Use this tag for questions about improving the performance and/or efficiency of database queries.

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0answers
162 views

Mysql performance issue when selecting text column

I have a performance problem when selecting rows containing text fields: SELECT id FROM message WHERE NOT(message.sender_id = 368352 AND message.is_deleted_sender = 1) AND ...
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0answers
166 views

Optimising Large SQL Server Tables [closed]

I have a large table with around 50 million rows and 15 columns. Whenever I read, I always need all columns so I can't split them. I have a clustered index on the table with 4 keys (ALL INT) and I ...
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0answers
181 views

Mysql key_buffer_size already 16GB but some fulltext searches are still slow

I have a query w/ full text search which takes 5 - 10 secs. key_buffer_size is already 16GB. Table has 15 million records and has a compound fulltext index on fields: categories and company. Table ...
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0answers
134 views

Identical Postgres index scan taking 5x longer on server [closed]

I have an intermediate table for managing a many-to-many relation between tables called Expert and Subject: Column | Type | Modifiers ...
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3answers
4k views

How do I use subquery on the same table in MySQL?

I have a query like this which takes a really long time to run. The table is around 4 million rows. DELETE FROM TABLE WHERE value_was IS NULL OR value_was <= value_now; I'm hoping I could ...
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1answer
183 views

SQL Server 2008 search joining query

I have two table as one is the message table and another one is messageUser table. Now i need to check before insert a new row. for example, M_MessageMessageId========= ...
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0answers
491 views

SOLVED: Postgres 8.4.5: Bad query plan vs Good query plan when changing date range on large data table

SOLVED. I was able to resolve this issue by altering the time.date column to allow 1000 stats: ALTER TABLE time ALTER COLUMN date SET STATISTICS 1000; Now the queries are running very fast, down to ...
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0answers
218 views

How can I use mongoDB efficiently in this scenario?

I'm trying to build a system of documents that have hundreds of tags assigned to them, but each document-tag association has a certain condition it has to also meet so the document would be returned: ...
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1answer
305 views

mysql freeze/crash on JOIN

here is query: SELECT nw.news_id, nw.title, nw.description, nw.url, nw.date, nw.image, nw.status, src.title as src_title, src.keyword as src_keyword, src.url as src_url, src.icon as ...
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1answer
489 views

Optimizing User Defined Custom Columns

I am building a web based app that has the potential to have very high traffic and collect a lot of data. Most of this traffic will be utilizing the database. Database is MySQL InnoDB. I want to give ...
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2answers
1k views

Slow mysql fulltext query

I have a little problem with the performance of a mysql-query which uses a fulltext index. The following query SELECT Mention.id FROM mentions AS Mention WHERE (MATCH (`Mention`.`title_text`, ...
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1answer
435 views

MySQL query optimization with aggregate ORDER BY

I have an analytics table that stores metrics aggregated the day level. I need to ask questions such as "For a given date range and client, what are the most popular items." The schema is as follows: ...
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1answer
146 views

Slow queries InnoDB occasionaly

I have the next table: CREATE TABLE `sessions` ( `session_id` char(32) COLLATE utf8_unicode_ci NOT NULL, `session_expires` int(11) NOT NULL DEFAULT '0', `session_data` varchar(10000) COLLATE ...
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2answers
75 views

How to improve perfomance or Query Execution Time in MySQL?

This is my query: SELECT a.z_companyid_pk "z_companyid_pk" , a.company_name "Client" , a.display_name "Display_Name" , ...
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4answers
676 views

Can migration from MS Access to SQL Server or … make database faster? [closed]

A company asked me to migrate their database from MS Access to SQL Server or MySQL because they think that on those engines their database will run faster. But I wonder if their problem isn't because ...
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2answers
97 views

Can I improve this query?

SELECT * FROM SameLogTable WHERE ID_Table IN (SELECT ID_Table-1 FROM SameLogTable WHERE <SameCondition>) OR ID_Table IN (SELECT ID_Table ...
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1answer
61 views

execution plan question

I have this query running for long time (@P0 nvarchar(4000)) select emaildmo0_.Id as Id7_ ,emaildmo0_.CreatedDate as CreatedD2_7_ ,emaildmo0_.EmailAddress as EmailAdd3_7_ ...
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2answers
99 views

How can I replace the following query with ISNULL function in SQL?

