2
votes
2answers
569 views

How do I determine how much data is being written per day through insert, update and delete operations?

The longevity of SSDs is largely determined by the amount of bytes written by insert, update and delete operations. What is the best way to accurately determine how much data is being written by ...
2
votes
2answers
684 views

Which first: upgrade mysql version or convert storage engine?

I inherited a production mysql server at 5.0. It uses MyISAM exclusively. It is not a high volume database but it does have some large datasets. I am planning on: upgrading to 5.5 converting ...
2
votes
1answer
593 views

Create a custom log table in MySQL

Is it possible to create a custom log table. For example I have 10 schema and I would like to log if somebody is using the "areva" schema. I want to know the last executed command time and the user. ...
2
votes
1answer
642 views

MySQL Cluster — Storing table data on data nodes

I have setup MySQL Cluster with the MySQL server node and the Management node on a single server, and 2 data nodes (each on a different server for 3 servers in all). After installing, I run ndb_mgm ...
2
votes
2answers
1k views

Preventing mysql deadlocks in your php application that uses SELECT… LOCK IN SHARE MODE

If I understand SELECT ... LOCK IN SHARE MODE correctly, you can place it into a mysql transaction to select the rows you will be working with during that transaction. This is done in order to "lock ...
1
vote
1answer
2k views

gain admin access to sql express 2008

I have inherited a Windows 7 Professional pc with an existing instance of SQL Express 2008. I have local admin rights on the machine. I do not know the SA password. I am unable to create databases or ...
1
vote
1answer
484 views

Removing/overwriting sensitive data located in already deleted records in ibdata files

As far as I know, using InnoDB tables with innodb_file_per_table = off does not prevent deleted data from being visible in the ibdata1 file. I know this is by-design, and that I could switch the ...
1
vote
1answer
679 views

decreased performance of stored procedure when migrated from mysql server 5.0 to 5.5

i recently testing the move of our db from one server to another. as part of this process i copied all the data to the new db and started testing it. as a comparison i run a store procedure whose ...
1
vote
1answer
695 views

Secure method beside phpMyAdmin for remote mysql

Recently, one of my centos linux servers was hacked and the cause of due to phpMyAdmin. It was said due to this problem PhpMyAdmin vulnerability CVE-2011-2505 ...
0
votes
1answer
599 views

Inserting query result to another table hangs on “Copying to temp table on disk” on MySQL

I started the process of inserting returned results to another table. The query groups the rows in respect of indexed IDs. This causes 149,000,000 rows to be decreased to 460,000 rows. The query ...
116
votes
14answers
24k views

How do you document your databases?

I find that most of my clients are not documenting their databases at all and I find that pretty scary. To introduce some better practice I would like to know what tools/process you are using. How ...
175
votes
15answers
57k views

Can MySQL reasonably perform queries on billions of rows?

I am planning on storing scans from a mass spectrometer in a MySQL database and would like to know whether storing and analyzing this amount of data is remotely feasible. I know performance varies ...
60
votes
4answers
8k views

Why use both TRUNCATE and DROP?

In the system I work on there are a lot of stored procedures and SQL scripts that make use of temporary tables. After using these tables it's good practice to drop them. Many of my colleagues (almost ...
45
votes
5answers
12k views

When to use TINYINT over INT?

In general, I always use Ints. I know that in theory this is not the best practice, though, since you should use the smallest data type that will be guaranteed to store the data. For example, it's ...
56
votes
5answers
5k views

Do stored procedures prevent SQL injection?

Is it true that stored procedures prevent SQL injection attacks against PostgreSQL databases? I did a little research and found out that SQL Server, Oracle and MySQL are not safe against SQL injection ...
11
votes
7answers
11k views

Get the rank of a user in a score table

I have a very simple MySQL table where I save highscores. It looks like that: Id Name Score So far so good. The question is: How do I get what's a users rank? For example, I have a users ...
21
votes
3answers
5k views

Parameter Sniffing vs VARIABLES vs Recompile vs OPTIMIZE FOR UNKNOWN

So we had a long running proc causing problems this morning (30 sec + run time). We decided to check to see if parameter sniffing was to blame. So, we rewrote the proc and set the incoming ...
22
votes
13answers
5k views

How to implement a 'default' flag that can only be set on a single row

For example, with a table similar to this: create table foo(bar int identity, chk char(1) check (chk in('Y', 'N'))); It doesn't matter if the flag is implemented as a char(1), a bit or whatever. I ...
15
votes
3answers
4k views

How Does Table Partitioning Help?

