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First files for reference pages.

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Thomas G. Lockhart 1998-05-13 05:34:00 +00:00
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commit 7402eda97c
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<!-- allfiles.sgml
-
- Complete list of usable sgml source files in this directory.
-
- -->
<!entity intro-ref system "intro-ref.sgml">
<!entity commands system "commands.sgml">
<!-- these will go into the "operators" reference chapter -->
<!entity all system "all.sgml">
<!entity any system "any.sgml">
<!entity between system "between.sgml">
<!entity in system "in.sgml">
<!entity like system "like.sgml">
<!-- these will go into the "functions" reference chapter -->
<!entity avg system "avg.sgml">
<!entity cast system "cast.sgml">
<!entity charLength system "char_length.sgml">
<!entity count system "count.sgml">
<!entity currentDate system "current_date.sgml">
<!entity currentTime system "current_time.sgml">
<!entity currentTimestamp system "current_timestamp.sgml">
<!entity currentUser system "current_user.sgml">
<!entity exists system "exists.sgml">
<!entity extract system "extract.sgml">
<!entity initcap system "initcap.sgml">
<!entity lower system "lower.sgml">
<!entity lpad system "lpad.sgml">
<!entity max system "max.sgml">
<!entity min system "min.sgml">
<!entity position system "position.sgml">
<!entity rpad system "rpad.sgml">
<!entity substring system "substring.sgml">
<!entity sum system "sum.sgml">
<!entity translate system "translate.sgml">
<!entity trim system "trim.sgml">
<!entity upper system "upper.sgml">
<!-- these are folded into create_table.sgml
<!entity check system "check.sgml">
<!entity constraints system "constraint.sgml">
<!entity default system "default.sgml">
<!entity notNull system "not_null.sgml">
<!entity primaryKey system "primary_key.sgml">
<!entity unique system "unique.sgml">
-->
<!-- these are folded into select.sgml
<!entity groupBy system "group_by.sgml">
<!entity having system "having.sgml">
<!entity orderBy system "order_by.sgml">
<!entity union system "union.sgml">
-->
<!-- these are in the "commands" reference chapter -->
<!entity alterTable system "alter_table.sgml">
<!entity alterUser system "alter_user.sgml">
<!entity begin system "begin.sgml">
<!entity close system "close.sgml">
<!entity cluster system "cluster.sgml">
<!entity commit system "commit.sgml">
<!entity copy system "copy.sgml">
<!entity createAggregate system "create_aggregate.sgml">
<!entity createDatabase system "create_database.sgml">
<!entity createFunction system "create_function.sgml">
<!entity createIndex system "create_index.sgml">
<!entity createLanguage system "create_language.sgml">
<!entity createOperator system "create_operator.sgml">
<!entity createRule system "create_rule.sgml">
<!entity createSequence system "create_sequence.sgml">
<!entity createTable system "create_table.sgml">
<!entity createTrigger system "create_trigger.sgml">
<!entity createType system "create_type.sgml">
<!entity createUser system "create_user.sgml">
<!entity createView system "create_view.sgml">
<!entity declare system "declare.sgml">
<!entity delete system "delete.sgml">
<!entity dropAggregate system "drop_aggregate.sgml">
<!entity dropDatabase system "drop_database.sgml">
<!entity dropFunction system "drop_function.sgml">
<!entity dropIndex system "drop_index.sgml">
<!entity dropLanguage system "drop_language.sgml">
<!entity dropOperator system "drop_operator.sgml">
<!entity dropRule system "drop_rule.sgml">
<!entity dropSequence system "drop_sequence.sgml">
<!entity dropTable system "drop_table.sgml">
<!entity dropTrigger system "drop_trigger.sgml">
<!entity dropType system "drop_type.sgml">
<!entity dropUser system "drop_user.sgml">
<!entity dropView system "drop_view.sgml">
<!entity explain system "explain.sgml">
<!entity fetch system "fetch.sgml">
<!entity grant system "grant.sgml">
<!entity insert system "insert.sgml">
<!entity listen system "listen.sgml">
<!entity load system "load.sgml">
<!entity lock system "lock.sgml">
<!entity move system "move.sgml">
<!entity notify system "notify.sgml">
<!entity reset system "reset.sgml">
<!entity revoke system "revoke.sgml">
<!entity rollback system "rollback.sgml">
<!entity select system "select.sgml">
<!entity set system "set.sgml">
<!entity show system "show.sgml">
<!entity update system "update.sgml">
<!entity vacuum system "vacuum.sgml">

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<REFENTRY ID="SQL-ALTERTABLE-1">
<REFMETA>
<REFENTRYTITLE>
ALTER TABLE
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>
ALTER TABLE
</REFNAME>
<REFPURPOSE>
Modifies table properties
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
ALTER TABLE <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>
[*] ADD [COLUMN] <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> <REPLACEABLE CLASS="PARAMETER">type</REPLACEABLE>
ALTER TABLE <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>
[*] RENAME [COLUMN] <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> TO <REPLACEABLE CLASS="PARAMETER">newcolumn</REPLACEABLE>
ALTER TABLE <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>
RENAME TO <REPLACEABLE CLASS="PARAMETER">newtable</REPLACEABLE>
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-ALTERTABLE-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER"> table </REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
The name of an existing table to alter.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER"> column </REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
Name of a new or existing column.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER"> type </REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
Type of the new column.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER"> newcolumn </REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
New name for an existing column.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER"> newtable </REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
New name for an existing column.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-ALTERTABLE-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>status</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>ALTER</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
Message returned from column or table renaming.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>NEW</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
Message returned from column addition.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>ERROR</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
Message returned if table or column is not available.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-ALTERTABLE-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
ALTER TABLE changes the definition of an existing table.
The new columns and their types are specified in the same style
and with the the same restrictions as in CREATE TABLE.
The RENAME clause causes the name of a table or column
to change without changing any of the data contained in
the affected table. Thus, the table or column will
remain of the same type and size after this command is
executed.
<PARA>
You must own the table in order to change its schema.
</PARA>
<REFSECT2 ID="R2-SQL-ALTERTABLE-3">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Notes
</TITLE>
<PARA>
The keyword COLUMN is noise and can be omitted.
<PARA>
ALTER TABLE/RENAME is a PostgreSQL language extension.
<PARA>
<Quote>[*]</Quote> following a name of a table indicates that statement
should be run over that table and all tables below it in the
inheritance hierarchy.
Refer to PostgreSQL User's Guide for further
information on inheritance.
<PARA>
Refer to the CREATE TABLE reference for further description
of valid arguments.
</REFSECT2>
</REFSECT1>
<REFSECT1 ID="R1-SQL-ALTERTABLE-2">
<TITLE>
Usage
</TITLE>
<PARA>
To add a column of type VARCHAR to a table:
<ProgramListing>
ALTER TABLE distributors ADD COLUMN address VARCHAR(30);
</ProgramListing>
<PARA>
To rename an existing column:
<ProgramListing>
ALTER TABLE distributors RENAME COLUMN address TO city;
</ProgramListing>
<PARA>
To rename an existing table:
<ProgramListing>
ALTER TABLE distributors RENAME TO suppliers;
</ProgramListing>
</REFSECT1>
<REFSECT1 ID="R1-SQL-ALTERTABLE-3">
<TITLE>
Compatibility
</TITLE>
<REFSECT2 ID="R2-SQL-ALTERTABLE-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
SQL92
</TITLE>
<PARA>
SQL92 specifies some additional capabilities for ALTER TABLE
statement which are not yet directly supported by <ProductName>Postgres</ProductName>:
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<Synopsis>
ALTER TABLE <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE> ALTER [COLUMN] <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE>
SET DEFAULT <REPLACEABLE CLASS="PARAMETER">default</REPLACEABLE>
ALTER TABLE <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE> ALTER [COLUMN] <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE>
ADD [CONSTRAINT <REPLACEABLE CLASS="PARAMETER">constraint</REPLACEABLE>] <REPLACEABLE CLASS="PARAMETER">table-constraint</REPLACEABLE>
</Synopsis>
</TERM>
<LISTITEM>
<PARA>
Puts the default value or constraint specified into the
definition of column in the table. See CREATE TABLE for the
syntax of the default and table-constraint clauses.
If a default clause already exists, it will be replaced by
the new definition. If any constraints on this column already
exist, they will be retained using a boolean AND with the new
constraint.
<PARA>
Currently, to set new default constraints on an existing column
the table must be recreated and reloaded:
<ProgramListing>
CREATE TABLE temp AS SELECT * FROM distributors;
DROP TABLE distributors;
CREATE TABLE distributors (
did DECIMAL(3) DEFAULT 1,
name VARCHAR(40) NOT NULL,
city VARCHAR(30)
);
INSERT INTO distributors SELECT * FROM temp;
DROP TABLE temp;
</ProgramListing>
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<Synopsis>
ALTER TABLE <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>
DROP DEFAULT <REPLACEABLE CLASS="PARAMETER">default</REPLACEABLE>
ALTER TABLE <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>
DROP CONSTRAINT <REPLACEABLE CLASS="PARAMETER">constraint</REPLACEABLE> { RESTRICT | CASCADE }
</Synopsis>
</TERM>
<LISTITEM>
<PARA>
Removes the default value specified by default or the rule
specified by constraint from the definition of a table.
