Sophie: postgresql-docs-7.4.1-2.5.100mdk i586

postgresql-docs-7.4.1-2.5.100mdk.i586.rpm

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>Chapter 18. Managing Databases</H1
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><DL
><DT
><B
>Table of Contents</B
></DT
><DT
>18.1. <A
HREF="managing-databases.html#MANAGE-AG-OVERVIEW"
>Overview</A
></DT
><DT
>18.2. <A
HREF="manage-ag-createdb.html"
>Creating a Database</A
></DT
><DT
>18.3. <A
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>Template Databases</A
></DT
><DT
>18.4. <A
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>Database Configuration</A
></DT
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>Alternative Locations</A
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>18.6. <A
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>Destroying a Database</A
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><P
>  Every instance of a running <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>
  server manages one or more databases.  Databases are therefore the
  topmost hierarchical level for organizing <ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
>
  objects (<SPAN
CLASS="QUOTE"
>"database objects"</SPAN
>).  This chapter describes
  the properties of databases, and how to create, manage, and destroy
  them.
 </P
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><A
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>18.1. Overview</A
></H1
><A
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></A
><P
>   A database is a named collection of <ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> objects
   (<SPAN
CLASS="QUOTE"
>"database objects"</SPAN
>).  Generally, every database
   object (tables, functions, etc.) belongs to one and only one
   database.  (But there are a few system catalogs, for example
   <TT
CLASS="LITERAL"
>pg_database</TT
>, that belong to a whole cluster and
   are accessible from each database within the cluster.)  More
   accurately, a database is a collection of schemas and the schemas
   contain the tables, functions, etc.  So the full hierarchy is:
   server, database, schema, table (or something else instead of a
   table).
  </P
><P
>   An application that connects to the database server specifies in
   its connection request the name of the database it wants to connect
   to. It is not possible to access more than one database per
   connection. (But an application is not restricted in the number of
   connections it opens to the same or other databases.)  It is
   possible, however, to access more than one schema from the same
   connection.  Schemas are a purely logical structure and who can
   access what is managed by the privilege system.  Databases are
   physically separated and access control is managed at the
   connection level.  If one <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> server
   instance is to house projects or users that should be separate and
   for the most part unaware of each other, it is therefore
   recommendable to put them into separate databases.  If the projects
   or users are interrelated and should be able to use each other's
   resources they should be put in the same databases but possibly
   into separate schemas.  More information about managing schemas is
   in <A
HREF="ddl-schemas.html"
>Section 5.8</A
>.
  </P
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><BLOCKQUOTE
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><P
><B
>Note: </B
>    <ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> calls databases <SPAN
CLASS="QUOTE"
>"catalogs"</SPAN
>, but there is no
    difference in practice.
   </P
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