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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3answers
42 views

500 databases or 1 database with 500 tables or just 1 table with all the records?

I currently have an application that is used by a single end customer. For ease of discussion assume the application only needs a single database table for all records. I now need to support ...
-4
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0answers
26 views

personal database [on hold]

Normalize each of the following datasets by splitting them into multiple tables where repeating fields are placed into a separate table with a foreign key. For each dataset, show how many tables ...
0
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1answer
30 views

How to check SQL database files for physical fragmentation?

I search the Internet and did not find clear explanation if I have to try defragmenting physical database files when my DB resides on SAN. I understand that there are tools and procedures inside some ...
0
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1answer
22 views

Difference between FIND_IN_SET and LIKE

is there a difference in behavior or performance in choosing FIND_IN_SET over LIKE for a operation that looks like: SELECT * FROM my_table WHERE column_1 LIKE %string% vs SELECT * FROM my_table ...
1
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1answer
29 views

Optimizing for data that does not fit in memory

We have a database that contains around 235 GB of data (calculcated using pg_total_relation_size for each table) on a server with around 77GB of memory. The server is used for nothing else (aside from ...
0
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2answers
25 views

VARCHAR primary key - MySQL

Currently, I have a categories table with 2 columns - category VARCHAR(50) NOT NULL PRIMARY KEY and parent VARCHAR(50). The parent column is a foreign key (FK) to the category column. This seems like ...
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0answers
13 views

How to model efficient permission checks for a social network?

The goal is to build a facebook like permission system. So that users can grant other users access on objects based on a direct assignment (allow user X to see posts) or allow users to access them ...
1
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2answers
45 views

Upgrading hardware for MySQL. If we get SSDs, are CPUs likely to become a bottleneck

We are upgrading hardware for a MySQL database server (DB is around 200GB). We're getting 4x Samsung 850 Pro SSDs and are planning to run them in a RAID10 configuration. Also, 128GB of RAM. The ...
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1answer
33 views

Problem with procedure performance

I'm having problem in Oracle, where I have two procedures that are executed one after the other. Where the first procedure, I have a cursor that does insert into a table. This insert has about 30 ...
1
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1answer
22 views

Can I build relationships in existing system without breaking it?

This is my first question here, so I would love help to make it work for SO:DBA. I inherited an older relational system that is sitting on a SQL Server 2005 box and the database is at SQL2000 ...
1
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1answer
46 views

Is there a faster way to get OR behavior in Postgres?

Is there a faster way to do an inner join with an OR clause. I have a query that looks something like this: INNER JOIN (select u_id, b_id from t1) AS t2 ON t2.u_id = t1.u_id OR (t2.b_id = ...
0
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0answers
9 views

MySQL Cluster Disk Data Tables - worth it?

I'm working on improving the performance of our 4-node MySQL cluster for a webapp with lots of DB writes. We've got a Solr index sitting 'on top' of the SQL in order to give us fast querying, and we ...
2
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1answer
48 views

Dramatic decrease in SQL Azure performance after scaling to new edition

Yesterday, we scaled one of our databases in Azure from the old Business edition to the new Standard one (S2). Since then, it has been behaving rather erratically. We have a relatively simple table ...
1
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0answers
12 views

Is there a faster way to get UNION ALL behavior in Postgres? [duplicate]

I have a table (t0), in my Postgres DB, with data that looks something like this: t1_id t2_id 1 1 2 1 2 1 4 null 4 null 5 null And I have a query to return my ...
1
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3answers
62 views

Is there a faster way to get UNION ALL behavior in Postgres?

I have a table (t0), in my Postgres DB, with data that looks something like this: t1_id t2_id 1 1 2 1 2 1 4 null 4 null 5 null And I have a query to return my ...
-1
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0answers
20 views

MySQL 5.1 on Windows server - Increasing value in open_files_limit does not apply

I have increased the value of open_files_limit from 2048 to 4096 in my.ini file. But, this change has not been reflected. Below is my dedicated DB server configuration: OS: Windos 2008 R2 standard - ...
0
votes
1answer
34 views

Complex query on big table

I have a big user table (3M), of structure: age (int) country (FK) city (text) gender (text) active (bool) My objective is to run a search finding 15 users of given age area, gender, city and ...
6
votes
1answer
107 views

Does tempDB disk perf matter if you have plenty of unused memory?