If RESTRICT is specified only a constraint with no dependent
constraints can be destroyed.
If CASCADE is specified, Any constraints that are dependent on
this constraint are also dropped.
<PARA>
Currently, to remove a default value or constraints on an
existing column the table must be recreated and reloaded:
<ProgramListing>
CREATE TABLE temp AS SELECT * FROM distributors;
DROP TABLE distributors;
CREATE TABLE distributors AS SELECT * FROM temp;
DROP TABLE temp;
</ProgramListing>
<VARLISTENTRY>
<TERM>
<Synopsis>
ALTER TABLE <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>
DROP [COLUMN] <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> { RESTRICT | CASCADE }
</Synopsis>
</TERM>
<LISTITEM>
<PARA>
Removes a column from a table.
If RESTRICT is specified only a column with no dependent
objects can be destroyed.
If CASCADE is specified, all objects that are dependent on
this column are also dropped.
<PARA>
Currently, to remove an existing column the table must be
recreated and reloaded:
<ProgramListing>
CREATE TABLE temp AS SELECT did, city FROM distributors;
DROP TABLE distributors;
CREATE TABLE distributors (
did DECIMAL(3) DEFAULT 1,
name VARCHAR(40) NOT NULL,
);
INSERT INTO distributors SELECT * FROM temp;
DROP TABLE temp;
</ProgramListing>
</PARA>
</VARIABLELIST>
</REFENTRY>
<!--
<REPLACEABLE CLASS="PARAMETER">
</REPLACEABLE>
<ReturnValue></ReturnValue>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>&bull;
</TERM>
<LISTITEM>
<PARA>
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
<PARA>
</PARA>
-->

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<REFENTRY ID="SQL-ALTERUSER-1">
<REFMETA>
<REFENTRYTITLE>
ALTER USER
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>
ALTER USER
</REFNAME>
<REFPURPOSE>
Modifies user account information
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<synopsis>
ALTER USER <replaceable class="PARAMETER">username</replaceable>
[WITH PASSWORD <replaceable class="PARAMETER">password</replaceable>]
[CREATEDB | NOCREATEDB]
[CREATEUSER | NOCREATEUSER]
[IN GROUP <replaceable class="PARAMETER">groupname</replaceable> [, ...] ]
[VALID UNTIL '<replaceable class="PARAMETER">abstime</replaceable>']
</synopsis>
<REFSECT2 ID="R2-SQL-ALTERUSER-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
Refer to CREATE USER statement for a detailed description of each
clause.
</para>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER"> username </REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
The Postgres account name of the user whose details are to be altered.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER"> password </REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
The new password to be used for this account.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER"> groupname </REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
The name of an access group into which this account is to be put.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER"> abstime </REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
The date (and, optionally, the time) at which this user's access is to be terminated.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-ALTERUSER-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>status</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>ALTER USER</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
Message returned if the alteration was successful.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>ERROR: alterUser: user "username" does not exist</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
Error message returned if the user specified doesn't
exist.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</para>
</listitem>
</varlistentry>
</variablelist>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-ALTERUSER-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
ALTER USER is used to change the attributes of a user's
PostgreSQL account. Please note that it is not possible
to alter a user's "usesysid" via the alter user
statement. Also, it is only possible for the PostgreSQL
user or any user with read and modify permissions on
"pg_shadow" to alter user passwords.
</PARA>
<para>
If any of the clauses of the alter user statement are
omitted, the corresponding value in the "pg_shadow" table
is left unchanged.
</para>
<REFSECT2 ID="R2-SQL-ALTERUSER-3">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Notes
</TITLE>
<PARA>
ALTER USER statement is a PostgreSQL language extension.
</para>
<para>
Refer to CREATE/DROP USER statements to create/remove an user
account.
</para>
<para>
At the current release (6.3.2), the IN GROUP clause is parsed
but has no effect. When it is fully implemented, it is
intended to modify the pg_group relation.
</para>
</REFSECT2>
</refsect1>
<REFSECT1 ID="R1-SQL-ALTERUSER-2">
<TITLE>
Usage
</TITLE>
<PARA>
Change a user password
</PARA>
<ProgramListing>
ALTER USER davide WITH PASSWORD hu8jmn3;
</ProgramListing>
<para>
Change a user's valid until date
</para>
<ProgramListing>
ALTER USER manuel VALID UNTIL 'Jan 31 2030';
</ProgramListing>
<para>
Change a user's valid until date, specifying that his
authorisation should expire at midday on 4th May 1998 using
the time zone which is one hour ahead of UTC
</para>
<ProgramListing>
ALTER USER chris VALID UNTIL 'May 4 12:00:00 1998 +1';
</ProgramListing>
<para>
Give a user the ability to create other users and new databases.
</para>
<programlisting>
ALTER USER miriam CREATEUSER CREATEDB;
</programlisting>
<para>
Place a user in two groups
</para>
<programlisting>
ALTER USER miriam IN GROUP sales, payroll;
</programlisting>
</REFSECT1>
<REFSECT1 ID="R1-SQL-ALTERUSER-3">
<TITLE>
Compatibility
</TITLE>
<PARA>
</PARA>
<REFSECT2 ID="R2-SQL-ALTERUSER-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
SQL92
</TITLE>
<PARA>
There is no ALTER USER statement in SQL92. The standard leaves
the definition of users to the implementation.
</PARA>
</refsect1>
</REFENTRY>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
sgml-parent-document:nil
sgml-default-dtd-file:"../reference.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:"/usr/lib/sgml/catalog"
sgml-local-ecat-files:nil
End:
-->

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<REFENTRY ID="SQL-BEGINWORK-1">
<REFMETA>
<REFENTRYTITLE>
BEGIN WORK
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>
BEGIN WORK
</REFNAME>
<REFPURPOSE>
Begins a transaction
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
BEGIN { WORK | TRANSACTION }
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-BEGINWORK-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>
None
</ReturnValue>
</TERM>
<LISTITEM>
<para></para>
</LISTITEM>
</varlistentry>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-BEGINWORK-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
status
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>BEGIN</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
This signifies that a new transaction has been started.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>
NOTICE: BeginTransactionBlock and not in default state
</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
This indicates that a transaction was already in progress.
<comment>
What happens to command queries already run
in the transaction? Does this have no effect, or does
it restart the transaction?
</comment>
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</para>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-BEGINWORK-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<para>
BEGIN begins a user transaction which PostgreSQL will
guarantee is serialisable with respect to all concurrently
executing transactions. PostgreSQL uses two-phase locking
to perform this task. If the transaction is committed,
PostgreSQL will ensure either that all updates are done orelse
that none of
them are done. Transactions have the standard ACID
(atomic, consistent, isolatable, and durable) property.
</para>
<REFSECT2 ID="R2-SQL-BEGINWORK-3">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Notes
</TITLE>
<PARA>
The keyword TRANSACTION is just a cosmetic alternative to WORK.
Neither keyword need be specified.
</PARA>
<PARA>
BEGIN statement is a PostgreSQL language extension.
</PARA>
<PARA>
Refer to the LOCK statement for further information about locking
tables inside a transaction.
</PARA>
<PARA>
Use COMMIT or ROLLBACK to terminate a transaction.
</PARA>
</REFSECT2>
<REFSECT1 ID="R1-SQL-BEGINWORK-2">
<TITLE>
Usage
</TITLE>
<PARA>To begin a user transaction:
</PARA>
<ProgramListing>
BEGIN WORK;
</ProgramListing>
</REFSECT1>
<REFSECT1 ID="R1-SQL-BEGINWORK-3">
<TITLE>
Compatibility
</TITLE>
<PARA>
</PARA>
<REFSECT2 ID="R2-SQL-BEGINWORK-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
SQL92
</TITLE>
<PARA>
There is no explicit "BEGIN WORK" in SQL92; transaction initiation
is always implicit and it terminates either with a COMMIT or with
a ROLLBACK statement.
</PARA>
</refsect2>
</refsect1>
</REFENTRY>
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<REFENTRY ID="SQL-CLOSE-1">
<REFMETA>
<REFENTRYTITLE>
CLOSE
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>
CLOSE
</REFNAME>
<REFPURPOSE>
Close a cursor
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
CLOSE <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-CLOSE-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>
<REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
The name of an open cursor to close.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-CLOSE-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>
CLOSE
</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
Message returned if the cursor is successfully closed.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>
NOTICE PerformPortalClose: portal "<REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>" not found
</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
This warning is given if
<REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE> is not
declared or has already been closed.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-CLOSE-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
CLOSE frees the resources associated with an open cursor.
