In the context of a database, optimisation refers to the process of the query optimiser selecting an efficient physical execution plan.

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Modification to GEQO (Genetic Query Optimization) of PostgreSQL

I need to implement a functionality that is in line with the GEQO functionality of PostgreSQL. I understand that GEQO approach is to encode query plans as integer strings and GEQO generates these ...
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157 views

Form builder schema for SQL database?

There are many ways one can envision the solution, from the top of my head: Two table approach: Field table with (name, field_name, type, description, meta) attributes Form table with (name, ...
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321 views

Slow transactions, many locks

At high load conditions the server app stops responding to client because begin/commit statements are executing very slowly (some take 15 seconds). The queries are simple - insert, update two columns ...
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69 views

Tagged questions

I have similar to StackExchange network that utilises tagged questions. In my web application Users also can find questions by tags. The query below returns a set of tagged questions: SELECT ...
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109 views

Two queries usually run fast but get slow when joined

There are those 2 tables CREATE TABLE IF NOT EXISTS `media` ( `mid` int(11) NOT NULL AUTO_INCREMENT, `user` int(11) NOT NULL, `order_type` int(11) NOT NULL, `media_id` varchar(50) COLLATE ...
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62 views

Performance differs on same query against two (almost) identical tables?

I'm running these two queries in SQL Server 2012: SELECT tpua.Field1, CAST(round(twg.Field2 * 2, 0) / 2 As Decimal(8,1)) As Field2, CAST((round((twg.Field3/10.0) * 2, 0) / 2) * 10 As int) As ...
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73 views

SQL - Optimize table population with dynamic queries

I need to optimize the following pl/sql procedure. So, fundamentally my question is: There is a way you can do a bulk insert in a pl/sql that could be more efficient than loop through an associative ...
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29 views

Query optimization - contact should be extracted at most once for a particular customer

I have created a database for a telemarketing company Scenario is, the telemarketing company is selling contacts to the customers. Customers log on to the website and search for the contacts for ...
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48 views

Efficiently joining two irregular series representing changes

(This is a PostgreSQL-specific question, using version 9.1, but could be upgraded to 9.3.) I have a number of tables that represent a series of changes. These tables all have the same structure: ...
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51 views

Set default fields

Is there a way to inform the database that some fields are default (have always the same value) so that I don't need include them in all my queries? Suppose: Select ... where f1=a, f2=b, f3=c, f4=d ...
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1k views

Query optimization on a large table in PostgreSQL

I am not super experienced with databases, just have a college level course under my belt. I am trying to see if an existing query can be optimized. Currently on average takes over 300ms. There is a ...
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173 views

How to give permissions to 90+ SQL Servers without tweaking in each of them?

There are over 90+ MS SQL Servers (SQL Server 2005, 2008 and 2012). All in the same Windows domain (but physically all over the world). How to give a domain user (administrative, or other) ...
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233 views

Postgres - Partitioning old tables, partition query planning, optimisation

I've been trying to optimise our database, but not being a DBA and not having done a whole lot of tuning before I'm struggling a little with "too many options". I've already run pg_tune and bumped a ...
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1k views

which role-permission database design?

I want to manage roles and permissions. Most of designs on web look like this tables: Users Roles UserRoles Permissions RolePermissions Here, what is permissions? I am thinking for such a design ...
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833 views

MySQL: Improve performance for one row insert into table with unique constraint

I have a table with ~ 40 mil records, with a unique index on the url collumn, of type varchar(255). Now the insert speed is about 30/s, is this expected? how could I improve it? I can't use bulk ...
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81 views

Optimizations for new SQL Server 2000 database that will act as email queue AND API database

Due to limitations put on me I've got to put my outgoing Email Queue in the same database as my customer information. What are some optimizations I can make, specifically to the Email portion that ...
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1k views

SQL query optimization in Prestashop e-Commerce solution

I'm working on a layered navigation module within Prestashop e-Commerce solution. I'm trying to optimize a SQL query which creates a temp table during execution. I think this is creating a ...
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27 views

Disable/Remove Table Index for INSERT Performance

I am doing a database maintenance where I have to add new fields to a table with over 10GB of data about (20 million rows). To solve that I renamed tableA to be old_tableA and created a new table ...
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41 views

Slow query - PostgreSQL 9.2

I've got a Query that takes some time to be executed... Can you guys help to improve the total time? Thank you! QUERY: SELECT file.inode_id AS file_id, file.parent_inode_id AS ...
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27 views

Most Similar Records Query Performance

I have a mysql database table with 20 million records. It grows at roughly 25,000 records per day. Each record has a number of numeric fields. I have a similarity query that selects the 10 most ...
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13 views

Variables for Merging MySQL InnoDB Tables

I have several thousand InnoDB tables in MySQL 5.6 that I am trying to merge together into a single table. A simplified form of the queries I am executing (one for each of the tables to merge) is ...
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67 views

Queries which return more than 100k rows

I have a following query SELECT * FROM table_name WHERE #3_column BETWEEN start_date AND end_date which is taking about 10 seconds on my computer to execute and returns about 180k rows. Table schema ...
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10 views

PostGIS Intersects Query takes lot of time to get the result

I am developing a webmapping application in which I used PosgreSQL with PostGIS plugin as my DB. I have this two tables namely; evidensapp_polystructures and evidensapp_seniangcbr. Both tables ...
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44 views

Oracle tuning strategy for columns with long tails

We have an Oracle 11g database, where the two biggest tables are Customer and Order. The order profile of our customers has a long tail: we have millions of customers, with most only having a small ...
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16 views

Optiming ACT_RU_JOB Query

We're using Activiti version 5.15.1 with timers in our workflow which sends reminders to users who are in the workflow. Problem is that we're creating jobs in ACT_RU_JOB table and even though there ...
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227 views

Why my sql query run faster than my stored procedure?

