Size of an empty database

database-sizeoracleoracle-10goracle-11g

Continuing with my school-project, now I have to estimate the size of the database from here to 5 years. They give me a formula, so, in that formula, one of the values is the size of the empty database (when it is created, and doesn't have any tables, index, etc.).

For example, for MySQL, I found here that it is 10 MB.

But, for Oracle, what is the size?

I don't have Oracle or any RDBMS to make queries, it is just a work of research. I've googled a little, but I haven't found for Oracle.

Any version of Oracle (9 or later) is okay.

Best Answer

First, are you using "database" in the Oracle sense of the term? Or are you using it in the sense that other database vendors (such as SQL Server or MySQL) use the term?

If you are using "database" in the Oracle sense, that would be the size of the SYSTEM and SYSAUX tablespaces at a minimum and would possibly include the size of the UNDO and TEMP tablespaces. On a small laptop system, that's probably on the order of 2 - 3 GB but it could be much bigger.

If you are using "database" in the sense that other database vendors use it, that's what Oracle calls a schema. An empty schema (a schema with no objects), by definition, consumes 0 bytes of storage. That's because space is allocated to tablespaces which are independent of schemas-- a single schema can have objects in many different tablespaces, a single tablespace can have objects owned by many different schemas, and a single object (if you're using partitioning) can be spread across multiple tablespaces.

Related Solutions

How to estimate database size needed

A rough estimate for bare tables is pretty simple. The number of bytes in a row is roughly

  Total number of bytes for all columns 
+ dbms overhead

dbms overhead might include a fixed or variable number of bytes per row or per column. The number of bytes of overhead often depends on the datatype of the column. The dbms might also apply padding to make bit columns, for example, align with a machine word boundary.

Multiply the bytes per row by the expected number of rows one year, two years, or five years from now. Repeat for every table, or for only a statistically representative sample of the tables.

You can often find leads to the details for your dbms by searching for "your_dbms row format". If you searched for

sql server row format

you'd probably find this blog article.

Your dbms might require you to take into account compression, compact storage formats, and indexes. Compression and compact storage formats reduce the amount of storage space you need; indexes usually increase it.

If you want a really good estimate, build a testbed. Fill it with statistically representative sample data. Do the arithmetic based on what that tells you. Include estimates for new tables to implement new features.

Mysql – Database schema size result differs from file size when exported

The export does not contain the indexes. It only contains the definition of the indexes but not the data that is stored in there.

Additionally the size of SQL export will also not reflect the size of your data (just think of the SQL keywords that are needed for the SQL export).

When you move data from one representation to another (MySQL "on-disk" format -> Binary Export -> SQL Script) it is to be expected that the different formats show a different size.

But I don't understand what you problem actually is.

Best Answer

Related Solutions

How to estimate database size needed

Mysql – Database schema size result differs from file size when exported

Related Question