After the cursor is closed, no subsequent operations
are allowed on it. A cursor should be closed when it is
no longer needed.
</PARA>
<PARA>
An implicit close is executed for every open cursor when a
transaction is terminated by COMMIT or ROLLBACK.
</PARA>
<REFSECT2 ID="R2-SQL-CLOSE-3">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Notes
</TITLE>
<PARA>
PostgreSQL does not have an explicit OPEN cursor statement;
a cursor is considered open when it is DECLAREd.
Use DECLARE to declare a cursor.
</PARA>
</REFSECT2>
</refsect1>
<REFSECT1 ID="R1-SQL-CLOSE-2">
<TITLE>
Usage
</TITLE>
<PARA>
Close the cursor liahona:
</PARA>
<ProgramListing>
CLOSE liahona;
</ProgramListing>
</REFSECT1>
<REFSECT1 ID="R1-SQL-CLOSE-3">
<TITLE>
Compatibility
</TITLE>
<PARA>
</PARA>
<REFSECT2 ID="R2-SQL-CLOSE-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
SQL92
</TITLE>
<PARA>
CLOSE is fully compatibile with SQL92.
</PARA>
</refsect2>
</refsect1>
</REFENTRY>
<!-- Keep this comment at the end of the file
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mode: sgml
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<REFENTRY ID="SQL-CLUSTER-1">
<REFMETA>
<REFENTRYTITLE>
CLUSTER
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>
CLUSTER
</REFNAME>
<REFPURPOSE>
Gives storage clustering advice to PostgreSQL
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
CLUSTER <REPLACEABLE CLASS="PARAMETER">indexname</REPLACEABLE> ON <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-CLUSTER-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>
<REPLACEABLE CLASS="PARAMETER">indexname</REPLACEABLE>
</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
The name of an index.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>
<REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>
</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
The name of a table.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-CLUSTER-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>CLUSTER</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
The clustering was done successfully.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>ERROR: relation &lt;<REPLACEABLE CLASS="PARAMETER">tablerelation_number</REPLACEABLE>&gt; inherits "invoice"</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
???
<comment>
This is not documented anywhere. It seems not to be possible to
cluster a table that is inherited.
</comment>
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>ERROR: Relation x does not exist!</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
???
<comment>
The relation complained of was not shown in the error message,
which contained a random string instead of the relation name.
</comment>
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-CLUSTER-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
This command instructs PostgreSQL to cluster the class specified
by <replaceable class="parameter">classname</replaceable> approximately
based on the index specified by
<replaceable class="parameter">indexname</replaceable>. The index must
already have been defined on <replaceable class="parameter">classname</replaceable>.
</PARA>
<para>
When a class is clustered, it is physically reordered
based on the index information. The clustering is static.
In other words, as the class is updated, the changes are
not clustered. No attempt is made to keep new instances or
updated tuples clustered. If he wishes, the user can
recluster manually by issuing the command again.
</para>
<para>
The table is actually copied to a temporary table in index
order, then renamed back to the original name. For this
reason, all grant permissions and other indexes are lost
when clustering is performed.
</para>
<para>
In cases where you are accessing single rows randomly
within a table, the actual order of the data in the heap
table is unimportant. However, if you tend to access some
data more than others, and there is an index that groups
them together, you will benefit from using the CLUSTER
command.
</para>
<para>
Another place CLUSTER is good is in cases where you use an
index to pull out several rows from a table. If you are
requesting a range of indexed values from a table, or a
single indexed value that has multiple rows that match,
CLUSTER will help because once the index identifies the
heap page for the first row that matches, all other rows
that match are probably already on the same heap page,
saving disk accesses and speeding up the query.
</para>
<para>
There are two ways to cluster data. The first is with the
CLUSTER command, which reorders the original table with
the ordering of the index you specify. This can be slow
on large tables because the rows are fetched from the heap
in index order, and if the heap table is unordered, the
entries are on random pages, so there is one disk page
retrieved for every row moved. PostgreSQL has a cache,
but the majority of a big table will not fit in the cache.
</para>
<para>
Another way is to use
<programlisting>SELECT ... INTO TABLE temp FROM ... ORDER BY ...</programlisting>
This uses the PostgreSQL sorting code in
ORDER BY to match the index, and is much faster for
unordered data. You then drop the old table, use
<programlisting>ALTER TABLE RENAME</programlisting>
to rename 'temp' to the old name, and
recreate the b bindexes. The only problem is that oids
will not be preserved. From then on, CLUSTER should be
fast because most of the heap data has already been
ordered, and the existing index is used.
</para>
<REFSECT1 ID="R1-SQL-CLUSTER-2">
<TITLE>
Usage
</TITLE>
<PARA>
Cluster the employees relation on the basis of its salary attribute
</PARA>
<ProgramListing>
CLUSTER emp_ind ON emp
</ProgramListing>
</REFSECT1>
<REFSECT1 ID="R1-SQL-CLUSTER-3">
<TITLE>
Compatibility
</TITLE>
<PARA>
</PARA>
<REFSECT2 ID="R2-SQL-CLUSTER-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
SQL92
</TITLE>
<PARA>
There is no CLUSTER statement in SQL92.
</PARA>
</refsect2>
</refsect1>
</REFENTRY>
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<Chapter>
<Title>Commands</Title>
<Para>
</Para>
&alterTable;
&alterUser;
&begin;
&close;
&cluster;
&commit;
&copy;
&createAggregate;
&createDatabase;
&createFunction;
&createIndex;
&createLanguage;
&dropFunction;
&select;
</Chapter>
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<REFENTRY ID="SQL-COMMIT-1">
<REFMETA>
<REFENTRYTITLE>
COMMIT
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>
COMMIT
</REFNAME>
<REFPURPOSE>
Commits the current transaction
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
COMMIT [ WORK ]
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-COMMIT-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>None</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-COMMIT-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>END</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
Message returned if the transaction is successfully committed.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>NOTICE EndTransactionBlock and not inprogress/abort state
</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
If there is no transaction in progress.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-COMMIT-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
COMMIT commits the current transaction. All
changes made by the transaction become visible to others
and are guaranteed to be durable if a crash occurs.
</PARA>
<REFSECT2 ID="R2-SQL-COMMIT-3">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Notes
</TITLE>
<PARA>
The keyword WORK is noise and can be omitted.
</PARA>
<para>
Refer to ROLLBACK statements to abort a transaction.
</para>
</REFSECT2>
</refsect1>
<REFSECT1 ID="R1-SQL-COMMIT-2">
<TITLE>
Usage
</TITLE>
<PARA>
To make all changes permanent:
</PARA>
<ProgramListing>
COMMIT WORK;
</ProgramListing>
</REFSECT1>
<REFSECT1 ID="R1-SQL-COMMIT-3">
<TITLE>
Compatibility
</TITLE>
<PARA>
</PARA>
<REFSECT2 ID="R2-SQL-COMMIT-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
SQL92
</TITLE>
<PARA>
Full compatibility.
</PARA>
</refsect2>
</refsect1>
</REFENTRY>
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<REFENTRY ID="SQL-COPY-1">
<REFMETA>
<REFENTRYTITLE>
COPY
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>
COPY
</REFNAME>
<REFPURPOSE>
Copies data between files and tables
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
COPY [BINARY] <replaceable class="parameter">table</replaceable> [WITH OIDS]
TO|FROM '<replaceable class="parameter">filename</replaceable>'|stdin|stdout
[USING DELIMITERS '<replaceable class="parameter">delimiter</replaceable>']
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-COPY-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue><replaceable class="parameter">table</replaceable></ReturnValue>
</TERM>
<LISTITEM>
<PARA>
The name of a table.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue><replaceable class="parameter">delimiter</replaceable></ReturnValue>
</TERM>
<LISTITEM>
<PARA>
A character that delimits fields.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-COPY-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
Status
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>COPY</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
The copy completed successfully.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>ERROR: <replaceable>error message</replaceable></ReturnValue>
</TERM>
<LISTITEM>
<PARA>
The copy failed for the reason stated in the error message.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-COPY-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
<command>COPY</command> moves data between PostgreSQL tables and
standard Unix files. The keyword <function>BINARY</function>
changes the behavior of field formatting, as described
below. <replaceable class="parameter">Table</replaceable> is the
name of an existing table. The keyword <function>WITH
OIDS</function> copies the internal unique object id (OID) for each
row. <replaceable class="parameter">Filename</replaceable> is the
absolute Unix pathname of the file. In place of a filename, the
keywords <function>stdin</function> and <function>stdout</function>
can be used, so that input to <command>COPY</command> can be written
by a libpq application and output from <command>COPY</command> can
be read by a libpq application.
</para>
<para>
The <function>BINARY</function> keyword will force all data to be
stored/read as binary objects rather than as ASCII text. It is
somewhat faster than the normal copy command, but is not
generally portable, and the files generated are somewhat larger,
although this factor is highly dependent on the data itself. By
default, an ASCII copy uses a tab (\t) character as a delimiter.
