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Add more new pages.
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Thomas G. Lockhart
parent
e57cfd81d1
commit
e6c1fbab5c
@ -27,6 +27,11 @@
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&declare;
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&delete;
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&dropFunction;
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&listen;
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&load;
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&lock;
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&move;
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¬ify;
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&reset;
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&revoke;
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&rollback;
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148
doc/src/sgml/ref/listen.sgml
Normal file
148
doc/src/sgml/ref/listen.sgml
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@ -0,0 +1,148 @@
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<REFENTRY ID="SQL-LISTEN">
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<REFMETA>
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<REFENTRYTITLE>
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LISTEN
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</REFENTRYTITLE>
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<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
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</REFMETA>
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<REFNAMEDIV>
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<REFNAME>
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LISTEN
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</REFNAME>
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<REFPURPOSE>
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Listen for notification on a relation
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</REFPURPOSE>
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<REFSYNOPSISDIV>
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<REFSYNOPSISDIVINFO>
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<DATE>1998-09-01</DATE>
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</REFSYNOPSISDIVINFO>
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<SYNOPSIS>
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LISTEN <REPLACEABLE CLASS="PARAMETER">classname</REPLACEABLE>
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</SYNOPSIS>
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<REFSECT2 ID="R2-SQL-LISTEN-1">
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<REFSECT2INFO>
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<DATE>1998-09-01</DATE>
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</REFSECT2INFO>
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<TITLE>
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Inputs
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</TITLE>
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<PARA>
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</PARA>
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<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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<REPLACEABLE CLASS="PARAMETER">classname</REPLACEABLE>
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</TERM>
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<LISTITEM>
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<PARA>
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Table object used for notification.
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</VARIABLELIST>
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</REFSECT2>
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<REFSECT2 ID="R2-SQL-LISTEN-2">
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<REFSECT2INFO>
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<DATE>1998-04-15</DATE>
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</REFSECT2INFO>
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<TITLE>
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Outputs
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</TITLE>
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<PARA>
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</PARA>
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<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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LISTEN
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</TERM>
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<LISTITEM>
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<PARA>
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Message returned upon successful completion of registration.
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</VARIABLELIST>
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</REFSECT2>
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</REFSYNOPSISDIV>
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<REFSECT1 ID="R1-SQL-LISTEN-1">
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<REFSECT1INFO>
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<DATE>1998-04-15</DATE>
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</REFSECT1INFO>
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<TITLE>
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Description
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</TITLE>
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<PARA>
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LISTEN is used to register the current backend as a listener on the relation
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<REPLACEABLE CLASS="PARAMETER">classname</REPLACEABLE>.
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When the command
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<command>NOTIFY <REPLACEABLE CLASS="PARAMETER">classname</REPLACEABLE></command>
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is called either from within a rule or at the query level, the
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frontend applications corresponding to the listening backends
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are notified. When the backend process exits, this registration
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is cleared.
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<para>
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This event notification is performed through the libpq protocol
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and frontend application interface. The application program
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must call the routine
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<function>PQnotifies</function>
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in order to find out the name of the class to which a given
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notification corresponds. If this code is not included in
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the application, the event notification will be queued and
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never be processed.
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<REFSECT2 ID="R2-SQL-LISTEN-3">
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<REFSECT2INFO>
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<DATE>1998-04-15</DATE>
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</REFSECT2INFO>
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<TITLE>
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Notes
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</TITLE>
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<para>
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Note that <REPLACEABLE CLASS="PARAMETER">classname</REPLACEABLE>
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needs not to be a valid class name but can be any string valid as a name up to 32
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characters long.
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<para>
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A restriction in some previous releases of
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<productname>Postgres</productname> that a
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<REPLACEABLE CLASS="PARAMETER">classname</REPLACEABLE>
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which does not correspond to an actual table must be enclosed in double-quotes
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is no longer present.