I have the following query. For performance optimization reasons I have been asked to replace the logic with ISNULL function in SQL. How can I achieve this? please advice. SELECT ...
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4answers
178 views

Single SQL query to retrieve data in a particular order (not ASC/DESC)

I have a MySQL table, let's say called reviews review_id, product_id, language_id, rating, review, author language_id ranges from 1 to 10 for 10 different languages. Let's say I determine that my ...
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2answers
541 views

Tsql Query speed slow due to Or within where clause, causing index scan instead of seek

I have been working on making this query work more efficiently. I found that the number of Ors within the where clause are the biggest problem within this query. This query sits in a stored ...
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2answers
267 views

Database SQL Script very, very slow (string manipulation over 700k rows)

I have table containing 700,000 rows containing a string id field with values such as rec-232276-dup-0 and rec-354240-org. The rec- is constant but the other parts of the id can change. I want to ...
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2answers
964 views

Why would a long running query remain sleeping and with null wait_info

The following query was run on SQL Server 2008 R2 and took over 1 hour to run: select log_id, type, instance_id from ts_cache_log where log_id > 146400 order by log_id It produced 0 rows ...
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3answers
5k 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 ...
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2answers
69 views

Oracle query optimization

We have a query that runs on a view and its execution time is about 6 min. SELECT COUNT(*) FROM someschema.item_total_violations WHERE channel_id = 122507833 AND item_date >= ...
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1answer
68 views

Similar hardware, Same DBconfiguration and Database but different status variables result between Windows and Linux server [closed]

I have two database servers - one is Windows - 2008 and another is RHEL5 with similar hardware configuration. Both OS are 64 bit. MySQL 5.1.58 community edition is installed on Windows servers while ...
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2answers
60 views

Which one is better way to insert data? [closed]

I have two cases case create proc createEmployee @firstName varchar(255), @lastName varchar(255) = null as insert into Employee_Tbl values (@firstName, @lastName) case create proc ...
0
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2answers
75 views

A simple database and Query System? [closed]

I am new to databases and trying to solve one problem in which I have to build a simple database having few entries and then querying that database and then recording that answers from the database. I ...
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2answers
1k views

How to get rid of using temporary when using DISTINCT in MySQL?

When I do the following, I get Using where; Using index; Using temporary. How do I get rid of Using temporary? http://sqlfiddle.com/#!8/f61a2/3/0 CREATE TABLE `test` ( `a` varchar(45) NOT NULL, ...
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votes
3answers
2k views

Duration Field in Profiler

I would like to monitor the script which takes more than 25 Sec. When i use filter i am not able to see the duration taken by the script. How can we get the time taken to execute the query. My ...
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2answers
976 views

how to find similar word with more similarities

how to Find words with length less than or equal... declare @inp nvarchar(max),@data nvarchar(max) set @inp='You can dance, you can jive, having .... jove... jve, ...' set @data = 'jeve' ...
0
votes
1answer
130 views

Similar queries taking different times to complete

I had the following query: SELECT nvl(sum(adjust1),0) FROM ( SELECT ManyOperationsOnFieldX adjust1, a, b, c, d, e FROM ( SELECT a, b, c, d, e, SubStr(balance, ...
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votes
1answer
32 views

Clustering a heap by date in stead of unique composite key

I've been working on improving the performance of a large reporting database. This database is 2TB in size, and one of the larger tables is a heap with three non-clustered indexes on it. The ...
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2answers
65 views

Does it make sense to order condition in where query?

We have a clustered index in table Tbl with order of A,B,C. Does it make senses to write a query to have WHERE A = @a, B = @b, C = @c or it'll be as same as WHERE C = @c, B = @b, A = @a Does the ...
0
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3answers
77 views

How to return last used record?