The delimiter may also be changed to any other single character
with the keyword <function>USING DELIMITERS</function>. Characters
in data fields which happen to match the delimiter character will
be quoted.
</para>
<REFSECT2 ID="R2-SQL-COPY-3">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Notes
</TITLE>
<para>
You must have select access on any table whose values are read by
<command>COPY</command>, and either insert or update access to a
table into which values are being inserted by <command>COPY</command>.
The backend also needs appropriate Unix permissions for any file read
or written by <command>COPY</command>.
<comment>
Is this right? The man page talked of read, write and append access, which
is neither SQL nor Unix terminology.
</comment>
</para>
<para>
The keyword <function>USING DELIMITERS</function> is inaptly
named, since only a single character may be specified. (If a
group of characters is specified, only the first character is
used.)
</para>
<para>
WARNING: do not confuse <command>COPY</command> with the
<command>psql</command> instruction <command>\copy</command>.
</para>
</REFSECT2>
</refsect1>
<refsect1 ID="R1-SQL-COPY-2">
<refsect1info>
<date>1998-05-04</date>
</refsect1info>
<title>Format of output files</title>
<refsect2>
<refsect2info>
<date>1998-05-04</date>
</refsect2info>
<title>ASCII copy format</title>
<para>
When <command>COPY</command> is used without <function>BINARY</function>,
the file generated will have each instance on a single line, with each
attribute separated by the delimiter character. Embedded
delimiter characters will be preceded by a backslash character
(\). The attribute values themselves are strings generated by the
output function associated with each attribute type. The output
function for a type should not try to generate the backslash
character; this will be handled by <command>COPY</command> itself.
</para>
<para>
The actual format for each instance is
<programlisting>
&lt;attr1&gt;&lt;<replaceable class=parameter>separator</replaceable>&gt;&lt;attr2&gt;&lt;<replaceable class=parameter>separator</replaceable>&gt;...&lt;<replaceable class=parameter>separator</replaceable>&gt;&lt;attr<replaceable class="parameter">n</replaceable>&gt;&lt;newline&gt;</programlisting>
The oid is placed on the beginning of the line
if <function>WITH OIDS</function> is specified.
</para>
<para>
If <command>COPY</command> is sending its output to standard
output instead of a file, it will send a backslash(\) and a period
(.) followed immediately by a newline, on a separate line,
when it is done. Similarly, if <command>COPY</command> is reading
from standard input, it will expect a backslash (\) and a period
(.) followed by a newline, as the first three characters on a
line, to denote end-of-file. However, <command>COPY</command>
will terminate (followed by the backend itself) if a true EOF is
encountered.
</para>
<para>
The backslash character has special meaning. NULL attributes are
output as \N. A literal backslash character is output as two
consecutive backslashes. A literal tab character is represented
as a backslash and a tab. A literal newline character is
represented as a backslash and a newline. When loading ASCII data
not generated by PostgreSQL, you will need to convert backslash
characters (\) to double-backslashes (\\) to ensure that they are loaded
properly.
</para>
</refsect2>
<refsect2>
<refsect2info>
<date>1998-05-04</date>
</refsect2info>
<title>Binary copy format</title>
<para>
In the case of <command>COPY BINARY</command>, the first four
bytes in the file will be the number of instances in the file. If
this number is zero, the <command>COPY BINARY</command> command
will read until end of file is encountered. Otherwise, it will
stop reading when this number of instances has been read.
Remaining data in the file will be ignored.
</para>
<para>
The format for each instance in the file is as follows. Note that
this format must be followed <emphasis>exactly</emphasis>.
Unsigned four-byte integer quantities are called uint32 in the
table below.
</para>
<table frame="all">
<title>Contents of a binary copy file</title>
<tgroup cols="2"colsep="1" rowsep="1" align="center">
<COLSPEC COLNAME="col1">
<COLSPEC COLNAME="col2">
<spanspec namest="col1" nameend="col2" spanname="subhead">
<tbody>
<row>
<entry align="center" spanname="subhead">At the start of the file</entry>
</row>
<row>
<entry>uint32</entry>
<entry>number of tuples</entry>
</row>
<row>
<entry align="center" spanname="subhead">For each tuple</entry>
</row>
<row>
<entry>uint32</entry>
<entry>total length of tuple data</entry>
</row>
<row>
<entry>uint32</entry>
<entry>oid (if specified)</entry>
</row>
<row>
<entry>uint32</entry>
<entry>number of null attributes</entry>
</row>
<row>
<entry>[uint32</entry>
<entry>attribute number of first null attribute, counting from 0</entry>
</row>
<row>
<entry>...</entry>
<entry>...</entry>
</row>
<row>
<entry>uint32</entry>
<entry>attribute number of last null attribute]</entry>
</row>
<row>
<entry>-</entry>
<entry>&lt;tuple data&gt;</entry>
</row>
</tbody>
</tgroup>
</table>
</refsect2>
<refsect2>
<refsect2info>
<date>1998-05-04</date>
</refsect2info>
<title>Alignment of binary data</title>
<para>
On Sun-3s, 2-byte attributes are aligned on two-byte boundaries,
and all larger attributes are aligned on four-byte boundaries.
Character attributes are aligned on single-byte boundaries. On
other machines, all attributes larger than 1 byte are aligned on
four-byte boundaries. Note that variable length attributes are
preceded by the attribute's length; arrays are simply contiguous
streams of the array element type.
</para>
</refsect2>
</refsect1>
<REFSECT1 ID="R1-SQL-COPY-3">
<TITLE>
Usage
</TITLE>
<PARA>
To copy a table to standard output, using | as a delimiter
</PARA>
<ProgramListing>
COPY country TO stdout USING DELIMITERS '|';
</ProgramListing>
<PARA>
To copy data from a Unix file into a table:
</PARA>
<ProgramListing>
COPY country FROM '/usr1/proj/bray/sql/country_data';
</ProgramListing>
<PARA>
A sample of data suitable for copying into a table from <filename>stdin</filename> (so it
has the termination sequence on the last line):
</PARA>
<ProgramListing>
AF AFGHANISTAN
AL ALBANIA
DZ ALGERIA
...
ZM ZAMBIA
ZW ZIMBABWE
\.
</ProgramListing>
<PARA>
The same data, output in binary format on a Linux Intel machine.
The data is shown after filtering through the Unix utility <command>od -c</command>. The table has
three fields; the first is <classname>char(2)</classname> and the second is <classname>text</classname>. All the
rows have a null value in the third field). Notice how the <classname>char(2)</classname>
field is padded with nulls to four bytes and the text field is
preceded by its length:
</PARA>
<ProgramListing>
355 \0 \0 \0 027 \0 \0 \0 001 \0 \0 \0 002 \0 \0 \0
006 \0 \0 \0 A F \0 \0 017 \0 \0 \0 A F G H
A N I S T A N 023 \0 \0 \0 001 \0 \0 \0 002
\0 \0 \0 006 \0 \0 \0 A L \0 \0 \v \0 \0 \0 A
L B A N I A 023 \0 \0 \0 001 \0 \0 \0 002 \0
\0 \0 006 \0 \0 \0 D Z \0 \0 \v \0 \0 \0 A L
G E R I A
... \n \0 \0 \0 Z A M B I A 024 \0
\0 \0 001 \0 \0 \0 002 \0 \0 \0 006 \0 \0 \0 Z W
\0 \0 \f \0 \0 \0 Z I M B A B W E
</ProgramListing>
</refsect1>
<refsect1 ID="R1-SQL-COPY-4">
<title>See also</title>
<para>
insert(l), create table(l), vacuum(l), libpq.
</para>
</refsect1>
<refsect1 ID="R1-SQL-COPY-5">
<title>Bugs</title>
<para>
<command>COPY</command> stops operation at the first error. This
should not lead to problems in the event of a copy from, but the
target relation will, of course, be partially modified in a copy
to. The <command>VACUUM</command> query should be used to clean up
after a failed copy.
</para>
<para>
Because Postgres' current directory is not the same as the user's
working directory, the result of copying to a file "foo" (without
additional path information) may yield unexpected results for the
naive user. In this case, "foo" will wind up in $PGDATA/foo. In
general, the full pathname should be used when specifying files to
be copied.
</para>
<para>
Files used as arguments to the copy command must reside on or be
accessible to the database server machine by being either on
local disks or on a networked file system.
</para>
<para>
When a TCP/IP connection from one machine to another is used, and a
target file is specified, the target file will be written on the
machine where the backend is running rather than the user's
machine.
</para>
</refsect1>
<REFSECT1 ID="R1-SQL-COPY-6">
<TITLE>
Compatibility
</TITLE>
<PARA>
</PARA>
<REFSECT2 ID="R2-SQL-COPY-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
SQL92
</TITLE>
<PARA>
There is no COPY statement in SQL92.