We have a SQL Server 2012 Enterprise setup with a large amount of RAM (256 GB), and at this time fairly small databases (about 17GB). Right now we are experiencing performance issues due to various ...
2
votes
1answer
99 views

Can you put a SQL DB on a NAS? [closed]

Can you put a SQL DB on a NAS drive? For example can I put the PostgreSQL DB "files" on a Sinology NAS or am I better to leave everything on a "real" PC? (like, say, a regular PC server running Linux) ...
0
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0answers
27 views

MYSQL : Copying to TMP table nightmare

I'm having a (AFAIK) random issue. My server is MySQL and I have a query that is sometimes 10000 times slower as you can see on this screensot : http://snag.gy/vJJ39.jpg The long time occurs during 2 ...
0
votes
1answer
27 views

How to configure my.cnf in 5.6.17?

On production server(linux machine mysql 5.6.17), I tried to find my.cnf to change the system variables, but my.cnf was not in /etc/my.cnf location. It was in usr/ directory. Also that file contains ...
1
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0answers
41 views

SELECT query with DISTINCT on a table-structure for graphs is very slow

I have 2 tables where nodes contains about 60m rows and edges about 500m rows (both growing fast). These two tables represent a directed graph. CREATE TABLE edges ( node_from bigint NOT NULL, ...
0
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2answers
40 views

too many connection error mysql: how to calculate max_connections

how to calculate this values to get the best results to resolve this error "too many connection error mysql" and make my API faster in mysql wait_timeout = ?? max_connections = ?? ...
0
votes
1answer
38 views

How can I determine the average number of transactions per second in MySQL?

I'd like to see how many transactions per second an instance of MySQL server is processing, on average (per hour and per day). Is there some query to determine this? I've looked through ...
0
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0answers
17 views

is there any limit of MySQL status variable value?

As we know MySQL status variable is a counter variable since the service start. MySQL service in my DB server restart every week (on sunday). Below is my observation since last few week: Suddenly ...
0
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1answer
22 views

MySQL: What do we mean by 0 value in in_use column of show open tables statement?

If I run show open tables command, system return 73 records. But, in_use column value for every record is 0. What does this mean? Are these tables available in cache but not used by any thread?
0
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1answer
26 views

How to setup large database access/cache on LAMP environment? [closed]

My application is getting very slow I guess because of the ever growing database (30+ tables some with 50,000+ rows). Using CodeIgniter's model tier to call MySQL database, I optimized queries & ...
2
votes
0answers
33 views

Mysql search matching multiple values in multiple columns

I need to speed up a search. Currently we let our users input a name: John Doe Then in Java we split that string to create multiple values (or "terms") ["John", "Doe"] and loop through the terms ...
0
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1answer
54 views

MySQL uses more than 500% of the CPU

Everything was going fine, but since a couple of hours ago MySQL is using from 400% to 550% of the CPU. I'm getting a lot of these errors: 1003 14:03:17 [ERROR] /usr/sbin/mysqld: Incorrect key file ...
7
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1answer
120 views

T-SQL - OPTION (FAST x) and trace flag 8722

I have searched a long time and still haven't found the answer to my problem. Our Dynamics AX is generating queries with the query hint OPTION (FAST x), which sometimes forces a bad execution plan to ...
0
votes
1answer
85 views

How to split one big table that has 100 million data to multiple tables?

I have one database in Sql server 2012 and in that there is one table that has more than 100 million data and I wanted to split that table to multiple similar table with 1 million data in each table. ...
0
votes
1answer
30 views

Sudden periods of performance degradation

For the past couple of days, Ive been observing periods of huge performance degradation. CPU usage on our master MySQL server (Percona Server (GPL), Release rel24.1, Revision 217, InnoDB version ...
0
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0answers
21 views

MySQL: What should I do if too many tables opened during peak hours?

In Peak hours: When I run below statement, I found around 100 tables out of 250 have opened. show open tables where in_use>0; There are around 10 tables for which in_use value are >50. Storage ...
0
votes
1answer
41 views

Optimisation and Performance Mysql , Zend Framework 2 and Doctrine 2?

i'm facing some problem with performance in an application using zend framework2 and doctrine 2. i would like to optimis it but i don't know from where to start , i read some many questions/ answers ...
1
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1answer
23 views

Do threads in cache still use memory?

