Questions tagged [index-tuning]

The process of determining which indexes are useful and which are not.

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What is the best relationship model for high performance?

I want to model a relationship between Customer and Transaction. However, because Customer is only described by a unique string and no extra info, I have two possibilities to implement it in the ...
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1answer
555 views

Analyzing TCB Index Status for DB2

The Following is the TCB index that I could get using a command for my DB2 database. I don't know how to analyze it. Which columns are important? What do they mean? TCB Index Stats: Address ...
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1answer
341 views

INDEX Creation Advice Oracle

I have a table that has time data of 2 billion records obtained from the clients. The data has two main columns, date and entity_id. The attributes date, and entity_id would make a unique pair. ...
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2answers
16k views

How can I improve the speed of a query on a 20 million+ row table?

I have a query that is used for getting internet traffic statistics of certain IP addresses. There are separate IP address fields for hosts and blocks of IPs called assignments. The data is stored ...
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1answer
830 views

Oracle function based index is not used in query

I cannot figure out why the following is not working as I expect it : CREATE TABLE table1(table1_id INT NOT NULL PRIMARY KEY, col1 INT NOT NULL, val1 VARCHAR(50)); CREATE INDEX ...
4
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1answer
973 views

Using indexes to create multiple relationships to a table in order to enforce data integrity and add meaning

I'm working on an inventory database that uses supertype/subtype model. My question regards creating multiple relationships with the same tables using the primary key and composite indexes that also ...
4
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1answer
254 views

Where to place non clustered index

Execution plan clearly showing that one of my table used in query is useing Clustered Index Scan. From this node, how can i guess that which columns should be part of my non clustered index key and ...
2
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2answers
873 views

Reorganize Indexes T-SQL

I'm moving a database to SQL Azure and with that I lose the maintenance plans so I am going to use a Worker Role to schedule them. When I open the properties of the Rebuild Index Task and click on ...
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2answers
10k views

Primary key vs. unique index: performance difference with foreign keys?

Will there be any difference in performance if you compare a query fetching data via a join between two tables where there's a relationship against either of the following: A primary key A unique ...
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3answers
4k views

SQL server indexing foreign keys, covering indexes included columns

I have pulled a list of FK's that do not have indexes on them. If a FK does not have a dedicated index on them but are part of wider indexes used for covering queries, Should they have a dedicated ...
2
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1answer
331 views

Indexing or changing one-to-many relationship

I have these two Microsoft SQL Server 2005 tables: ObjectLicenses (ObjectLicenseID [PK]; ObjectID; LicenseType; LicenseNumber) 1|1|A|000001 2|1|A|000002 3|1|B|000003 4|2|C|000004 Objects (ObjectID [...
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2answers
114 views

MySQL using a index referencing a different column

I have a large table which uses a versioning system in the table. When a record is updated a new record is inserted with the old data and the original record is updated ( so to maintain the same ...
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1answer
86 views

Can you search using an index while indexes are being updated in oracle11g?

I am using oracle 11g. I noticed some performance problems that causes hanging on some search operations. Can I still search based on an index while that index is being updated in the database?
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3answers
18k views

Will more indexes on a table affect performance? [duplicate]

Possible Duplicate: How do indices impact query performance? How to know when/if I have too many indexes? Say ‘X’ report using some "where" condition in the statement so we are creating an ...
4
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1answer
232 views

Filtered index statistics refresh threshold

We have filtered indexes in our production environment. While doing some research about them, I came across this article "Filtered indexes and filtered stats might become seriously out-of-date" It'...
2
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1answer
3k views

Index Strategies on Text or NVARCHAR(MAX) Fields

I have the following query (simplified for question) I'm trying to speed up for a read only DB ... SELECT [sysid] ,[Date]=CONVERT(CHAR, DATEADD(D, [date], '1800-12-28'),101) ,[From]=[from_addr] ...
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1answer
183 views

Creating Indexes to optimize query

I have this query and I want to increase its performance by adding appropriate Indexes. DELETE FROM MYTAB1 WHERE MYID1 IN ( SELECT MYID2 FROM MYTAB2 ); I am not familiar with the ...
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2answers
1k views

Why is a secondary index chosen over a clustered index for SELECT COUNT(*) …?

In this query: select count(*) from largetable; a secondary index is chosen: mysql> explain select count(*) from largetable; +----+-------------+------------+-------+---------------+------+------...
4
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3answers
266 views

Most efficient (or meaningful) way to index grid-based data

I have a MySQL table which I expect to be in surplus of a few million rows and 99% select statements. The problem I am having is coming up with a meaningful way to determine the Primary Key. (I have ...
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2answers
11k views

What is the difference between ALTER INDEX and DBCC DBREINDEX?

Is the only difference between ALTER INDEX [index_name] on [object_name] REBUILD with (ONLINE=OFF, FILLFACTOR=90) and DBCC DBREINDEX([dbname], 90) just that the DBCC command will reindex all of ...
3
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1answer
4k views

Oracle not using index when > used in where clause

We have a relatively classic scenario where the date clause of the query generated by the application uses a "greater than" for a given date. Because there is no end clause to the date range, oracle ...
2
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1answer
471 views

In DB2, what are the alternative ways of evaluating an index's (or several indexes) benefit?

I'm trying to evaluate different approaches to analyzing the benefit of changing the set of indexes that are available. If I pick some representative queries from my workload, I can run EXPLAIN and ...
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4answers
779 views

What are the performance considerations between using a broad PK vs a separate synthetic key and UQ?

I have several tables where records can be uniquely identified with several broad business fields. In the past, I've used these fields as a PK, with these benefits in mind: Simplicity; there are no ...
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1answer
3k views

Reindexing Partitioned Table Indexes

Historic Reporting Server running SQL 2008 R2. I'm trying to tweak the fill factor. I have a job that records the fragmentation when the jobs runs in the early hours. For every table that had high ...
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2answers
17k views

How to know when/if I have too many indexes?

Running Microsoft SQL Server Profiler every now and then, it suggests me with a bunch of new indexes and statistics to create ("...97% estimated improvement..."). From my understanding every added ...