public inbox for [email protected]
help / color / mirror / Atom feedFrom: Jürgen Purtz <[email protected]>
To: [email protected]
Subject: Re: Shrinking SVG (Again)
Date: Fri, 14 Feb 2020 18:42:02 +0100
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
<[email protected]>
<[email protected]>
The attached patch extends the previous one by one more figure, a rework
of the old explanations plus additional explanations.
J. Purtz
Attachments:
[image/png] hierarchy.png (73.1K, 2-hierarchy.png)
download | view image
[text/x-patch] architecture-02.patch (144.0K, 3-architecture-02.patch)
download | inline diff:
diff --git a/doc/src/sgml/advanced.sgml b/doc/src/sgml/advanced.sgml
index ae5f3fac75..965eb751c0 100644
--- a/doc/src/sgml/advanced.sgml
+++ b/doc/src/sgml/advanced.sgml
@@ -1,7 +1,7 @@
<!-- doc/src/sgml/advanced.sgml -->
<chapter id="tutorial-advanced">
- <title>Advanced Features</title>
+ <title>Advanced SQL Features</title>
<sect1 id="tutorial-advanced-intro">
<title>Introduction</title>
diff --git a/doc/src/sgml/architecture.sgml b/doc/src/sgml/architecture.sgml
new file mode 100644
index 0000000000..4c328c37f1
--- /dev/null
+++ b/doc/src/sgml/architecture.sgml
@@ -0,0 +1,562 @@
+<!-- doc/src/sgml/architecture.sgml -->
+
+ <chapter id="tutorial-architecture">
+ <title>The Architecture</title>
+
+ <para>
+ Every DBMS implements basic strategies to achieve a fast and
+ robust system. This chapter provides an overview about some
+ of the techniques which are used by <productname>
+ PostgreSQL</productname> to reach this aim.
+ </para>
+
+ <sect1 id="tutorial-ram-proc-file">
+ <title>Collabortion of Processes, RAM, and Files</title>
+ <para>
+ As is a matter of course, in a client/server architecture
+ clients do not have direct access to the database. Instead,
+ at the server side there is a group of processes, which
+ receive all requests comming from client applications,
+ handle them, and send resulting information back to
+ the clients.
+ These server-side processes work in close cooperation to
+ each other. Together with their common
+ <xref linkend="glossary-shared-memory"/> they are called an
+ <link linkend="glossary-instance">Instance</link>.
+ </para>
+
+ <para>
+ The instance is initiated by the
+ <xref linkend="glossary-postmaster"/> process.
+ He loads the configuration files, allocates the
+ <firstterm>Shared Memory</firstterm>
+ and starts the comprehensive network of processes:
+ <xref linkend="glossary-background-writer"/>,
+ <xref linkend="glossary-checkpointer"/>,
+ <xref linkend="glossary-wal-writer"/>,
+ <xref linkend="glossary-archiver"/>,
+ <xref linkend="glossary-auto-vacuum"/>,
+ <xref linkend="glossary-stats-collector"/>,
+ <xref linkend="glossary-log-writer"/>, and more.
+ <xref linkend="tutorial-architecture-figure"/> visualizes
+ main aspects of their collaboration.
+ </para>
+
+ <para>
+ Whenever a client application tries to connect to a
+ <xref linkend="glossary-database"/>, this request is handled
+ in a first step by the <firstterm>Postmaster
+ process</firstterm>. He checks the authorization, starts a
+ new <xref linkend="glossary-backend-process"/>,
+ and instructs the client application to connect to this
+ new <firstterm>Backend process</firstterm>. All further
+ client requests go to this process and are handled
+ by him. Thus - after the initial phase - each client
+ application communicates with exactly
+ one <firstterm>Backend process</firstterm>.
+ </para>
+
+ <figure id="tutorial-architecture-figure">
+ <title>Architecture</title>
+ <mediaobject>
+ <imageobject role="html">
+ <!-- attribute 'width=..px' is necessary to keep font-size of SVG text
+ in correlation with font-size of surrounding HTML -->
+ <imagedata fileref="images/ram-proc-file-raw.svg" format="SVG" width="900px" />
+ </imageobject>
+ <imageobject role="fo">
+ <!-- For PDF attribute 'width=100%' is necessary to keep complete SVG visible
+ on the page, which has a fixed width. Font sizes will be adopted. -->
+ <imagedata fileref="images/ram-proc-file-raw.svg" format="SVG" width="100%" />
+ </imageobject>
+ </mediaobject>
+ </figure>
+
+ <para>
+ Client requests (SELECT, UPDATE, ...) usually leads to the
+ necessity to read or write some data. In an first attempt
+ the client's <firstterm>Backend process</firstterm> tries
+ to get the information out of <firstterm>Shared
+ Memory</firstterm>. This <firstterm>Shared
+ Memory</firstterm> is a mirror of parts of the
+ <xref linkend="glossary-heap"/> and
+ <xref linkend="glossary-index"/> files. Because files are
+ much huger than memory, it is easily possible that
+ the desired information is not (completely) available
+ in the RAM. In this case the <firstterm>Backend process
+ </firstterm> must transfer additional file pages to
+ <firstterm>Shared Memory</firstterm>. Files are physically
+ organized in pages. Every transfer between files and
+ RAM is performed in units of complete pages while retaining
+ their size and layout.
+ </para>
+
+ <para>
+ Reading file pages is notedly slower than reading
+ RAM. This is the main motivation for the existence of
+ <firstterm>Shared Memory</firstterm>. As soon as one
+ of the <firstterm>Backend processes</firstterm> has done
+ the job, this pages are available for all other
+ <firstterm>Backend processes</firstterm> for direct
+ access in RAM.
+ </para>
+
+ <para>
+ <firstterm>Shared Memory</firstterm> is limited in size.
+ Sooner or later it is necessary to overwrite old RAM
+ pages. As long as the content of such pages hasn't
+ changed, this is not a problem. But in
+ <firstterm>Shared Memory</firstterm> also write
+ actions take place
+ - performed by any of the <firstterm>Backend
+ processes</firstterm> (or the
+ <firstterm>Auto Vacuum</firstterm> or other
+ processes).
+ Such modified pages are called
+ <firstterm>dirty pages</firstterm>.
+ Before <firstterm>dirty pages</firstterm> can be overwritten,
+ they must be saved to disk. This is a two-step process.
+ </para>
+
+ <para>
+ First, whenever the content of a page changes, a
+ <xref linkend="glossary-wal-record"/> is created out
+ of the delta-information (difference between old and
+ new content) and stored in another area of the
+ <firstterm>Shared Memory</firstterm>. These
+ <firstterm>WAL records</firstterm> are read by the
+ <firstterm>WAL writer</firstterm> process,
+ who runs in parallel to the <firstterm>Backend
+ processes</firstterm> and all other processes of
+ the <firstterm>instance</firstterm>. He writes
+ the continuously arising <firstterm>WAL
+ records</firstterm> to
+ the end of the current <firstterm>WAL
+ file</firstterm>. Because of the sequential
+ nature of this writing, it is much faster than
+ the more or less random access
+ to data files with <firstterm>heap</firstterm>
+ and <firstterm>index</firstterm> information.
+ As mentioned, this WAL-writing happens
+ in an independent process. Nevertheless all
+ <firstterm>WAL records</firstterm> created out of one
+ <firstterm>dirty page</firstterm> must be transfered
+ to disk before the <firstterm>dirty page</firstterm>
+ itself can be transfered to disk (???).
+ </para>
+
+ <para>
+ Second, the transfer of <firstterm>dirty pages</firstterm>
+ from <firstterm>Shared Memory</firstterm> to files must
+ take place. This is the primarily duty of the
+ <firstterm>Background Writer</firstterm> process. Because
+ huge I/O activities can block other processes significantly,
+ he starts periodically and acts only for a short period.
+ Doing so, his expensive I/O activities are spread over
+ time avoiding huge I/O peaks. Also the <firstterm>
+ Checkpointer</firstterm> process transfers
+ <firstterm>dirty pages</firstterm> to files, see next
+ paragraph.
+ </para>
+
+ <para>
+ The <firstterm>Checkpointer</firstterm> has a special
+ duty. As its name suggests, he has to create
+ <firstterm>Checkpoints</firstterm>. Such a
+ <xref linkend="glossary-checkpoint"/> is a point in time
+ when all older <firstterm>dirty pages</firstterm>,
+ all older <firstterm>WAL records</firstterm>, and
+ lastly a special <firstterm>Checkpoint record
+ </firstterm> have been written and flushed to disk.
+ In consequence, after a <firstterm>Checkpoint</firstterm>
+ data files and <firstterm>WAL files</firstterm> are in sync.
+ In case of a recovery (after a crash of the instance)
+ it is known, that the information of all
+ <firstterm>WAL records</firstterm> preceding
+ the last <firstterm>Checkpoint record</firstterm>
+ is already integrated into the data files. This
+ speeds up a possibly occurring recovery.
+ </para>
+
+ <para>
+ In correlation with data changes,
+ <firstterm>WAL records</firstterm> arise and are writen
+ to <firstterm>WAL files</firstterm>.
+ Those <firstterm>WAL files</firstterm> - in combination with
+ a previously taken <firstterm>Base Backup</firstterm> -
+ are necessary to restore a database after a crash of the
+ disk, where data files have been stored. Therefore it is
+ recommended to transfer a copy of the <firstterm>
+ WAL files</firstterm>
+ to a second, independent place. The purpose of the
+ <xref linkend="glossary-archiver"/> process is to perform
+ this copy action.
+ </para>
+
+ <para>
+ The <firstterm>Stats Collector</firstterm> process collects
+ counter about accesses to <firstterm>SQL
+ objects</firstterm> like tables, rows, indexes, pages,
+ and others. He stores the obtained information in system
+ tables.
+ </para>
+
+ <para>
+ The <firstterm>Log Writer</firstterm> process writes
+ readable text lines about serious and non-serious events,
+ which can happen during database access, e.g.: wrong password,
+ no permission, long-running query, ... .
+ </para>
+
+ </sect1>
+
+ <sect1 id="tutorial-cluster-db-schema">
+ <title>Cluster, Database, Schema</title>
+ <para>
+ <productname>PostgreSQL</productname> organizes data and
+ meta data in a strict hierarchy and allows connections
+ - depending on the user's rights - to access objects of
+ different hierarchy levels.
+ </para>
+ <sect2 id="tutorial-ownership">
+ <title>Ownership</title>
+
+ <para>
+ <xref linkend="tutorial-internal-objects-hierarchy-figure"/>
+ shows the relation of internal objects to each other, especially
+ their hierarchical nature.
+ </para>
+
+ <para>
+ On a <xref linkend="glossary-server"/>
+ exists one or more <xref linkend="glossary-cluster"/>.
+ A <firstterm>cluster</firstterm> essentially contains
+ <link linkend="managing-databases">databases</link>, but also
+ <link linkend="manage-ag-tablespaces">tablespaces</link>,
+ <link linkend="replication-origins">replication origins</link>,
+ subscriptions for
+ <link linkend="logical-replication">logical replication</link>,
+ <link linkend="database-roles">roles</link>, and information about all
+ <link linkend="catalog-pg-database">database names</link>
+ within this cluster.
+ <!--, as well as associated
+ comments, descriptions and toast-tables for such objects. -->
+ A <firstterm>database</firstterm> essentially contains
+ <firstterm>schemas</firstterm>, but also
+ <link linkend="collation">collations</link>, and - if created -
+ <link linkend="extend-extensions">extensions</link>.
+ A <firstterm>schema</firstterm> contains such objects
+ with which users interact mostly: <firstterm>tables,
+ views</firstterm>, and many more.
+ </para>
+
+ <figure id="tutorial-internal-objects-hierarchy-figure">
+ <title>Hierarchy of Internal Objects</title>
+ <mediaobject>
+ <imageobject role="html">
+ <!-- attribute 'width=..px' is necessary to keep font-size of SVG text
+ in correlation with font-size of surrounding HTML -->
+ <imagedata fileref="images/internal-objects-hierarchy-raw.svg" format="SVG" width="900px" />
+ </imageobject>
+ <imageobject role="fo">
+ <!-- For PDF attribute 'width=100%' is necessary to keep complete SVG visible
+ on the page, which has a fixed width. Font sizes will be adopted. -->
+ <imagedata fileref="images/internal-objects-hierarchy-raw.svg" format="SVG" width="100%" />
+ </imageobject>
+ </mediaobject>
+ </figure>
+
+ <para>
+ The hierarchy is strict, which means that each object has
+ exactly one parent, e.g.: each <firstterm>table</firstterm>
+ or <firstterm>view</firstterm> belongs to a certain
+ <firstterm>schema</firstterm>, it cannot belong to another
+ <firstterm>schema</firstterm>. An <firstterm>extension
+ </firstterm> like a <firstterm>foreign data wrapper
+ </firstterm> belongs to exactly one
+ <firstterm>database</firstterm>. If it is needed in another
+ <firstterm>database</firstterm> as well, it must be installed
+ twice.
+ </para>
+
+ <para>
+ <firstterm>Schemas</firstterm> contain <firstterm>SQL objects
+ </firstterm> of different type: <firstterm>table, view,
+ materialized view, index, constraint, sequence, function,
+ procedure, trigger, data type, operator</firstterm>, and more.
+ A schema is a namespace for all of its objects, independent
+ from the object type, and ensures that within its scope object
+ names are unique. E.g.: It is not possible
+ to have a table <literal>employee</literal> and a view
+ <literal>employee</literal> within the same
+ <firstterm>schema</firstterm>. But it is possible to have
+ two tables <literal>employee</literal> in different
+ <firstterm>schemas</firstterm>. In this case the two tables
+ are different objects and absolutely independent from each
+ other.
+ </para>
+
+ </sect2>
+
+ <sect2 id="tutorial-visibility">
+ <title>Visibility</title>
+ <para>
+ Independent from this strict 'belong-to' hierarchy in most
+ cases the knowledge about objects of the same or another
+ level is available via the <firstterm>system catalog</firstterm>.
+ Also the access to them is possible, if appropriate privileges
+ are granted.
+ All connections act at the database level (bold ellipse in the
+ above figure). From here they know about and have access to
+ nearly all objects:
+ <itemizedlist>
+ <listitem>
+ <para>
+ Their direct child objects <firstterm>schema, extension,
+ </firstterm> and <firstterm>collation</firstterm>. They can
+ access different schemas and use all extensions and
+ collations of this database.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Their grandchild objects <firstterm>tables, view, ...
+ </firstterm>. The sequence of schemas for locating
+ such objects is defined via the variable <firstterm>
+ search_path</firstterm>.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ All <firstterm>tablespaces</firstterm>. If a tablespace is
+ defined in any database, it is automatically visible and
+ active in all other databases. It's name cannot be used
+ in any of the other databases for creating an additional
+ tablespace.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ All <firstterm>roles</firstterm>. If a role is defined
+ in any database, it is visible and active in all
+ other databases. This implies, that the same
+ role cannot be created again in a different
+ <firstterm>database</firstterm>, it
+ exists already. But a DBA can grant different
+ privilegs to the same roles depending on databases.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ All <firstterm>database names</firstterm> of this cluster.
+ Although the database names are known, the current
+ connection is not able to switch to a different
+ <firstterm>database</firstterm>. To do so, a different
+ connection is necessary. This behaviour results from the
+ implementation of connections.
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
+ Cluster limits are unbreachable boarders for a single
+ connection. No information about other clusters or their
+ content is visible or accessible. Only <firstterm>
+ foreing data wrappers</firstterm> and <firstterm>
+ replication</firstterm> mechanisms are able to communicate
+ across cluster limits. To do so, they use additional
+ communication lines.
+ </para>
+ </listitem>
+
+ </itemizedlist>
+ </para>
+ </sect2>
+
+ <sect2 id="tutorial-initial-objects">
+ <title>Initial Objects</title>
+
+ <para>
+ As a result of its initialization process
+ (<command>initdb</command>) a cluster
+ contains certain objects with predefined names. When
+ DBAs create more objects to satisfy their needs, these
+ user-created objects fit into the same hierarchy
+ and comply to the same visibility rules.
+ <xref linkend="tutorial-cluster-db-schema-figure"/>
+ shows the objects and their names.
+ </para>
+
+ <figure id="tutorial-cluster-db-schema-figure">
+ <title>Cluster, Database, Schema</title>
+ <mediaobject>
+ <imageobject role="html">
+ <!-- attribute 'width=..px' is necessary to keep font-size of SVG text
+ in correlation with font-size of surrounding HTML -->
+ <imagedata fileref="images/cluster-db-schema-raw.svg" format="SVG" width="900px" />
+ </imageobject>
+ <imageobject role="fo">
+ <!-- For PDF attribute 'width=100%' is necessary to keep complete SVG visible
+ on the page, which has a fixed width. Font sizes will be adopted. -->
+ <imagedata fileref="images/cluster-db-schema-raw.svg" format="SVG" width="100%" />
+ </imageobject>
+ </mediaobject>
+ </figure>
+
+ <para>
+ By default the command <command>initdb</command> creates the
+ cluster <literal>data</literal>.
