5
votes
1answer
852 views

MySQL EXPLAIN doesn't show 'use index' for FULLTEXT

I have a basic table : create table fullTextTest ( id INT(11) NOT NULL, superText CHAR(255) NOT NULL, superLongText TEXT NOT NULL, primary key (`id`), FULLTEXT KEY `superText` ...
5
votes
3answers
3k views

Why is SSMS inserting new rows at the top of a table not the bottom?

Whenever I manually insert a row into a table in SQL Server Management Studio 2008 (the database is SQL Server 2005) my new row appears at the TOP of the list rather than the bottom. I'm using ...
4
votes
1answer
1k views

How does max_allowed_packet affect the backup and restore of a database?

I have a database based on mysql 5.0.75-0Ubuntu10.2, running under Ubuntu 9.04. I have a table in that database with a medium blob column. I have been using automysqlbackup to do nightly backups/dumps ...
1
vote
1answer
6k views

How to enable MySQL general log?

I would like to enable the MySQL General Log to view all the (slow) queries. I'm using XAMPP as server and have no idea how to enable it. I can't find a good guide on the internet. Can someone help ...
1
vote
1answer
4k views

ERROR 1114 (HY000) at line 6308 in file & The table user_analysis is full

There is a SAN mounted 1TB partition for Mysql backups in our server with version 5.0.45-log. From two days, im seeing the log entries ERROR 1114 (HY000) at line 6308 in file & The table ...
35
votes
6answers
32k views

What are the main causes of deadlocks and can they be prevented?

Recently one of our ASP.NET applications displayed a database deadlock error and I was requested to check and fix the error. I managed to find the cause of the deadlock was a stored procedure that was ...
15
votes
4answers
6k views

Determining how a schema change occurred?

Something bad happened yesterday. A view that was created sometime back ago was modified by someone which eventually broke the reports. Unfortunately. somebody (knowingly or unknowingly) did this ...
21
votes
3answers
21k views

Is it safe to use innodb_flush_log_at_trx_commit = 2

I turned innodb_flush_log_at_trx_commit = 2 and get a very fast write speed. But is it safe be used in production web site?
15
votes
7answers
41k views

Need to migrate SQL Server to MySQL

I have a database on SQL Server 2008 on a Windows server and I want to move all of the data to a MySQL database on a Ubuntu server. I have tried using the SQL Server Import and Export Wizard with the ...
11
votes
3answers
13k views

Why is 'LOAD DATA INFILE' faster than normal INSERT statements?

I've read an article that mentioned we can achieve 60,000 inserts per second by LOAD DATA IN FILE statement that read from csv files and insert it into database. Why should it differ from normal ...
23
votes
1answer
6k views

Designing a platform: one database or multiple databases?

We are building a web platform that incorporates multiple services, each with its own underlying data. These services are being built independently following the principles of Service-Oriented ...
17
votes
1answer
20k views

How do I attach a database in SQL Server?

Some common questions relating to attaching databases in SQL Server: What does it mean to attach or detach a database? How do I detach a database? How do I attach a database? What ...
6
votes
2answers
3k views

Scaling Percona datacenters: setup and replication

Since our startup has taken off nicely we are now meeting with some of those issues that you always assumed would NEVER effect you. We have already scaled alot of our application stack: we offloaded ...
18
votes
4answers
6k views

Using SQL Profiler on a database that's in production

As a developer, I use SQL Profiler quite often. It's a good debugging tool, both to track what my code is doing and to analyse performance problems. But I've always used it on my development ...
9
votes
2answers
4k views

How to create an Event Notification that runs a Job/procedure when mirroring state changes

I'm asking this question in the sequence of this one Can I send a string over TCP using T-SQL? Remus Rusanu exposes what it seems to be an optimal solution for my problem, but... I'm too immature to ...
4
votes
1answer
2k views

Proper tuning for 30GB InnoDB table on server with 48GB RAM

I have a 30GB 15M rows InnoDB MySQL 5.5.15 table. It is running on a server with many other MyISAM tables (300GB db). The system has 48GB RAM. Besides the default configurations, I've changed the ...
13
votes
2answers
1k views

What can we do in MySQL 5.0 Replication to address bandwidth concerns?

I am developing an application to run on the client PC (Win) which is configured with a MySQL server 5.1 instance that will act as read-only slave to the remote master. The remote master has dozens of ...
6
votes
3answers
5k views

Should I add an arbitrary length limit to VARCHAR columns?

According to PostgreSQL's docs, there's no performance difference between VARCHAR, VARCHAR(n) and TEXT. Should I add an arbitrary length limit to a name or address column?
5
votes
1answer
4k views

Best solution for cross-datacenter MySQL master-slave replication

We are working on a new system architecture for our company. We have a HPC, which runs in our own data-center and we are planning our front-end and a fallback system on Amazon Web Service. System ...
5
votes
1answer
667 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, ...
4
votes
1answer
316 views

How badly does innodb fragment in the face of somewhat out-of-order insertions?

Let's say there's a composite primary key on (field1, field2) Also, let be X a theoretical set of n numbers Inserts look like this: INSERT INTO table(field1, field2) VALUES([a number picked at ...
4
votes
1answer
2k views

Mysql Memory table getting many locks

On my site I log every pageview (date, ip, referrer, page, etc) in a simple mysql table. This table has the following activity: 1 SELECT per minute 1 DELETE per minute no UPDATE queries Lots of ...
16
votes
4answers
28k views

Logical operators OR AND in condition and order of conditions in WHERE

Let's examine these two statements: IF (CONDITION 1) OR (CONDITION 2) ... IF (CONDITION 3) AND (CONDITION 4) ... If CONDITION 1 is TRUE, will CONDITION 2 be checked? If CONDITION 3 is FALSE, will ...
8
votes
3answers
13k views

How do you re-sync the Master MySQL DB with Slave DB changes if the Master goes offline?