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</REFSECT2>
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<REFSECT1 ID="R1-SQL-LISTEN-2">
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<TITLE>
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Usage
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</TITLE>
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<PARA>
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<ProgramListing>
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postgres=> listen virtual;
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LISTEN
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postgres=> notify virtual;
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NOTIFY
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ASYNC NOTIFY of 'virtual' from backend pid '11239' received
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</ProgramListing>
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</REFSECT1>
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<REFSECT1 ID="R1-SQL-LISTEN-3">
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<TITLE>
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Compatibility
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</TITLE>
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<PARA>
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</PARA>
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<REFSECT2 ID="R2-SQL-LISTEN-4">
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<REFSECT2INFO>
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<DATE>1998-09-01</DATE>
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</REFSECT2INFO>
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<TITLE>
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SQL92
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</TITLE>
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<PARA>
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There is no LISTEN statement in <acronym>SQL92</acronym>.
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</REFENTRY>
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157
doc/src/sgml/ref/load.sgml
Normal file
157
doc/src/sgml/ref/load.sgml
Normal file
@ -0,0 +1,157 @@
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<REFENTRY ID="SQL-LOAD">
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<REFMETA>
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<REFENTRYTITLE>
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LOAD
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</REFENTRYTITLE>
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<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
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</REFMETA>
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<REFNAMEDIV>
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<REFNAME>
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LOAD
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</REFNAME>
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<REFPURPOSE>
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Dynamically loads an object file
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</REFPURPOSE>
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<REFSYNOPSISDIV>
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<REFSYNOPSISDIVINFO>
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<DATE>1998-09-01</DATE>
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</REFSYNOPSISDIVINFO>
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<SYNOPSIS>
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<REPLACEABLE CLASS="PARAMETER">
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</REPLACEABLE>
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LOAD '<REPLACEABLE CLASS="PARAMETER">filename</REPLACEABLE>'
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</SYNOPSIS>
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<REFSECT2 ID="R2-SQL-LOAD-1">
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<REFSECT2INFO>
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<DATE>1998-09-01</DATE>
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</REFSECT2INFO>
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<TITLE>
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Inputs
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</TITLE>
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<PARA>
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</PARA>
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<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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<REPLACEABLE CLASS="PARAMETER">filename</REPLACEABLE>
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</TERM>
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<LISTITEM>
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<PARA>
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Object file for dynamic loading.
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</VARIABLELIST>
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</REFSECT2>
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<REFSECT2 ID="R2-SQL-LOAD-2">
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<REFSECT2INFO>
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<DATE>1998-04-15</DATE>
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</REFSECT2INFO>
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<TITLE>
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Outputs
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</TITLE>
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<PARA>
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</PARA>
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<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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LOAD
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</TERM>
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<LISTITEM>
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<PARA>
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</VARIABLELIST>
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</REFSECT2>
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</REFSYNOPSISDIV>
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<REFSECT1 ID="R1-SQL-LOAD-1">
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<REFSECT1INFO>
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<DATE>1998-04-15</DATE>
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</REFSECT1INFO>
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<TITLE>
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Description
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</TITLE>
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<PARA>
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Loads an object (or ".o") file into the
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<productname>Postgres</productname> backend address space. Once a
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file is loaded, all functions in that file can be accessed. This
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function is used in support of ADT's.
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<para>
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If a file is not loaded using
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<command>LOAD</command>,
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the file will be loaded automatically the first time the
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function is called by <productname>Postgres</productname>.
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<command>LOAD</command>
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can also be used to reload an object file if it has been edited and
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recompiled. Only objects created from C language files are supported
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at this time.
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<REFSECT2 ID="R2-SQL-LOAD-3">
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<REFSECT2INFO>
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<DATE>1998-04-15</DATE>
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</REFSECT2INFO>
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<TITLE>
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Notes
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</TITLE>
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<PARA>
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Functions in loaded object files should not call functions in other
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object files loaded through the
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<command>LOAD</command>
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command, meaning, for example, that all functions in file A should
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call each other, functions in the standard or math libraries, or in
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Postgres itself. They should not call functions defined in a different
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loaded file B. This is because if B is reloaded, the Postgres loader is
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not able to relocate the calls from the functions in A into
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the new address space of B. If B is not reloaded, however, there will
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not be a problem.