I was studying about how and how much memory allocated to each connection thread and found below MySQL tutorial: http://dev.mysql.com/doc/refman/5.1/en/memory-use.html There is a point mentioned as ...
2
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1answer
44 views

3 minutes to import 327Mo database

We do database import a lot of times per day on a server with those specs : Xeon E5-1620v2 4c/8t @ 3,8Ghz 32 Go DDR3 ECC 1600MHz Hard Drive 2x 3 To SATA3 MariaDB 10.14 with XtraDB Given a 327Mb ...
2
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0answers
37 views

PL/pgSQL - Indexes vs Collation vs Pattern Ops

I'm using PostgreSQL 9.3. Having already read articles and answers on DBA stackexchange: Why would you index text pattern ops on a text column PostgreSQL documentation: Indexes - Opclass Pattern ...
2
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2answers
121 views

Overhead of decomposing complex query into multiple simple queries?

What kind of overhead should I expect when replacing a single complex query with multiple simple queries? My goal is to improve the readability and portability of all SQL code so I will be favoring ...
0
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0answers
13 views

What is the recommended pgpool mode?

I'm trying to determine which pgpool mode to use (http://www.pgpool.net/docs/latest/pgpool-en.html#config). In order of importance my requirements are: All nodes accessible via shared public ...
0
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0answers
10 views

Can I use MySQL-SERVER tunning variables in MYSQL CLUSTER?

When tunning MySQL-SERVER for best performance, the edition is done down my.cnf file. Such as: max_connections = 500 wait_timeout = 600 sort_buffer_size = 2M Can I improve MySQL CLUSTER ...
0
votes
2answers
58 views

How can I tune MySQL to behave better under load

We have a typical master-slave set up. When we find ourselves under considerable load, the master grinds to a halt. The slave continues to march along all happy like. So during a recent slow-down, I ...
1
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0answers
29 views

Best index to apply for modifier query in i2b2 [closed]

Below is a query being run by a tool called i2b2. I'm unable to change how the query is run. What can I do to the indices in "observation_fact" and/or "modifier_dimension" tables so that this query ...
0
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1answer
26 views

SQL Server data, logs, backups files in mounted foldersin C:\

I know that is a good practice to have data, logs and backups files of SQL Server in diferent disk, for example D:\ for Data files, E:\ for Logs files, F:\ for backup files. But if I want to use this ...
0
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0answers
14 views

Does PGStrom calculate relational comparisons?

I prefer index calculation and comparison be executed on the GPU. I have stumbled upon PGStrom. It seems one could infer that it will calculate index comparisons, but the claim doesn't seem to be ...
1
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1answer
71 views

PostgreSQL performance worse when adding CPUs

I ran into a strange behaviour when benchmarking PostgreSQL. The setup is like this: Virtual box VM, with 3 GB of RAM. The host has 16GB of RAM and 4 CPUs. Ubuntu 14.04, standard PostgreSQL 9.3 ...
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1answer
32 views

How much should I care about prepared statements for simple queries?

I wonder how much I should care about prepared statements (and therefore try to optimize my code) in case of pretty simple statements. The question originates from the fact that I recently noticed ...
2
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1answer
42 views

What is the best storing device for DB transaction log?

I'm using MySQL with InnoDB storing engine. Transactional log is placed to dedicated HDD. Still as it is HDD atopsar shows big load (>50%) to this HDD because of big amount of small IOs (about 50 ...
1
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1answer
68 views

Searching for array elements nested in MongoDB Documents

I need to store card documents in my database. Cards need to be stored with a set of integers that represent the bundle, box and pallet, or whatever other entity they belong to. The packaging ...
1
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1answer
46 views

Still i am not satisfying with Logfile Shrinking in SQL Server? [duplicate]

Already i asked this question but still i'm not getting the very clear answer. In my server holds more than 20 live databases in that my logfile(.ldf) is use to grow more than 5 GB per day. Using the ...
0
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1answer
23 views

MySQL: Adding innodb_log_file_size in my.cnf causes not starting MySQL service [duplicate]

I checked and found that InnoDB pluginis active. By default, Innodb_log_file_size=5MB. As per the MySQL Documentation, its ideal values range from 1MB to 1/N-th of the size of the buffer pool, where ...