+ </para>
+
+ <para>
+ <literal>template0</literal> is the very first
+ <firstterm>database</firstterm> of any <firstterm>
+ cluster</firstterm>. <literal>template0</literal>
+ is created by C-routines during the initialization phase
+ of the <firstterm>cluster</firstterm>.
+ In a second step <literal>template1</literal> is generated
+ as a copy of <literal>template0</literal> and finally
+ <literal>postgres</literal> as a copy of
+ <literal>template1</literal>. All other
+ <link linkend="app-createdb">new databases</link>
+ of this <firstterm>cluster</firstterm>,
+ such as <literal>my_db</literal>, are also copied from
+ <literal>template1</literal>. Due to the special
+ role of <literal>template0</literal> as the origin
+ of all other <firstterm>databases</firstterm>, no client
+ can connect to it.
+ </para>
+
+ <para>
+ The schema <literal>public</literal> acts as the default
+ schema and contains all such
+ <firstterm>SQL objects</firstterm>, which are created
+ within <literal>public</literal> or without using any schema
+ name. <literal>public</literal> should not contain user defined
+ <firstterm>SQL objects</firstterm>. It is recommended to
+ create a separate <firstterm>schema</firstterm> which
+ holds individual objects like application-specific tables or
+ views.
+ </para>
+
+ <para>
+ <literal>pg_catalog</literal> is a schema for all tables
+ and views of the <xref linkend="glossary-system-catalog"/>.
+ <literal>information_schema</literal> is a schema for several
+ tables and views of the <firstterm>System Catalog</firstterm>
+ in a way, which conforms to the SQL standard.
+ </para>
+
+ </sect2>
+ </sect1>
+
+ <sect1 id="tutorial-directories">
+ <title>Directory Structure</title>
+
+ <para>
+ <productname>PostgreSQL</productname> organizes long lasting
+ data as well as temporary state information about transactions
+ or replication actions in the file system. Every
+ <xref linkend="glossary-cluster"/> has its own root directory
+ anywhere in the file system. In many cases, the environment
+ variable <literal>PGDATA</literal> points to this directory.
+ The example of the following survey, which is shown in
+ <xref linkend="tutorial-directories-figure"/>, uses
+ <literal>data</literal> as the name of this root directory.
+ </para>
+
+ <figure id="tutorial-directories-figure">
+ <title>Directory Structure</title>
+ <mediaobject>
+ <imageobject role="html">
+ <!-- attribute 'width=..px' is necessary to keep font-size of SVG text
+ in correlation with font-size of surrounding HTML -->
+ <imagedata fileref="images/directories-raw.svg" format="SVG" width="900px" />
+ </imageobject>
+ <imageobject role="fo">
+ <!-- For PDF attribute 'width=100%' is necessary to keep complete SVG visible
+ on the page, which has a fixed width. Font sizes will be adopted. -->
+ <imagedata fileref="images/directories-raw.svg" format="SVG" width="100%" />
+ </imageobject>
+ </mediaobject>
+ </figure>
+
+ <para>
+ <literal>data</literal> contains many subdirectories and
+ some files, all of which are necessary to store long lasting
+ as well as temporary data. The following paragraphs
+ describe the files and subdirectories in
+ <literal>data</literal>.
+ </para>
+
+ <para>
+ <literal>base</literal> is a subdirectory in which one
+ subdirectory per <firstterm>database</firstterm> exists.
+ The names of those sudirectories consists of numbers.
+ These are the internal
+ <firstterm>Object Identifiers (OID)</firstterm>, which are
+ numbers to identify the database definition in the
+ <xref linkend="glossary-system-catalog"/>.
+ </para>
+
+ <para>
+ Within the database-specific
+ subdirectories there are many files. Primarily they contain
+ the <firstterm>heap</firstterm> and <firstterm>
+ index</firstterm>. But there are also optimization information
+ like <link linkend="storage-fsm">Free Space Maps</link> or
+ <link linkend="storage-vm">Visibility Maps</link>.
+ </para>
+
+ <para>
+ Another important subdirectory is <literal>global</literal>.
+ In analogy to the <firstterm>database</firstterm>-specific
+ subdirectories, there are files containing information about
+ <xref linkend="glossary-global-sql-object"/>s. One type
+ of such <firstterm>Global Objects</firstterm> are
+ <firstterm>tablespaces</firstterm>. In
+ <literal>global</literal> there are information about
+ the <firstterm>tablespaces</firstterm>, neither the
+ <firstterm>tablespaces</firstterm> itself nor the
+ symbolic links to them.
+ </para>
+
+ <para>
+ The subdirectory <literal>pg_wal</literal> contains
+ <link linkend="glossary-wal-file">WAL files</link>.
+ They arise and grow in parallel with data changes in the
+ <firstterm>cluster</firstterm> and remain alive as long as
+ they are required for recovery, archiving, or replication.
+ Please note that they belong to the complete cluster, not
+ to single databases.
+ </para>
+
+ <para>
+ The subdirectory <literal>pg_xact</literal> contains
+ information about the status of each transaction.
+ </para>
+
+ <para>
+ In <literal>pg_tblspc</literal> there are symbolic links
+ that point to directories containing such<firstterm>
+ SQL objects</firstterm> that are created within
+ <firstterm>tablespaces</firstterm>.
+ </para>
+
+ <para>
+ In the directory <literal>data</literal> exists also some
+ files. As long as the
+ <firstterm>cluster</firstterm> is up and running, the file
+ <literal>postmaster.pid</literal> exists and contains the ID of
+ the <firstterm>Postmaster</firstterm> process. In many cases
+ the configuration files of this <firstterm>cluster</firstterm>
+ are stored here.
+ </para>
+
+ </sect1>
+
+ </chapter>
diff --git a/doc/src/sgml/filelist.sgml b/doc/src/sgml/filelist.sgml
index 3da2365ea9..022c2efda3 100644
--- a/doc/src/sgml/filelist.sgml
+++ b/doc/src/sgml/filelist.sgml
@@ -8,9 +8,10 @@
<!ENTITY problems SYSTEM "problems.sgml">
<!-- tutorial -->
-<!ENTITY advanced SYSTEM "advanced.sgml">
-<!ENTITY query SYSTEM "query.sgml">
-<!ENTITY start SYSTEM "start.sgml">
+<!ENTITY start SYSTEM "start.sgml">
+<!ENTITY architecture SYSTEM "architecture.sgml">
+<!ENTITY query SYSTEM "query.sgml">
+<!ENTITY advanced SYSTEM "advanced.sgml">
<!-- user's guide -->
<!ENTITY array SYSTEM "array.sgml">
@@ -169,6 +170,7 @@
<!ENTITY release-13 SYSTEM "release-13.sgml">
<!ENTITY limits SYSTEM "limits.sgml">
+<!ENTITY glossary SYSTEM "glossary.sgml">
<!ENTITY acronyms SYSTEM "acronyms.sgml">
<!ENTITY features-supported SYSTEM "features-supported.sgml">
diff --git a/doc/src/sgml/glossary.sgml b/doc/src/sgml/glossary.sgml
new file mode 100644
index 0000000000..664d6d23b3
--- /dev/null
+++ b/doc/src/sgml/glossary.sgml
@@ -0,0 +1,502 @@
+<!-- doc/src/sgml/glossary.sgml -->
+
+<appendix id="glossary">
+ <title>Glossary</title>
+
+ <para>
+ The glossary contains a collection of
+ <productname>PostgreSQL</productname> related terms.
+ In order to keep such terms together, which are related
+ to each other or can be easily confused, they are not
+ ordered alphabetically.
+ </para>
+ <para>
+ In some cases terms are extended by an alternative wording
+ in parenthesize, e.g.: '(or: Database Server)'. Such deviant
+ formulations are sometimes used at various points in the
+ documentation, but will be replaced by the preferred term
+ in a future release.
+ </para>
+
+ <glosslist>
+
+ <glossentry id="glossary-server">
+ <glossterm>Server (or: Host)</glossterm>
+ <glossdef>
+ <para>
+ The term <firstterm>server</firstterm> denotes real hardware,
+ a container, or a Virtual Machine.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-instance">
+ <glossterm>Instance (or: Database Server, or: Backend Server)</glossterm>
+ <glossdef>
+ <para>
+ An <link linkend="app-postgres">instance</link> is a group
+ of processes plus their common
+ <firstterm>Shared Memory</firstterm> running on a single
+ <firstterm>server</firstterm>. The instance handles all key
+ features of a DBMS: read and write access to files and
+ <firstterm>Shared Memory</firstterm>, assurance of the
+ <firstterm>ACID paradigm</firstterm>, <firstterm>MVCC</firstterm>,
+ <firstterm>connections</firstterm> to client programms,
+ <firstterm>backup</firstterm>, <firstterm>recovery</firstterm>,
+ <firstterm>replication</firstterm>, <firstterm>privileges</firstterm>, … .
+ </para>
+ <para>
+ An instance manages exactly one <firstterm>cluster</firstterm>.
+ </para>
+ <para>
+ Many <firstterm>instances</firstterm> can run on the same
+ <firstterm>server</firstterm> – as
+ long as they use different IP ports and manage different
+ <firstterm>clusters</firstterm>. Different
+ <firstterm>instances</firstterm> on a
+ <firstterm>server</firstterm> may use the same or different
+ versions of PostgreSQL.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-cluster">
+ <glossterm>Cluster (or: Database Cluster)</glossterm>
+ <glossdef>
+ <para>
+ A <link linkend="app-initdb">cluster</link> is a
+ group of 3 or more databases (<literal>template0</literal>,
+ <literal>template1</literal>, <literal>postgres</literal>,
+ ...) plus their <link linkend="glossary-global-sql-object">
+ Global SQL objects</link>. The cluster is managed by exactly one
+ <firstterm>instance</firstterm>.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-database">
+ <glossterm>Database</glossterm>
+ <glossdef>
+ <para>
+ A <link linkend="manage-ag-overview">database</link> is
+ a named collection of <firstterm>SQL objects</firstterm>.
+ The database is stored in files of a single directory plus
+ – optionally - in additional tablespaces.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-schema">
+ <glossterm>Schema</glossterm>
+ <glossdef>
+ <para>
+ A <link linkend="ddl-schemas">schema</link> is a
+ namespace for <firstterm>SQL objects</firstterm>, which
+ reside in the same <firstterm>database</firstterm>. The
+ names of such objects are unique - even across different
+ types of objects. Same object names can only
+ be used in different schemas.
+ </para>
+ <para>
+ There are some predefined schemas:
+ </para>
+ <para>
+ Schema <literal>public</literal>: A schema for objects, which
+ were created within this schema or outside of any schema.
+ It is recommended that users do not store their new
+ objects in <literal>public</literal>. Instead, they shall
+ create their own schema, e.g. <literal>my_schema</literal> and
+ store everything over there.
+ </para>
+ <para>
+ Schema <literal>pg_catalog</literal>: A schema for all tables and
+ views of the <literal>System Catalog</literal>.
+ </para>
+ <para>
+ Schema <literal>information_schema</literal>: A schema for several
+ tables and views of the <literal>System Catalog</literal> in a way,
+ which conforms to the SQL standard.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-system-catalog">
+ <glossterm>System Catalog</glossterm>
+ <glossdef>
+ <para>
+ The <link linkend="ddl-schemas-catalog">
+ System Catalog</link> is a collection of tables and
+ views, which describes the structure of all
+ <firstterm>SQL objects</firstterm> of this
+ <firstterm>database</firstterm> and the
+ <firstterm>Global SQL objects</firstterm> of the
+ <firstterm>cluster</firstterm>.
+ The System Catalog resides in the schema
+ <literal>pg_catalog</literal>. Main parts are mirrored as
+ views in the schema <literal>information_schema</literal>.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-catalog">
+ <glossterm>Catalog</glossterm>
+ <glossdef>
+ <para>
+ The SQL standard uses the standalone term
+ <link linkend=" manage-ag-overview">Catalog</link>
+ for what is called a <firstterm>database</firstterm> in
+ PostgreSQL's terminology.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-sql-object">
+ <glossterm>SQL Object</glossterm>
+ <glossdef>
+ <para>
+ An <link linkend="manage-ag-overview">SQL object</link>
+ is a <firstterm>table, view, materialized view, index,
+ constraint, sequence, function, procedure, trigger, data type,
+ operator</firstterm>, … . Every SQL object belongs
+ to exactly one <firstterm>schema</firstterm>. Within this
+ <firstterm>schema</firstterm> its name is unique.
+ </para>
+ <para>
+ See also: <link linkend="glossary-global-sql-object">
+ Global SQL objects</link>.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-global-sql-object">
+ <glossterm>Global SQL Object</glossterm>
+ <glossdef>
+ <para>
+ Not all objects belong to a certain
+ <firstterm>schema</firstterm> but to their
+ <firstterm>database</firstterm> or even to the complete
+ <firstterm>cluster</firstterm>. Therefore they are called
+ <firstterm>Global SQL objects</firstterm>.
+ <firstterm>Collations</firstterm> and <firstterm>Extensions
+ </firstterm> like <firstterm>foreing data wrappers</firstterm>
+ reside at the database level;
+ <firstterm>database names</firstterm>,
+ <firstterm>roles</firstterm>,
+ <firstterm>tablespaces</firstterm>,
+ <firstterm>replication origins</firstterm>, and
+ subscriptions for <firstterm>logical replication</firstterm>
+ at the cluster level.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-shared-memory">
+ <glossterm>Shared Memory</glossterm>
+ <glossdef>
+ <para>
+ <link linkend="runtime-config-resource-memory">
+ Shared Memory</link> is RAM which is used by the processes
+ of an <firstterm>instance</firstterm> in common. It
+ mirrors parts of database files, provides an area for
+ <firstterm>WAL records</firstterm>, and stores some more
+ common information. Please notice, that Shared Memory
+ belongs to the complete <firstterm>instance</firstterm>,
+ not to a single <firstterm>database</firstterm>.
+ </para>
+ <para>
+ Shared Memory is organized in <firstterm>pages</firstterm>.
+ If such a page gets modified, she is called a
+ <firstterm>dirty page</firstterm> until she is written
+ back to the file system.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-postmaster">
+ <glossterm>Postmaster</glossterm>
+ <glossdef>
+ <para>
+ <link linkend="server-start">Postmaster</link> is the
+ name for the very first process of an
+ <firstterm>instance</firstterm>. He starts
+ the other processes and creates <firstterm>
+ backend processes</firstterm> on demand.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-backend-process">
+ <glossterm>Backend Process</glossterm>
+ <glossdef>
+ <para>
+ <link linkend="guc-max-connections">
+ Backend processes</link> are such processes of an
+ <firstterm>instance</firstterm>, which act
+ on behalf of client <firstterm>connections</firstterm>
+ and process their requests.
+ </para>
+ <para>
+ (Don't confuse the term with the similar terms
+ <firstterm>Background Writer</firstterm> or
+ <firstterm>Background Worker</firstterm>).
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-connection">
+ <glossterm>Connection</glossterm>
+ <glossdef>
+ <para>
+ A connection is a <firstterm>TCP/IP</firstterm> or
+ <firstterm>socket</firstterm> line for inter-process
+ communication. If the two involved processes reside on
+ different servers, TCP/IP must be used. Otherwise both
+ techniques are possible.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-background-writer">
+ <glossterm>Background Writer</glossterm>
+ <glossdef>
+ <para>
+ The <link linkend="runtime-config-resource-background-writer">
+ Background Writer</link> process writes continuously dirty
+ pages from <firstterm>Shared Memory</firstterm> to the
+ file system. He starts periodically. But he works only for a
+ short period in order to distribute his expensive I/O activity
+ over time instead of generating few and huge I/O peaks, which
+ could block other processes.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-background-worker">
+ <glossterm>Background Worker</glossterm>
+ <glossdef>
+ <para>
+ <link linkend="bgworker">Background Workers</link> are
+ individual processes within an
+ <firstterm>instance</firstterm>, which run system- or
+ user-supplied code. A typically use case are processes
+ which handle parts of an SQL query to take advantage of parallel
+ execution on <firstterm>servers</firstterm> with multiple CPUs.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-wal-writer">
+ <glossterm>WAL Writer</glossterm>
+ <glossdef>
+ <para>
+ The <link linkend="runtime-config-wal">WAL writer</link>
+ process writes <firstterm>WAL records</firstterm>
+ from the <firstterm>Shared Memory</firstterm> to
+ <firstterm>WAL files</firstterm>.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-wal-record">
+ <glossterm>WAL Record (or: Log Record)</glossterm>
+ <glossdef>
+ <para>
+ A <link linkend="wal-internals">WAL record</link>
+ contains either new or changed heap or index
+ data or COMMIT, ROLLBACK, SAVEPOINT, or CHECKPOINT
+ information in binary format.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-wal-file">
+ <glossterm>WAL File (or: WAL Segment, or WAL Segment File or: WAL Log)</glossterm>
+ <glossdef>
+ <para>
+ <firstterm>WAL records</firstterm> are continously
+ written to the end of the current
+ <link linkend="wal-internals">WAL file</link>. Please notice,
+ that WAL files as well as <firstterm>WAL records</firstterm>
+ belong to the complete <firstterm>cluster</firstterm>,
+ not to a single <firstterm>database</firstterm>.
