Tagged Questions

0
votes
0answers
38 views

is it good to use combined primary key for MySQL InnoDB clustered index?

I'm trying to build a aggregated reader website of multiple forums. Because most queries are likely to be within same time periods for written_time column, I'm thinking about taking advantage of ...
2
votes
2answers
43 views

What can I do to make mysql use the expected indices?

What can I do to make mysql use the expected indices? I've got 4 tables, two containing resources, and the others containing historical changes. One pair uses indexes correctly, the other doesn't, ...
0
votes
1answer
19 views

Which of tables key to reference?

MySQL. There is a table users with autoincrement primary key id. There is also a table employees (every employee is a user but not vice versa). The employees primary key is userid. The field userid ...
2
votes
2answers
125 views

MySQL - Normalization over meaningless data - Compound Primay Keys or Surrogate ID field

Please forgive my title; if you have a suggestion for it, feel free to comment. I have a database: DROP TABLE IF EXISTS `books`; CREATE TABLE `books` ( `isbn` VARCHAR(255) NOT NULL, `title` ...
1
vote
1answer
106 views

Is there a tuning parameter for MySQL that allows you to set an on-disk gap between non-sequential primary keys?

I understand that one of the primary issues with using a non-sequential primary key is that every disk/memory write that does not come after the last known key causes a re-write of everything from the ...
2
votes
1answer
204 views

Unique insert performance: Primary Key vs Unique Index

I have a table of unique values (domains_unique), with collumn domain varchar(255), with more than 20 mil records. What's the fastest way to insert into the table, by keeping the domain unique ...
0
votes
1answer
109 views

Maintain table with too many insert

I have to create a table. Its size is going to increase very fast. Is there going to be any issue if many insert queries are fired at the same instant as mentioned here - User autoincrement ID for ...
1
vote
1answer
102 views

does last_insert_id() returns correct result when writes from multiple sessions?

I have a table in which there is a combination of 4 columns that will act as a unique key. Instead of using a composite primary key, I want to keep an id column as the primary key. This field is on ...
0
votes
1answer
152 views

MySQL non-sequential primary key of certain length

what's the best way to create a non-sequential primary key of a certain length in MySQL? I'm looking to use the primary key as a 'Pin' number which real actual human people can use to refer to the ...
1
vote
1answer
426 views

What should one do if the auto increment primary key exceeds the maximum?

I have a primary key for a table with the following structure, **Field** **Type** nid int(10)unsigned I know the maximum limit of int(10) is 4294967295. But What ...
1
vote
1answer
104 views

Are these custom module Drupal tables lacking foreign keys? mysqldump with table structures without data is included

I am troubleshooting a some tables in MySQL used by a custom Drupal module. Documentation for these tables is poor so I used mysqldump to get the structures in the Drupal database without the data. I ...
3
votes
3answers
941 views

Does the MySQL primary key affect the efficiency of a SELECT query?

Does the primary key serve any purposes apart from uniquely identifying a specific row? For example, a table with an autoincremented primary INT key could greatly aid in search due to the option of ...
1
vote
5answers
544 views

How should I save apache logs into a mysql table?

This is a php script to view apache logs. I want to save apache logs into a mysql database. Then add some rules for tagging urls using mysql REGEXP search, like: SET tag='some tag' WHERE url REGEXP ...
0
votes
0answers
112 views

setting timestamp column as pk to prevent concurrent editing of records?

While I was familiarizing myself with all the new data types in MySQL, I noticed the TIMESTAMP data type, and thought "What if I make this TIMESTAMP field and the CustomerID field (the other pk) a ...
4
votes
3answers
139 views

Most efficient (or meaningful) way to index grid-based data

I have a MySQL table which I expect to be in surplus of a few million rows and 99% select statements. The problem I am having is coming up with a meaningful way to determine the Primary Key. (I have ...
4
votes
4answers
3k views

Mysql int vs varchar as primary key (InnoDB Storage Engine?