I am having difficulty to grab the idea of pros and cons of table partitioning. I am about to start work on a project which would have 8 tables and one of them will be the main data table which will ...
13
votes
5answers
750 views

Needing A Database Design Book

I am designing a database and it has so many relationships among my tables and i need a book that teaches database design very well.I am looking for a book where table relationships simple and complex ...
24
votes
2answers
7k views

I/O requests taking longer than 15 seconds

Usually our weekly full backups finish in about 35 minutes, with daily diff backups finishing in ~5 minutes. Since tuesday the dailies have taken almost 4 hours to complete, way more than should be ...
18
votes
1answer
889 views

Cast to date is sargable but is it a good idea?

In SQL Server 2008 the date datatype was added. In this Connect item you can see that casting a datetime column to date is sargable and may use an index on the datetime column. select * from T where ...
7
votes
1answer
1k views

SQL injection in Postgres functions vs prepared queries

In Postgres, are prepared queries and user defined functions equivalent as a mechanism for guarding against SQL injection? Are there particular advantages in one approach over the other?
7
votes
5answers
702 views

Over use/correct use of schemas?

Having asked This question on Stackoverflow, I wondered where what I have done is correct/best practise. Basically, every object that I create is going into a schema with the schema name reflecting a ...
7
votes
2answers
3k views

Performance of a Trigger vs Stored Procedure in MySQL

A post here on DBA.StackExchange (What are the best practices for triggers to maintain a revision number on records?) has spawned an interesting question (at least, interesting to me) regarding ...
15
votes
5answers
4k views

Handling concurrent access to a key table without deadlocks in SQL Server

I have a table that is used by a legacy application as a substitute for IDENTITY fields in various other tables. Each row in the table stores the last used ID LastID for the field named in IDName. ...
12
votes
4answers
25k views

How to add sysadmin to user in SQL Server 2008 when no sysadmin accounts exist

I have a SQL server 2008 instance running. Unfortunately during testing I deselected the sysadmin rights for my login and now can't readd it (because I don't have sysadmin rights). There are no other ...
9
votes
2answers
5k views

innodb_file_format Barracuda

I have a couple questions for those more familiar. Most of my instances have been running Antelope despite having support for Barracuda. I was looking to play around with some compresses innodb ...
7
votes
5answers
3k views

Survey database design: associate an answer to a user

I'm doing the conceptual model for a survey database. The goal is store the answers given by users (it going to be an Android app). I have three entities: user, question and option. A question will ...
3
votes
1answer
5k views

InnoDB - High disk write I/O on ibdata1 file and ib_logfile0

Server Specification: VPS with following info model name : Intel(R) Xeon(R) CPU E5649 @ 2.53GHz MemTotal: 2058776 kB MemFree: 244436 kB We are running IP.Board from Invision ...
9
votes
3answers
638 views

Need Help Troubleshooting Sql Server 2005 Deadlock Scenario

I am running into a deadlock scenario where the only participants in the deadlock appear to be a single table and a single stored procedure that deletes from that table. I drew that conclusion based ...
9
votes
4answers
3k views

Help me choose a RAID level combination for a SQL Server 2008 instance

I am going to rebuild one IBM 3400 server from scratch. This server is dedicated to a SQL Server 2008 instance running on Windows 2008 R2. I am going to make new RAID configuration. I have 6 SCSI ...
9
votes
3answers
2k views

How is LIKE implemented?

