An evaluation of whether a system works well enough to be fit for purpose. Normally performance refers to the speed with which a system completes an operation or set of operations over time.

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45 views

Preventing sysquerymetrics from being created ASE 15.7

Can I prevent Sybase ASE 15.7 from creating the sysquerymetrics view for a database upon creation? And also, if the view is dropped how can it be added later?
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0answers
21 views

How can I decrease FULLTEXT initialization time?

I'm trying to decrease execution time of the a query. Using SHOW PROFILE, FULLTEXT initialization takes about 0.3, which is too high. Other values are at normal level. How can I decrease FULLTEXT ...
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2answers
72 views

SQL 2008 Server - performance loss possibly connected with a very large table

Migrated from http://serverfault.com/questions/615129/sql-2008-server-performance-loss-possibly-connected-with-a-very-large-table We have SQL Server 2008 with 3 active databases running on it. DB1 ...
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2answers
141 views

Improving a search query

I have a query for search function. Basically search function allowed user to define what they "have" and "want". Then this query will filter out all the possible result which created by other user. ...
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2answers
34 views

Optimize rows to columns conversion

I have a big Oracle table (around 40 million rows) that looks like this: ID Name Question Answer Reason 3 Name1 1 Yes blah blah 3 Name1 2 No NA 3 Name1 3 ...
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2answers
49 views

How do dirty reads at both the transaction and table level provide increased performance?

I ran the following code past our architect as I thought there may have been a tautology between the isolation level and table hint: SET NOCOUNT ON SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED ...
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1answer
70 views

Oracle 11g max login fail attempts workaround

My problem with database starts with situation where I cant really modify anything in database. My project specialist has limited time to help me. Here is the thing: My user in Oracle database has ...
6
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2answers
352 views

Explanation requested for slow DELETE with SQL Server

I would like to get some extra insights/reasoning for SQL Server delete behavior. We have a fairly large database of over 1800 GB. In there are some very shallow tables (only a few integer columns) ...
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2answers
56 views

Rapidly increasing TempDB write latency

We have two servers that were set very similarly, but not identically. These two servers have hugely different performance running the same application. On server A the application runs successfully ...
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2answers
77 views

Table design for multi-type data

The information model I am modelling from includes an "any type". For example a customer can have zero or more 'entries' each of which can have a number of values. Each value could be a either date, ...
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2answers
42 views

Does leaving a connection open for a matter of seconds cause deadlocks?

I have been testing a system application and have noticed that it is slow when it connects to the database overseas. This is to be expected to some extent, but there is a big difference with the ...
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1answer
53 views

Seeking help to test a use case on sql server memory

This is a question which came out of curiosity to know of how sql server handles memory. Assume I set a very low value for max server memory and I increase my workload like running dbcc checkdb, ...
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1answer
24 views

Perl - MySQL/MariaDB - slow with no identifiable bottleneck

I am running a Perl script (using DBI) which reads from raw files from a hard disk, and updates MySQL database (which is on a separate SSD). My performance is rather slow (1000 files processed in ...
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1answer
25 views

Tuning Mongo (TokuMX) for fastest bulk reads

What options do I have for tuning MongoDB / TokuMX for reading the results of queries with large result sets? I'm currently on a single server (no sharding) with the data on an SSD drive. My queries ...
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2answers
158 views

Query planner thinks doing a sequential scan on a very large table is faster than using an index?

I've got a query that selects the most favorited photo for each of the last 12 editions for a particular domain (this is just a segment of a larger query, but the problem seems to stem from here): ...
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0answers
11 views

firebird update very slow

I am writing a stored procedure for Firebird 2.5 in which I sometimes need to update a single row in a data table more than once in the same transaction. However, I have noticed that the performance ...
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0answers
33 views

performance questions in database design

I need to describe a set of studies that are practiced to a patient, every patient have a "Clinical History", that are described in another table called "Clinical History Lines"(hclines) Every visit ...
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1answer
183 views

Internal query on CDEF$ and CON$ very CPU bound

I am checking an application (Infor ERP LN) that loads a lot of data into an oracle 10.2 database. While checking one of the user sessions with SQL_TRACE and its output with tkprof, I found that the ...
3
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1answer
486 views

Select * from statement execute very slowly, innodb io read speed is low

I have a very simple query " select * from ap_statistic " running in my servers. the servers have the same hardware and software configuration (CPU 8 core, mem :32G, OS: redhat 5.5, mysql version: ...
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6answers
47k views

How can I optimize a mysqldump of a large database?