MySQL Server 1 is running as Master. MySQL Server 2 is running as Slave. With both DBs online, they are in "perfect sync". If Slave goes offline, there's no problem if Master still online; they will ...
4
votes
2answers
4k views

When should I think about upgrading our RDS MySQL instance based on memory usage?

It seems like our DB server is doing garbage collection at a increasingly faster rate, which seem normal since it's growing. What's a good rule of thumb of when to switch to a bigger instance, I'm not ...
3
votes
4answers
11k views

Optimized my.cnf for high-end and busy server

Curretly my main culprit of poor performance is MySQL and I'm not a DB savvy. So far, I've had little luck in optimizing mysql configs on my server, which has a Sandy Bridge processor with 16GB ram ...
13
votes
3answers
9k views

Is it possible to restore sql-server bak and shrink the log at the same time?

We have a bak file from a client that we have transferred to our developer offices for problem investigation. The backup is currently 25GB and the restored database is about the same size however it ...
10
votes
2answers
645 views

Postgres query plan of a UDF invocation written in pgpsql

It's possible when using the pgadmin or plsql to get a hold of a query plan for a sql statement executed via a UDF (using EXPLAIN). So, how do I get a hold of the query plan for a particular ...
6
votes
2answers
3k views

Multicolumn index and performance

I have a table with a multicolumn index, and I have doubts about the proper sorting of the indexes to get the maximum performance on the queries. The scenario: PostgreSQL 8.4, table with about 1MM ...
6
votes
2answers
2k views

Insert-heavy InnoDB table won't use all my CPU

I have a packet log database, which is almost never queried. It just needs to be fast on inserts. I'm using InnoDB because I'd like to maintain ACID compliance, since even losing a single packet could ...
4
votes
3answers
1k views

Log MySQL DB changing queries and users

For security reasons I need a server-side (running Debian 6.0 Squeeze) logging of all queries that may have changed the content of a MySQL DB (v. 5.1) and the user who issued it. I had to rule out ...
15
votes
1answer
4k views

DELETE vs TRUNCATE

I am trying to get a greater understanding on the differences between the DELETE and TRUNCATE commands. My understanding of the internals goes something along the lines of: DELETE -> the database ...
5
votes
1answer
3k views

Many to Many and Weak Entities

I have an entity that cannot exist without being defined by another, and I want this entity to participate in a many-to-many relationship. Example: An artist has an album (the album cannot exist ...
5
votes
1answer
772 views

Does MySQL still handle indexes in this way?

Dropping a duplicate index in MySQL was taking rather long, so while I was waiting I searched about it & found this post from 2006, talking about how MySQL handles ADD and DROP index. If a ...
1
vote
2answers
3k views

Stress test MySQL with queries captured with general log in MySQL

Is there any tool available which can do stress testing using the log file created by MySQL general log? After a lot of search on google I found few stress testing tools which only use some benchmarks ...
6
votes
3answers
609 views

Issue with composite type in an UPSERT function

I have a function in PostgreSQL 9.1 called fun_test. It has a composite type as input parameter and I keep getting a casting error when I call it. CREATE OR REPLACE FUNCTION netcen.fun_test(myobj ...
6
votes
4answers
6k views

MySQL gives “Out of Memory” error when inserting a large file. From where is this filesize limitation arising?

I'm using a MySQL database to store files. The table I'm using is structured as follows: +--------------+----------+------+-----+---------+-------+ | Field | Type | Null | Key | Default ...
5
votes
1answer
1k views

MySQL Replication : 1 Slave / Multiple Masters

I have a web app with 2 web servers and 2 database servers. The DBs are setup for multimaster replication. (this is the primary environment) I also have the exact same setup on a different location ...
4
votes
2answers
5k views

How to refresh AD security group on Sql Server permissions

I am using Sql Server 2008 on Small Business Server 2003; client is using WinXP. I added a user to my Active Directory Security Group; Why can't this user immediately access the database? It seems ...
4
votes
1answer
4k views

Mysql Master-Master Replication Topologies on >2 machines

I have 3 Mysql servers that I would like to replicate: two (including the main server) are local and one is remote. Let's call my main server A, the secondary server B, and a remote, development ...
3
votes
1answer
863 views

query cache hit value is not changing in my database

The query cache hit value is not changing in my database only for some queries.If I write select * from drugs_info limit 1000; the query cache hit has changed, but if I execute the following ...
3
votes
1answer
1k views

FULLTEXT index ignored in BOOLEAN MODE with 'number of words' conditional

fulltext match is ignoring its index when I add a number of words conditional for its boolean mode. The selects are as follows: explain select * from seeds WHERE MATCH(text) AGAINST ("mount ...
2
votes
1answer
342 views

row locking within ACID transaction innodb

I have a financial transaction that looks something like this (pseudo): begin select record for update update record(same record as selected) insert another record into another table ...
2
votes
2answers
1k 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
1answer
2k views

MySQL upgrade 5.0.88 to latest

Very interesting and informative blog.. I have a question - i have a requirement of upgrading from 5.0.88 to latest version.. Why should i upgrade? if so, which version should i consider? What ...
2
votes
2answers
933 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
917 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. ...
129
votes
14answers
38k 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 ...
56
votes
6answers
20k views

What are the differences between NoSQL and a traditional RDBMS?

What are the differences between NoSQL and a traditional RDBMS? Over the last few months, NoSQL has been frequently mentioned in the technical news. What are its most significant features relative to ...
56
votes
5answers
5k views

How can a group track database schema changes?

What version control methodologies help teams of people track database schema changes?

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