- - thomas 1998-02-24
-->
-
-
Adding and Deleting Users
-
-
createuser enables specific users to access
-
destroyuser removes users and
- prevents them from accessing
Postgres.
- Note that these
- commands only affect users with respect to
- they have no effect on users other privileges or status with regards
- to the underlying
- operating system.
-
-
-
-
-
Disk Management
-
-
-
Alternate Locations
-
+
+
Adding and Deleting Users
+
+
createuser enables specific users to access
+
destroyuser removes users and
+ prevents them from accessing
Postgres.
+
+
+ These commands only affect users with respect to
+ they have no effect on a user's other privileges or status with regards
+ to the underlying operating system.
+
+
+
+
+
Disk Management
+
+
+
Alternate Locations
+
It is possible to create a database in a location other than the default
location for the installation. Remember that all database access actually
occurs through the database backend, so that any location specified must
be accessible by the backend.
- <Para>
+ <para>
Alternate database locations are created and referenced by an environment variable
which gives the absolute path to the intended storage location.
This environment variable must have been defined before the backend was started
to avoid confusion and conflict with other variables.
- <Note>
- <Para>
- In previous versions of <ProductName>Postgresame>,
+ <note>
+ <para>
+ In previous versions of <productname>Postgresame>,
it was also permissable to use an absolute path name
to specify an alternate storage location.
The environment variable style of specification
is to be preferred since it allows the site administrator more flexibility in
managing disk storage.
If you prefer using absolute paths, you may do so by defining
- "ALLOW_ABSOLUTE_DBPATHS" and recompiling <ProductName>Postgresame>
+ "ALLOW_ABSOLUTE_DBPATHS" and recompiling <productname>Postgresame>
To do this, either add this line
- <ProgramListing>
+ <programlisting>
#define ALLOW_ABSOLUTE_DBPATHS 1
- ProgramListing>
+ programlisting>
to the file src/include/config.h, or by specifying
- <ProgramListing>
+ <programlisting>
CFLAGS+= -DALLOW_ABSOLUTE_DBPATHS
- ProgramListing>
+ programlisting>
in your Makefile.custom.
- Para>
- Note>
+ para>
+ note>
- <Para>
+ <para>
Remember that database creation is actually performed by the database backend.
Therefore, any environment variable specifying an alternate location must have
been defined before the backend was started. To define an alternate location
PGDATA2 pointing to /home/postgres/data, first type
- <ProgramListing>
+ <programlisting>
% setenv PGDATA2 /home/postgres/data
- ProgramListing>
+ programlisting>
to define the environment variable to be used with subsequent commands.
Usually, you will want to define this variable in the
- <ProductName>Postgresame> superuser's
+ <productname>Postgresame> superuser's
.profile
or
.cshrc
overwriting other variables.
- <Para>
+ <para>
To create a data storage area in PGDATA2, ensure
that /home/postgres already exists and is writable
by the postgres administrator.
Then from the command line, type
- <ProgramListing>
+ <programlisting>
% setenv PGDATA2 /home/postgres/data
% initlocation $PGDATA2
Creating Postgres database system directory /home/postgres/data
Creating Postgres database system directory /home/postgres/data/base
- ProgramListing>
+ programlisting>
- <Para>
- To test the new location, create a database <Database>testatabase> by typing
+ <para>
+ To test the new location, create a database <database>testatabase> by typing
- <ProgramListing>
+ <programlisting>
% createdb -D PGDATA2 test
% destroydb test
- ProgramListing>
+ programlisting>
-
-
-
-
-
Managing a Database
-
- Now that
Postgres is up and running we can create
- some databases to experiment with. Here, we describe the
- basic commands for managing a database.
-
-
-
-
Creating a Database
-
- Let's say you want to create a database named mydb.
- You can do this with the following command:
-
-% createdb mydb
-
-
-
Postgres allows you to create
- any number of databases
- at a given site and you automatically become the
- database administrator of the database you just created.
- Database names must have an alphabetic first
- character and are limited to 16 characters in length.
- Not every user has authorization to become a database
- administrator. If
Postgres - refuses to create databases
- for you, then the site administrator needs to grant you
- permission to create databases. Consult your site
- administrator if this occurs.
-
-
-
-
-
Accessing a Database
-
- Once you have constructed a database, you can access it
- by:
-
-
-
- running the
Postgres terminal monitor program
- (
psql) which allows you to interactively
- enter, edit, and execute
SQL commands.
-
-
-
- writing a C program using the libpq subroutine
- library. This allows you to submit
SQL commands
- from C and get answers and status messages back to
- your program. This interface is discussed further
- in the PostgreSQL Programmer's Guide.
-
-
-
-
- You might want to start up
psql,
- to try out the examples in this manual. It can be activated for the mydb
- database by typing the command:
-
-% psql mydb
-
-
- You will be greeted with the following message:
-Welcome to the Postgres interactive sql monitor:
-
- type \? for help on slash commands
- type \q to quit
- type \g or terminate with semicolon to execute query
-You are currently connected to the database: mydb
-
-mydb=>
-
-
-
- This prompt indicates that the terminal monitor is listening
- to you and that you can type
SQL queries into a
- workspace maintained by the terminal monitor.
- The
psql program responds to escape
- codes that begin
- with the backslash character, "\". For example, you
- can get help on the syntax of various
-
Postgres SQL commands by typing:
-
-mydb=> \h
-
-
- Once you have finished entering your queries into the
- workspace, you can pass the contents of the workspace
- to the
Postgres server by typing:
-
-mydb=> \g
-
-
- This tells the server to process the query. If you
- terminate your query with a semicolon, the backslash-g is not
- necessary.
psql will automatically
- process semicolon terminated queries.
- To read queries from a file, say myFile, instead of
- entering them interactively, type:
-
-mydb=> \i fileName
-
-
- To get out of
psql and return to UNIX, type
-
-mydb=> \q
-
-
- and
psql will quit and return
- you to your command
- shell. (For more escape codes, type backslash-h at the monitor
- prompt.)
- White space (i.e., spaces, tabs and newlines) may be
- used freely in
SQL queries.
- Single-line comments are denoted by two dashes
- (--
). Everything after the dashes up to the end of the
- line is ignored. Multiple-line comments, and comments within a line,
- are denoted by /* ... */
, a convention borrowed
-
-
-
-
-
Destroying a Database
-
- If you are the database administrator for the database
- mydb, you can destroy it using the following UNIX command:
-
-% destroydb mydb
-
-
- This action physically removes all of the UNIX files
- associated with the database and cannot be undone, so
- this should only be done with a great deal of forethought.
-
-
-
-
+
+
projects / postgresql.git / commitdiff