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<para>
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Object files must be compiled to contain position independent code.
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For example,
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on DECstations you must use
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<application>/bin/cc</application>
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with the "-G 0" option when compiling object files to be
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loaded.
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<para>
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Note that if you are porting <productname>Postgres</productname>
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to a new platform, <command>LOAD</command>
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will have to work in order to support ADTs.
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</REFSECT2>
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<REFSECT1 ID="R1-SQL-LOAD-2">
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<TITLE>
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Usage
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</TITLE>
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<PARA>
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<ProgramListing>
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--Load the file /usr/postgres/demo/circle.o
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||||
--
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||||
LOAD "/usr/postgres/demo/circle.o"
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</ProgramListing>
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|
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</REFSECT1>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-LOAD-3">
|
||||
<TITLE>
|
||||
Compatibility
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-LOAD-4">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
SQL92
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||||
</TITLE>
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||||
<PARA>
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There is no LOAD statement in <acronym>SQL92</acronym>.
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||||
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</REFENTRY>
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||||
167
doc/src/sgml/ref/lock.sgml
Normal file
167
doc/src/sgml/ref/lock.sgml
Normal file
@ -0,0 +1,167 @@
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||||
<REFENTRY ID="SQL-LOCK">
|
||||
<REFMETA>
|
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<REFENTRYTITLE>
|
||||
LOCK
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||||
</REFENTRYTITLE>
|
||||
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
|
||||
</REFMETA>
|
||||
<REFNAMEDIV>
|
||||
<REFNAME>
|
||||
LOCK
|
||||
</REFNAME>
|
||||
<REFPURPOSE>
|
||||
Explicit lock of a table inside a transaction
|
||||
</REFPURPOSE>
|
||||
|
||||
<REFSYNOPSISDIV>
|
||||
<REFSYNOPSISDIVINFO>
|
||||
<DATE>1998-09-01</DATE>
|
||||
</REFSYNOPSISDIVINFO>
|
||||
<SYNOPSIS>
|
||||
LOCK [TABLE] <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>
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||||
</SYNOPSIS>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-LOCK-1">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-09-01</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
Inputs
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
<VARIABLELIST>
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
<REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
The name of an existing table to lock.
|
||||
</VARIABLELIST>
|
||||
|
||||
</REFSECT2>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-LOCK-2">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
Outputs
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
<VARIABLELIST>
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
DELETE 0
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
Message returned on a successful lock.
|
||||
<command>LOCK</command> is implemented as a
|
||||
<command>DELETE FROM <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE></command>
|
||||
which is guaranteed to not delete any rows.
|
||||
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
ERROR <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>: Table does not exist.
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
Message returned if table don't exist.
|
||||
|
||||
</VARIABLELIST>
|
||||
|
||||
</REFSECT2>
|
||||
</REFSYNOPSISDIV>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-LOCK-1">
|
||||
<REFSECT1INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT1INFO>
|
||||
<TITLE>
|
||||
Description
|
||||
</TITLE>
|
||||
<PARA>
|
||||
The LOCK statement locks in exclusive mode a table inside
|
||||
a transaction. The classic use for this is
|
||||
the case where you want to select some data, then
|
||||
update it inside a transaction.
|
||||
If you don't explicit lock a table using LOCK statement, it will be
|
||||
implicit locked only at first UPDATE, INSERT or DELETE operation.
|
||||
If you don't exclusive lock the table before the select, some
|
||||
other user may also read the selected data, and try and do
|
||||
their own update, causing a deadlock while you both wait
|
||||
for the other to release the select-induced shared lock so
|
||||
you can get an exclusive lock to do the update.