I am build a web application (project management system) and I have been wondering about this when it come to performance. I have an Issues table an inside it there are 12 foreign keys linking to ...
5
votes
3answers
687 views

Differences between “Unique Key” and “Primary Key”

What are the major differences between Unique Key and Primary Key in MySQL?
1
vote
1answer
658 views

Does the order of keys in compound Primary key make any difference?

Package Package ------- PackageID PackageName CityID PRIMARY KEY (PackageID) UNIQUE KEY (PackageName) FOREIGN KEY (CityID) REFERENCES City (CityID) Package versions: PackageVersion ...
2
votes
1answer
893 views

How is INDEX on Composite Primary Key in mysql?

When making a composite primary key for two or more columns, e.g. PRIMARY KEY(col1, col2, col3); will the system INDEX each column individually? The reason that I am asking this question is that when ...
2
votes
4answers
555 views

Two-sided UNIQUE INDEX for two columns

Creating a table with composite PRIMARY KEY or using UNIQUE INDEX for two columns guarantee uniqueness of col1, col2. Is there a tricky approach to make the reverse order of two columns UNIQUE too ...
2
votes
1answer
219 views

updating mysql primary keys

I need to be able to swap values that are used in a primary key. Meaning, in one update statement, I need to change id 1 to id 2, and id 2 to id 1. In other relational databases, (Sql Server and ...
2
votes
2answers
1k views

“on duplicate key update” all the non-key fields mentioned in the insert

How can I update the field values mentioned in the insert portion without listing them again in the on duplicate key update portion? insert into tablename set keyname = 'keyvalue', fieldname = ...
13
votes
2answers
633 views

Primary key index with a DATETIME as first part of the compound key is never used

I have a problem with INDEXING a DATETIME (or even a date) as first part of my PRIMARY KEY. I use MySQL 5.5 Here are my two tables: -- This is my standard table with dateDim as a dateTime CREATE ...
3
votes
2answers
154 views

Is index_type ignored on MySQL primary keys in create table?

I have seen a create table whose primary key had an identifier where it should have an index_type, something like that: create table a (foo INTEGER, PRIMARY KEY foo_id (foo)); The thing is that ...
20
votes
7answers
2k views

Why should I create an ID column when I can use others as key fields? [duplicate]

Possible Duplicate: Why use an int as a lookup table's primary key? So far, I'm accustomed to creating an ID column for every table and it is practical in a way that it makes me not ...
3
votes
4answers
5k views

MySQL: Why is auto_increment limited to just primary keys?

I know MySQL limits auto_increment columns to primary keys. Why is this? My first thought is that it's a performance restriction, since there probably is some counter table somewhere that must be ...
4
votes
4answers
368 views

How much will using a varchar(15) PK affect my tables performance?

I am parsing log file lines from a legacy, proprietary application into a nice easy to query DB. The log lines have no unique integer ID. They do have a UNIX timestamp as an 8 character hex string. ...
3
votes
3answers
511 views

Can I have create an InnoDB table without a PK? If so, would a secondary index be used as the clustered index?

Is it possible to create an InnoDB table without a Primary Key? Since InnoDB tables are structured as clustered index around the PK, what would be the structure of a table without PK? Would that ...
2
votes
1answer
382 views

Question on Design for User + User Groups + User Types + Subscriptions Model

I am redeveloping an existing web application with both weak source code and a weak underlying database design. I'm trying to develop things in a way that future expansion will be much easier, ...
6
votes
2answers
1k views

What's a good way to add a PRIMARY KEY to a large InnoDB table?

I have a table with around 30 million rows in MySQL 5.5 using the InnoDB storage engine. This table has a foreign key that links to another table with around 3 million rows. I want to add a primary ...
19
votes
3answers
2k views

Character vs Integer primary keys

I'm designing a database with multiple lookup tables containing possible attributes of the main entities. I'm thinking of using a 4 or 5-character key to identify these lookup values rather than an ...