+ After a WAL file is full
+ (default: 16 MB), a new WAL file is created or
+ - under certain conditions - one of the previous WAL
+ files is renamed and reused.
+ </para>
+ <para>
+ The sequence of <firstterm>WAL records</firstterm>
+ in combination with the sequence of WAL files
+ represents the sequence of changes that have
+ taken place in the <firstterm>cluster</firstterm>
+ over time (???).
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-segment">
+ <glossterm>File Segment (or: Segment)</glossterm>
+ <glossdef>
+ <para>
+ If a database file grows in size, he may be split into
+ multiple physical files. Those files are called
+ <link linkend="storage-file-layout">file segments</link>.
+ </para>
+ <para>
+ (Don't confuse the term with the similar term
+ <firstterm>WAL segment</firstterm>).
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-archiver">
+ <glossterm>Archiver</glossterm>
+ <glossdef>
+ <para>
+ The <link linkend="backup-archiving-wal">archiver</link>
+ process copies <firstterm>WAL files</firstterm> to a
+ different place in the file system.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-checkpointer">
+ <glossterm>Checkpointer</glossterm>
+ <glossdef>
+ <para>
+ When reaching certain time- or volume-depending criterias
+ or when an SQL CHECKPOINT command is issued, the
+ <link linkend="runtime-config-wal">checkpointer</link>
+ process creates a <link linkend="sql-checkpoint">
+ Checkpoint</link>. He writes <firstterm>dirty
+ pages</firstterm> and <firstterm>WAL records</firstterm>
+ to the file system, and generates a special
+ <firstterm>Checkpoint record</firstterm>.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-checkpoint">
+ <glossterm>Checkpoint</glossterm>
+ <glossdef>
+ <para>
+ A <link linkend="sql-checkpoint">
+ Checkpoint</link>
+ is a point in time when all older dirty
+ pages of the <firstterm>Shared Memory</firstterm>,
+ all older <firstterm>WAL records</firstterm>, and a
+ special <firstterm>Checkpoint record</firstterm>
+ have been written and flushed to disk.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-savepoint">
+ <glossterm>Savepoint</glossterm>
+ <glossdef>
+ <para>
+ A <link linkend="sql-savepoint">savepoint</link>
+ is a special mark (like a timestamp) inside
+ a transaction. Data modifications after this point in time
+ may be rolled back to the time of the savepoint.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-data-directory">
+ <glossterm>Data Directory (or: Data Area)</glossterm>
+ <glossdef>
+ <para>
+ A <link linkend="creating-cluster">data directory</link>
+ is the root directory of a
+ <firstterm>cluster</firstterm> (see also:
+ <link linkend="app-postgres">PGDATA</link>).
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <!-- no helpfull reference found -->
+ <glossentry id="glossary-heap">
+ <glossterm>Heap</glossterm>
+ <glossdef>
+ <para>
+ A heap contains the original values of row attributes,
+ i.e. the data. The heap is realized within database files
+ and mirrored in <firstterm>Shared Memory</firstterm>.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <!-- no helpfull reference found -->
+ <glossentry id="glossary-index">
+ <glossterm>Index</glossterm>
+ <glossdef>
+ <para>
+ An index consists of keys, which are copies of original
+ row attributes, and pointers to the location of this original
+ rows. Such key/value pairs are organized as a tree or a hash (???).
+ The index is realized within database files and mirrored in
+ <firstterm>Shared Memory</firstterm>.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-log-writer">
+ <glossterm>Log Writer</glossterm>
+ <glossdef>
+ <para>
+ If activated and parameterized, the
+ <link linkend="runtime-config-logging">Log Writer</link>
+ process writes information about database events into the
+ current <firstterm>Log file</firstterm>. When reaching
+ certain time- or volume-dependent criterias, he creates
+ a new <firstterm>Log file</firstterm>.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-log-file">
+ <glossterm>Log File</glossterm>
+ <glossdef>
+ <para>
+ <link linkend="logfile-maintenance">LOG files</link>
+ contain readable text lines about serious
+ and non-serious events, e.g.: use of
+ wrong password, long-running queries, ... .
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-auto-vacuum">
+ <glossterm>AutoVacuum</glossterm>
+ <glossdef>
+ <para>
+ The <link linkend="routine-vacuuming">AutoVacuum</link>
+ processes remove outdated
+ MVCC records of the <firstterm>heap</firstterm>
+ and <firstterm>index</firstterm>.
+ </para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry id="glossary-stats-collector">
+ <glossterm>Stats Collector</glossterm>
+ <glossdef>
+ <para>
+ The <link linkend="monitoring-stats">
+ Stats Collector</link> process collects
+ statistical information about the
+ <firstterm>cluster</firstterm> activities.
+ </para>
+ </glossdef>
+ </glossentry>
+
+<!-- ToDo:
+ WAL (LSN, logical decoding, ... )
+ MVCC
+ backup and recovery
+ replication
+-->
+
+ </glosslist>
+</appendix>
diff --git a/doc/src/sgml/images/cluster-db-schema-ink-svgo.svg b/doc/src/sgml/images/cluster-db-schema-ink-svgo.svg
new file mode 100644
index 0000000000..6acb2b69fe
--- /dev/null
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@@ -0,0 +1,160 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="900" height="685" viewBox="0 0 900 685">
+ <title>
+ Server (Hardware, Container, or VM)
+ </title>
+ <style>
+ .text_normal,.text_small{font-style:normal;font-weight:400;font-family:"Open Sans",sans-serif;fill:#000}.text_small{font-size:12px}.text_normal{font-size:16px}
+ </style>
+ <defs>
+ <symbol id="rectangles_special_0">
+ <rect width="225" height="155" rx="10" stroke="blue" fill="none"/>
+ <rect x="15" y="40" width="195" height="50" rx="10" stroke="blue" fill="none" stroke-dasharray="4 2"/>
+ <text class="text_normal" x="20" y="60">
+ schema 'public'
+ </text>
+ <text class="text_small" x="20" y="80">
+ tables, views, ...
+ </text>
+ <rect x="15" y="105" width="195" height="30" rx="10" stroke="blue" fill="none" stroke-dasharray="4 2"/>
+ <text class="text_small" x="20" y="125">
+ (more system schemas)
+ </text>
+ </symbol>
+ <symbol id="rectangles_special_1">
+ <rect width="245" height="225" rx="10" stroke="blue" fill="none"/>
+ <rect x="15" y="40" width="205" height="50" rx="10" stroke="blue" fill="none" stroke-dasharray="4 2"/>
+ <text class="text_normal" x="20" y="60">
+ schema 'public'
+ </text>
+ <text class="text_small" x="20" y="80">
+ tables, views, ...
+ </text>
+ <rect x="15" y="105" width="205" height="50" rx="10" stroke="blue" fill="none" stroke-dasharray="4 2"/>
+ <text class="text_normal" x="20" y="125">
+ 'my_schema' (optional)
+ </text>
+ <text class="text_small" x="20" y="145">
+ tables, views, ...
+ </text>
+ <rect x="15" y="170" width="205" height="30" rx="10" stroke="blue" fill="none" stroke-dasharray="4 2"/>
+ <text class="text_small" x="20" y="190">
+ (more system schemas)
+ </text>
+ </symbol>
+ <symbol id="note" stroke="black" fill="lightyellow">
+ <title>
+ UML Note
+ </title>
+ <path d="M450 10v230H0V0h440v10h10L440 0"/>
+ </symbol>
+ <marker id="arrowhead_end" markerWidth="10" markerHeight="10" refX="6" refY="3" orient="auto">
+ <path d="M0 0l6 3-6 3" stroke="black" fill="none"/>
+ </marker>
+ </defs>
+ <rect x="1" y="1" rx="5" width="99%" height="99%" stroke="black" fill="none"/>
+ <text x="270" y="40" font-weight="400" font-size="24" font-family=""Open Sans",sans-serif">
+ Server (Hardware, Container, or VM)
+ </text>
+ <path stroke="blue" stroke-width="2" fill="none" d="M20 110h790v555H20z"/>
+ <text class="text_normal" x="180" y="25" transform="translate(20 110)">
+ cluster 'data' (default, managed by one instance)
+ </text>
+ <path d="M50 110V80h790v555h-30" stroke="blue" stroke-width="2" fill="none"/>
+ <text class="text_normal" x="190" y="-10" transform="translate(45 110)">
+ cluster 'cluster_2' (optional, managed by a different instance)
+ </text>
+ <g transform="translate(40 155)">
+ <use xlink:href="#rectangles_special_0"/>
+ <text class="text_normal" x="10" y="25">
+ database 'template0'
+ </text>
+ </g>
+ <g transform="translate(290 155)">
+ <use xlink:href="#rectangles_special_0"/>
+ <text class="text_normal" x="10" y="25">
+ database 'template1'
+ </text>
+ </g>
+ <g transform="translate(540 155)">
+ <use xlink:href="#rectangles_special_1"/>
+ <text class="text_normal" x="10" y="25">
+ database 'postgres'
+ </text>
+ </g>
+ <g transform="translate(40 350)">
+ <use xlink:href="#rectangles_special_1"/>
+ <text class="text_normal" x="10" y="25">
+ database 'my_db' (optional)
+ </text>
+ </g>
+ <g transform="translate(320 330)">
+ <rect width="180" height="45" rx="10" stroke="blue" fill="none" stroke-dasharray="10 4 4 4"/>
+ <text class="text_normal" x="15" y="27">
+ Global SQL objects
+ </text>
+ <path d="M0 5l-65-35" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path d="M80 0v-30" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path d="M180 40h50" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path d="M0 40l-45 20" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ </g>
+ <g transform="translate(335 405)">
+ <use xlink:href="#note"/>
+ <text class="text_small" x="10" y="20">
+ 1)
+ </text>
+ <text class="text_small" x="30" y="20">
+ By default, you work in the cluster 'data', database 'postgres',
+ </text>
+ <text class="text_small" x="30" y="35">
+ schema 'public'.
+ </text>
+ <text class="text_small" x="10" y="55">
+ 2)
+ </text>
+ <text class="text_small" x="30" y="55">
+ More system schemas: pg_catalog, information_schema,
+ </text>
+ <text class="text_small" x="30" y="70">
+ pg_temp, pg_toast.
+ </text>
+ <text class="text_small" x="10" y="90">
+ 3)
+ </text>
+ <text class="text_small" x="30" y="90">
+ Global SQL objects: Some SQL objects are automatically active
+ </text>
+ <text class="text_small" x="30" y="105">
+ and known database- or even cluster-wide.
+ </text>
+ <text class="text_small" x="10" y="125">
+ 4)
+ </text>
+ <text class="text_small" x="30" y="125">
+ The command 'initdb' creates a new cluster with the three
+ </text>
+ <text class="text_small" x="30" y="140">
+ databases 'template0', 'template1', and 'postgres'. The command
+ </text>
+ <text class="text_small" x="30" y="155">
+ 'createdb' creates a new database.
+ </text>
+ <text class="text_small" x="10" y="175">
+ 5)
+ </text>
+ <text class="text_small" x="30" y="175">
+ If multiple clusters are active on one server at the same time,
+ </text>
+ <text class="text_small" x="30" y="190">
+ each one is managed by an individual instance. Each such instance
+ </text>
+ <text class="text_small" x="30" y="205">
+ uses a different port.
+ </text>
+ <text class="text_small" x="10" y="225">
+ 6)
+ </text>
+ <text class="text_small" x="30" y="225">
+ No client application is allowed to connect to 'template0'.
+ </text>
+ </g>
+</svg>
diff --git a/doc/src/sgml/images/cluster-db-schema-ink.svg b/doc/src/sgml/images/cluster-db-schema-ink.svg
new file mode 100644
index 0000000000..beb1f00481
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+ <cc:Work
+ rdf:about="">
+ <dc:format>image/svg+xml</dc:format>
+ <dc:type
+ rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+ <dc:title>Server (Hardware, Container, or VM)</dc:title>
+ </cc:Work>
+ </rdf:RDF>
+ </metadata>
+ <sodipodi:namedview
+ pagecolor="#ffffff"
+ bordercolor="#666666"
+ borderopacity="1"
+ objecttolerance="10"
+ gridtolerance="10"
+ guidetolerance="10"
+ inkscape:pageopacity="0"
+ inkscape:pageshadow="2"
+ inkscape:window-width="958"
+ inkscape:window-height="660"
+ id="namedview149"
+ showgrid="false"
+ inkscape:zoom="0.34452555"
+ inkscape:cx="450"
+ inkscape:cy="458.60169"
+ inkscape:window-x="61"
+ inkscape:window-y="27"
+ inkscape:window-maximized="0"
+ inkscape:current-layer="svg147" />
+ <title
+ id="title2">Server (Hardware, Container, or VM)</title>
+ <!-- common text classes -->
+ <style
+ type="text/css"
+ id="style4">
+ .text_small {font-style:normal;
+ font-weight:normal;
+ font-size:12px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ .text_normal {font-style:normal;
+ font-weight:normal;
+ font-size:16px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ .text_big {font-style:normal;
+ font-weight:normal;
+ font-size:24px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ </style>
+ <defs
+ id="defs49">
+ <!-- a rectangle with rounded corners and inner definitions for schemas -->
+ <symbol
+ id="rectangles_special_0">
+ <!-- the database -->
+ <rect
+ width="225"
+ height="155"
+ rx="10"
+ stroke="blue"
+ fill="none"
+ id="rect6" />
+ <!-- schemas -->
+ <rect
+ x="15"
+ y="40"
+ width="195"
+ height="50"
+ rx="10"
+ stroke="blue"
+ fill="none"
+ stroke-dasharray="4 2"
+ id="rect8" />
+ <text
+ class="text_normal"
+ x="20"
+ y="60"
+ id="text10">schema 'public'</text>
+ <text
+ class="text_small"
+ x="20"
+ y="80"
+ id="text12">tables, views, ...</text>
+ <rect
+ x="15"
+ y="105"
+ width="195"
+ height="30"
+ rx="10"
+ stroke="blue"
+ fill="none"
+ stroke-dasharray="4 2"
+ id="rect14" />
+ <text
+ class="text_small"
+ x="20"
+ y="125"
+ id="text16">(more system schemas)</text>
+ </symbol>
+ <!-- same as before, but one more schema -->
+ <symbol
+ id="rectangles_special_1">
+ <!-- the database -->
+ <rect
+ width="245"
+ height="225"
+ rx="10"
+ stroke="blue"
+ fill="none"
+ id="rect19" />
+ <!-- schemas -->
+ <rect
+ x="15"
+ y="40"
+ width="205"
+ height="50"
+ rx="10"
+ stroke="blue"
+ fill="none"
+ stroke-dasharray="4 2"
+ id="rect21" />
+ <text
+ class="text_normal"
+ x="20"
+ y="60"
+ id="text23">schema 'public'</text>
+ <text
+ class="text_small"
+ x="20"
+ y="80"
+ id="text25">tables, views, ...</text>
+ <rect
+ x="15"
+ y="105"
+ width="205"
+ height="50"
+ rx="10"
+ stroke="blue"
+ fill="none"
+ stroke-dasharray="4 2"
+ id="rect27" />
+ <text
+ class="text_normal"
+ x="20"
+ y="125"
+ id="text29">'my_schema' (optional)</text>
+ <text
+ class="text_small"
+ x="20"
+ y="145"
+ id="text31">tables, views, ...</text>
+ <rect
+ x="15"
+ y="170"
+ width="205"
+ height="30"
+ rx="10"
+ stroke="blue"
+ fill="none"
+ stroke-dasharray="4 2"
+ id="rect33" />
+ <text
+ class="text_small"
+ x="20"
+ y="190"
+ id="text35">(more system schemas)</text>
+ </symbol>
+ <symbol
+ id="note"
+ stroke="black"
+ fill="lightyellow">
+ <title
+ id="title38">UML Note</title>
+ <path
+ d="M 450,10 v 230 h -450 v -240 h 440 v 10 h 10 l -10,-10"
+ id="path40" />
+ </symbol>
+ <!-- marker start/end -->
+ <marker
+ id="arrowhead_start"
+ markerWidth="10"
+ markerHeight="10"
+ refX="0"
+ refY="3"
+ orient="auto">
+ <path
+ d="M 6,0 l -6,3 l 6,3"
+ stroke="black"
+ fill="none"
+ id="path43" />
+ </marker>
+ <marker
+ id="arrowhead_end"
+ markerWidth="10"
+ markerHeight="10"
+ refX="6"
+ refY="3"
+ orient="auto">
+ <path
+ d="M 0,0 l 6,3 l -6,3"
+ stroke="black"
+ fill="none"
+ id="path46" />
+ </marker>
+ </defs>
+ <!-- start of rendering area -->
+ <!-- enclosing rectangle -->
+ <rect
+ x="1"
+ y="1"
+ rx="5"
+ width="99%"
+ height="99%"
+ stroke="black"
+ fill="none"
+ id="rect51" />
+ <text
+ class="text_big"
+ x="270"
+ y="40"
+ id="text53">Server (Hardware, Container, or VM)</text>
+ <!-- two clusters -->
+ <g
+ transform="translate(20 110)"
+ id="g59">
+ <rect
+ x="0"
+ y="0"
+ width="790"
+ height="555"
+ stroke="blue"
+ stroke-width="2px"
+ fill="none"
+ id="rect55" />
+ <text
+ class="text_normal"
+ x="180"
+ y="25"