</PARA>
</refsect2>
</refsect1>
</REFENTRY>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
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sgml-local-ecat-files:nil
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<REFENTRY ID="SQL-CREATEAGGREGATE-1">
<REFMETA>
<REFENTRYTITLE>
CREATE AGGREGATE
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<comment>This entry needs a lot of work, especially some
usefully complex examples. Since I don't yet understand it, I
haven't done this.</comment>
<REFNAMEDIV>
<REFNAME>
CREATE AGGREGATE
</REFNAME>
<REFPURPOSE>
Defines a new aggregate function
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
CREATE AGGREGATE <REPLACEABLE CLASS="PARAMETER">name</REPLACEABLE> [AS]
([ SFUNC1 = <REPLACEABLE CLASS="PARAMETER">state_transition_function1</REPLACEABLE>
, BASETYPE = <REPLACEABLE CLASS="PARAMETER">data_type</REPLACEABLE>
, STYPE1 = <REPLACEABLE CLASS="PARAMETER">sfunc1_return_type</REPLACEABLE> ]
[, SFUNC2 = <REPLACEABLE CLASS="PARAMETER">state_transition_function2</REPLACEABLE>
, STYPE2 = <REPLACEABLE CLASS="PARAMETER">sfunc2_return_type</REPLACEABLE> ]
[, FINALFUNC = <REPLACEABLE CLASS="PARAMETER">final_function</REPLACEABLE> ]
[, INITCOND1 = <REPLACEABLE CLASS="PARAMETER">initial_condition1</REPLACEABLE> ]
[, INITCOND2 = <REPLACEABLE CLASS="PARAMETER">initial_condition2</REPLACEABLE> ]
)
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-CREATEAGGREGATE-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<variablelist>
<varlistentry>
<term></term>
<listitem>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">name</REPLACEABLE>
</TERM>
<LISTITEM>
<para>
The name of an aggregate function to create.
</para>
</LISTITEM>
</varlistentry>
<varlistentry>
<term>
<REPLACEABLE CLASS="PARAMETER">state_transition_function1</REPLACEABLE>
</term>
<listitem>
<para>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<REPLACEABLE CLASS="PARAMETER">data_type</REPLACEABLE>
</term>
<listitem>
<para>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<REPLACEABLE CLASS="PARAMETER">sfunc1_return_type</REPLACEABLE>
</term>
<listitem>
<para>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<REPLACEABLE CLASS="PARAMETER">state-transition_function2</REPLACEABLE>
</term>
<listitem>
<para>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<REPLACEABLE CLASS="PARAMETER">sfunc2_return_type</REPLACEABLE>
</term>
<listitem>
<para>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<REPLACEABLE CLASS="PARAMETER">final_function</REPLACEABLE>
</term>
<listitem>
<para>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<REPLACEABLE CLASS="PARAMETER">initial_condition1</REPLACEABLE>
</term>
<listitem>
<para>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<REPLACEABLE CLASS="PARAMETER">initial_condition2</REPLACEABLE>
</term>
<listitem>
<para>
</para>
</listitem>
</varlistentry>
</variablelist>
</PARA>
</listitem>
</varlistentry>
</variablelist>
</REFSECT2>
<REFSECT2 ID="R2-SQL-CREATEAGGREGATE-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>CREATE</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
Message returned if the command completes successfully.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-CREATEAGGREGATE-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
An aggregate function can use up to three functions, two
state transition functions, X1 and X2:
X1( internal-state1, next-data_item ) ---> next-internal-state1
X2( internal-state2 ) ---> next-internal-state2
and a final calculation function, F:
F(internal-state1, internal-state2) ---> aggregate-value
These functions are required to have the following properties:
<itemizedlist>
<listitem>
<para>
The arguments to state-transition-function-1 must
be (stype1,basetype), and its return value must be
stype1.
</para>
</listitem>
<listitem>
<para>
The argument and return value of state-transition-
function-2 must be stype2.
</para>
</listitem>
<listitem>
<para>
The arguments to the final-calculation-function
must be (stype1,stype2), and its return value must
be a POSTGRES base type (not necessarily the same
as basetype.
</para>
</listitem>
<listitem>
<para>
The final-calculation-function should be specified
if and only if both state-transition functions are
specified.
</para
</listitem>
</itemizedlist>
</PARA>
<para>
Note that it is possible to specify aggregate functions
that have varying combinations of state and final functions.
For example, the "count" aggregate requires sfunc2
(an incrementing function) but not sfunc1 or finalfunc,
whereas the "sum" aggregate requires sfunc1 (an addition
function) but not sfunc2 or finalfunc and the "average"
aggregate requires both of the above state functions as
well as a finalfunc (a division function) to produce its
answer. In any case, at least one state function must be
defined, and any sfunc2 must have a corresponding initcond2.
</para>
<para>
Aggregates also require two initial conditions, one for
each transition function. These are specified and stored
in the database as fields of type text.
</para>
<REFSECT2 ID="R2-SQL-CREATEAGGREGATE-3">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Notes
</TITLE>
<PARA>
CREATE AGGREGATE function is a PostgreSQL language extension.
</PARA>
<para>
Refer to DROP AGGREGATE function to drop aggregate functions.
</para>
</REFSECT2>
<REFSECT1 ID="R1-SQL-CREATEAGGREGATE-2">
<TITLE>
Usage
</TITLE>
<PARA>
</PARA>
<ProgramListing>
</ProgramListing>
</REFSECT1>
<REFSECT1 ID="R1-SQL-CREATEAGGREGATE-3">
<TITLE>
Compatibility
</TITLE>
<PARA>
</PARA>
<REFSECT2 ID="R2-SQL-CREATEAGGREGATE-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
SQL92
</TITLE>
<PARA>
There is no CREATE AGGREGATE function on SQL92.
</PARA>
</REFENTRY>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
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<REFENTRY ID="SQL-CREATEDATABASE-1">
<REFMETA>
<REFENTRYTITLE>
CREATE DATABASE
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>
CREATE DATABASE
</REFNAME>
<REFPURPOSE>
Creates a new database
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
CREATE DATABASE <REPLACEABLE CLASS="PARAMETER">name</REPLACEABLE> [WITH LOCATION = '<replaceable class="parameter">dbpath</replaceable>']
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-CREATEDATABASE-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">name</replaceable>
</TERM>
<LISTITEM>
<PARA>
The name of a database to create.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">dbpath</replaceable>
</TERM>
<LISTITEM>
<PARA>
An alternate location can be specified as either an
environment variable known to the backend server
(e.g. '<envar>PGDATA2</envar>') or as an absolute path name
(e.g. '<filename>/usr/local/pgsql/data</filename>').
In either case, the location must be pre-configured
by <command>initlocation</command>.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-CREATEDATABASE-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>CREATEDB</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
Message returned if the command completes successfully.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>WARN: createdb: database "<replaceable class="parameter">name</replaceable>" already exists.</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
This occurs if <replaceable class="parameter">database</replaceable> specified already exists.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>ERROR: Unable to create database directory <replaceable class="parameter">directory</replaceable>
</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
There was a problem with creating the required directory; this operation will
need permissions for the <literal>postgres</literal> user on the specified location.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-CREATEDATABASE-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
CREATE DATABASE creates a new PostgreSQL database.
The creator becomes the administrator of the new database.
</PARA>
<REFSECT2 ID="R2-SQL-CREATEDATABASE-3">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Notes
</TITLE>
<PARA>
CREATE DATABASE statement is a PostgreSQL language extension.
</PARA>
<para>
Refer to DROP DATABASE statement to remove a database.
</para>
</REFSECT2>
<REFSECT1 ID="R1-SQL-CREATEDATABASE-2">
<TITLE>
Usage
</TITLE>
<PARA>
To create a new database:
</PARA>
<ProgramListing>
CREATE DATABASE lusiadas;
</ProgramListing>
<PARA>
To create a new database in <filename>~/private_db</filename>:
</PARA>
<ProgramListing>
$ mkdir private_db
$ initlocation ~/private_db
<computeroutput>Creating Postgres database system directory /home/olly/private_db/base</computeroutput>
$ chmod a+rx private_db
$ chmod a+rwx private_db/base
$ psql
<computeroutput>Welcome to the POSTGRESQL interactive sql monitor:
Please read the file COPYRIGHT for copyright terms of POSTGRESQL
type \? for help on slash commands
type \q to quit
type \g or terminate with semicolon to execute query
You are currently connected to the database: template1
template1=></computeroutput> <userinput>create database elsewhere with location = '/home/olly/private_db';</userinput>
<computeroutput>CREATEDB</computeroutput>
</ProgramListing>
</REFSECT1>
<REFSECT1 ID="R1-SQL-CREATEDATABASE-3">
<TITLE>
Bugs
</TITLE>
<PARA>
Where an ordinary user cannot change the ownership of files to other users
(which is correct from a security point of view), there is no easy way
to give the postgres backend access to files in a database at a
non-standard location without
giving similar access to all users. The situation shown in the usage
example makes <filename>/home/olly/private_db</filename> world-accessible.