I have a symfony application with an InnoDB database that is ~2GB with 57 tables. The majority of the size of the database resides in a single table (~1.2GB). I am currently using mysqldump to ...
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0answers
14 views

What is the optimal way to get a tabular view from an Entity-Attribute-Model table?

Following up on my previous question, I have created a table for storing measurements of different physical quantities. The schema looks like this: CREATE TABLE sensorreadings ( time TIMESTAMP, ...
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0answers
37 views

Database design for large incoming data

I've been tasked to design a database to handle a large volume of incoming traffic from sensor readings, possibly 1,000s an hour when it's at full strength. Each reading will be relatively short - ...
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0answers
54 views

A working view now starts timing out

I have 2 identical databases (one larger, one smaller) with identical views. Recently a view on the smaller DB started timing out. Google searches seems to point to deadlocking of some sorts. If I ...
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0answers
11 views

Disable MongoDB journaling?

Are there any benefits in disabling mongodb journaling besides performance gain? I know journaling provides write durability and crash resiliency. But I can tune syncdelay parameter to make data files ...
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0answers
35 views

Handling a chat room in a database

I have been searching all day to find a better answer to my question but those I found was useful but do not critically analyse my question. I am building a chat room using php, mysql, jquery and ...
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2answers
215 views

Major Discrepancy Between SQLIO IOPS/Throughput Stats and DBCC CHECKDB Operations

I'm conducting time trials on a new SSD array running both SQLIO tests and a real-world workload of DB restores and DBCC CHECKDB calls. I'm seeing a major discrepancy between the IOPS and throughput ...
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1answer
48 views

How can I control the order of a query regarding to inner join

I have 3 tables. They have table_a 5m records table_b 20m records table_c 20m records I'm performing the query below. SELECT * FROM table_a a INNER JOIN table_b b ON a.a_id = b.a_id AND ...
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2answers
2k views

Oracle 11g: “With Clause” very slow

I have written a query utilizing Oracle's with clause. I have identified one particular with clause in a larger query to be really, really slow. Here are three versions of the same query, they all ...
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1answer
11 views

mongodb - “replication oplog window” possibly reduced due to profiling - when profiling disabled no change?

PROBLEM I have a 3 member replica set (no sharding) running mongodb version 2.4.8. Using MMS (Mongo Monitoring) I can see that on 7th July 2014 at 12:00 my "replication oplog window" dropped from ...
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1answer
67 views

Optimizing large MySQL SELECT WHERE IN clauses

How can the following SELECT WHERE IN case be optimized? I have a table with over 100 million rows with only 3 columns. The primary key (col1) is a 127 varchar. I am performing a SELECT col1 WHERE ...
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1answer
185 views

MySQL select by primary key against 100M of records within 30ms

I have no expirience with MySQL and database performance tuning in general. Wondering whether it is possible to perform a large number of selects against 100 millions of records by primary key within ...
3
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2answers
46 views

SQL Server Baseline and Performance Optimization

I've been struggling a little bit around Performance Troubleshooting including baseline and troubleshooting of SQL Performance. Could anyone help with this or point me to where I can possibly get a ...
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0answers
11 views

Sysadmin tools for SQLAnywhere

I'm seeing a performance issue in a 3rd party application based on SQLAnywhere 7. The DB engine seems to be dramatically underperforming on the hardware provided. It seems to have a upper limit on the ...
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2answers
182 views

SQL server query is slow *without* including execution plan

I have just set up fresh installation of SQL Server 2012 on a new server and I'm experiencing very strange performance problems. Long story short, for some reason not including execution plan makes my ...
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2answers
172 views

How to fix slow LIMIT queries with big offsets without heavily rewriting them?

