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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MySQL: system variables and status variables related with Disk I/O

How disk I/O is related with MySQL performance improvement. I have a MySQL-5.1.58 based Intranet application equipped with Windows 2008 server and 8 GB RAM. Even, When my application face performance ...
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1answer
70 views

Maximum dataset size for a well-performing SQL Server 2012? [closed]

We're planning a project using SQL Server 2012 for storing about a billion records over less than 50 fields. Assuming good hardware, is SQL Server up to that task? Roughly how many request/second can ...
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58 views

MySQL cluster performance very poor on Amazon

We have currently a project running where we need to store 1 to 20,30 million 500B to 2kB records. We need to use MySQL cluster on 4 EC2 instances (8GB Ram, 2 cores) and ephemeral storage (Records ...
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1answer
41 views

Patterns/Designs to help with concurrency/performance [closed]

I'm working on a SQL Server 2008 R2 DB and I'm experiencing some performance/concurrency issues with probably the main table in the DB. Problems like slow reads, deadlocks, poor performance in ...
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1answer
109 views

Is this amount of disk IO expected with MySQL?

I am running MySQL 5.5.34 on an Amazon EC2 micro instance with EBS (elastic block storage). The instance has been running for around 10 days and according to Amazon I've accumulated around 8.5 ...
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1answer
112 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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1answer
132 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 ...
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97 views

MySQl: slow query is not using index in joining

Below is the configuration of my DB server: Apache version : Apache/2.2.22 (Win32) mod_ssl/2.2.22 OpenSSL/0.9.8 PHP version : 5.3.13 MySQL version : mysqlnd 5.1.11 Windows Server 2008 Standard ...
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1answer
81 views

Slow queries related to subqueries using aggregation

Here's a simplified version of the queries I am running: select ... from editions join edition_events on edition_events.edition_id = editions.id join events on events.id = ...
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99 views

how I can set tmp_table_size for 16GB long table?

I am posting the same question as I posted in SO, but somebody advice me to post it here. I have a 16GB big table with 8 partition. And RAM 4 GB. I am running a query - SELECT ...
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14 views

how I can set tmp_table_size for 16GB long table? [duplicate]

I have a 16GB big table with 8 partition. And RAM 4 GB. I am running a query - SELECT c.eveDate,SUM(c.dataVolumeDownLink)+SUM(c.dataVolumeUpLink) FROM cdr c WHERE c.evedate>='2013-10-01' GROUP ...
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1answer
33 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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1answer
44 views

Suggest performance tradeoffs

I have a an inner query that needs outer query column values as input. It looks something like this CREATE TABLE TISSET( COL1 int ,COL2 int,COL3 int) INSERT INTO TISSET VALUES (1,1,1); INSERT ...
2
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0answers
49 views

SQL Server 2012 STIntersects

I have one table, T_PIN, with 300,000 pins and another, T_POLYGON, with 36,000 polygons. T_PIN has this index : CREATE SPATIAL INDEX [T_PIN_COORD] ON [dbo].[T_PIN] ( [Coord] )USING GEOGRAPHY_GRID ...
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1answer
71 views

Restore With Move has poor performance

As part of our regular development cycle we need to take a copy of production into development databases. To do this, we take a copy of production backups and move them to the Development Server. ...
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2answers
134 views

Architectural Help Needed - MySQL or NoSQL for a table with 54 million records

We have a table with 54 million records. Here is the table structure. CREATE TABLE `metaplay` ( `track_id` int(11) NOT NULL DEFAULT '0', `user_id` int(11) DEFAULT NULL, `completed` int(11) ...
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2answers
67 views

distinguish single-block vs multi-block reads in Oracle explain plan

If I am looking at a query plan in Oracle 11g, is there any way I can tell which operations will result in single-block reads and which will result in multi-block?
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1answer
112 views