</PARA>
<para>
If, on the other hand, the user gets the system administrator to give
file ownership to the <literal>postgres</literal> superuser and restrict access, he will
then be unable to delete the <filename><replaceable>directory</replaceable>/base</filename> directory.
</para>
<comment>
initlocation does not create a PG_VERSION file in the specified location.
How will PostgreSQL handle the situation if it is upgraded to an
incompatible database version?
</comment>
</refsect1>
<REFSECT1 ID="R1-SQL-CREATEDATABASE-4">
<TITLE>
Compatibility
</TITLE>
<PARA>
</PARA>
<REFSECT2 ID="R2-SQL-CREATEDATABASE-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
SQL92
</TITLE>
<PARA>
There is no <command>CREATE DATABASE</command> statement on SQL92.
</PARA>
<para>
The equivalent command in standard SQL is <command>CREATE SCHEMA</command>.
</para>
</refsect2>
</refsect1>
</REFENTRY>
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<REFENTRY ID="SQL-CREATEFUNCTION-1">
<REFMETA>
<REFENTRYTITLE>
CREATE FUNCTION
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>
CREATE FUNCTION
</REFNAME>
<REFPURPOSE>
Defines a new function
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
CREATE FUNCTION <replaceable class="parameter">name</replaceable> ([<replaceable class="parameter">ftype</replaceable> [, ...]])
RETURNS <replaceable class="parameter">rtype</replaceable>
AS <replaceable class="parameter">path</replaceable>
LANGUAGE '<replaceable class="parameter">langname</replaceable>'
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-CREATEFUNCTION-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">name</replaceable>
</TERM>
<LISTITEM>
<PARA>
The name of a function to create.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">ftype</replaceable>
</TERM>
<LISTITEM>
<PARA>
The data type of function arguments.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">rtype</replaceable>
</TERM>
<LISTITEM>
<PARA>
The return data type.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">path</replaceable>
</TERM>
<LISTITEM>
<PARA>
May be either an SQL-query or an absolute path to an
object file.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">langname</replaceable>
</TERM>
<LISTITEM>
<PARA>
may be '<literal>c</literal>', '<literal>sql</literal>', '<literal>internal</literal>' or '<replaceable class="parameter">plname</replaceable>'.
(where '<replaceable class="parameter">plname</replaceable>' is the language name of a created procedural
language. See <command>CREATE LANGUAGE</command> for details).
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-CREATEFUNCTION-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>CREATE</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
This is returned if the command completes successfully.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-CREATEFUNCTION-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
With this command, a PostgreSQL user can register a function
with PostgreSQL. Subsequently, this user is treated as the
owner of the function.
</PARA>
<REFSECT2 ID="R2-SQL-CREATEFUNCTION-3">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Notes
</TITLE>
<PARA>
Refer to <citetitle>PostgreSQL User's Guide</citetitle> chapter 6 for further information.
<comment>This reference needs to be corrected.</comment>
</PARA>
<PARA>
Refer to the <citerefentry>
<refentrytitle>DROP FUNCTION</refentrytitle>
</citerefentry> statement to drop functions.
</PARA>
</REFSECT2>
<REFSECT1 ID="R1-SQL-CREATEFUNCTION-2">
<TITLE>
Usage
</TITLE>
<PARA>
To create a simple SQL function:
</PARA>
<ProgramListing>
CREATE FUNCTION one() RETURNS int4
AS 'SELECT 1 AS RESULT'
LANGUAGE 'sql';
SELECT one() AS answer;
<computeroutput>answer
------
1 </computeroutput>
</ProgramListing>
<para>
To create a C function, calling a routine from a user-created
shared library. This particular routine calculates a check
digit and returns TRUE if the check digit in the function parameters
is correct. It is intended for use in a CHECK contraint.
</para>
<programlisting>
<userinput>CREATE FUNCTION ean_checkdigit(bpchar, bpchar) RETURNS bool
AS '/usr1/proj/bray/sql/funcs.so' LANGUAGE 'c';
CREATE TABLE product
(
id char(8) PRIMARY KEY,
eanprefix char(8) CHECK (eanprefix ~ '[0-9]{2}-[0-9]{5}')
REFERENCES brandname(ean_prefix),
eancode char(6) CHECK (eancode ~ '[0-9]{6}'),
CONSTRAINT ean CHECK (ean_checkdigit(eanprefix, eancode))
);</userinput>
</programlisting>
</REFSECT1>
<REFSECT1 ID="R1-SQL-CREATEFUNCTION-3">
<TITLE>
Bugs
</TITLE>
<PARA>
A C function cannot return a set of values.
</PARA>
</REFSECT1>
<REFSECT1 ID="R1-SQL-CREATEFUNCTION-4">
<TITLE>
Compatibility
</TITLE>
<PARA>
The CREATE FUNCTION statement is a PostgreSQL language extension.
</PARA>
<REFSECT2 ID="R2-SQL-CREATEFUNCTION-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
SQL/PSM<footnote>
<para>
PSM stands for Persistent Stored Modules, it is a procedural
language and it was originally hoped that PSM would be ratified
as an official standard by late 1996. However PSM will
eventually become a standard.
</para>
</footnote>
</TITLE>
<para>
The SQL/PSM CREATE FUNCTION statement has the following syntax:
<programlisting>
CREATE FUNCTION <replaceable class="parameter">name</replaceable>
( [ [IN|OUT|INOUT] <replaceable class="parameter">parm</replaceable> <replaceable class="parameter">type</replaceable> [, ...] ])
RETURNS <replaceable class="parameter">rtype</replaceable>
LANGUAGE '<replaceable class="parameter">langname</replaceable>'
ESPECIFIC <replaceable class="parameter">routine</replaceable>
<replaceable class="parameter">SQL-statement</replaceable>
</programlisting>
</para>
</refsect2>
</refsect1>
</REFENTRY>
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<REFENTRY ID="SQL-CREATEINDEX-1">
<REFMETA>
<REFENTRYTITLE>
CREATE INDEX
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>
CREATE INDEX
</REFNAME>
<REFPURPOSE>
Constructs a secondary index
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
CREATE [UNIQUE] INDEX <replaceable class="parameter">index_name</replaceable>
ON <replaceable class="parameter">table</replaceable> [USING <replaceable class="parameter">acc_name</replaceable> ]
( <replaceable class="parameter">column</replaceable> [<replaceable class="parameter">ops_name</replaceable>] [, ...] )
CREATE [UNIQUE] INDEX <replaceable class="parameter">index_name</replaceable>
ON <replaceable class="parameter">table</replaceable> [USING <replaceable class="parameter">acc_name</replaceable> ]
( <replaceable class="parameter">func_name</replaceable>( <replaceable class="parameter">column</replaceable> [, ... ]) <replaceable class="parameter">ops_name</replaceable> )
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-CREATEINDEX-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<function>UNIQUE</function>
</TERM>
<LISTITEM>
<PARA>
<function>UNIQUE</function> causes the system to check for
duplicate values when the index is created (if data
already exist) and each time data is added. Attempts to
insert or update non-duplicate data will generate an
error.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">index_name</replaceable>
</TERM>
<LISTITEM>
<PARA>
The name of the index to be created.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">table</replaceable>
</TERM>
<LISTITEM>
<PARA>
The name of the table to be indexed.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">acc_name</replaceable>
</TERM>
<LISTITEM>
<PARA>
the name of the access method which is to be used for
the index. The default access method is BTREE.
Postgres provides three access methods for secondary indices:
<variablelist>
<varlistentry>
<term>BTREE</term>
<listitem>
<para>
an implementation of the Lehman-Yao
high-concurrency btrees.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>RTREE</term>
<listitem>
<para>implements standard rtrees using Guttman's
quadratic split algorithm.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>HASH</term>
<listitem>
<para>
an implementation of Litwin's linear hashing.
</para>
</listitem>
</varlistentry>
</variablelist>
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">column</replaceable>
</TERM>
<LISTITEM>
<PARA>
The name of a column of the table.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">ops_name</replaceable>
</TERM>
<LISTITEM>
<PARA>
An associated operator class.
The following select list returns all ops_names:
<programlisting>
SELECT am.amname AS acc_name,
opc.opcname AS ops_name,
opr.oprname AS ops_comp
FROM pg_am am, pg_amop amop,
pg_opclass opc, pg_operator opr
WHERE amop.amopid = am.oid AND
amop.amopclaid = opc.oid AND
amop.amopopr = opr.oid
ORDER BY acc_name, ops_name, ops_comp
</programlisting>
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">func_name</replaceable>
</TERM>
<LISTITEM>
<PARA>
A user-defined function, which returns a value that can
be indexed.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-CREATEINDEX-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>CREATE</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
The message returned if the index is successfully created.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>ERROR: Cannot create index: 'index_name' already exists.</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
This error occurs if it is impossible to create the index.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-CREATEINDEX-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
This command constructs an index called <replaceable class="parameter">index_name</replaceable>.
