MySQL That Extra Database: Difference between revisions
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== Extra database == | == Extra database == | ||
After creating a new user with access to only one database, you discover to your horror an extra database named information_schema. You try to remove it to no avail | After creating a new user with access to only one database, you discover to your horror that there's an extra database, named information_schema. You try to remove it to no avail. What is it and has your system been compromised? | ||
=== No threat === | === No threat === | ||
Relax it poses no threats | Relax; it poses no threats. The information schema is a comprehensible, rich source of metadata. It was first introduced in MySQL 5.0.02 or thereabouts. MySQL automatically populates the database. | ||
=== Current user only === | === Current user only === | ||
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=== Read only === | === Read only === | ||
It does not support addition, deletion or modification of data. Direct manipulation of the data contained within it is out of bounds so do not even think about it unless you really do know what you are doing. | It does not support addition, deletion or modification of data. Direct manipulation of the data contained within it is out of bounds, so do not even think about it unless you really do know what you are doing. | ||
=== Stable === | === Stable === | ||
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You can’t remove it so use it. | You can’t remove it so use it. | ||
[[Category: MySQL]] | [[Category: MySQL]] | ||
Latest revision as of 21:25, 22 June 2013
| MySQL: General information. |
MySQL information_schema database - That extra database
Extra database
After creating a new user with access to only one database, you discover to your horror that there's an extra database, named information_schema. You try to remove it to no avail. What is it and has your system been compromised?
No threat
Relax; it poses no threats. The information schema is a comprehensible, rich source of metadata. It was first introduced in MySQL 5.0.02 or thereabouts. MySQL automatically populates the database.
Current user only
The information_schema database is accessible to every user. MySQL populates it dynamically to contain only the metadata for those objects that are accessible to the current user. You should not attempt to manipulate its structure because of its virtual nature.
Read only
It does not support addition, deletion or modification of data. Direct manipulation of the data contained within it is out of bounds, so do not even think about it unless you really do know what you are doing.
Stable
You can rely on the information schema database structure to remain stable because of its tight specification and adherence to the SQL standard. If you ever need to obtain metadata in MySQL, this is the place to obtain it.
Conclusion
You can’t remove it so use it.