Shulou(Shulou.com)06/01 Report--

This article mainly explains the "oracle database parameter files are divided into several categories", the content of the article is simple and clear, easy to learn and understand, the following please follow the editor's ideas slowly in depth, together to study and learn "oracle database parameter files are divided into several categories" bar!

Database parameter files are divided into two categories:

1. Initial parameter file: pfile (initialization parameter file)

two。 Server parameter file: spfile (server-side parameter file)

The main differences are:

1.pfile is a text file, spfile is a binary file

2.pfile can be modified through a text editor, and spfile is mainly modified through alter system set parameter=value [scope=memory | spfile | both]

When oracle starts, the order in which the parameter files are read is:

1.spfile$ORACLE_SID.ORA (spfile created when the database is created)

2.spfile.ora (oracle default spfile file)

3.init$ORACLE_SID.ora (pfile created when the database is created)

4.init.ora (oracle default pfile file)

Oracle will read out the parameter files in order, and if it is not found in 1, go to 2 until it is found.

Common SQL related to parameter files are as follows:

1. View the location of spfile and pfile currently in use: show parameter spfile/show parameter pfile

two。 View the specific settings of the parameter file: show parameters

3. Get pfile from spfile:

Create pfile='pfilesid.ora' from spfile

Create pfile='pfilesid.ora' from spfile='/$ORACLE_HOME/dbs/spfile.ora'

4. Modify parameters

Alter system set parameter=value [scope=memory | spfile | both]

1. The modified current instance works, but restarting the database does not work: scope=memory

two。 The modified current instance will not work until the next database restart: scope=spfile

3. The modified current instance will work, and the next database restart will also work: scope=both

Notice: what is the default value of the command alter system set parameter=value without the scope option? Most friends may answer both without thinking. The actual situation is that when oracle is started with the spfile parameter, the default value is both, while when started with pfile, the default value is memory, that is, only the current value is modified. So if you are not sure about the startup parameter file, you can use show parameter spfile to view it.

5. Specify the initial parameter file to start the database: startup pfile='/$ORACLE_HOME/dbs/init$ORACLE_SID.ora'

You cannot start the database with the specified server parameter file spfile, you can convert spfile to pfile first, and then use this command to achieve your goal.

6. Check to see if the system starts with pfile or spfile: show parameter spfile. If it is a null value, it is started by pfile.

two。 The action principle of parameter file

When the oracle instance starts, it reads the configuration in the parameter file. The process goes like this:

You can specify which pfile to start with in the startup command of the database, but note that only pfile can be specified, not spfile.

When using the startup command without a pfile clause, Oracle reads initialization parameters from the server parameter file (spfile) at the default location specified by the platform. The order in which Oracle looks for spfile or init.ora is as follows: at the default location specified by the platform, Oracle first looks for a file named spfile$ORACLE_SID.ora, and if it doesn't have a spfile.ora file, it looks for an init$ORACLE_SID.ora file.

Under $ORACLE_BASE\ admin\ db_name\ spfile, you can see a file with the name init.ora.1 92003215317], which is the initialization parameter file, but with the timestamp. For Oracle920, the default is to start using spfile, but this spfile is not created out of thin air, but based on this file, you can remove this long suffix, which is a standard pfile file.

Thank you for your reading, the above is the content of "oracle database parameter files are divided into several categories". After the study of this article, I believe you have a deeper understanding of the problem that oracle database parameter files are divided into several categories, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.