I am trying to write a script in MYSQL Workbench to update my database every day using stored procedure but I find it too slow compared normal query or temporary tables. If i use temporary table the ...
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365 views

Oracle 10.2.0.4 query hundreds times slower than the same query on Oracle 10.2.0.3

I have an issue with query on Oracle 11.2.0.4.0 (it takes forever to complete and CPU is at 100% all the time) so I was trying to change optimizer_features_enable to previous versions. It worked with ...
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24 views

Optimizing MySQL for write throughput ceiling

We have a large MySQL database on AWS RDS, with a huge table around ~1.8TB with massive write workload. We recently hit a write throughput bottleneck, which caps our provisioned IOPS way below the ...
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30 views

Subquery optimization

I was reading through this article - http://explainextended.com/2009/09/18/not-in-vs-not-exists-vs-left-join-is-null-mysql/ I am working with an existing design. What I want is to be able to select ...
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58 views

Is there a way to improve this query further?

I've got a query that over time I've been improving. Originally it simply selected * from the records table, and the data was formatted on the webapp side. But that was slow and I wanted to make ...
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134 views

How to optimize inefficient query in PostGIS

I'm doing some queries on a PostGIS, and some of them take a really long time ( > 60 secs). My queries are like this, except querying different tables (like osm_placesbelow). This query takes about ...
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91 views

Delete Query throwing warning db2

I am trying to delete multiple records from view The view has Instead of Trigger defined .. The view has records consolidated from multiple tables. [db2inst1@testServer001 ~]$ db2 "delete from ...
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265 views

How to Insert records from remote database to local database using dblink in postgresql 9.3

I have a scenario like i have a two DB, one resides in remote server and other resides local. Now i have to fetch the records from remote DB when new records are inserted on tables (in remote DB) and ...
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196 views

Performance tuning self-joining MySQL query

I asked a question recently on the correct way to update a table using multiple joins to itself in order to generate the desired values. Updating MySQL innodb table based on multiple joins After ...
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105 views

Optimizing SELECT queries

I'm not very experienced with database query optimization. I've been reading through similar questions here and Postgres tuning articles online, but unfortunately I haven't had any luck. Here's what I ...
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666 views

Optimization Tips For MYSQL Tuner/Primer

So I have a site that has a crap ton of traffic. I see a decent amount of latency when the site has over 1,000 active visitors on it. I have new relic installed and it seems Im only using 10% of the ...
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107 views

Refactoring IN Subquery, Avoiding Query in a Loop

I've got a table which was designed as both the current data set for participants, as well as being the historical changeset for those participants. This table has been in use for approximately three ...
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41 views

Need help in optimizing a Slow Query

I am using userpoints module to provide points for different actions that they do on my site. mysql> desc userpoints; +-------------+---------+------+-----+---------+----------------+ | Field ...
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77 views

Querying number of tries since last successful log, checking IP as well as user

I asked this question before on stackoverflow, but it might fit better here, since it is mainly about database performance. The actual question With performance in mind, how would you go about ...
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144 views

Significant difference between duration for querys in SHOW PROFILE and SHOW PROFILES?

I have use mysql profiler to optimize an opencart query which takes more than 10 seconds to executes. mysql> SHOW PROFILES; ...
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Truncating Table Partitions Containing Data and Global Indexes

I have to truncate a partition (392,000 records) of a table with 20.000.000 records. At the moment, I'm making a truncate table and rebuilding indexes. But the table has 37 indexes and it takes 20 ...
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112 views

MySQL query with order by decreased performance

Here is my schema: CREATE TABLE `UserMst` ( `UserID` mediumint(8) unsigned NOT NULL AUTO_INCREMENT, `EMailID` varchar(50) DEFAULT NULL, `UserName` varchar(20) DEFAULT NULL, `FullName` ...
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92 views

Query optimization, SQL Server cache query, SQL Server execution query

I have 2 queries, the results of their execution is the same, but I don't know which of these is the best in terms of performance and why. Query #1: SELECT CASE WHEN ( EXISTS (SELECT 1 AS [C1] ...
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108 views

can this mysql query be optimized further?

I have this query select counterparty_id, max(id) max_id from client_administrations where counterparty_type = 1 and effective_on <= '2013-10-22' group by counterparty_id When I ...
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206 views

How to index for a group by with columns from different tables?

Is it possible to create an index from columns of 2 different tables? If not, how do we optimize a query that does a group by on columns of 2 different tables? For example: the following ...
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209 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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1k views

How can I join one to one to (many to one) without using group_concat

I have a table structure as follows: -- -- Table structure for table `emails` -- CREATE TABLE IF NOT EXISTS `emails` ( `ID` int(5) NOT NULL AUTO_INCREMENT, `email` varchar(255) COLLATE ...
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503 views

Finding the bottleneck by analyzing Munin graphs

We’ve been experiencing some issues with our database server during peak hours. In our Nginx error-log we can see that a lot of requests get timed out. The requests are also very slow. We have had ...
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The most-recent-record problem with partitioned tables

Today's variant on the most-recent-record problem involves a table partitioned on the timestamp field relevant to the most-recent-record selection, and efficiently joining the result of the ...
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22 views

In which order does a mongodump --query executes

In which order does a mongodump --query executes, is from last insert to first insert or the other way around, if it is other way around is there any option that I can pass to mongodump --query, so ...