ver 4.1.5.21

Could someone please help me on how to configure a Covering Index (INCLUDE option) in Oracle Sql Developer (Data Modeller) ver 4.1.5.21. I could find only the option to create a normal index or to use 'index expression' where we can directly put the…
Moinak Roy
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CREATE INDEX in SQL Server 2008 not result in "visible index"

I am using SQL Server 2008 Express. In the DB in question, there is only one schema: dbo. If I run the following script: CREATE UNIQUE INDEX IX_ClientSocialTypes_Cover ON ClientSocialTypes(ClientID, SocialTypeClassID, [Source]) INCLUDE (URLID); ...…
IamIC
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MySQL select seems very slow but cannot think how to improve?

I have a single table with four columns... `id` INT(11) NOT NULL AUTO_INCREMENT `tid` INT(11) NOT NULL `cid` INT(11) NOT NULL `name` NVARCHAR(4096) NULL DEFAULT NULL id is the unique primary key. The other columns are not unique. I want to…
Phil Wright
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Why the mysql optimizer is not using the complete index?

I am trying to understand why MySQL is not using the complete index to answer the query. Let me explain. I am using imdb database through MySQL version 5.1.73-1 (Debian). I created and index "itid_inf25_mid_ndx" on the table movie_info_idx with…
Manuel Barrena
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Database: Help me with correct index(es) for a table and query

I am running some queries in my database and want to increase the performance and have created some indexes but I still think that the response time is to great so I want to see if I can create a better or another index to increase the speed. My…
Emil Devantie Brockdorff
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A question about indexes regarding to the gain of inserts & updates in database

I’m having a question about the fine line between the gain of an index to a table there is growing steadily in size every month and the gain of queries with an index. The situation is, that I’ve two tables, Table1 and Table2. Each table grows slowly…
Emil Devantie Brockdorff
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Covering indexes when extra columns uniquely determined by clustered index

Suppose I need to update myTab from luTab as follows update myTab set LookupVale = (select LookupValue from luTab B where B.idLookup = myTab.idLookup) luTab consists of 2 columns (idLookup(unique),…
cindi
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The clarification of using covering indexes

As I know the covering index is index that should include all columns in SELECT statement. If so, what if I have query as following: SELECT ActionDate -- Дата мероприятия ,ManagerName -- ФИО менеджера ,City -- Город…
tesicg
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How can you check whether a MySQL query is making use of a Covering Index?

How can you check whether a MySQL query is making use of a Covering Index and getting all the data it needs solely from that Index?
ProgrammerGirl
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Usefulness of Covering indexes

I have a query that performs joins on multiple tables. I have non-clustered index on the foreign keys of the tables and clustered index on primary keys. On analyzing the query plan, I figured that the query optimizer was choosing clustered index…
Manish Mulani
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Why MySQL can perform LIKE in the index, when there is some leading wildcard in the index, when using "covering-index"?

This is an example of "High Performance MySQL 3rd". mysql> EXPLAIN SELECT * FROM products WHERE actor='SEAN CARREY' AND title like '%APOLLO%'; The book said that MySQL can't perform the LIKE as below. MySQL can’t perform the LIKE operation in the…
lxyscls
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