+ id="text57">cluster 'data' (default, managed by one instance)</text>
+ </g>
+ <g
+ transform="translate(45 110)"
+ id="g65">
+ <path
+ d="M 5,0 v -30 h 790 v 555 h -30"
+ stroke="blue"
+ stroke-width="2px"
+ fill="none"
+ id="path61" />
+ <text
+ class="text_normal"
+ x="190"
+ y="-10"
+ id="text63">cluster 'cluster_2' (optional, managed by a different instance)</text>
+ </g>
+ <!-- database template 0 -->
+ <g
+ transform="translate(40 155)"
+ id="g71">
+ <use
+ xlink:href="#rectangles_special_0"
+ id="use67" />
+ <text
+ class="text_normal"
+ x="10"
+ y="25"
+ id="text69">database 'template0'</text>
+ </g>
+ <!-- database template 1 -->
+ <g
+ transform="translate(290 155)"
+ id="g77">
+ <use
+ xlink:href="#rectangles_special_0"
+ id="use73" />
+ <text
+ class="text_normal"
+ x="10"
+ y="25"
+ id="text75">database 'template1'</text>
+ </g>
+ <!-- database postgres -->
+ <g
+ transform="translate(540 155)"
+ id="g83">
+ <use
+ xlink:href="#rectangles_special_1"
+ id="use79" />
+ <text
+ class="text_normal"
+ x="10"
+ y="25"
+ id="text81">database 'postgres'</text>
+ </g>
+ <!-- database my_db -->
+ <g
+ transform="translate(40 350)"
+ id="g89">
+ <use
+ xlink:href="#rectangles_special_1"
+ id="use85" />
+ <text
+ class="text_normal"
+ x="10"
+ y="25"
+ id="text87">database 'my_db' (optional)</text>
+ </g>
+ <!-- global objects -->
+ <g
+ transform="translate(320 330)"
+ id="g103">
+ <rect
+ x="0"
+ y="0"
+ width="180"
+ height="45"
+ rx="10"
+ stroke="blue"
+ fill="none"
+ stroke-dasharray="10 4 4 4"
+ id="rect91" />
+ <text
+ class="text_normal"
+ x="15"
+ y="27"
+ id="text93">Global SQL objects</text>
+ <path
+ d="M 0,5 l-65,-35"
+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path95" />
+ <path
+ d="M 80,0 v-30"
+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path97" />
+ <path
+ d="M 180,40 h50"
+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path99" />
+ <path
+ d="M 0,40 l-45,20"
+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path101" />
+ </g>
+ <!-- Some comments -->
+ <g
+ transform="translate(335 405)"
+ id="g145">
+ <use
+ xlink:href="#note"
+ x="0"
+ y="0"
+ id="use105" />
+ <text
+ class="text_small"
+ x="10"
+ y="20"
+ id="text107">1)</text>
+ <text
+ class="text_small"
+ x="30"
+ y="20"
+ id="text109">By default, you work in the cluster 'data', database 'postgres',</text>
+ <text
+ class="text_small"
+ x="30"
+ y="35"
+ id="text111">schema 'public'.</text>
+ <text
+ class="text_small"
+ x="10"
+ y="55"
+ id="text113">2)</text>
+ <text
+ class="text_small"
+ x="30"
+ y="55"
+ id="text115">More system schemas: pg_catalog, information_schema,</text>
+ <text
+ class="text_small"
+ x="30"
+ y="70"
+ id="text117">pg_temp, pg_toast.</text>
+ <text
+ class="text_small"
+ x="10"
+ y="90"
+ id="text119">3)</text>
+ <text
+ class="text_small"
+ x="30"
+ y="90"
+ id="text121">Global SQL objects: Some SQL objects are automatically active</text>
+ <text
+ class="text_small"
+ x="30"
+ y="105"
+ id="text123">and known database- or even cluster-wide.</text>
+ <text
+ class="text_small"
+ x="10"
+ y="125"
+ id="text125">4)</text>
+ <text
+ class="text_small"
+ x="30"
+ y="125"
+ id="text127">The command 'initdb' creates a new cluster with the three</text>
+ <text
+ class="text_small"
+ x="30"
+ y="140"
+ id="text129">databases 'template0', 'template1', and 'postgres'. The command</text>
+ <text
+ class="text_small"
+ x="30"
+ y="155"
+ id="text131">'createdb' creates a new database.</text>
+ <text
+ class="text_small"
+ x="10"
+ y="175"
+ id="text133">5)</text>
+ <text
+ class="text_small"
+ x="30"
+ y="175"
+ id="text135">If multiple clusters are active on one server at the same time,</text>
+ <text
+ class="text_small"
+ x="30"
+ y="190"
+ id="text137">each one is managed by an individual instance. Each such instance</text>
+ <text
+ class="text_small"
+ x="30"
+ y="205"
+ id="text139">uses a different port.</text>
+ <text
+ class="text_small"
+ x="10"
+ y="225"
+ id="text141">6)</text>
+ <text
+ class="text_small"
+ x="30"
+ y="225"
+ id="text143">No client application is allowed to connect to 'template0'.</text>
+ </g>
+</svg>
diff --git a/doc/src/sgml/images/cluster-db-schema-raw.svg b/doc/src/sgml/images/cluster-db-schema-raw.svg
new file mode 100644
index 0000000000..a4919165e2
--- /dev/null
+++ b/doc/src/sgml/images/cluster-db-schema-raw.svg
@@ -0,0 +1,173 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg xmlns="http://www.w3.org/2000/svg"
+ xmlns:xlink="http://www.w3.org/1999/xlink"
+ version="1.1"
+ width="900px" height="685px"
+ viewBox="0 0 900 685" >
+
+ <title>Server (Hardware, Container, or VM)</title>
+
+ <!-- common text classes -->
+ <style type="text/css">
+ .text_small {font-style:normal;
+ font-weight:normal;
+ font-size:12px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ .text_normal {font-style:normal;
+ font-weight:normal;
+ font-size:16px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ .text_big {font-style:normal;
+ font-weight:normal;
+ font-size:24px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ </style>
+
+ <defs>
+ <!-- a rectangle with rounded corners and inner definitions for schemas -->
+ <symbol id="rectangles_special_0">
+
+ <!-- the database -->
+ <rect width="225" height="155" rx="10" stroke="blue" fill="none"/>
+
+ <!-- schemas -->
+ <rect x="15" y="40" width="195" height="50" rx="10" stroke="blue" fill="none" stroke-dasharray="4 2" />
+ <text class="text_normal" x="20" y="60">schema 'public'</text>
+ <text class="text_small" x="20" y="80">tables, views, ...</text>
+
+ <rect x="15" y="105" width="195" height="30" rx="10" stroke="blue" fill="none" stroke-dasharray="4 2" />
+ <text class="text_small" x="20" y="125">(more system schemas)</text>
+ </symbol>
+
+ <!-- same as before, but one more schema -->
+ <symbol id="rectangles_special_1">
+ <!-- the database -->
+ <rect width="245" height="225" rx="10" stroke="blue" fill="none"/>
+
+ <!-- schemas -->
+ <rect x="15" y="40" width="205" height="50" rx="10" stroke="blue" fill="none" stroke-dasharray="4 2" />
+ <text class="text_normal" x="20" y="60">schema 'public'</text>
+ <text class="text_small" x="20" y="80">tables, views, ...</text>
+
+ <rect x="15" y="105" width="205" height="50" rx="10" stroke="blue" fill="none" stroke-dasharray="4 2" />
+ <text class="text_normal" x="20" y="125">'my_schema' (optional)</text>
+ <text class="text_small" x="20" y="145">tables, views, ...</text>
+
+ <rect x="15" y="170" width="205" height="30" rx="10" stroke="blue" fill="none" stroke-dasharray="4 2" />
+ <text class="text_small" x="20" y="190">(more system schemas)</text>
+ </symbol>
+
+ <symbol id="note" stroke="black" fill="lightyellow">
+ <title>UML Note</title>
+ <path d="M 450,10 v 230 h -450 v -240 h 440 v 10 h 10 l -10,-10" />
+ </symbol>
+
+ <!-- marker start/end -->
+ <marker id="arrowhead_start"
+ markerWidth="10"
+ markerHeight="10"
+ refX="0"
+ refY="3"
+ orient="auto">
+ <path d="M 6,0 l -6,3 l 6,3" stroke="black" fill="none" />
+ </marker>
+ <marker id="arrowhead_end"
+ markerWidth="10"
+ markerHeight="10"
+ refX="6"
+ refY="3"
+ orient="auto">
+ <path d="M 0,0 l 6,3 l -6,3" stroke="black" fill="none" />
+ </marker>
+
+ </defs>
+
+
+ <!-- start of rendering area -->
+ <!-- enclosing rectangle -->
+ <rect x="1" y="1" rx="5" width="99%" height="99%" stroke="black" fill="none" />
+ <text class="text_big" x="270" y="40">Server (Hardware, Container, or VM)</text>
+
+ <!-- two clusters -->
+ <g transform="translate(20 110)">
+ <rect x="0" y="0" width="790" height="555" stroke="blue" stroke-width="2px" fill="none" />
+ <text class="text_normal" x="180" y="25">cluster 'data' (default, managed by one instance)</text>
+ </g>
+ <g transform="translate(45 110)">
+ <path d="M 5,0 v -30 h 790 v 555 h -30" stroke="blue" stroke-width="2px" fill="none" />
+ <text class="text_normal" x="190" y="-10">cluster 'cluster_2' (optional, managed by a different instance)</text>
+ </g>
+
+
+ <!-- database template 0 -->
+ <g transform="translate(40 155)">
+ <use xlink:href="#rectangles_special_0" />
+ <text class="text_normal" x="10" y="25">database 'template0'</text>
+ </g>
+
+ <!-- database template 1 -->
+ <g transform="translate(290 155)">
+ <use xlink:href="#rectangles_special_0" />
+ <text class="text_normal" x="10" y="25">database 'template1'</text>
+ </g>
+
+ <!-- database postgres -->
+ <g transform="translate(540 155)">
+ <use xlink:href="#rectangles_special_1" />
+ <text class="text_normal" x="10" y="25">database 'postgres'</text>
+ </g>
+
+ <!-- database my_db -->
+ <g transform="translate(40 350)">
+ <use xlink:href="#rectangles_special_1" />
+ <text class="text_normal" x="10" y="25">database 'my_db' (optional)</text>
+ </g>
+
+ <!-- global objects -->
+ <g transform="translate(320 330)">
+ <rect x="0" y="0" width="180" height="45" rx="10" stroke="blue" fill="none" stroke-dasharray="10 4 4 4" />
+ <text class="text_normal" x="15" y="27">Global SQL objects</text>
+ <path d="M 0,5 l-65,-35" stroke="black" fill="none" marker-end="url(#arrowhead_end)" />
+ <path d="M 80,0 v-30" stroke="black" fill="none" marker-end="url(#arrowhead_end)" />
+ <path d="M 180,40 h50" stroke="black" fill="none" marker-end="url(#arrowhead_end)" />
+ <path d="M 0,40 l-45,20" stroke="black" fill="none" marker-end="url(#arrowhead_end)" />
+ </g>
+
+ <!-- Some comments -->
+ <g transform="translate(335 405)">
+ <use xlink:href="#note" x="0" y="0" />
+
+ <text class="text_small" x="10" y="20">1)</text>
+ <text class="text_small" x="30" y="20">By default, you work in the cluster 'data', database 'postgres',</text>
+ <text class="text_small" x="30" y="35">schema 'public'.</text>
+
+ <text class="text_small" x="10" y="55">2)</text>
+ <text class="text_small" x="30" y="55">More system schemas: pg_catalog, information_schema,</text>
+ <text class="text_small" x="30" y="70">pg_temp, pg_toast.</text>
+
+ <text class="text_small" x="10" y="90">3)</text>
+ <text class="text_small" x="30" y="90">Global SQL objects: Some SQL objects are automatically active</text>
+ <text class="text_small" x="30" y="105">and known database- or even cluster-wide.</text>
+
+ <text class="text_small" x="10" y="125">4)</text>
+ <text class="text_small" x="30" y="125">The command 'initdb' creates a new cluster with the three</text>
+ <text class="text_small" x="30" y="140">databases 'template0', 'template1', and 'postgres'. The command</text>
+ <text class="text_small" x="30" y="155">'createdb' creates a new database.</text>
+
+ <text class="text_small" x="10" y="175">5)</text>
+ <text class="text_small" x="30" y="175">If multiple clusters are active on one server at the same time,</text>
+ <text class="text_small" x="30" y="190">each one is managed by an individual instance. Each such instance</text>
+ <text class="text_small" x="30" y="205">uses a different port.</text>
+
+ <text class="text_small" x="10" y="225">6)</text>
+ <text class="text_small" x="30" y="225">No client application is allowed to connect to 'template0'.</text>
+
+ </g>
+
+</svg>
diff --git a/doc/src/sgml/images/directories-ink-svgo.svg b/doc/src/sgml/images/directories-ink-svgo.svg
new file mode 100644
index 0000000000..8dd88784ca
--- /dev/null
+++ b/doc/src/sgml/images/directories-ink-svgo.svg
@@ -0,0 +1,164 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="900" height="640" viewBox="0 0 900 640">
+ <title>
+ Directory structure of a cluster
+ </title>
+ <style>
+ .text_normal{font-style:normal;font-weight:400;font-size:16px;font-family:"Open Sans",sans-serif;fill:#000}
+ </style>
+ <defs>
+ <symbol id="directory" stroke="blue" stroke-width=".3" fill="aqua">
+ <title>
+ Directory
+ </title>
+ <path d="M0 10h110v20H0z"/>
+ <path d="M0 10V8l3-3h35l3 3v2"/>
+ </symbol>
+ <symbol id="file" stroke="black" fill="none">
+ <title>
+ File
+ </title>
+ <path stroke="blue" d="M0 0h40v50H0z"/>
+ <path d="M5 10h20" stroke-dasharray="4 2"/>
+ <path d="M5 17h15" stroke-dasharray="6 2"/>
+ <path d="M5 24h25" stroke-dasharray="4 2"/>
+ <path d="M5 31h20" stroke-dasharray="5 2"/>
+ </symbol>
+ </defs>
+ <rect x="1" y="1" rx="5" width="99%" height="99%" stroke="black" fill="none"/>
+ <text x="50" y="50" font-weight="400" font-size="24" font-family=""Open Sans",sans-serif">
+ Directory structure for storing durable and fluctuating information
+ </text>
+ <g transform="translate(20 100)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ ... /pg/
+ </text>
+ <text x="300" y="26" class="text_normal">
+ An arbitrary directory
+ </text>
+ </g>
+ <g transform="translate(70 130)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ data/
+ </text>
+ <text x="250" y="26" class="text_normal">
+ Root of cluster 'data' (see: PGDATA)
+ </text>
+ </g>
+ <g transform="translate(120 160)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ base/
+ </text>
+ <text x="200" y="26" class="text_normal">
+ Subdirectory containing per-database subdirectories
+ </text>
+ </g>
+ <g transform="translate(170 190)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ 1/
+ </text>
+ <text x="150" y="26" class="text_normal">
+ Subdirectory for data of first database 'template0'
+ </text>
+ </g>
+ <g transform="translate(170 220)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ 12992/
+ </text>
+ <text x="150" y="26" class="text_normal">
+ Subdirectory for data of second database 'template1'
+ </text>
+ </g>
+ <g transform="translate(170 250)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ 12999/
+ </text>
+ <text x="150" y="26" class="text_normal">
+ Subdirectory for data of third database 'postgres'
+ </text>
+ </g>
+ <g transform="translate(170 280)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ nnnnn/
+ </text>
+ <text x="150" y="26" class="text_normal">
+ Optional: more subdirectories for databases, e.g. 'my_db'
+ </text>
+ </g>
+ <g transform="translate(120 310)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ global/
+ </text>
+ <text x="200" y="26" class="text_normal">
+ Subdirectory with information about Global SQL Objects
+ </text>
+ </g>
+ <g transform="translate(120 340)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ pg_wal/
+ </text>
+ <text x="200" y="26" class="text_normal">
+ Subdirectory for Write Ahead Log files ('pg_xlog' before version 10)
+ </text>
+ </g>
+ <g transform="translate(120 370)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ pg_xact/
+ </text>
+ <text x="200" y="26" class="text_normal">
+ Subdirectory for transaction commit status ('pg_clog' before version 10)
+ </text>
+ </g>
+ <g transform="translate(120 400)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ pg_tblspc/
+ </text>
+ <text x="200" y="26" class="text_normal">
+ Subdirectory containing symbolic links to tablespaces
+ </text>
+ </g>
+ <g transform="translate(120 430)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ pg_... /
+ </text>
+ <text x="200" y="26" class="text_normal">
+ Some more subdirectories
+ </text>
+ </g>
+ <g transform="translate(120 465)">
+ <use xlink:href="#file"/>
+ <use xlink:href="#file" x="50"/>
+ <text x="200" y="26" class="text_normal">
+ 'postmaster.pid' and other files with cluster-wide relevance
+ </text>
+ </g>
+ <g transform="translate(20 540)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ ... /xyz/
+ </text>
+ <text x="300" y="26" class="text_normal">
+ Same or another arbitrary directory
+ </text>
+ </g>
+ <g transform="translate(70 570)">
+ <use xlink:href="#directory"/>
+ <text x="10" y="26" class="text_normal">
+ cluster_2/