Imagine a very basic example of your average discussion board. For example: CREATE TABLE threads ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, title VARCHAR(100), PRIMARY KEY (id) ) CREATE ...
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2answers
108 views

Oracle 11.2 using too few memory

it is about one year that I have changed my server from Oracle 10g to 11.2g (and also changed the hardware and Windows from 2003R2 to 2012). The problem is that with more than doubled cpu power, ...
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1answer
99 views

Why is this second query more expensive than the first?

While reading Graph Databases book, I came across this excerpt: I can't figure out why the second query is more expensive than the first. Indeed, both filter on the Bob person. May anyone ...
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0answers
70 views

SQL Server Perfmon % Processor Time unbalanced [closed]

I am somewhat of an accidental DBA, and I'm troubleshooting a SQL Server box where performance has been notoriously poor (as reported by the customer). I was not involved in the initial planning of ...
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0answers
26 views

Mysql table with only two columns, nothing unique: Will an index increase search performance?

If my table only has two columns (username, groupname) and a million or so rows, will an index improve performance at all? Wouldn't it take just as long to search the index file as it would to search ...
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1answer
109 views

Partition : understanding files and file groups

We are trying to partition a large history table. Being new to partitioning, I was trying to understand the concept of files and file groups. File groups can be set up in following three ways : 1. ...
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1answer
36 views

How performance schema in mysql 5.6 improve performance?

Since MySQL 5.5 performance_schema database has been added likewise information_schema. As we know that tables in information_schema contains statistical information like tables, plugins, partitions, ...
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0answers
28 views

MySQL 5.5, Xubuntu 14.04 - INSERT and UPDATE bottleneck

DBAs: I have been developing and maintaining plugins for Moodle for the last ~2 years, and have recently decided to try using my local desktop again, rather than my institutions ESX VMs, as a ...
0
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1answer
93 views

How to configure my.cnf for Mysql 5.1, which is using too much CPU?

I am new Database engineer. I am having trouble in my server which is using too much CPU on database query(simple count statement). I have googled about it, so i found out it depends on system ...
0
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1answer
32 views

MySQL ON DUPLICATE KEY UPDATE performance issue

We have a table with over 200k rows. Every row belongs to a category, there are almost 50k rows per category. What is the best way to update all rows of that category? We are using a script like ...
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1answer
35 views

Understanding pagefile.sys % Usage performance monitor (perfmon) counter correctly

Lately we run into performance inssues and I started tracking some recommended sql, memory, disk and cpu counters. I informed myself about the recommended values and numbers to look at. One of the ...
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1answer
1k views

Lazy Writes Performance Issues

My SQL Server sometimes reports high Lazy Writes e.g. "Lazy Writes per second is 119 Writes/sec" What should I be checking to find out why this is high? What are potential causes? Thanks.
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2answers
59 views

MySQL: How to avoid case sensitivity in SQL queries when migrate from Windows to Linux?

I have migrated my Database from Windows to Linux server. In many places, query has been written without focusing their cases (uppercase / lowercase). So, these queries are not getting executed and ...
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2answers
73 views

Why is this simple join taking so long?

I'm trying to run some reporting queries on a MySQL database, and I'm running into serious performance issues for some reason. One table, page_views, is extremely large (~70 million records), so some ...
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2answers
47 views

Are #tables and #procedures 'not best practice' or 'bad practice'?

I am working on a project and part of it is an interface tool that executes SQL code stored in a xml file to import/export files. In the file, temp procedures and temp tables are used quite heavily ...
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1answer
34 views

Detailed optimal column order with large text and bytea

I read this excellent answer on optimal column ordering and noticed the summation: Generally speaking, if you put the 8-byte-types first then the 4-byte-types and the 2-byte-types last you can't ...