A database structure that can improve the speed of queries at the cost of disk space and slower inserts/updates. It stores a copy of one or more columns but structures the data differently to allow for faster access.

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3answers
356 views

Mysql - How to Optimize Retrieval Time in a Table

I have query like this! which has 200 million Records in a single table.. I am using BTree Indexes in my table... mysql> select COUNT(DISTINCT id) from [tablename] where [columname] >=3; ...
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1answer
677 views

SQL Azure: Drop Constraint and Index

This may be a stupid question, but I'm not a DBA and just wanna make sure of what I'm doing before I make a mistake. Here is my question: When dropping Constraints, are their indexes dropped as well? ...
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1answer
162 views

I would like to query a range of criteria on multiple columns in MySQL

I have 3 columns in a mysql table. I'm using Innodb engine. I want to be able to search for some values on those columns and also anything close to those values. For example : We have 3 columns as ...
4
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1answer
2k views

Schema design: Use of association (aka: bridge/junction) table vs foreign key constraint with composite index containing a non-key field

This is an inventory database for IT assets. The models used are trimmed in order to focus on the problem at hand. Using SQL Server 2008. Thanks for taking the time to read and for any input you can ...
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1answer
1k views

Creating indexes with t-sql scrips vs rebuild indexes in maintenance plan

I’m using SQL Server 2008 and I am running several (15) scripts each day to bulk insert to tables. Each script drops the table at the beginning. I create indexes in the scripts. Some of the scripts ...
3
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0answers
156 views

Key Lookup and Full-text index

I have the following query: SELECT T2.Title FROM TitleTable T1 INNER JOIN TitleTable T2 ON T2.FKID1 = T1.FKID1 WHERE T1.FKID2 = @ID_PARAM1 AND T2.FKID2 = @ID_PARAM2 AND ...
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1answer
160 views

What is the maximum number of rows in a clustered index on datetime column?

I would like know what the max no of rows is in a clustered index (non-unique) on a datetime column table in SQL Server 2008R2.
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1answer
323 views

Why do MySQL MyISAM table indexes go out of date?

I have few MyISAM tables, where only the auto_increment primary key is up to date with the number of columns, but not other indexes. Any idea, why this happens?
2
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1answer
171 views

Will a primary key be added as a clustered index?

I've inherited a database where no primary keys were defined on the tables. There are also no clustered indexes assigned to the tables. If I perform an alter table to assign a primary key will this ...
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1answer
143 views

Consolidating indexes

I have one big table that is used to generate business intelligence cube. Currently it has around 40M rows and 55 columns. A lot of the cube dimensions are generated by running 'select distinct' on a ...
11
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1answer
7k views

Possible INDEX on a VARCHAR field in MySql

I am working in a MySql database, with a table like this: +--------------+ | table_name | +--------------+ | myField | +--------------+ ...and I need to make a lot of queries like this (with ...
2
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1answer
433 views

How to improve INSERT speed in large table that has unique constraint

I have a simple MyISAM table: explain entities; +------------+-------------+------+-----+-------------------+----------------+ | Field | Type | Null | Key | Default | Extra ...
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1answer
175 views

Is there any reason to use index for very small tables (up to 1000 rows)?

During application development I have a lot of tables that store "small" amount of data (usually 10-40 values, id + value and sometimes type) which hold attributes for "objects", like fresh/rotten, ...
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1answer
42 views

Which text-index I should create for xooops engine to achieve better search results?

In one of projects we use xoops engine to manage content. In mysql slow query log most of queries are following : SELECT p.uid,f.forum_id, p.topic_id, p.poster_name, p.post_time, f.forum_name, ...
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2answers
913 views

Different results rebuilding an index online and offline

I have a non-clustered, non-unique index on a foreign key column of type bigint. When I rebuild the index online, the average fragmentation drops to 3%, with 2 fragments, and 30 pages. When I run ...
2
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0answers
68 views

How can one improve the performance of a query that selects on a low cardinality column in MySQL?