+ </text>
+ <text x="250" y="26" class="text_normal">
+ Root of another cluster 'cluster_2'
+ </text>
+ </g>
+</svg>
diff --git a/doc/src/sgml/images/directories-ink.svg b/doc/src/sgml/images/directories-ink.svg
new file mode 100644
index 0000000000..2b89d02096
--- /dev/null
+++ b/doc/src/sgml/images/directories-ink.svg
@@ -0,0 +1,397 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+ xmlns:dc="http://purl.org/dc/elements/1.1/"
+ xmlns:cc="http://creativecommons.org/ns#"
+ xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+ xmlns:svg="http://www.w3.org/2000/svg"
+ xmlns="http://www.w3.org/2000/svg"
+ xmlns:xlink="http://www.w3.org/1999/xlink"
+ xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+ xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+ version="1.1"
+ width="900px"
+ height="640px"
+ viewBox="0 0 900 640"
+ id="svg152"
+ sodipodi:docname="directories-ink.svg"
+ inkscape:version="0.92.3 (2405546, 2018-03-11)">
+ <metadata
+ id="metadata156">
+ <rdf:RDF>
+ <cc:Work
+ rdf:about="">
+ <dc:format>image/svg+xml</dc:format>
+ <dc:type
+ rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+ <dc:title>Directory structure of a cluster</dc:title>
+ </cc:Work>
+ </rdf:RDF>
+ </metadata>
+ <sodipodi:namedview
+ pagecolor="#ffffff"
+ bordercolor="#666666"
+ borderopacity="1"
+ objecttolerance="10"
+ gridtolerance="10"
+ guidetolerance="10"
+ inkscape:pageopacity="0"
+ inkscape:pageshadow="2"
+ inkscape:window-width="640"
+ inkscape:window-height="480"
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+ showgrid="false"
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+ inkscape:cx="450"
+ inkscape:cy="320"
+ inkscape:window-x="61"
+ inkscape:window-y="27"
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+ inkscape:current-layer="svg152" />
+ <title
+ id="title2">Directory structure of a cluster</title>
+ <style
+ type="text/css"
+ id="style4">
+ .text_normal {font-style:normal;
+ font-weight:normal;
+ font-size:16px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ .text_big {font-style:normal;
+ font-weight:normal;
+ font-size:24px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ </style>
+ <defs
+ id="defs26">
+ <!-- Directory -->
+ <symbol
+ id="directory"
+ stroke="blue"
+ stroke-width="0.3px"
+ fill="aqua">
+ <title
+ id="title6">Directory</title>
+ <rect
+ x="0"
+ y="10"
+ width="110"
+ height="20"
+ id="rect8" />
+ <path
+ d="M 0,10 l 0,-2 3,-3 35,0, 3,3 0,2"
+ id="path10" />
+ </symbol>
+ <!-- File -->
+ <symbol
+ id="file"
+ stroke="black"
+ fill="none">
+ <title
+ id="title13">File</title>
+ <rect
+ x="0"
+ y="0"
+ width="40"
+ height="50"
+ stroke="blue"
+ id="rect15" />
+ <path
+ d="M 5,10 h 20"
+ stroke-dasharray="4 2"
+ id="path17" />
+ <path
+ d="M 5,17 h 15"
+ stroke-dasharray="6 2"
+ id="path19" />
+ <path
+ d="M 5,24 h 25"
+ stroke-dasharray="4 2"
+ id="path21" />
+ <path
+ d="M 5,31 h 20"
+ stroke-dasharray="5 2"
+ id="path23" />
+ </symbol>
+ </defs>
+ <!-- start of rendering area -->
+ <!-- enclosing rectangle -->
+ <rect
+ x="1"
+ y="1"
+ rx="5"
+ width="99%"
+ height="99%"
+ stroke="black"
+ fill="none"
+ id="rect28" />
+ <!-- caption -->
+ <text
+ x="50"
+ y="50"
+ class="text_big"
+ id="text30">Directory structure for storing durable and fluctuating information</text>
+ <!-- the directories -->
+ <g
+ transform="translate(20, 100)"
+ id="g38">
+ <use
+ xlink:href="#directory"
+ id="use32" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text34">... /pg/</text>
+ <text
+ x="300"
+ y="26"
+ class="text_normal"
+ id="text36">An arbitrary directory</text>
+ </g>
+ <g
+ transform="translate(70, 130)"
+ id="g46">
+ <use
+ xlink:href="#directory"
+ id="use40" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text42">data/</text>
+ <text
+ x="250"
+ y="26"
+ class="text_normal"
+ id="text44">Root of cluster 'data' (see: PGDATA)</text>
+ </g>
+ <g
+ transform="translate(120, 160)"
+ id="g54">
+ <use
+ xlink:href="#directory"
+ id="use48" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text50">base/</text>
+ <text
+ x="200"
+ y="26"
+ class="text_normal"
+ id="text52">Subdirectory containing per-database subdirectories</text>
+ </g>
+ <!-- -->
+ <g
+ transform="translate(170, 190)"
+ id="g62">
+ <use
+ xlink:href="#directory"
+ id="use56" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text58">1/</text>
+ <text
+ x="150"
+ y="26"
+ class="text_normal"
+ id="text60">Subdirectory for data of first database 'template0'</text>
+ </g>
+ <g
+ transform="translate(170, 220)"
+ id="g70">
+ <use
+ xlink:href="#directory"
+ id="use64" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text66">12992/</text>
+ <text
+ x="150"
+ y="26"
+ class="text_normal"
+ id="text68">Subdirectory for data of second database 'template1'</text>
+ </g>
+ <g
+ transform="translate(170, 250)"
+ id="g78">
+ <use
+ xlink:href="#directory"
+ id="use72" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text74">12999/</text>
+ <text
+ x="150"
+ y="26"
+ class="text_normal"
+ id="text76">Subdirectory for data of third database 'postgres'</text>
+ </g>
+ <g
+ transform="translate(170, 280)"
+ id="g86">
+ <use
+ xlink:href="#directory"
+ id="use80" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text82">nnnnn/</text>
+ <text
+ x="150"
+ y="26"
+ class="text_normal"
+ id="text84">Optional: more subdirectories for databases, e.g. 'my_db'</text>
+ </g>
+ <g
+ transform="translate(120, 310)"
+ id="g94">
+ <use
+ xlink:href="#directory"
+ id="use88" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text90">global/</text>
+ <text
+ x="200"
+ y="26"
+ class="text_normal"
+ id="text92">Subdirectory with information about Global SQL Objects</text>
+ </g>
+ <g
+ transform="translate(120, 340)"
+ id="g102">
+ <use
+ xlink:href="#directory"
+ id="use96" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text98">pg_wal/</text>
+ <text
+ x="200"
+ y="26"
+ class="text_normal"
+ id="text100">Subdirectory for Write Ahead Log files ('pg_xlog' before version 10)</text>
+ </g>
+ <g
+ transform="translate(120, 370)"
+ id="g110">
+ <use
+ xlink:href="#directory"
+ id="use104" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text106">pg_xact/</text>
+ <text
+ x="200"
+ y="26"
+ class="text_normal"
+ id="text108">Subdirectory for transaction commit status ('pg_clog' before version 10)</text>
+ </g>
+ <g
+ transform="translate(120, 400)"
+ id="g118">
+ <use
+ xlink:href="#directory"
+ id="use112" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text114">pg_tblspc/</text>
+ <text
+ x="200"
+ y="26"
+ class="text_normal"
+ id="text116">Subdirectory containing symbolic links to tablespaces</text>
+ </g>
+ <g
+ transform="translate(120, 430)"
+ id="g126">
+ <use
+ xlink:href="#directory"
+ id="use120" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text122">pg_... /</text>
+ <text
+ x="200"
+ y="26"
+ class="text_normal"
+ id="text124">Some more subdirectories</text>
+ </g>
+ <g
+ transform="translate(120, 465)"
+ id="g134">
+ <use
+ xlink:href="#file"
+ x="0"
+ y="0"
+ id="use128" />
+ <use
+ xlink:href="#file"
+ x="50"
+ y="0"
+ id="use130" />
+ <text
+ x="200"
+ y="26"
+ class="text_normal"
+ id="text132">'postmaster.pid' and other files with cluster-wide relevance</text>
+ </g>
+ <!-- next cluster -->
+ <g
+ transform="translate(20, 540)"
+ id="g142">
+ <use
+ xlink:href="#directory"
+ id="use136" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text138">... /xyz/</text>
+ <text
+ x="300"
+ y="26"
+ class="text_normal"
+ id="text140">Same or another arbitrary directory</text>
+ </g>
+ <g
+ transform="translate(70, 570)"
+ id="g150">
+ <use
+ xlink:href="#directory"
+ id="use144" />
+ <text
+ x="10"
+ y="26"
+ class="text_normal"
+ id="text146">cluster_2/</text>
+ <text
+ x="250"
+ y="26"
+ class="text_normal"
+ id="text148">Root of another cluster 'cluster_2'</text>
+ </g>
+</svg>
diff --git a/doc/src/sgml/images/directories-raw.svg b/doc/src/sgml/images/directories-raw.svg
new file mode 100644
index 0000000000..92e766dd89
--- /dev/null
+++ b/doc/src/sgml/images/directories-raw.svg
@@ -0,0 +1,144 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg xmlns="http://www.w3.org/2000/svg"
+ xmlns:xlink="http://www.w3.org/1999/xlink"
+ version="1.1"
+ width="900px" height="640px"
+ viewBox="0 0 900 640">
+
+ <title>Directory structure of a cluster</title>
+
+ <style type="text/css">
+ .text_normal {font-style:normal;
+ font-weight:normal;
+ font-size:16px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ .text_big {font-style:normal;
+ font-weight:normal;
+ font-size:24px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ </style>
+
+ <defs>
+
+ <!-- Directory -->
+ <symbol id="directory" stroke="blue" stroke-width="0.3px" fill="aqua">
+ <title>Directory</title>
+ <rect x="0" y="10" width="110" height="20" />
+ <path d="M 0,10 l 0,-2 3,-3 35,0, 3,3 0,2" />
+ </symbol>
+
+ <!-- File -->
+ <symbol id="file" stroke="black" fill="none" >
+ <title>File</title>
+ <rect x="0" y="0" width="40" height="50" stroke="blue" />
+ <path d="M 5,10 h 20" stroke-dasharray="4 2" />
+ <path d="M 5,17 h 15" stroke-dasharray="6 2" />
+ <path d="M 5,24 h 25" stroke-dasharray="4 2" />
+ <path d="M 5,31 h 20" stroke-dasharray="5 2" />
+ </symbol>
+
+ </defs>
+
+
+ <!-- start of rendering area -->
+ <!-- enclosing rectangle -->
+ <rect x="1" y="1" rx="5" width="99%" height="99%" stroke="black" fill="none" />
+
+ <!-- caption -->
+ <text x="50" y="50" class="text_big">Directory structure for storing durable and fluctuating information</text>
+
+ <!-- the directories -->
+ <g transform="translate(20, 100)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">... /pg/</text>
+ <text x="300" y="26" class="text_normal">An arbitrary directory</text>
+ </g>
+
+ <g transform="translate(70, 130)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">data/</text>
+ <text x="250" y="26" class="text_normal">Root of cluster 'data' (see: PGDATA)</text>
+ </g>
+
+ <g transform="translate(120, 160)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">base/</text>
+ <text x="200" y="26" class="text_normal">Subdirectory containing per-database subdirectories</text>
+ </g>
+
+ <!-- -->
+ <g transform="translate(170, 190)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">1/</text>
+ <text x="150" y="26" class="text_normal">Subdirectory for data of first database 'template0'</text>
+ </g>
+ <g transform="translate(170, 220)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">12992/</text>
+ <text x="150" y="26" class="text_normal">Subdirectory for data of second database 'template1'</text>
+ </g>
+ <g transform="translate(170, 250)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">12999/</text>
+ <text x="150" y="26" class="text_normal">Subdirectory for data of third database 'postgres'</text>
+ </g>
+ <g transform="translate(170, 280)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">nnnnn/</text>
+ <text x="150" y="26" class="text_normal">Optional: more subdirectories for databases, e.g. 'my_db'</text>
+ </g>
+
+ <g transform="translate(120, 310)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">global/</text>
+ <text x="200" y="26" class="text_normal">Subdirectory with information about Global SQL Objects</text>
+ </g>
+
+ <g transform="translate(120, 340)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">pg_wal/</text>
+ <text x="200" y="26" class="text_normal">Subdirectory for Write Ahead Log files ('pg_xlog' before version 10)</text>
+ </g>
+
+ <g transform="translate(120, 370)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">pg_xact/</text>
+ <text x="200" y="26" class="text_normal">Subdirectory for transaction commit status ('pg_clog' before version 10)</text>
+ </g>
+
+ <g transform="translate(120, 400)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">pg_tblspc/</text>
+ <text x="200" y="26" class="text_normal">Subdirectory containing symbolic links to tablespaces</text>
+ </g>
+
+ <g transform="translate(120, 430)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">pg_... /</text>
+ <text x="200" y="26" class="text_normal">Some more subdirectories</text>
+ </g>
+
+ <g transform="translate(120, 465)">
+ <use xlink:href="#file" x="0" y="0" />
+ <use xlink:href="#file" x="50" y="0" />
+ <text x="200" y="26" class="text_normal">'postmaster.pid' and other files with cluster-wide relevance</text>
+ </g>
+
+ <!-- next cluster -->
+ <g transform="translate(20, 540)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">... /xyz/</text>
+ <text x="300" y="26" class="text_normal">Same or another arbitrary directory</text>
+ </g>
+
+ <g transform="translate(70, 570)">
+ <use xlink:href="#directory" />
+ <text x="10" y="26" class="text_normal">cluster_2/</text>
+ <text x="250" y="26" class="text_normal">Root of another cluster 'cluster_2'</text>
+ </g>
+
+</svg>
diff --git a/doc/src/sgml/images/internal-objects-hierarchy-ink-svgo.svg b/doc/src/sgml/images/internal-objects-hierarchy-ink-svgo.svg
new file mode 100644
index 0000000000..71b888b8b0
--- /dev/null
+++ b/doc/src/sgml/images/internal-objects-hierarchy-ink-svgo.svg
@@ -0,0 +1,85 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="900" height="485" viewBox="0 0 900 485">
+ <title>
+ Hierarchy of Internal Objects
+ </title>
+ <style>
+ .text_normal{font-style:normal;font-weight:400;font-size:16px;font-family:"Open Sans",sans-serif;fill:#000}
+ </style>
+ <rect x="1" y="1" rx="5" width="99%" height="99%" stroke="black" fill="none"/>
+ <text x="270" y="40" font-weight="400" font-size="24" font-family=""Open Sans",sans-serif">
+ Hierarchy of Internal Objects
+ </text>
+ <g transform="translate(450 270)" fill="none">
+ <ellipse rx="380" ry="200" stroke="blue"/>
+ <text class="text_normal" x="-140" y="-170">
+ Server
+ </text>
+ <ellipse rx="320" ry="170" stroke="blue"/>
+ <text class="text_normal" x="-140" y="-130">
+ Cluster
+ </text>
+ <g transform="translate(40 -125)">
+ <ellipse rx="80" ry="20" stroke="blue"/>
+ <text class="text_normal" x="-60" y="5">
+ Database Names
+ </text>
+ </g>
+ <g transform="translate(180 -70)">
+ <ellipse rx="60" ry="20" stroke="blue"/>
+ <text class="text_normal" x="-40" y="5">
+ Tablespace
+ </text>
+ </g>
+ <g transform="translate(230 -5)">
+ <ellipse rx="80" ry="20" stroke="blue"/>
+ <text class="text_normal" x="-70" y="5">
+ Replication Origins
+ </text>
+ </g>
+ <g transform="translate(200 70)">
+ <ellipse rx="78" ry="27" stroke="blue"/>
+ <text class="text_normal" x="-60" y="-3">
+ Subscription for
+ </text>
+ <text class="text_normal" x="-68" y="10">
+ Logical Replication
+ </text>
+ </g>
+ <g transform="translate(100 120)">
+ <ellipse rx="40" ry="20" stroke="blue"/>
+ <text class="text_normal" x="-15" y="5">
+ Role
+ </text>
+ </g>
+ <g transform="translate(-80 10)">
+ <ellipse rx="220" ry="110" stroke="blue" stroke-width="2"/>
+ <text class="text_normal" x="-60" y="-80">
+ Database
+ </text>
+ <g transform="translate(-150 -30)">
+ <ellipse rx="50" ry="20" stroke="blue"/>
+ <text class="text_normal" x="-35" y="5">
+ Extension
+ </text>
+ </g>
+ <g transform="translate(-155 35)">
+ <ellipse rx="40" ry="20" stroke="blue"/>
+ <text class="text_normal" x="-35" y="5">
+ Collation
+ </text>
+ </g>
+ <g transform="translate(30 20)">
+ <ellipse rx="140" ry="70" stroke="blue"/>
+ <text class="text_normal" x="-80" y="-35">
+ Schema
+ </text>
+ <g transform="translate(20 10)">
+ <ellipse rx="90" ry="30" stroke="blue"/>
+ <text class="text_normal" x="-50" y="5">
+ Table, View, ...