|
||||
|
||||
<para>
|
||||
Another example of deadlock is where one user locks one
|
||||
table, and another user locks a second table. While both
|
||||
keep their existing locks, the first user tries to lock
|
||||
the second user's table, and the second user tries to lock
|
||||
the first user's table. Both users deadlock waiting for
|
||||
the tables to become available. The only solution to this
|
||||
is for both users to lock tables in the same order, so
|
||||
user's lock acquisitions and requests to not form a deadlock.
|
||||
|
||||
<REFSECT2 ID="R2-SQL-LOCK-3">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
Notes
|
||||
</TITLE>
|
||||
<PARA>
|
||||
LOCK is a PostgreSQL language extension.
|
||||
<para>
|
||||
LOCK works only inside transactions.
|
||||
|
||||
<note>
|
||||
<title>Bug</title>
|
||||
<para>
|
||||
If the locked table is dropped then it will be automatically
|
||||
unlocked even if a transaction is still in progress.
|
||||
</note>
|
||||
|
||||
</REFSECT2>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-LOCK-2">
|
||||
<TITLE>
|
||||
Usage
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
<ProgramListing>
|
||||
--Explicit locking to prevent deadlock:
|
||||
--
|
||||
BEGIN WORK;
|
||||
LOCK films;
|
||||
SELECT * FROM films;
|
||||
UPDATE films SET len = INTERVAL '100 minute'
|
||||
WHERE len = INTERVAL '117 minute';
|
||||
COMMIT WORK;
|
||||
</ProgramListing>
|
||||
|
||||
</REFSECT1>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-LOCK-3">
|
||||
<TITLE>
|
||||
Compatibility
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-LOCK-4">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
SQL92
|
||||
</TITLE>
|
||||
<PARA>
|
||||
There is no <command>LOCK TABLE</command> in <acronym>SQL92</acronym>,
|
||||
it uses SET TRANSACTION to specify
|
||||
concurrency level on transactions.
|
||||
</REFENTRY>
|
||||
199
doc/src/sgml/ref/move.sgml
Normal file
199
doc/src/sgml/ref/move.sgml
Normal file
@ -0,0 +1,199 @@
|
||||
<REFENTRY ID="SQL-MOVE">
|
||||
<REFMETA>
|
||||
<REFENTRYTITLE>
|
||||
MOVE
|
||||
</REFENTRYTITLE>
|
||||
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
|
||||
</REFMETA>
|
||||
<REFNAMEDIV>
|
||||
<REFNAME>
|
||||
MOVE
|
||||
</REFNAME>
|
||||
<REFPURPOSE>
|
||||
Moves cursor position
|
||||
</REFPURPOSE>
|
||||
|
||||
<REFSYNOPSISDIV>
|
||||
<REFSYNOPSISDIVINFO>
|
||||
<DATE>1998-09-01</DATE>
|
||||
</REFSYNOPSISDIVINFO>
|
||||
<SYNOPSIS>
|
||||
MOVE [ <REPLACEABLE CLASS="PARAMETER">selector</REPLACEABLE> ] { [ <REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE> | ALL ] } IN <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
|
||||
</SYNOPSIS>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-MOVE-1">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-09-01</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
Inputs
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
<VARIABLELIST>
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
<REPLACEABLE CLASS="PARAMETER">selector</REPLACEABLE>
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
|
||||
<variablelist>
|
||||
<varlistentry>
|
||||
<term>
|
||||
FORWARD
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Skip next row(s), it is assumed by default
|
||||
if selector is omitted.
|
||||
|
||||
<varlistentry>
|
||||
<term>
|
||||
BACKWARD
|
||||
</term>
|
||||
<listitem>
|
||||
<para>
|
||||
Skip previous row(s).
|
||||
|
||||
</variablelist>
|
||||
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
<REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE>
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
An unsigned integer that specify how many rows to skip.
|
||||
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
ALL
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
Skip all remaining rows.
|
||||
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
<REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
An open cursor's name.
|
||||
|
||||
</VARIABLELIST>
|
||||
|
||||
</REFSECT2>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-MOVE-2">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-09-01</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
Outputs
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
<VARIABLELIST>
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
MOVE
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
Message returned if successfully.
|
||||
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
NOTICE: PerformPortalFetch: portal <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE> not found.