I have a "State" column that has a low cardinality (three possible value), on which most of my queries perform an equality selection (WHERE col = 'blah') AFAIK you need something like a bitmap index ...
14
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1answer
10k views

Create index if it does not exist

I am working on a function that allows me to add an index if it does not exist. I am running into the problem that I cannot get a list of indexes to compare to. Any thoughts? This is a similar issue ...
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2answers
515 views

Mysql. Block/disconnect slow queries

I am experiencing issue. Someone 'attacked' my server: simply by searching the same phrase with multiple requests. As it is text search request and database indices are not used, the engine searches ...
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0answers
65 views

Does disabling index exists in a table? [closed]

So I have a script that runs daily. It creates a temp table then inserts the records to a table from the temp table. The script used to create indexes but few months ago I commented out the index ...
0
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1answer
159 views

Microsoft Access - performance difference between index and constraint?

I've looked around a bit but haven't come across anything talking specifically about MS Access. So: what, if any, is the performance difference between a field with a constraint and a field with an ...
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1answer
671 views

Query is not using indexes on third table in left join

My query is not using indexes on third table(pci promotion_coupon_images) . i was tried with using index and force index in query but there is no change in result. any body please suggest me how ...
2
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1answer
117 views

index doesn't work properly

I have this query SELECT user_id, MAX( highscore ) AS highscore, stage, COUNT( * ) AS count FROM single GROUP BY user_id, stage table engine is innodb, plus I haven't use any indexes except one key ...
2
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1answer
2k views

Unique insert performance: Primary Key vs Unique Index

I have a table of unique values (domains_unique), with collumn domain varchar(255), with more than 20 mil records. What's the fastest way to insert into the table, by keeping the domain unique ...
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1answer
55 views

Column order for better index

let say I have two tables like tbl_parent and tbl_children (just as an example), in the first table I have parent_id, and in the second one I (will) have something like child_id plus the parent_id, ...
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2answers
110 views

I have table with 17 Indexes if i add 1 more index for search in two columns [closed]

I have table with 17 Indexes if i add 1 more index for search in two columns insert , update and delete queries will be slow.I dont want them to slow...what to do
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2answers
79 views

Indexing is not working

Following is the table and index information for which I have the queries at the end. Create Table: CREATE TABLE `food` ( `id` int(10) unsigned NOT NULL DEFAULT '0', `page_no` int(11) DEFAULT ...
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1answer
2k views

Indexing strategy when using the between operator SQL Server 2008

I have a large table ~25 million rows with the structure CREATE TABLE [dbo].[rx]( [pat_id] [int] NOT NULL, [fill_Date] [date] NOT NULL, [script_End_Date] AS ...
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1answer
933 views

MySQL Index Fragmentation

Is there any way to find out the fragmentation of indexes in MySQL ? If such an output can be obtained, it would be helpful to identify which all indexes need to be rebuilt. I'm using MySQL 5.1 on ...
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1answer
1k views

db INDEX on ORDER BY FIELD in very simple query does not help - still slow response?

I have very simple query which returns 200K records very slow (20 seconds). SELECT * FROM TABLE ORDER BY ID DESC If I do just SELECT * FROM TABLE it returns quick result. I created INDEX on ...
6
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3answers
1k views

Clustered index in SQL Server vs index organized tables in Oracle

I am making the transition as a database developer from SQL Server to Oracle and found some fantastic resources here already (How to make a transition from SQL Server DBA to Oracle? and As a DBA, how ...
2
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1answer
521 views

Does rowlocks on index cause keylocks? : Transaction (Process ID xy) was deadlocked, example included

I am currently experiencing the error (logged via traceID 1222 ): keylock hobtid= 8205698989 objectname=mydb.dbo.Orders indexname = _dta_Index_Orders_5_120345_K1_K2_7_1 id=lock43fe181 mode=S ...
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5answers
440 views

Efficiently Filter Large Set With Disjunctions

Let's say I have a single table CREATE TABLE Ticket ( TicketId int NOT NULL, InsertDateTime datetime NOT NULL, SiteId int NOT NULL, StatusId tinyint NOT NULL, AssignedId int NULL, ...
1
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1answer
57 views

MySql include partition key in index?