+ </text>
+ </g>
+ </g>
+ </g>
+ </g>
+</svg>
diff --git a/doc/src/sgml/images/internal-objects-hierarchy-ink.svg b/doc/src/sgml/images/internal-objects-hierarchy-ink.svg
new file mode 100644
index 0000000000..052726e7ae
--- /dev/null
+++ b/doc/src/sgml/images/internal-objects-hierarchy-ink.svg
@@ -0,0 +1,268 @@
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+ sodipodi:docname="internal-objects-hierarchy-ink.svg"
+ inkscape:version="0.92.3 (2405546, 2018-03-11)">
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+ <cc:Work
+ rdf:about="">
+ <dc:format>image/svg+xml</dc:format>
+ <dc:type
+ rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+ <dc:title>Hierarchy of Internal Objects</dc:title>
+ </cc:Work>
+ </rdf:RDF>
+ </metadata>
+ <defs
+ id="defs92" />
+ <sodipodi:namedview
+ pagecolor="#ffffff"
+ bordercolor="#666666"
+ borderopacity="1"
+ objecttolerance="10"
+ gridtolerance="10"
+ guidetolerance="10"
+ inkscape:pageopacity="0"
+ inkscape:pageshadow="2"
+ inkscape:window-width="640"
+ inkscape:window-height="480"
+ id="namedview90"
+ showgrid="false"
+ inkscape:zoom="0.41555556"
+ inkscape:cx="450"
+ inkscape:cy="242.5"
+ inkscape:window-x="61"
+ inkscape:window-y="27"
+ inkscape:window-maximized="0"
+ inkscape:current-layer="svg88" />
+ <title
+ id="title2">Hierarchy of Internal Objects</title>
+ <!-- common text classes -->
+ <style
+ type="text/css"
+ id="style4">
+ .text_normal {font-style:normal;
+ font-weight:normal;
+ font-size:16px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ .text_big {font-style:normal;
+ font-weight:normal;
+ font-size:24px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ </style>
+ <!-- start of rendering area -->
+ <!-- enclosing rectangle -->
+ <rect
+ x="1"
+ y="1"
+ rx="5"
+ width="99%"
+ height="99%"
+ stroke="black"
+ fill="none"
+ id="rect6" />
+ <text
+ class="text_big"
+ x="270"
+ y="40"
+ id="text8">Hierarchy of Internal Objects</text>
+ <g
+ fill="none"
+ id="g86">
+ <!-- set default value -->
+ <g
+ transform="translate(450 270)"
+ id="g84">
+ <ellipse
+ rx="380"
+ ry="200"
+ stroke="blue"
+ id="ellipse10" />
+ <text
+ class="text_normal"
+ x="-140"
+ y="-170"
+ id="text12">Server</text>
+ <g
+ id="g50">
+ <ellipse
+ rx="320"
+ ry="170"
+ stroke="blue"
+ id="ellipse14" />
+ <text
+ class="text_normal"
+ x="-140"
+ y="-130"
+ id="text16">Cluster</text>
+ <g
+ transform="translate(40 -125)"
+ id="g22">
+ <ellipse
+ rx="80"
+ ry="20"
+ stroke="blue"
+ id="ellipse18" />
+ <text
+ class="text_normal"
+ x="-60"
+ y="5"
+ id="text20">Database Names</text>
+ </g>
+ <g
+ transform="translate(180 -70)"
+ id="g28">
+ <ellipse
+ rx="60"
+ ry="20"
+ stroke="blue"
+ id="ellipse24" />
+ <text
+ class="text_normal"
+ x="-40"
+ y="5"
+ id="text26">Tablespace</text>
+ </g>
+ <g
+ transform="translate(230 -5)"
+ id="g34">
+ <ellipse
+ rx="80"
+ ry="20"
+ stroke="blue"
+ id="ellipse30" />
+ <text
+ class="text_normal"
+ x="-70"
+ y="5"
+ id="text32">Replication Origins</text>
+ </g>
+ <g
+ transform="translate(200 70)"
+ id="g42">
+ <ellipse
+ rx="78"
+ ry="27"
+ stroke="blue"
+ id="ellipse36" />
+ <text
+ class="text_normal"
+ x="-60"
+ y="-3"
+ id="text38">Subscription for</text>
+ <text
+ class="text_normal"
+ x="-68"
+ y="10"
+ id="text40">Logical Replication</text>
+ </g>
+ <g
+ transform="translate(100 120)"
+ id="g48">
+ <ellipse
+ rx="40"
+ ry="20"
+ stroke="blue"
+ id="ellipse44" />
+ <text
+ class="text_normal"
+ x="-15"
+ y="5"
+ id="text46">Role</text>
+ </g>
+ </g>
+ <g
+ transform="translate(-80 10)"
+ id="g82">
+ <ellipse
+ rx="220"
+ ry="110"
+ stroke="blue"
+ stroke-width="2px"
+ id="ellipse52" />
+ <text
+ class="text_normal"
+ x="-60"
+ y="-80"
+ id="text54">Database</text>
+ <g
+ transform="translate(-120 -50)"
+ id="g80">
+ <g
+ transform="translate(-30 20)"
+ id="g60">
+ <ellipse
+ rx="50"
+ ry="20"
+ stroke="blue"
+ id="ellipse56" />
+ <text
+ class="text_normal"
+ x="-35"
+ y="5"
+ id="text58">Extension</text>
+ </g>
+ <g
+ transform="translate(-35 85)"
+ id="g66">
+ <ellipse
+ rx="40"
+ ry="20"
+ stroke="blue"
+ id="ellipse62" />
+ <text
+ class="text_normal"
+ x="-35"
+ y="5"
+ id="text64">Collation</text>
+ </g>
+ <g
+ transform="translate(150 70)"
+ id="g78">
+ <ellipse
+ rx="140"
+ ry="70"
+ stroke="blue"
+ id="ellipse68" />
+ <text
+ class="text_normal"
+ x="-80"
+ y="-35"
+ id="text70">Schema</text>
+ <g
+ transform="translate(20 10)"
+ id="g76">
+ <ellipse
+ rx="90"
+ ry="30"
+ stroke="blue"
+ id="ellipse72" />
+ <text
+ class="text_normal"
+ x="-50"
+ y="5"
+ id="text74">Table, View, ...</text>
+ </g>
+ </g>
+ </g>
+ </g>
+ </g>
+ </g>
+</svg>
diff --git a/doc/src/sgml/images/internal-objects-hierarchy-raw.svg b/doc/src/sgml/images/internal-objects-hierarchy-raw.svg
new file mode 100644
index 0000000000..531a24d3be
--- /dev/null
+++ b/doc/src/sgml/images/internal-objects-hierarchy-raw.svg
@@ -0,0 +1,99 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg xmlns="http://www.w3.org/2000/svg"
+ xmlns:xlink="http://www.w3.org/1999/xlink"
+ version="1.1"
+ width="900px" height="485px"
+ viewBox="0 0 900 485" >
+
+ <title>Hierarchy of Internal Objects</title>
+
+ <!-- common text classes -->
+ <style type="text/css">
+ .text_normal {font-style:normal;
+ font-weight:normal;
+ font-size:16px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ .text_big {font-style:normal;
+ font-weight:normal;
+ font-size:24px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ </style>
+
+ <!-- start of rendering area -->
+ <!-- enclosing rectangle -->
+ <rect x="1" y="1" rx="5" width="99%" height="99%" stroke="black" fill="none" />
+ <text class="text_big" x="270" y="40">Hierarchy of Internal Objects</text>
+
+
+ <g fill="none"> <!-- set default value -->
+
+ <g transform="translate(450 270)">
+ <ellipse rx="380" ry="200" stroke="blue" />
+ <text class="text_normal" x="-140" y="-170">Server</text>
+
+ <g>
+ <ellipse rx="320" ry="170" stroke="blue" />
+ <text class="text_normal" x="-140" y="-130">Cluster</text>
+
+ <g transform="translate(40 -125)">
+ <ellipse rx="80" ry="20" stroke="blue" />
+ <text class="text_normal" x="-60" y="5">Database Names</text>
+ </g>
+
+ <g transform="translate(180 -70)">
+ <ellipse rx="60" ry="20" stroke="blue" />
+ <text class="text_normal" x="-40" y="5">Tablespace</text>
+ </g>
+
+ <g transform="translate(230 -5)">
+ <ellipse rx="80" ry="20" stroke="blue" />
+ <text class="text_normal" x="-70" y="5">Replication Origins</text>
+ </g>
+
+ <g transform="translate(200 70)">
+ <ellipse rx="78" ry="27" stroke="blue" />
+ <text class="text_normal" x="-60" y="-3">Subscription for</text>
+ <text class="text_normal" x="-68" y="10">Logical Replication</text>
+ </g>
+
+ <g transform="translate(100 120)">
+ <ellipse rx="40" ry="20" stroke="blue" />
+ <text class="text_normal" x="-15" y="5">Role</text>
+ </g>
+
+ </g>
+
+ <g transform="translate(-80 10)">
+ <ellipse rx="220" ry="110" stroke="blue" stroke-width="2px" />
+ <text class="text_normal" x="-60" y="-80">Database</text>
+
+ <g transform="translate(-120 -50)">
+ <g transform="translate(-30 20)">
+ <ellipse rx="50" ry="20" stroke="blue" />
+ <text class="text_normal" x="-35" y="5">Extension</text>
+ </g>
+
+ <g transform="translate(-35 85)">
+ <ellipse rx="40" ry="20" stroke="blue" />
+ <text class="text_normal" x="-35" y="5">Collation</text>
+ </g>
+
+ <g transform="translate(150 70)">
+ <ellipse rx="140" ry="70" stroke="blue" />
+ <text class="text_normal" x="-80" y="-35">Schema</text>
+
+ <g transform="translate(20 10)">
+ <ellipse rx="90" ry="30" stroke="blue" />
+ <text class="text_normal" x="-50" y="5">Table, View, ...</text>
+ </g>
+ </g>
+ </g>
+ </g>
+ </g>
+ </g>
+
+</svg>
diff --git a/doc/src/sgml/images/ram-proc-file-ink-svgo.svg b/doc/src/sgml/images/ram-proc-file-ink-svgo.svg
new file mode 100644
index 0000000000..ed026fc04a
--- /dev/null
+++ b/doc/src/sgml/images/ram-proc-file-ink-svgo.svg
@@ -0,0 +1,288 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" width="900" height="600" viewBox="0 0 900 600">
+ <title>
+ PG Overall Server Architecture
+ </title>
+ <style>
+ .text_big{font-style:normal}.text_big,.text_comment,.text_normal,.text_small{font-weight:400;font-family:"Open Sans",sans-serif;fill:#000}.text_normal,.text_small{font-style:normal}.text_small{font-size:12px}.text_normal{font-size:16px}.text_big{font-size:24px}.text_comment{font-style:italic;font-size:16px}
+ </style>
+ <defs>
+ <symbol id="note_200x20" stroke="black" fill="lightyellow">
+ <title>
+ UML Note (200 x 20 px)
+ </title>
+ <path d="M200 10v10H0V0h190v10h10L190 0"/>
+ </symbol>
+ <symbol id="note_250x20" stroke="black" fill="lightyellow">
+ <title>
+ UML Note (250 x 20 px)
+ </title>
+ <path d="M250 10v10H0V0h240v10h10L240 0"/>
+ </symbol>
+ <symbol id="note_100x35" stroke="black" fill="lightyellow">
+ <title>
+ UML Note (100 x 35 px)
+ </title>
+ <path d="M100 10v25H0V0h90v10h10L90 0"/>
+ </symbol>
+ <symbol id="note_170x50" stroke="black" fill="lightyellow">
+ <title>
+ UML Note (170 x 50 px)
+ </title>
+ <path d="M170 10v40H0V0h160v10h10L160 0"/>
+ </symbol>
+ <symbol id="state_300x120">
+ <title>
+ UML State, big
+ </title>
+ <rect width="300" height="120" rx="10" stroke="blue" fill="none"/>
+ </symbol>
+ <symbol id="state_350x120">
+ <title>
+ UML State, big
+ </title>
+ <rect width="350" height="120" rx="10" stroke="blue" fill="none"/>
+ </symbol>
+ <symbol id="disc" stroke="blue" fill="none">
+ <title>
+ Disc
+ </title>
+ <ellipse cx="51" cy="13" rx="50" ry="12"/>
+ <path d="M1 13v60"/>
+ <path d="M101 13v60"/>
+ <path d="M1 73a50 12 0 00100 0"/>
+ </symbol>
+ <symbol id="laptop" stroke="black" fill="none">
+ <title>
+ Laptop
+ </title>
+ <path d="M20 40V0h54v40l15 15H5l15-15h54"/>
+ <path d="M23 3h48v34H23z"/>
+ <path d="M30 10h20"/>
+ <path d="M30 15h25"/>
+ <path d="M30 20h10"/>
+ <path d="M30 30h20"/>
+ <path d="M25 50h45l2 2H22z"/>
+ </symbol>
+ <marker id="arrowhead_start" markerWidth="10" markerHeight="10" refX="0" refY="3" orient="auto">
+ <path d="M6 0L0 3l6 3" stroke="black" fill="none"/>
+ </marker>
+ <marker id="arrowhead_end" markerWidth="10" markerHeight="10" refX="6" refY="3" orient="auto">
+ <path d="M0 0l6 3-6 3" stroke="black" fill="none"/>
+ </marker>
+ </defs>
+ <rect x="1" y="1" rx="5" width="99%" height="99%" stroke="black" fill="none"/>
+ <text x="15" y="40" class="text_big">
+ Client
+ </text>
+ <text x="140" y="40" class="text_big">
+ Server
+ </text>
+ <use xlink:href="#laptop" x="5" y="210"/>
+ <g transform="translate(130 70)">
+ <use xlink:href="#state_350x120"/>
+ <text x="10" y="20" class="text_normal">
+ maintenance_work_mem (per connection)
+ </text>
+ <text x="10" y="40" class="text_normal">
+ work_mem (per query operation)
+ </text>
+ <text x="10" y="60" class="text_normal">
+ autovacuum_work_mem (per worker
+ </text>
+ <text x="230" y="75" class="text_normal">
+ process)
+ </text>
+ <text x="10" y="95" class="text_normal">
+ temp_buffer (per connection)
+ </text>
+ <text x="10" y="110" class="text_normal">
+ ...
+ </text>
+ <use xlink:href="#note_200x20" x="140" y="-15"/>
+ <text x="150" class="text_comment">
+ Individual Memory
+ </text>
+ </g>
+ <g transform="translate(520 70)">
+ <use xlink:href="#state_300x120"/>
+ <text x="10" y="30" class="text_normal">
+ shared_buffers (heap and index)
+ </text>
+ <text x="10" y="70" class="text_normal">
+ wal_buffers (WAL records)
+ </text>
+ <text x="10" y="100" class="text_normal">
+ ...