Performance issue with TOP (1) on a nullable column

I need help to identify the reason for a performance issue. Actually following query sits in a scalar-valued-function but that is not the reason for the issue since it needs the same time as query: ...
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1answer
51 views

SQL Server 2000 Replication, Performance, and Query Priorities

I'm a developer and wanting to confirm the following: Does anyone here have experience with SQL Server Replication (transactional) on 2000? We are trying to convince the DBAs to allow this in a ...
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0answers
81 views

Postgres chooses a bad query plan

The following query finishes in 1.5s (which is ok, the table contains about 500M rows): explain (analyze, buffers) select sales.* from sales join product on (product.id = sales.productid) join date ...
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250 views

SQL Server 2012 performance issues (maybe due to linked server) [closed]

Summary of the problem We've spit our one database server environment into two servers. We are now having intermittent performance issues I am hoping someone can offer clues - perhaps direction ...
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2answers
368 views

Mysql Performance optimization, max CPU load, low qps

I would like if anybody could look into performance optimize this: I have a Ubuntu 12.04 running on VMWare 5.1, with 32 GB RAM and 8 Cores (No problems regarding cpu scheduling as the VM is almost ...
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0answers
31 views

Recommended plan for 0min RTO and RPO

I have a Windows Server 2008R2 Server, running SQL Server 2008R2 SP2. The server currently only does a full backup once daily. The server's operational hours are between 8am and 5pm. The server's new ...
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1answer
36 views

Does size of one particular column in a database affect query performance?

I have a table user_list CREATE TABLE IF NOT EXISTS `user_list` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `username` varchar(40) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, `email` ...
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1answer
79 views

Would you use MongoDB in high-transaction environment? [closed]

using other words: does the one-write-lock-per-database policy (it's not a "bug" but a "feature" by design) affect contention making its usage in certain kind of workloads less then optimal? if not ...
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2answers
101 views

mysql need help optimizing query

I have a table containing servers logs, and another table containing rules to match certain and drop them. The logs tables contains around 1 million rows, and there are about 20-30 rules. The ...
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1answer
104 views

Precautions when designing database schema if tables are going to have billons of rows

I am about to start work on telephone dictionary kind of project. Its confirm that there are going to be billions of records in dictionary table, and each entry from this dictionary table may have ...
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1answer
108 views

How can I detect which indexes are being rebuilt offline and how long?

The rebuild of indexes takes appr. the same 55 min. with both "Do not rebuild indexes and "Rebuild indexes offline" "For index types that do not support index rebuilds" with "Keep index online while ...
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0answers
40 views

how to design my database for faster reads for my situation

I have a situation where i have two categories. Lets say type A and type B. In my database I have some 50,000 type A entries and 100,000 type B entries as of now. For each entry mentioned above(type ...
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2answers
51 views

What does enabling containment on server incur?

Having read in a book of Patrick LeBlank "Microsoft® SQL Server® 2012 Step by Step": "Benefits and limitations of contained databases As with most features, there are benefits and ...
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3answers
132 views

Oracle: terrible execution times from virtual application server

I've been provided with an Oracle VM linux box playing host to an Oracle 11g installation. I've also been provided with an Oracle VM Windows Server 2008 64-bit box acting as an application server. ...
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1answer
52 views

is keeping idle / unused mysql databases bad?

Is there any harm like eating up resources etc. Or is mySQL engineered to just work for the used ones and keep others at hand. If so, why is there such thing like taking a db offline? Should I do ...
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99 views

Oracle - How can I improve this query?

We have performance problems with some queries. We always use the rank() function to get the latest entries with a status. The question is, how to speed up things. CREATE TABLE PAYMENT ( CLIENT ...
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1answer
520 views

MySQL - Server collation utf8_unicode_ci vs table collation utf8_bin: compatibility and performance

I'm not sure whether this belongs to SE DBA, but it sounds more logical ... Our MySQL 5.5.32 on Ubuntu 12.04 64 uses utf8_unicode_ci for the Server collation and some tables, like phpBB3, uses ...
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1answer
228 views

TCP sockets bottleneck with InnoDB/Debian?