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
If cursor is not declared.
|
||||
|
||||
</VARIABLELIST>
|
||||
|
||||
</REFSECT2>
|
||||
</REFSYNOPSISDIV>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-MOVE-1">
|
||||
<REFSECT1INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT1INFO>
|
||||
<TITLE>
|
||||
Description
|
||||
</TITLE>
|
||||
<PARA>
|
||||
MOVE allows a user to move cursor position for specified
|
||||
number of rows. MOVE works like fetch command: it
|
||||
fetches rows, but put them nowhere.
|
||||
|
||||
<REFSECT2 ID="R2-SQL-MOVE-3">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-04-15</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
Notes
|
||||
</TITLE>
|
||||
<PARA>
|
||||
MOVE is a <productname>Postgres</productname> language extension.
|
||||
|
||||
<para>
|
||||
Refer to FETCH statements for further description
|
||||
of valid arguments.
|
||||
Refer to DECLARE statements to declare a cursor.
|
||||
Refer to BEGIN WORK, COMMIT WORK, ROLLBACK WORK statements
|
||||
for further information about transactions.
|
||||
|
||||
</REFSECT2>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-MOVE-2">
|
||||
<TITLE>
|
||||
Usage
|
||||
</TITLE>
|
||||
<PARA>
|
||||
<ProgramListing>
|
||||
--set up and use a cursor:
|
||||
--
|
||||
BEGIN WORK;
|
||||
DECLARE liahona CURSOR
|
||||
FOR SELECT * FROM films;
|
||||
|
||||
--Skip first 5 rows:
|
||||
--
|
||||
MOVE FORWARD 5 IN liahona;
|
||||
|
||||
--Fetch 6th row in the cursor liahona:
|
||||
--
|
||||
FETCH 1 IN liahona;
|
||||
|
||||
code |title |did| date_prod|kind |len
|
||||
-----+------+---+----------+----------+------
|
||||
P_303|48 Hrs|103|1982-10-22|Action | 01:37
|
||||
|
||||
-- close the cursor liahona and commit work:
|
||||
--
|
||||
CLOSE liahona;
|
||||
COMMIT WORK;
|
||||
</ProgramListing>
|
||||
|
||||
</REFSECT1>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-MOVE-3">
|
||||
<TITLE>
|
||||
Compatibility
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-MOVE-4">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-09-01</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
SQL92
|
||||
</TITLE>
|
||||
<PARA>
|
||||
There is no SQL92 MOVE statement.
|
||||
</REFENTRY>
|
||||
161
doc/src/sgml/ref/notify.sgml
Normal file
161
doc/src/sgml/ref/notify.sgml
Normal file
@ -0,0 +1,161 @@
|
||||
<REFENTRY ID="SQL-NOTIFY">
|
||||
<REFMETA>
|
||||
<REFENTRYTITLE>
|
||||
NOTIFY
|
||||
</REFENTRYTITLE>
|
||||
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
|
||||
</REFMETA>
|
||||
<REFNAMEDIV>
|
||||
<REFNAME>
|
||||
NOTIFY
|
||||
</REFNAME>
|
||||
<REFPURPOSE>
|
||||
Signals all frontends and backends listening on a class
|
||||
</REFPURPOSE>
|
||||
|
||||
<REFSYNOPSISDIV>
|
||||
<REFSYNOPSISDIVINFO>
|
||||
<DATE>1998-09-01</DATE>
|
||||
</REFSYNOPSISDIVINFO>
|
||||
<SYNOPSIS>
|
||||
<REPLACEABLE CLASS="PARAMETER">
|
||||
</REPLACEABLE>
|
||||
NOTIFY <REPLACEABLE CLASS="PARAMETER">classname</REPLACEABLE>
|
||||
</SYNOPSIS>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-NOTIFY-1">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-09-01</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
Inputs
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
<VARIABLELIST>
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
<REPLACEABLE CLASS="PARAMETER">classname</REPLACEABLE>
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
Table or arbitrary relation class used for notification.