+ </text>
+ <use xlink:href="#note_250x20" x="40" y="-15"/>
+ <text x="50" class="text_comment">
+ Shared Memory (per Cluster)
+ </text>
+ </g>
+ <path stroke="blue" fill="none" d="M190 215h200v30H190z"/>
+ <text x="10" y="20" class="text_normal" transform="translate(190 215)">
+ Postmaster process
+ </text>
+ <path d="M90 230h85" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <g transform="translate(140 230)">
+ <circle r="8" stroke="black" fill="lightyellow"/>
+ <text x="-4" y="4" class="text_small">
+ 1
+ </text>
+ </g>
+ <path stroke="blue" fill="none" d="M150 315h370v30H150z"/>
+ <text x="10" y="20" class="text_normal" transform="translate(150 315)">
+ Backend processes (one per connection)
+ </text>
+ <path d="M155 315v-5h370v30h-5" stroke="blue" fill="none"/>
+ <path d="M160 310v-5h370v30h-5" stroke="blue" fill="none"/>
+ <path d="M90 240l63 63" stroke="black" fill="none" marker-start="url(#arrowhead_start)" marker-end="url(#arrowhead_end)"/>
+ <g transform="translate(140 290)">
+ <circle r="8" stroke="black" fill="lightyellow"/>
+ <text x="-4" y="4" class="text_small">
+ 3
+ </text>
+ </g>
+ <path d="M360 250v50" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <g transform="translate(190 255)">
+ <use xlink:href="#note_250x20"/>
+ <text x="10" y="15" class="text_comment">
+ Creates backend processes
+ </text>
+ </g>
+ <g transform="translate(360 281)">
+ <circle r="8" stroke="black" fill="lightyellow"/>
+ <text x="-4" y="4" class="text_small">
+ 2
+ </text>
+ </g>
+ <path d="M460 300V200" stroke="black" fill="none" marker-start="url(#arrowhead_start)" marker-end="url(#arrowhead_end)"/>
+ <path d="M498 300V95h30" stroke="black" fill="none" marker-start="url(#arrowhead_start)" marker-end="url(#arrowhead_end)"/>
+ <path d="M508 300V135h20" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path stroke="blue" fill="none" d="M550 220h120v30H550z"/>
+ <text x="10" y="20" class="text_normal" transform="translate(550 220)">
+ WAL Writer
+ </text>
+ <path d="M590 150v65" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path d="M590 255v230" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path stroke="blue" fill="none" d="M610 340h140v30H610z"/>
+ <text x="10" y="20" class="text_normal" transform="translate(610 340)">
+ Checkpointer
+ </text>
+ <path d="M740 110v220" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path d="M605 355H475v130" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path d="M700 330V150" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <g transform="translate(570 330)">
+ <use xlink:href="#note_100x35" x="50" y="-50"/>
+ <text x="60" y="-35" class="text_comment">
+ Checkpoint
+ </text>
+ <text x="60" y="-20" class="text_comment">
+ Record
+ </text>
+ </g>
+ <path stroke="blue" fill="none" d="M610 380h180v30H610z"/>
+ <text x="10" y="20" class="text_normal" transform="translate(610 380)">
+ Background Writer
+ </text>
+ <path d="M770 110v260" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path d="M605 395H485v90" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path stroke="blue" fill="none" d="M610 420h180v30H610z"/>
+ <text x="50" y="20" class="text_normal" transform="translate(610 420)">
+ Archiver
+ </text>
+ <path d="M620 485l30-30" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path d="M740 455v30" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path stroke="blue" fill="none" d="M135 380h120v30H135z"/>
+ <text x="10" y="20" class="text_normal" transform="translate(135 380)">
+ AutoVacuum
+ </text>
+ <path d="M140 380v-5h120v30h-5" stroke="blue" fill="none"/>
+ <path d="M145 375v-5h120v30h-5" stroke="blue" fill="none"/>
+ <path stroke="blue" fill="none" d="M135 430h120v30H135z"/>
+ <text x="10" y="20" class="text_normal" transform="translate(135 430)">
+ Log Writer
+ </text>
+ <path stroke="blue" fill="none" d="M290 370h140v30H290z"/>
+ <text x="10" y="20" class="text_normal" transform="translate(290 370)">
+ Stats Collector
+ </text>
+ <g transform="translate(145 490)">
+ <use xlink:href="#disc"/>
+ <text x="35" y="45" class="text_normal">
+ Log
+ </text>
+ <text x="15" y="60" class="text_small">
+ (text lines,
+ </text>
+ <text x="20" y="75" class="text_small">
+ sequential)
+ </text>
+ </g>
+ <path d="M195 465v20" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <g transform="translate(410 490)">
+ <use xlink:href="#disc"/>
+ <text x="10" y="40" class="text_normal">
+ Heap and
+ </text>
+ <text x="25" y="55" class="text_normal">
+ Index
+ </text>
+ <text x="10" y="70" class="text_small">
+ (binary blocks,
+ </text>
+ <text x="30" y="80" class="text_small">
+ random)
+ </text>
+ </g>
+ <path d="M450 485V350" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <g transform="translate(295 420)">
+ <use xlink:href="#note_170x50"/>
+ <text x="5" y="15" class="text_comment">
+ Read heap and index
+ </text>
+ <text x="5" y="30" class="text_comment">
+ pages and transfer
+ </text>
+ <text x="5" y="45" class="text_comment">
+ them to shared_buffers
+ </text>
+ </g>
+ <g transform="translate(550 490)">
+ <use xlink:href="#disc"/>
+ <text x="30" y="45" class="text_normal">
+ WAL
+ </text>
+ <text x="5" y="60" class="text_small">
+ (binary records,
+ </text>
+ <text x="20" y="75" class="text_small">
+ sequential)
+ </text>
+ </g>
+ <g transform="translate(690 490)">
+ <use xlink:href="#disc"/>
+ <text x="16" y="40" class="text_normal">
+ Archived
+ </text>
+ <text x="36" y="55" class="text_normal">
+ WAL
+ </text>
+ </g>
+ <path d="M110 20v550" stroke="black" fill="none"/>
+ <g transform="rotate(90 -33.5 156.5)">
+ <use xlink:href="#note_200x20"/>
+ <text class="text_comment" x="10" y="15">
+ Via TCP/IP or socket
+ </text>
+ </g>
+ <text class="text_big" x="95" transform="rotate(90 425 425)">
+ RAM
+ </text>
+ <text class="text_big" x="250" transform="rotate(90 425 425)">
+ PROCESSES
+ </text>
+ <text class="text_big" x="500" transform="rotate(90 425 425)">
+ FILES
+ </text>
+</svg>
diff --git a/doc/src/sgml/images/ram-proc-file-ink.svg b/doc/src/sgml/images/ram-proc-file-ink.svg
new file mode 100644
index 0000000000..5f179c1688
--- /dev/null
+++ b/doc/src/sgml/images/ram-proc-file-ink.svg
@@ -0,0 +1,846 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+ xmlns:dc="http://purl.org/dc/elements/1.1/"
+ xmlns:cc="http://creativecommons.org/ns#"
+ xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+ xmlns:svg="http://www.w3.org/2000/svg"
+ xmlns="http://www.w3.org/2000/svg"
+ xmlns:xlink="http://www.w3.org/1999/xlink"
+ xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+ xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+ version="1.1"
+ width="900px"
+ height="600px"
+ viewBox="0 0 900 600"
+ id="svg308"
+ sodipodi:docname="ram-proc-file-ink.svg"
+ inkscape:version="0.92.3 (2405546, 2018-03-11)">
+ <metadata
+ id="metadata312">
+ <rdf:RDF>
+ <cc:Work
+ rdf:about="">
+ <dc:format>image/svg+xml</dc:format>
+ <dc:type
+ rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+ <dc:title>PG Overall Server Architecture</dc:title>
+ </cc:Work>
+ </rdf:RDF>
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+ font-size:16px;
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+ <!-- UML states (used for buffers) -->
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+ <!-- Discs -->
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+ id="disc"
+ stroke="blue"
+ fill="none">
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+ id="title36">Disc</title>
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+ cy="13"
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+ <!-- Laptop -->
+ <symbol
+ id="laptop"
+ stroke="black"
+ fill="none">
+ <title
+ id="title47">Laptop</title>
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+ <!-- symbolize some lines -->
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+ d="M 30,15 h 25"
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+ d="M 30,20 h 10"
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+ <path
+ d="M 30,30 h 20"
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+ <!-- symbolize keyboard -->
+ <path
+ d="M 25,50 h 45 l 2,2 h -50 z "
+ id="path61" />
+ </symbol>
+ <!-- marker start/end -->
+ <marker
+ id="arrowhead_start"
+ markerWidth="10"
+ markerHeight="10"
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+ d="M 6,0 l -6,3 l 6,3"
+ stroke="black"
+ fill="none"
+ id="path64" />
+ </marker>
+ <marker
+ id="arrowhead_end"
+ markerWidth="10"
+ markerHeight="10"
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+ refY="3"
+ orient="auto">
+ <path
+ d="M 0,0 l 6,3 l -6,3"
+ stroke="black"
+ fill="none"
+ id="path67" />
+ </marker>
+ </defs>
+ <!-- start of rendering area -->
+ <!-- enclosing rectangle -->
+ <rect
+ x="1"
+ y="1"
+ rx="5"
+ width="99%"
+ height="99%"
+ stroke="black"
+ fill="none"
+ id="rect72" />
+ <!-- caption, client side -->
+ <text
+ x="15"
+ y="40"
+ class="text_big"
+ id="text74">Client</text>
+ <text
+ x="140"
+ y="40"
+ class="text_big"
+ id="text76">Server</text>
+ <use
+ xlink:href="#laptop"
+ x="5"
+ y="210"
+ id="use78" />
+ <!-- individual memory -->
+ <g
+ transform="translate(130, 70)"
+ id="g98">
+ <use
+ xlink:href="#state_350x120"
+ x="0"
+ y="0"
+ id="use80" />
+ <text
+ x="10"
+ y="20"
+ class="text_normal"
+ id="text82">maintenance_work_mem (per connection)</text>
+ <text
+ x="10"
+ y="40"
+ class="text_normal"
+ id="text84">work_mem (per query operation)</text>
+ <text
+ x="10"
+ y="60"
+ class="text_normal"
+ id="text86">autovacuum_work_mem (per worker</text>
+ <text
+ x="230"
+ y="75"
+ class="text_normal"
+ id="text88">process)</text>
+ <text
+ x="10"
+ y="95"
+ class="text_normal"
+ id="text90">temp_buffer (per connection)</text>
+ <text
+ x="10"
+ y="110"
+ class="text_normal"
+ id="text92">...</text>
+ <use
+ xlink:href="#note_200x20"
+ x="140"
+ y="-15"
+ id="use94" />
+ <text
+ x="150"
+ y="0"
+ class="text_comment"
+ id="text96">Individual Memory</text>
+ </g>
+ <!-- shared memory -->
+ <g
+ transform="translate(520, 70)"
+ id="g112">
+ <use
+ xlink:href="#state_300x120"
+ x="0"
+ y="0"
+ id="use100" />
+ <text
+ x="10"
+ y="30"
+ class="text_normal"
+ id="text102">shared_buffers (heap and index)</text>
+ <text
+ x="10"
+ y="70"
+ class="text_normal"
+ id="text104">wal_buffers (WAL records)</text>
+ <text
+ x="10"
+ y="100"
+ class="text_normal"
+ id="text106">...</text>
+ <use
+ xlink:href="#note_250x20"
+ x="40"
+ y="-15"
+ id="use108" />
+ <text
+ x="50"
+ y="0"
+ class="text_comment"
+ id="text110">Shared Memory (per Cluster)</text>
+ </g>
+ <!-- postmaster -->
+ <g
+ transform="translate(190, 215)"
+ id="g118">
+ <rect
+ width="200"
+ height="30"
+ stroke="blue"
+ fill="none"
+ id="rect114" />
+ <text
+ x="10"
+ y="20"
+ class="text_normal"
+ id="text116">Postmaster process</text>
+ </g>
+ <path
+ d="M 90,230 h 85"
+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path120" />
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+ transform="translate(140, 230)"
+ id="g126">
+ <circle
+ r="8"
+ stroke="black"
+ fill="lightyellow"
+ id="circle122" />
+ <text
+ x="-4"
+ y="4"
+ class="text_small"
+ id="text124">1</text>
+ </g>
+ <!-- backend processes -->
+ <g
+ transform="translate(150, 315)"
+ id="g136">
+ <rect
+ width="370"
+ height="30"
+ stroke="blue"
+ fill="none"
+ id="rect128" />
+ <text
+ x="10"
+ y="20"
+ class="text_normal"
+ id="text130">Backend processes (one per connection)</text>
+ <path
+ d="M 5,0 v -5 h 370 v 30 h -5"
+ stroke="blue"
+ fill="none"
+ id="path132" />
+ <path
+ d="M 10,-5 v -5 h 370 v 30 h -5"
+ stroke="blue"
+ fill="none"
+ id="path134" />
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+ <path
+ d="M 90,240 153,303"
+ stroke="black"
+ fill="none"
+ marker-start="url(#arrowhead_start)"
+ marker-end="url(#arrowhead_end)"
+ id="path138" />
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+ transform="translate(140, 290)"
+ id="g144">
+ <circle
+ r="8"
+ stroke="black"
+ fill="lightyellow"
+ id="circle140" />
+ <text
+ x="-4"
+ y="4"
+ class="text_small"
+ id="text142">3</text>
+ </g>
+ <!-- connection between postmaster and backend processes -->
+ <path
+ d="M 360,250 v 50"
+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path146" />
+ <g
+ transform="translate(190, 255)"
+ id="g152">
+ <use
+ xlink:href="#note_250x20"
+ id="use148" />
+ <text
+ x="10"
+ y="15"
+ class="text_comment"
+ id="text150">Creates backend processes</text>
+ </g>
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+ transform="translate(360, 281)"
+ id="g158">
+ <circle
+ r="8"
+ stroke="black"
+ fill="lightyellow"
+ id="circle154" />
+ <text
+ x="-4"
+ y="4"
+ class="text_small"
+ id="text156">2</text>
+ </g>
+ <!-- backend process' access to individual memory -->
+ <path
+ d="M 460,300 v -100"
+ stroke="black"
+ fill="none"
+ marker-start="url(#arrowhead_start)"
+ marker-end="url(#arrowhead_end)"
+ id="path160" />
+ <!-- its access to shared buffers and WAL buffers -->
+ <path
+ d="M 498,300 v -205 h 30"
+ stroke="black"
+ fill="none"
+ marker-start="url(#arrowhead_start)"
+ marker-end="url(#arrowhead_end)"
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+ <path
+ d="M 508,300 v -165 h 20"
+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path164" />
+ <!-- WAL writer -->
+ <g
+ transform="translate(550, 220)"
+ id="g170">
+ <rect
+ width="120"
+ height="30"
+ stroke="blue"
+ fill="none"
+ id="rect166" />
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+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path172" />
+ <path
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+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path174" />
+ <!-- Checkpoiner -->
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+ id="g180">
+ <rect
+ width="140"
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+ stroke="blue"
+ fill="none"
+ id="rect176" />
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+ transform="translate(570, 330)"
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+ <use
+ xlink:href="#note_100x35"
+ x="50"
+ y="-50"
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+ <text
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+ y="-35"
+ class="text_comment"
+ id="text190">Checkpoint</text>
+ <text
+ x="60"
+ y="-20"
+ class="text_comment"
+ id="text192">Record</text>
+ </g>
+ <!-- BG writer -->
+ <g
+ transform="translate(610, 380)"
+ id="g200">
+ <rect
+ width="180"
+ height="30"
+ stroke="blue"
+ fill="none"
+ id="rect196" />
+ <text
+ x="10"
+ y="20"
+ class="text_normal"
+ id="text198">Background Writer</text>
+ </g>
+ <path
+ d="M 770,110 v 260"
+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path202" />
+ <path
+ d="M 605,395 h -120 v 90"
+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path204" />
+ <!-- Archiver -->
+ <g
+ transform="translate(610, 420)"
+ id="g210">
+ <rect
+ width="180"
+ height="30"
+ stroke="blue"
+ fill="none"
+ id="rect206" />
+ <text
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+ y="20"
+ class="text_normal"
+ id="text208">Archiver</text>
+ </g>
+ <path
+ d="M 620,485 l 30,-30"
+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path212" />
+ <path
+ d="M 740,455 v 30"