Please look at the following Mysql table: http://pastebin.com/b0NDSbdz I've partitioned the table by sent_at and I'm making sure that most of the queries pass sent_at. do I need to include sent_at in ...
4
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1answer
290 views

Does the order of fields in SELECT query matter when using composite indexing?

I understand that the order of columns in the index itself matters immensely; however, what about the order of columns in the subsequent SELECT queries that make use of that index? For example, if I ...
3
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1answer
598 views

Index Key Column Order

I have created a joining table for many-to-many relationship. The table only has 2 cols in it, ticketid and groupid typical data would be groupid ticketid 20 56 20 87 20 ...
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1answer
546 views

Possible to query all SQL Server Indexes which have page locks enabled?

Is it possible to run a SQL Server Query in order to view all SQL Server Indexes which have page locks enabled?
2
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1answer
535 views

Use GIN to index bit strings

I'm trying to extend PostgreSQL to index bit strings up to 1000 bits. (These bit strings are created by quantization of high-dimensional vectors, so for each dimension up to 4 bits are assigned). ...
6
votes
1answer
133 views

What is the effect of replacing indexes with filtered (non-null value) indexes?

Our project runs a very large, very complicated database. So about a month ago, we noticed that the space used by indexed columns containing null values was getting too large. As a response to that, I ...
3
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3answers
1k views

PostgreSQL 8.3: Slow GROUP BY on large table

I have a table with about 10 million records. I want to do a simple group by, but it's using a sequential scan and is slow... select run_id, count(*) from result group by run_id; I have an index ...
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1answer
217 views

What are the performance implications of creating an index in MySQL?

The MySQL reference guide doesn't (from what I see) detail the implications of creating an index; by this I mean the performance implications and any locks it may take on the table or columns against ...
3
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1answer
216 views

Query optimization with extreme statistic

I have a table: mysql> describe table_1; +---------------+------------------+------+-----+---------------------+----------------+ | Field | Type | Null | Key | Default ...
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3answers
317 views

When to create Indexes?

I have a stored procedure that takes around 2 minutes to execute. The execution plan suggested me to create a non clustered index on a table (which is a high traffic table with millions of records in ...
2
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1answer
607 views

SQL Server manage indexes

Is it possible to automate the managing of indexes on my database? I'm looking to see if there are any scripts or programs that can automate this process. Would it be possible to use stats generated ...
6
votes
2answers
2k views

Multicolumn index and performance

I have a table with a multicolumn index, and I have doubts about the proper sorting of the indexes to get the maximum performance on the queries. The scenario: PostgreSQL 8.4, table with about 1MM ...
0
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2answers
762 views

Indexing a longtext field

I would like to run an index on a longtext field using: CREATE INDEX post_meta ON wp_postmeta (meta_value(8)); There are currently ~1 million records. Questions: Will creating this index affect ...
5
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2answers
105 views

Algorithmic order of table indexes for table operations

I have not been able to find a clear indication of the impact table indexes have on the algorithmic order of table operations. I am not interested in the nuts & bolts of specific implementations; ...
8
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2answers
542 views

At What Point Does Having an Index Become Efficient

I've found a lot of resources that mention that adding an index to a table makes searches faster and inserts slower, but only if the table is large. This creates a tradeoff, which is a design ...
1
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1answer
64 views

Is it a good idea to have an index when the column value changes several times over record lifetime?

I have a table where one of the columns represents an object state - let it be State of type int. The State value starts with 1 and changes to 7 with values in between. Over a row lifetime there're ...
4
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2answers
138 views

Performance of different precedence pseudocolumn solutions with LIMIT

I was wondering about the relative performance of the solutions provided in the answers to a question on stackoverflow, I decided to run some tests. The OP wanted to get the first matching row given ...
0
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1answer
681 views

Group By on column from joined table

its about the following query. EXPLAIN SELECT phrase, infinitiv FROM `dict_verbs_all` `t` INNER JOIN `dict_verbs_all_language` `verbsGerman_c` ON (`t`.`id`=`verbsGerman_c`.`verb_id`) INNER JOIN ...