|
||||
|
||||
</VARIABLELIST>
|
||||
|
||||
</REFSECT2>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-NOTIFY-2">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-09-01</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
Outputs
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
<VARIABLELIST>
|
||||
<VARLISTENTRY>
|
||||
<TERM>
|
||||
NOTIFY
|
||||
</TERM>
|
||||
<LISTITEM>
|
||||
<PARA>
|
||||
Notification message from backend.
|
||||
|
||||
</VARIABLELIST>
|
||||
|
||||
</REFSECT2>
|
||||
</REFSYNOPSISDIV>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-NOTIFY-1">
|
||||
<REFSECT1INFO>
|
||||
<DATE>1998-09-01</DATE>
|
||||
</REFSECT1INFO>
|
||||
<TITLE>
|
||||
Description
|
||||
</TITLE>
|
||||
<PARA>
|
||||
NOTIFY is used to awaken all backends and consequently all
|
||||
frontends that have executed <command>LISTEN</command> on
|
||||
<replaceable class="parameter">classname</replaceable>.
|
||||
This can be used either within an instance-level rule
|
||||
as part of the action body or from a normal query.
|
||||
|
||||
<para>
|
||||
When used from within a normal query,
|
||||
this can be thought of as interprocess communication (IPC). When
|
||||
used from within a rule, this can be thought of as an alerter mechanism.
|
||||
<para>
|
||||
Notice that the mere fact that a notify has been
|
||||
executed does not imply anything in particular about the state
|
||||
of the class (e.g., that it has been updated),
|
||||
nor does the notification protocol transmit any useful information
|
||||
other than the class name.
|
||||
Therefore, all notify does is indicate that some backend wishes its peers to
|
||||
examine <replaceable class="parameter">classname</replaceable>
|
||||
in some application-specific way.
|
||||
<para>
|
||||
In fact, <replaceable class="parameter">classname</replaceable>
|
||||
need not be the name of an SQL class at all.
|
||||
It is best thought of as a condition name
|
||||
that the application programmer selects.
|
||||
<para>
|
||||
This event notification is performed through the libpq protocol
|
||||
and frontend application interface. The application program
|
||||
must call the routine <function>PQnotifies</function> in order to find out the
|
||||
name of the class to which a given
|
||||
notification corresponds.
|
||||
If this code is not included in the application,
|
||||
the event notification will be
|
||||
queued and never be processed.
|
||||
|
||||
<REFSECT2 ID="R2-SQL-NOTIFY-3">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-09-01</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
Notes
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
|
||||
</REFSECT2>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-NOTIFY-2">
|
||||
<TITLE>
|
||||
Usage
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
<ProgramListing>
|
||||
-- Configure and execute a listen/notify sequence
|
||||
-- from psql
|
||||
postgres=> create table t (i int4);
|
||||
postgres=> listen t;
|
||||
LISTEN
|
||||
postgres=> notify t;
|
||||
NOTIFY
|
||||
ASYNC NOTIFY of 't' from backend pid '10949' received
|
||||
</ProgramListing>
|
||||
|
||||
</REFSECT1>
|
||||
|
||||
<REFSECT1 ID="R1-SQL-NOTIFY-3">
|
||||
<TITLE>
|
||||
Compatibility
|
||||
</TITLE>
|
||||
<PARA>
|
||||
</PARA>
|
||||
|
||||
<REFSECT2 ID="R2-SQL-NOTIFY-4">
|
||||
<REFSECT2INFO>
|
||||
<DATE>1998-09-01</DATE>
|
||||
</REFSECT2INFO>
|
||||
<TITLE>
|
||||
SQL92
|
||||
</TITLE>
|
||||
<PARA>
|
||||
There is no NOTIFY statement in <acronym>SQL92</acronym>.
|
||||
|
||||
</REFENTRY>
|
||||
Loading…
x
Reference in New Issue
Block a user