We have a big mysql performance issue on a production environment with 18 "front" servers sending mysql queries to a unique mysql server. We are using Redis on each front server for a number of ...
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0answers
113 views

SQL queries are very slow

I have noticed that my queries are getting slower. Some update queries take about 48-50 seconds. Here's how it looks: [root@db-1 ~]# tail /var/lib/mysql/mysql-slow.log # Time: 131113 17:09:48 # ...
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0answers
24 views

optimizing a CTE Hierarchy [duplicate]

I have a table of accounts with a typical acct/parent account architecture to represent a hierarchy of accounts (SQL Server 2012). I created a VIEW using a CTE to hash out the hierarchy, and on the ...
0
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1answer
285 views

Slow MySql Server Performance - What and How to check?

start:disclaimer I'm not a MySql Server DBA; I know mostly of MSSQL - which is why i need your help end:disclaimer I've been asked to check why the MySql server engine is performing poorly - i have ...
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2answers
4k views

MySQL creates temporary tables on disk. How do I stop it?

We are running a site (Moodle) that the users currently find slow. I think I have tracked down the problem to MySQL creating temporary tables on disk. I watch the variable created_tmp_disk_tables in ...
2
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1answer
58 views

Can SQL Server WebAdmin degrade the performance of my site?

Once upon a time a had to use the Parallels WebAdmin interface. After contacting the support team that hosts my website and informing them that I must use the Webadmin, they informed me that: MS ...
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0answers
214 views

SQL Server: Batch Requests/sec showed increase in performance, but performance actually decreased

We are currently on SQL Server 2005, with a plan to move to SQL 2012. To make this move we have to test new database drivers for the application (Java). We performed 2 load tests using the 2 different ...
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2answers
173 views

Which is better? A join or a SELECT IN? [closed]

I have a set of ids that I extract using a join of 2 tables. Now I need some information from 2 other tables. What would normally be the best approach? So a SELECT IN using the set of ids I already ...
10
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1answer
318 views

Should NOT IN be avoided?

Among SQL Server developers, it's a widely held belief that NOT IN is terribly slow, and queries should be rewritten so that they return the same result but do not use the "evil" keywords. (Example) ...
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1answer
87 views

MySql - is possible that performance issues are caused by dynamic SQL?

We have this MySQL SP, which uses dynamic SQL. It seems it does NOT perform well under load. It is possible that this SP becomes slow under load because it uses dynamic SQL? Can dynamic SQL cause ...
1
vote
1answer
64 views

How is the number of records on a select determined as high or low by optimizer?

What is the threshold between using the index and doing an direct access to the database? I assume this decision is related to the number of index access (and subsequent access to the tables). If this ...
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1answer
42 views

Can MySql nested SP be a bottleneck?

We have this MySQL SP, which calls a nested SP. It seems it does NOT perform well under load. It is possible that this SP becomes slow under load because it calls a nested SP and uses temporary ...
3
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1answer
440 views

Table-valued function runs fast, but slow from another function [closed]

Disclaimer: I'm a senior sysadmin who's trying to help our development team speed up the production database. Our users are hurting, bad. Please don't shoot me for not being great with SQL The ...
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4answers
190 views

Which of these queries is best for performance?

Which of these queries are best for performance ? Sometimes I wonder if SHORT scripts really is the best thing to focus on. These scripts performs the same task. With left joins i can achieve what i ...
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0answers
238 views

Fastest way to perform simple operations on 1 million rows

I have a simple table with more than 1 million rows in an InnoDB MySQL table. Here are the steps that I need to perform on each row: SELECT * FROM tbl where work_done=0 make some data processings ...
2
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0answers
55 views

Find Most active databases that can be offloaded from a busy server

I am in the process of identifying the most active databases on the server and will be moving the databases off the current server to alleviate the load. The reason to do it is that our servers are ...