Can anyone explain how the LIKE operator is implemented in current database systems (e.g. MySQL or Postgres)? or point me to some references that explain it? The naive approach would be to inspect ...
7
votes
1answer
1k views

Algorithm for finding the longest prefix

I have two tables. First one is a table with prefixes code name price 343 ek1 10 3435 nt 4 3432 ek2 2 Second is call records with phone numbers number time 834353212 10 ...
7
votes
3answers
6k views

InnoDB table SELECT returns ERROR 2006 (HY000): MySQL server has gone away (after power outage)

This server is a virtual machine running CentOS 6.0, MySQL 5.5.21 There is a database named devSystem. There are InnoDB tables within. Running the following commands causes error ERROR 2006 ...
7
votes
3answers
5k views

What is the default order of records for a SELECT statement in MySQL?

Suppose you have the following table and data: create table t(k int, v int,index k(k)) engine=memory; insert into t values(10, 1), (10, 2), (10, 3); When issuing select * from t where k = 10 with ...
6
votes
4answers
6k views

How to improve InnoDB DELETE performance?

So I have this audit table (tracks actions on any table in my database): CREATE TABLE `track_table` ( `id` int(16) unsigned NOT NULL, `userID` smallint(16) unsigned NOT NULL, `tableName` ...
5
votes
1answer
5k views

How to use aes-encryption in PostgreSQL?

I tried aes-encryption by using following statement: SELECT encrypt('test', 'key', 'aes'); which worked, but I am not able to decrypt the value. I inserted it in a field of datatype bytea but I'm ...
5
votes
3answers
10k views

How to get the most out of MySQL on a QuadCore machine with 16 GB of RAM?

I'm running a MySQL 5.5 server on my workstation for scientific data analysis and wonder how to configure MySQL in order to get the most out of it performance-wise. The types of query that I typically ...
5
votes
1answer
547 views

Should I use a storage engine other than MyISAM to optimise these tables or should I get better disks?

There's a production database I'm working on, whose 4 largest tables contain between 4 million and 10 million rows each and about 15 fields each, with indexes on different field types (numbers, ...
5
votes
1answer
452 views

The use of NOT logic in relation to indexes

According to Microsoft's book on database development Exam 70-433: Microsoft SQL Server 2008 Database Development: Neither leading wildcard characters not NOT logic allow the query optimizer to ...
4
votes
2answers
10k views

SQL Server Transaction Timeout

Is there a way in SQL Server 2008 R2 to cause a timeout for a database modification involving a transaction? We have a scenario where our application code hangs or throws an exception and fails to ...
3
votes
1answer
241 views

VLDB with large quantity of data file imports

I am a little out of my league with this scenario and hope this community can help get me on the right direction. I have recently been tasked with re-designing and implementing a database application ...
27
votes
5answers
4k views

Downgrading from SQL Server 2008 to 2005

Database files that are built using SQL 2008 are not compatable with 2005. Is there a work around?
13
votes
3answers
4k views

Is it common practice to mix InnoDB and MyISAM tables on same server?

I've got a single database of about 4.5GB running on a server with 8GB RAM. The vast majority of the tables are MyIsam (about 4.3GB), but I'm soon going to be converting some of them to InnoDB. (It's ...
8
votes
1answer
3k views

Duplicate an Oracle database user

We'll be having external auditors coming over to perform a review on our Oracle database. They will be running a tool to perform the review and for that, they require a user ID that can connect to the ...
8
votes
1answer
3k views

Deadlock error isn't returning the deadlock SQL

Transaction (Process ID) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction. I am getting this error randomly when one of my ...
4
votes
2answers
5k views

MySQL Event does not run

i am running mysql 5.1.41 that came bundled with xampp on windows. the problem is that the event doesnt run automatically even when the event scheduler is ON. i have a table named ta_table using ...
2
votes
3answers
189 views

Move Complete ORACLE from one system to another

I have 2 identical server with exact disk partitions (OS CENTOS 6.4 both ) [My college central oracle server]. Entire ORACLE HOME ( bin , control files, data files everything on oracle) is on 2nd ...
2
votes
1answer
2k views

Is there a progress indicator for OPTIMIZE TABLE progress?

MySQL 5.1.4x (Windows) | Innodb I recently purged data from a mySQL DB (a few hundred thousand rows) and I'm planning to use OPTIMIZE TABLE LOGTABLEFOO1,LOGTABLEFOO2,LOGTABLEFOO3; to reduce the ...

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