+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path214" />
+ <!-- Vacuum -->
+ <g
+ transform="translate(135, 380)"
+ id="g224">
+ <rect
+ width="120"
+ height="30"
+ stroke="blue"
+ fill="none"
+ id="rect216" />
+ <text
+ x="10"
+ y="20"
+ class="text_normal"
+ id="text218">AutoVacuum</text>
+ <path
+ d="M 5,0 v -5 h 120 v 30 h -5"
+ stroke="blue"
+ fill="none"
+ id="path220" />
+ <path
+ d="M 10,-5 v -5 h 120 v 30 h -5"
+ stroke="blue"
+ fill="none"
+ id="path222" />
+ </g>
+ <!-- Log Writer -->
+ <g
+ transform="translate(135, 430)"
+ id="g230">
+ <rect
+ width="120"
+ height="30"
+ stroke="blue"
+ fill="none"
+ id="rect226" />
+ <text
+ x="10"
+ y="20"
+ class="text_normal"
+ id="text228">Log Writer</text>
+ </g>
+ <!-- Stats Collector (135, 460) -->
+ <g
+ transform="translate(290, 370)"
+ id="g236">
+ <rect
+ width="140"
+ height="30"
+ stroke="blue"
+ fill="none"
+ id="rect232" />
+ <text
+ x="10"
+ y="20"
+ class="text_normal"
+ id="text234">Stats Collector</text>
+ </g>
+ <!-- -->
+ <!-- files -->
+ <!-- -->
+ <g
+ transform="translate(145, 490)"
+ id="g246">
+ <use
+ xlink:href="#disc"
+ id="use238" />
+ <text
+ x="35"
+ y="45"
+ class="text_normal"
+ id="text240">Log</text>
+ <text
+ x="15"
+ y="60"
+ class="text_small"
+ id="text242">(text lines,</text>
+ <text
+ x="20"
+ y="75"
+ class="text_small"
+ id="text244">sequential)</text>
+ </g>
+ <path
+ d="M 195,465 v 20"
+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path248" />
+ <g
+ transform="translate(410, 490)"
+ id="g260">
+ <use
+ xlink:href="#disc"
+ id="use250" />
+ <text
+ x="10"
+ y="40"
+ class="text_normal"
+ id="text252">Heap and</text>
+ <text
+ x="25"
+ y="55"
+ class="text_normal"
+ id="text254">Index</text>
+ <text
+ x="10"
+ y="70"
+ class="text_small"
+ id="text256">(binary blocks,</text>
+ <text
+ x="30"
+ y="80"
+ class="text_small"
+ id="text258">random)</text>
+ </g>
+ <path
+ d="M 450,485 v -135"
+ stroke="black"
+ fill="none"
+ marker-end="url(#arrowhead_end)"
+ id="path262" />
+ <g
+ transform="translate(295, 420)"
+ id="g272">
+ <use
+ xlink:href="#note_170x50"
+ id="use264" />
+ <text
+ x="5"
+ y="15"
+ class="text_comment"
+ id="text266">Read heap and index</text>
+ <text
+ x="5"
+ y="30"
+ class="text_comment"
+ id="text268">pages and transfer</text>
+ <text
+ x="5"
+ y="45"
+ class="text_comment"
+ id="text270">them to shared_buffers</text>
+ </g>
+ <g
+ transform="translate(550, 490)"
+ id="g282">
+ <use
+ xlink:href="#disc"
+ id="use274" />
+ <text
+ x="30"
+ y="45"
+ class="text_normal"
+ id="text276">WAL</text>
+ <text
+ x="5"
+ y="60"
+ class="text_small"
+ id="text278">(binary records,</text>
+ <text
+ x="20"
+ y="75"
+ class="text_small"
+ id="text280">sequential)</text>
+ </g>
+ <g
+ transform="translate(690, 490)"
+ id="g290">
+ <use
+ xlink:href="#disc"
+ id="use284" />
+ <text
+ x="16"
+ y="40"
+ class="text_normal"
+ id="text286">Archived</text>
+ <text
+ x="36"
+ y="55"
+ class="text_normal"
+ id="text288">WAL</text>
+ </g>
+ <!-- boarder between client and server side -->
+ <path
+ d="M 110,20 v 550"
+ stroke="black"
+ fill="none"
+ id="path292" />
+ <g
+ transform="translate(123, 190) rotate(90)"
+ id="g298">
+ <use
+ xlink:href="#note_200x20"
+ id="use294" />
+ <text
+ class="text_comment"
+ x="10"
+ y="15"
+ id="text296">Via TCP/IP or socket</text>
+ </g>
+ <!-- right side -->
+ <g
+ transform="translate(850, 0) rotate(90)"
+ id="g306">
+ <text
+ class="text_big"
+ x="95"
+ id="text300">RAM</text>
+ <text
+ class="text_big"
+ x="250"
+ id="text302">PROCESSES</text>
+ <text
+ class="text_big"
+ x="500"
+ id="text304">FILES</text>
+ </g>
+</svg>
diff --git a/doc/src/sgml/images/ram-proc-file-raw.svg b/doc/src/sgml/images/ram-proc-file-raw.svg
new file mode 100644
index 0000000000..ddb9ec6cb6
--- /dev/null
+++ b/doc/src/sgml/images/ram-proc-file-raw.svg
@@ -0,0 +1,302 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg xmlns="http://www.w3.org/2000/svg"
+ xmlns:xlink="http://www.w3.org/1999/xlink"
+ version="1.1"
+ width="900px" height="600px"
+ viewBox="0 0 900 600">
+
+ <title>PG Overall Server Architecture</title>
+
+ <style type="text/css">
+ .text_small {font-style:normal;
+ font-weight:normal;
+ font-size:12px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ .text_normal {font-style:normal;
+ font-weight:normal;
+ font-size:16px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ .text_big {font-style:normal;
+ font-weight:normal;
+ font-size:24px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ .text_comment {font-style:italic;
+ font-weight:normal;
+ font-size:16px;
+ font-family:"Open Sans", sans-serif;
+ fill:black;
+ }
+ </style>
+
+ <defs>
+
+ <!-- Some notes in different sizes -->
+ <symbol id="note_200x20" stroke="black" fill="lightyellow">
+ <title>UML Note (200 x 20 px)</title>
+ <path d="M 200,10 v 10 h -200 v -20 h 190 v 10 h 10 l -10,-10" />
+ </symbol>
+ <symbol id="note_250x20" stroke="black" fill="lightyellow">
+ <title>UML Note (250 x 20 px)</title>
+ <path d="M 250,10 v 10 h -250 v -20 h 240 v 10 h 10 l -10,-10" />
+ </symbol>
+ <symbol id="note_100x35" stroke="black" fill="lightyellow">
+ <title>UML Note (100 x 35 px)</title>
+ <path d="M 100,10 v 25 h -100 v -35 h 90 v 10 h 10 l -10,-10" />
+ </symbol>
+ <symbol id="note_170x50" stroke="black" fill="lightyellow">
+ <title>UML Note (170 x 50 px)</title>
+ <path d="M 170,10 v 40 h -170 v -50 h 160 v 10 h 10 l -10,-10" />
+ </symbol>
+
+ <!-- UML states (used for buffers) -->
+ <symbol id="state_300x120">
+ <title>UML State, big</title>
+ <rect x="0" y="0" width="300" height="120" rx="10" stroke="blue" fill="none"/>
+ </symbol>
+ <symbol id="state_350x120">
+ <title>UML State, big</title>
+ <rect x="0" y="0" width="350" height="120" rx="10" stroke="blue" fill="none"/>
+ </symbol>
+
+ <!-- Discs -->
+ <symbol id="disc" stroke="blue" fill="none" >
+ <title>Disc</title>
+ <ellipse cx="51" cy="13" rx="50" ry="12" /> <!-- top -->
+ <path d="M 1,13 v 60" /> <!-- left -->
+ <path d="M 101,13 v 60" /> <!-- right -->
+ <path d="M 1,73 A 50, 12, 0, 0, 0, 101,73" /> <!-- bottom -->
+ </symbol>
+
+ <!-- Laptop -->
+ <symbol id="laptop" stroke="black" fill="none" >
+ <title>Laptop</title>
+ <path d="M 20,40 v -40 h 54 v 40 l 15,15 h -84 l 15,-15 h 54" />
+ <rect x="23" y="3" width="48" height="34" />
+ <!-- symbolize some lines -->
+ <path d="M 30,10 h 20" />
+ <path d="M 30,15 h 25" />
+ <path d="M 30,20 h 10" />
+ <path d="M 30,30 h 20" />
+ <!-- symbolize keyboard -->
+ <path d="M 25,50 h 45 l 2,2 h -50 z " />
+ </symbol>
+
+ <!-- marker start/end -->
+ <marker id="arrowhead_start"
+ markerWidth="10"
+ markerHeight="10"
+ refX="0"
+ refY="3"
+ orient="auto">
+ <path d="M 6,0 l -6,3 l 6,3" stroke="black" fill="none" />
+ </marker>
+ <marker id="arrowhead_end"
+ markerWidth="10"
+ markerHeight="10"
+ refX="6"
+ refY="3"
+ orient="auto">
+ <path d="M 0,0 l 6,3 l -6,3" stroke="black" fill="none" />
+ </marker>
+
+ </defs>
+
+
+ <!-- start of rendering area -->
+ <!-- enclosing rectangle -->
+ <rect x="1" y="1" rx="5" width="99%" height="99%" stroke="black" fill="none" />
+
+ <!-- caption, client side -->
+ <text x="15" y="40" class="text_big">Client</text>
+ <text x="140" y="40" class="text_big">Server</text>
+ <use xlink:href="#laptop" x="5" y="210" />
+
+
+ <!-- individual memory -->
+ <g transform="translate(130, 70)">
+ <use xlink:href="#state_350x120" x="0" y="0" />
+ <text x="10" y="20" class="text_normal">maintenance_work_mem (per connection)</text>
+ <text x="10" y="40" class="text_normal">work_mem (per query operation)</text>
+ <text x="10" y="60" class="text_normal">autovacuum_work_mem (per worker</text>
+ <text x="230" y="75" class="text_normal">process)</text>
+ <text x="10" y="95" class="text_normal">temp_buffer (per connection)</text>
+ <text x="10" y="110" class="text_normal">...</text>
+ <use xlink:href="#note_200x20" x="140" y="-15" />
+ <text x="150" y="0" class="text_comment">Individual Memory</text>
+ </g>
+
+ <!-- shared memory -->
+ <g transform="translate(520, 70)">
+ <use xlink:href="#state_300x120" x="0" y="0" />
+ <text x="10" y="30" class="text_normal">shared_buffers (heap and index)</text>
+ <text x="10" y="70" class="text_normal">wal_buffers (WAL records)</text>
+ <text x="10" y="100" class="text_normal">...</text>
+ <use xlink:href="#note_250x20" x="40" y="-15" />
+ <text x="50" y="0" class="text_comment">Shared Memory (per Cluster)</text>
+ </g>
+
+ <!-- postmaster -->
+ <g transform="translate(190, 215)">
+ <rect width="200" height="30" stroke="blue" fill="none" />
+ <text x="10" y="20" class="text_normal">Postmaster process</text>
+ </g>
+ <path d="M 90,230 h 85" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <g transform="translate(140, 230)">
+ <circle r="8" stroke="black" fill="lightyellow" />
+ <text x="-4" y="4" class="text_small">1</text>
+ </g>
+
+ <!-- backend processes -->
+ <g transform="translate(150, 315)">
+ <rect width="370" height="30" stroke="blue" fill="none" />
+ <text x="10" y="20" class="text_normal">Backend processes (one per connection)</text>
+ <path d="M 5,0 v -5 h 370 v 30 h -5" stroke="blue" fill="none" />
+ <path d="M 10,-5 v -5 h 370 v 30 h -5" stroke="blue" fill="none" />
+ </g>
+
+ <path d="M 90,240 153,303" stroke="black" fill="none"
+ marker-start="url(#arrowhead_start)" marker-end="url(#arrowhead_end)"/>
+ <g transform="translate(140, 290)">
+ <circle r="8" stroke="black" fill="lightyellow" />
+ <text x="-4" y="4" class="text_small">3</text>
+ </g>
+
+ <!-- connection between postmaster and backend processes -->
+ <path d="M 360,250 v 50" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <g transform="translate(190, 255)">
+ <use xlink:href="#note_250x20" />
+ <text x="10" y="15" class="text_comment">Creates backend processes</text>
+ </g>
+ <g transform="translate(360, 281)">
+ <circle r="8" stroke="black" fill="lightyellow" />
+ <text x="-4" y="4" class="text_small">2</text>
+ </g>
+
+ <!-- backend process' access to individual memory -->
+ <path d="M 460,300 v -100" stroke="black" fill="none"
+ marker-start="url(#arrowhead_start)" marker-end="url(#arrowhead_end)"/>
+ <!-- its access to shared buffers and WAL buffers -->
+ <path d="M 498,300 v -205 h 30" stroke="black" fill="none"
+ marker-start="url(#arrowhead_start)" marker-end="url(#arrowhead_end)"/>
+ <path d="M 508,300 v -165 h 20" stroke="black" fill="none"
+ marker-end="url(#arrowhead_end)"/>
+
+ <!-- WAL writer -->
+ <g transform="translate(550, 220)">
+ <rect width="120" height="30" stroke="blue" fill="none" />
+ <text x="10" y="20" class="text_normal">WAL Writer</text>
+ </g>
+ <path d="M 590,150 v 65" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path d="M 590,255 v 230" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+
+ <!-- Checkpoiner -->
+ <g transform="translate(610, 340)">
+ <rect width="140" height="30" stroke="blue" fill="none" />
+ <text x="10" y="20" class="text_normal">Checkpointer</text>
+ </g>
+ <path d="M 740,110 v 220" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path d="M 605,355 h -130 v 130" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path d="M 700,330 v -180" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <g transform="translate(570, 330)">
+ <use xlink:href="#note_100x35" x="50" y="-50" />
+ <text x="60" y="-35" class="text_comment">Checkpoint</text>
+ <text x="60" y="-20" class="text_comment">Record</text>
+ </g>
+
+ <!-- BG writer -->
+ <g transform="translate(610, 380)">
+ <rect width="180" height="30" stroke="blue" fill="none" />
+ <text x="10" y="20" class="text_normal">Background Writer</text>
+ </g>
+ <path d="M 770,110 v 260" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path d="M 605,395 h -120 v 90" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+
+ <!-- Archiver -->
+ <g transform="translate(610, 420)">
+ <rect width="180" height="30" stroke="blue" fill="none" />
+ <text x="50" y="20" class="text_normal">Archiver</text>
+ </g>
+ <path d="M 620,485 l 30,-30" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+ <path d="M 740,455 v 30" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+
+ <!-- Vacuum -->
+ <g transform="translate(135, 380)">
+ <rect width="120" height="30" stroke="blue" fill="none" />
+ <text x="10" y="20" class="text_normal">AutoVacuum</text>
+ <path d="M 5,0 v -5 h 120 v 30 h -5" stroke="blue" fill="none" />
+ <path d="M 10,-5 v -5 h 120 v 30 h -5" stroke="blue" fill="none" />
+ </g>
+
+ <!-- Log Writer -->
+ <g transform="translate(135, 430)">
+ <rect width="120" height="30" stroke="blue" fill="none" />
+ <text x="10" y="20" class="text_normal">Log Writer</text>
+ </g>
+
+ <!-- Stats Collector (135, 460) -->
+ <g transform="translate(290, 370)">
+ <rect width="140" height="30" stroke="blue" fill="none" />
+ <text x="10" y="20" class="text_normal">Stats Collector</text>
+ </g>
+
+ <!-- -->
+ <!-- files -->
+ <!-- -->
+ <g transform="translate(145, 490)">
+ <use xlink:href="#disc" />
+ <text x="35" y="45" class="text_normal">Log</text>
+ <text x="15" y="60" class="text_small">(text lines,</text>
+ <text x="20" y="75" class="text_small">sequential)</text>
+ </g>
+ <path d="M 195,465 v 20" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+
+ <g transform="translate(410, 490)">
+ <use xlink:href="#disc" />
+ <text x="10" y="40" class="text_normal">Heap and</text>
+ <text x="25" y="55" class="text_normal">Index</text>
+ <text x="10" y="70" class="text_small">(binary blocks,</text>
+ <text x="30" y="80" class="text_small">random)</text>
+ </g>
+ <path d="M 450,485 v -135" stroke="black" fill="none" marker-end="url(#arrowhead_end)"/>
+
+ <g transform="translate(295, 420)">
+ <use xlink:href="#note_170x50" />
+ <text x="5" y="15" class="text_comment">Read heap and index</text>
+ <text x="5" y="30" class="text_comment">pages and transfer</text>
+ <text x="5" y="45" class="text_comment">them to shared_buffers</text>
+ </g>
+
+ <g transform="translate(550, 490)">
+ <use xlink:href="#disc" />
+ <text x="30" y="45" class="text_normal">WAL</text>
+ <text x="5" y="60" class="text_small">(binary records,</text>
+ <text x="20" y="75" class="text_small">sequential)</text>
+ </g>
+
+ <g transform="translate(690, 490)">
+ <use xlink:href="#disc" />
+ <text x="16" y="40" class="text_normal">Archived</text>
+ <text x="36" y="55" class="text_normal">WAL</text>
+ </g>
+
+ <!-- boarder between client and server side -->
+ <path d="M 110,20 v 550" stroke="black" fill="none" />
+ <g transform="translate(123, 190) rotate(90)">
+ <use xlink:href="#note_200x20" />
+ <text class="text_comment" x="10" y ="15">Via TCP/IP or socket</text>
+ </g>
+
+ <!-- right side -->
+ <g transform="translate(850, 0) rotate(90)">
+ <text class="text_big" x="95">RAM</text>
+ <text class="text_big" x="250">PROCESSES</text>
+ <text class="text_big" x="500">FILES</text>
+ </g>
+
+</svg>
diff --git a/doc/src/sgml/postgres.sgml b/doc/src/sgml/postgres.sgml
index e59cba7997..05d2862332 100644
--- a/doc/src/sgml/postgres.sgml
+++ b/doc/src/sgml/postgres.sgml
@@ -53,6 +53,7 @@
</partintro>
&start;
+ &architecture;
&query;
&advanced;
@@ -277,6 +278,7 @@
&sourcerepo;
&docguide;
&limits;
+ &glossary;
&acronyms;
</part>
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