</PARA>
<para>
In the first syntax shown above, the key fields for the
index are specified as column names; a column may also have
an associated operator class. An operator class is used
to specify the operators to be used for a particular
index. For example, a btree index on four-byte integers
would use the <literal>int4_ops</literal> class;
this operator class includes
comparison functions for four-byte integers. The default
operator class is the appropriate operator class for that
field type.
</para>
<para>
In the second syntax, an index is defined
on the result of a user-defined function
<replaceable class="parameter">func_name</replaceable> applied
to one or more attributes of a single class. These functional
indices can be used to obtain fast access to data
based on operators that would normally require some
transformation to apply them to the base data.
</para>
<REFSECT2 ID="R2-SQL-CREATEINDEX-3">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Notes
</TITLE>
<PARA>
Currently, only the BTREE access method supports multi-column
indices. Up to 7 keys may be specified.
</PARA>
<para>
Use the <citerefentry>
<refentrytitle>DROP INDEX</refentrytitle>
</citerefentry>
statement to remove indexes.
</para>
</REFSECT2>
<REFSECT1 ID="R1-SQL-CREATEINDEX-2">
<TITLE>
Usage
</TITLE>
<PARA>To create a btree index on the field <literal>title</literal>
in the table <literal>films</literal>:
</PARA>
<ProgramListing>
CREATE UNIQUE INDEX title_idx
ON films (title);
</ProgramListing>
<para>
To create a rtree index on a point attribute so that we
can efficiently use box operators on the result of the
conversion function:
</para>
<programlisting>
CREATE INDEX pointloc
ON points USING RTREE (point2box(location) box_ops);
SELECT * FROM points
WHERE point2box(points.pointloc) = boxes.box;
<comment>
Is this example correct?
</comment>
</programlisting>
</REFSECT1>
<REFSECT1 ID="R1-SQL-CREATEINDEX-3">
<TITLE>
Compatibility
</TITLE>
<PARA>
</PARA>
<REFSECT2 ID="R2-SQL-CREATEINDEX-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
SQL92
</TITLE>
<PARA>
CREATE INDEX is a PostgreSQL language extension.
</PARA>
<para>
There is no CREATE INDEX command in SQL92.
</para>
</refsect2>
</refsect1>
</REFENTRY>
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<REFENTRY ID="SQL-CREATELANGUAGE-1">
<REFMETA>
<REFENTRYTITLE>
CREATE LANGUAGE
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>
CREATE LANGUAGE
</REFNAME>
<REFPURPOSE>
Defines a new language for functions
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
CREATE [TRUSTED] PROCEDURAL LANGUAGE '<replaceable class="parameter">langname</replaceable>'
HANDLER <replaceable class="parameter">call_handler</replaceable>
LANCOMPILER '<replaceable class="parameter">comment</replaceable>'
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-CREATELANGUAGE-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<function>TRUSTED</function>
</TERM>
<LISTITEM>
<PARA>
<function> TRUSTED</function> specifies that the call handler for
the language is safe; that is, it offers an unprivileged user
no functionality to get around access restrictions. If
this keyword is omitted when registering the language,
only users with the PostgreSQL superuser privilege can use
this language to create new functions
(like the 'C' language).
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">langname</replaceable>
</TERM>
<LISTITEM>
<PARA>
The name of the new procedural language.
The language name is case insensitive. A procedural
language cannot override one of the built-in languages of
PostgreSQL.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">call_handler</replaceable>
</TERM>
<LISTITEM>
<PARA>
The argument for <function>HANDLER</function> is the name
of a previously
registered function that will be called to execute the PL
procedures.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">comment</replaceable>
</TERM>
<LISTITEM>
<PARA>
The <function>LANCOMPILER</function> argument is the
string that will be
inserted in the <literal>LANCOMPILER</literal> attribute
of the new
<filename>pg_language</filename> entry. At present,
PostgreSQL doesn't use
this attribute in any way.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-CREATELANGUAGE-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>CREATE</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
This message is returned if the language is successfully
created.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>ERROR: PL handler function <replaceable class="parameter">funcname</replaceable>() doesn't exist</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
This error is returned if the function
<replaceable class="parameter">funcname</replaceable>()
is not found.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-CREATELANGUAGE-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
Using <command>CREATE LANGUAGE</command>, a PostgreSQL user can register
a new language with PostgreSQL. Subsequently, functions and
trigger procedures can be defined in this new language.
The user must have the PostgreSQL superuser privilege to
register a new language.
</PARA>
<REFSECT2 ID="R2-SQL-CREATELANGUAGE-3">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Writing PL handlers
</TITLE>
<PARA>
The call handler for a procedural language must be written
in a compiler language such as 'C' and registered with
PostgreSQL as a function taking no arguments and returning
opaque type.
<comment>What does `opaque type' mean?</comment>
This prevents the call handler from being
called directly as a function from queries.
</para>
<para>
However, arguments must be supplied on the actual call when a
PL function or trigger
procedure in the language offered by the handler is to be
executed.
<itemizedlist>
<listitem>
<para>
When called from the trigger manager, the only argument is
the object ID from the procedure's <filename>pg_proc</filename>
entry. All other
information from the trigger manager is found in the
global <structname>CurrentTriggerData</structname> pointer.
</para>
</listitem>
<listitem>
<para>
When called from the function manager, the arguments are
the object ID of the procedure's <filename>pg_proc</filename>
entry, the number
of arguments given to the PL function, the arguments in a
<structname>FmgrValues</structname> structure and a pointer
to a boolean where the
function tells the caller if the return value is the SQL
NULL value.
</para>
</listitem>
</itemizedlist>
</PARA>
<para>
It's up to the call handler to fetch the
<filename>pg_proc</filename> entry and
to analyze the argument and return types of the called
procedure. The <function>AS</function> clause from the
<command>CREATE FUNCTION</command> of
the procedure will be found in the <literal>prosrc</literal>
attribute of the
<filename>pg_proc</filename> entry. This may be the
source text in the procedural
language itself (like for PL/Tcl), a pathname to a
file or anything else that tells the call handler what to
do in detail.
</para>
<REFSECT2 ID="R2-SQL-CREATELANGUAGE-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Notes
</TITLE>
<PARA>
Use <citerefentry>
<refentrytitle>CREATE FUNCTION</refentrytitle>
</citerefentry>
to create a function.
</para>
<para>
Use <citerefentry>
<refentrytitle>DROP LANGUAGE</refentrytitle>
</citerefentry> to drop procedural languages.
</para>
<para>
Refer to the table <filename>pg_language</filename>
for further information:
<programlisting>
<computeroutput>
Table = pg_language
+--------------------------+--------------------------+-------+
| Field | Type | Length|
+--------------------------+--------------------------+-------+
| lanname | name | 32 |
| lancompiler | text | var |
+--------------------------+--------------------------+-------+
lanname |lancompiler
--------+--------------
internal|n/a
lisp |/usr/ucb/liszt
C |/bin/cc
sql |postgres
</computeroutput>
</programlisting>
</para>
</refsect2>
</refsect1>
<REFSECT1 ID="R1-SQL-CREATELANGUAGE-4">
<TITLE>
Restrictions
</TITLE>
<PARA>
Since the call handler for a procedural language must be
registered with PostgreSQL in the 'C' language, it inherits
all the restrictions of 'C' functions.
<comment>
What are these restrictions?
</comment>
</para>
</refsect1>
<REFSECT1 ID="R1-SQL-CREATELANGUAGE-5">
<TITLE>
Bugs
</TITLE>
<PARA>
At present, the definitions for a procedural language cannot be
changed once they have been created.
</para>
</refsect1>
<REFSECT1 ID="R1-SQL-CREATELANGUAGE-6">
<TITLE>
Usage
</TITLE>
<PARA>
This is a template for a PL handler written in 'C':
</PARA>
<ProgramListing>
#include "executor/spi.h"
#include "commands/trigger.h"
#include "utils/elog.h"
#include "fmgr.h" /* for FmgrValues struct */
#include "access/heapam.h"
#include "utils/syscache.h"
#include "catalog/pg_proc.h"
#include "catalog/pg_type.h"
Datum
plsample_call_handler(
Oid prooid,
int pronargs,
FmgrValues *proargs,
bool *isNull)
{
Datum retval;
TriggerData *trigdata;
if (CurrentTriggerData == NULL) {
/*
* Called as a function
*/
retval = ...
} else {
/*
* Called as a trigger procedure
*/
trigdata = CurrentTriggerData;
CurrentTriggerData = NULL;
retval = ...