I have simple table called ips with 2 field ip and address, which schema is following CREATE TABLE IF NOT EXISTS `ips` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `address` varchar(255) ...
0
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2answers
69 views

MySQL query optimization for legacy application

I'm working with a legacy application that started out with little data years ago (developed by a third party custom for this client), and now we're seeing MySQL load skyrocket on this query alone. ...
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1answer
556 views

Take query results and insert into new table [closed]

So I have the following query: DECLARE @tbl TABLE(value int) *--The same function but with the number of the random numbers ;WITH Nbrs (n) AS ( SELECT 1 UNION ALL SELECT 1 + n FROM ...
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2answers
987 views

How can I speed up this query on table with 65 million records

select hash_id, hash_value, substring(T.cri, 1, 7), substring(T.cri, 9, D2.Pos-9), substring(T.cri, D2.Pos + 1, D3.Pos - D2.Pos - 1), ...
0
votes
1answer
852 views

Calculating time spent on query cache lock

How can I calculate the total time my MySQL database is spending Waiting for query cache lock ? I've found two specific very simple tables that adding a SQL_NO_CACHE drastically improved the ...
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2answers
92 views

Query performance differs greatly between a development setup and production

I'll try to keep this question straightforward, though I am dealing with a big ball of mud. When I run my test query acrossed linked servers both located locally (on a shared virtual host), the ...
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votes
1answer
1k views

Optimizing ORDER BY for simple MySQL query

I'm trying to optimize this really simple query, and it gives me grief for a day now :( Seems pretty straightforward, I need to select with a JOIN from 2 tables, and get top X results sorted in a ...
0
votes
1answer
347 views

Database schema design help needed

I am developing a PHP application expecting millions of records both parent and children. My goal is to design an optimized database design to achieve high speed and performance. This application ...
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votes
2answers
415 views

Large time difference between two almost identical simple queries…why?

I'm trying to understand why is there so much difference in execution time and CPU usage between two simple queries that only differ in a computation. The queries are the following: SELECT ...
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votes
1answer
50 views

improve long running query

I have this query INSERT INTO interactions( user_id, external_object_id, origin, interaction_type, interaction_sub_type, published_at, origin_id, created_at, updated_at) SELECT ...
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votes
1answer
109 views

Optimizing key lookup in subquery with UNION ALL

I am trying to optimize following query (little bit more complex actually, but this is important part): SELECT Id, StatusDate, [...Lot Of Columns...] FROM ( ( SELECT Id, StatusDate, [...Lot ...
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votes
2answers
63 views

SQL Server 2005 query with multiple conditions, some indexed, some not

I have a table with 50 million rows. It is indexed on zip. A query Select * from table where zip = '12345' returns 20,000 rows in about 2 seconds When I add an additional condition it jumps to ...
0
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1answer
108 views

What is the best query to get the latest row version based on time?

I'm wondering what can be the most efficient query to get the latest rows from the following table. CREATE TABLE AGE_DATA ( INSERTED_DAY TIMESTAMP(6), HOSTNAME VARCHAR2(255 CHAR), CONCEPT ...
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4answers
101 views

Why does this query take 32 sec to execute?

I keep my history records in one table and my pertinent data in another. I want to grab only the files from myfiles that currently have a given status recorded in statuses (ie, the latest status is ...
0
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2answers
83 views

Querying MySQL, duration increases 10x fold after adding one more Join

I have a somewhat complicated query consisting of many joins on an issue tracker/project management database in MySQL. My issue is that my query was doing OK while I was in the process of building it ...
0
votes
1answer
82 views

Simplifying query by adding Computed Column, performance impact?

The dev team came across the following query (might be incomplete; it's retyped from a screenshot) which had caused slowness: SELECT d.catalogno, d.itemid, SUM(lineamount+taxamount) AS Amount, ...
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2answers
1k views

Increased query_cache_size, Queries slowed drastically on increased traffic

I increased our servers query_cache_size to 2gb, hoping for performance benefits. After sometime the query performance would drastically decrease. Once I dug in deeper, I found the queries in State ...