}
*isNull = false;
return retval;
}
</ProgramListing>
<para>
Only a few thousand lines of code have to be added instead
of the dots to complete the PL call handler. See <citerefentry>
<refentrytitle>CREATE FUNCTION</refentrytitle>
</citerefentry> for information on how to compile
it into a loadable module
.</para>
<para>
The following commands then register the sample procedural
language.</para>
<programlisting>
CREATE FUNCTION plsample_call_handler () RETURNS opaque
AS '/usr/local/pgsql/lib/plsample.so'
LANGUAGE 'C';
CREATE PROCEDURAL LANGUAGE 'plsample'
HANDLER plsample_call_handler
LANCOMPILER 'PL/Sample';
</programlisting>
</REFSECT1>
<REFSECT1 ID="R1-SQL-CREATELANGUAGE-7">
<TITLE>
Compatibility
</TITLE>
<PARA>
CREATE LANGUAGE is a PostgreSQL extension.
</PARA>
<REFSECT2 ID="R2-SQL-CREATELANGUAGE-5">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
SQL92
</TITLE>
<PARA>
There is no CREATE LANGUAGE statement in SQL92.
</PARA>
</refsect2>
</refsect1>
</REFENTRY>
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sgml-omittag:t
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sgml-minimize-attributes:nil
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<REFENTRY ID="SQL-DROPFUNCTION-1">
<REFMETA>
<REFENTRYTITLE>
DROP FUNCTION
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>
DROP FUNCTION
</REFNAME>
<REFPURPOSE>
Removes a user-defined C function
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
DROP FUNCTION <replaceable class="parameter">name</replaceable> ( [<replaceable class="parameter">type</replaceable> [, ...]] )
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-DROPFUNCTION-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter"> name</replaceable>
</TERM>
<LISTITEM>
<PARA>
The name of an existing function.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<replaceable class="parameter">type</replaceable>
</TERM>
<LISTITEM>
<PARA>
The type of function parameters.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-DROPFUNCTION-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
</TERM>
<LISTITEM>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<ReturnValue>DROP</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
Message returned if the command completes successfully.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>
WARN RemoveFunction: Function "<replaceable class="parameter">name</replaceable>" ("<replaceable class="parameter">types</replaceable>") does not exist</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
This message is given if the function specified does not
exist into database.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</variablelist>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-DROPFUNCTION-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
DROP FUNCTION will remove references to an existing C
function. To execute this command the user must be the
owner of the function. The input argument types to the
function must be specified, as only the function with the
given name and argument types will be removed.
</PARA>
<REFSECT2 ID="R2-SQL-DROPFUNCTION-3">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Notes
</TITLE>
<PARA>
Refer to the <citerefentry>
<refentrytitle>
CREATE FUNCTION</refentrytitle>
</citerefentry>
statement to create aggregate functions.
</PARA>
</REFSECT2>
<REFSECT1 ID="R1-SQL-DROPFUNCTION-2">
<TITLE>
Usage
</TITLE>
<PARA>
This command removes the square root function:
</PARA>
<ProgramListing>
DROP FUNCTION sqrt(int4);
</ProgramListing>
</REFSECT1>
<REFSECT1 ID="R1-SQL-DROPFUNCTION-3">
<TITLE>
Bugs
</TITLE>
<PARA>
No checks are made to ensure that types, operators or access
methods that rely on the function have been removed first.
</PARA>
</REFSECT1>
<REFSECT1 ID="R1-SQL-DROPFUNCTION-4">
<TITLE>
Compatibility
</TITLE>
<PARA
>DROP FUNCTION statement is a PostgreSQL language extension.
</PARA>
<REFSECT2 ID="R2-SQL-DROPFUNCTION-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
SQL/PSM
</TITLE>
<PARA>
The SQL/PSM DROP FUNCTION statement has the following syntax:
<programlisting>
DROP [ SPECIFIC ] FUNCTION <replaceable class="parameter">name</replaceable> { RESTRICT | CASCADE }</programlisting>
</PARA>
</refsect2>
</refsect1>
</REFENTRY>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
sgml-parent-document:nil
sgml-default-dtd-file:"../reference.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:"/usr/lib/sgml/catalog"
sgml-local-ecat-files:nil
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<REFENTRY ID="SQL-SELECT-1">
<REFMETA>
<REFENTRYTITLE>
SELECT
</REFENTRYTITLE>
<REFMISCINFO>SQL - Language Statements</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>
SELECT
</REFNAME>
<REFPURPOSE>
Retrieve rows from a table or view
</REFPURPOSE>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-04-15</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
<REPLACEABLE CLASS="PARAMETER">
</REPLACEABLE>
SELECT [ALL|DISTINCT]
<REPLACEABLE CLASS="PARAMETER">expression</REPLACEABLE> [AS <REPLACEABLE CLASS="PARAMETER">name</REPLACEABLE>] [, ...]
[INTO [TABLE] <REPLACEABLE CLASS="PARAMETER">intable</REPLACEABLE>]
[FROM <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE> [<REPLACEABLE CLASS="PARAMETER">alias</REPLACEABLE>] [, ...] ]
[WHERE <REPLACEABLE CLASS="PARAMETER">condition</REPLACEABLE>]
[GROUP BY <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> [, ...] ]
[HAVING <REPLACEABLE CLASS="PARAMETER">condition</REPLACEABLE> [, ...] ]
[UNION [ALL] <REPLACEABLE CLASS="PARAMETER">select</REPLACEABLE>]
[ORDER BY <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> [ASC | DESC] [, ...] ]
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-SELECT-1">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">expression</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
The name of a table's column or an expression.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">name</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
Specifies another name for a column or an expression using
the AS clause. <REPLACEABLE CLASS="PARAMETER">name</REPLACEABLE> cannot be used in the WHERE
condition. It can, however, be referenced in associated
ORDER BY or GROUP BY clauses.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">intable</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
If the INTO TABLE clause is specified, the result of the
query will be stored in another table with the indicated
name.
If <REPLACEABLE CLASS="PARAMETER">intable</REPLACEABLE> does not exist, it will be created automatically.
<Note>
<Para>
The CREATE TABLE AS statement will also create a new table from a select query.
</Para>
</Note>
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
The name of an existing table referenced by FROM clause.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">alias</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
An alternate name for the preceeding <REPLACEABLE CLASS="PARAMETER">table</REPLACEABLE>.
Used for brevity or to eliminate ambiguity for joins within a single table.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">condition</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
An expression leading to a boolean (true/false) result.
See the WHERE clause.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
The name of a table's column.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">select</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
A select statement with all features except the ORDER BY clause.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</PARA>
</REFSECT2>
<REFSECT2 ID="R2-SQL-SELECT-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
Rows
</TERM>
<LISTITEM>
<PARA>
The complete set of rows resulting from the query specification.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<ReturnValue>count</ReturnValue>
</TERM>
<LISTITEM>
<PARA>
The count of rows returned by the query.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-SELECT-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
</REFSECT1INFO>
<TITLE>
Description
</TITLE>
<PARA>
SELECT will get all rows which satisfy the WHERE condition
or all rows of a table if WHERE is omitted.
<PARA>
The GROUP BY clause allows a user to divide a table
conceptually into groups. (See GROUP BY clause).
<PARA>
The HAVING clause specifies a grouped table derived by the
elimination of groups from the result of the previously
specified clause. (See HAVING clause).
<PARA>
The ORDER BY clause allows a user to specify that he/she
wishes the rows sorted according to the ASCending or
DESCending mode operator. (See ORDER BY clause)
<PARA>
The UNION clause specifies a table derived from a Cartesian
product union join. (See UNION clause).
<PARA>
You must have SELECT privilege to a table to read its values
(See GRANT/REVOKE statements).
<REFSECT2 ID="R2-SQL-WHERE-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
WHERE clause
</TITLE>
<PARA>
The optional WHERE condition has the general form:
<Synopsis>
WHERE <REPLACEABLE CLASS="PARAMETER">expr</REPLACEABLE> <REPLACEABLE CLASS="PARAMETER">cond_op</REPLACEABLE> <REPLACEABLE CLASS="PARAMETER">expr</REPLACEABLE> [<REPLACEABLE CLASS="PARAMETER">log_op</REPLACEABLE> ...]
</Synopsis>
where <REPLACEABLE CLASS="PARAMETER">cond_op</REPLACEABLE> can be one of: =, &lt;, &lt;=, &gt;, &gt;=, &lt;&gt;
or a conditional operator like ALL, ANY, IN, LIKE, et cetera
and <REPLACEABLE CLASS="PARAMETER">log_op</REPLACEABLE> can be one of: AND, OR, NOT.
The comparison returns either TRUE or FALSE and all
instances will be discarded
if the expression evaluates to FALSE.
</PARA>
</REFSECT2>
<REFSECT2 ID="R2-SQL-GROUPBY-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
GROUP BY clause
</TITLE>
<PARA>
GROUP BY specifies a grouped table derived by the application
of the this clause:
<SYNOPSIS>
GROUP BY <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> [, ...]
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-HAVING-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
HAVING clause
</TITLE>
<PARA>
The optional HAVING condition has the general form:
<Synopsis>
HAVING <REPLACEABLE CLASS="PARAMETER">cond_expr</REPLACEABLE>
</Synopsis>
where <REPLACEABLE CLASS="PARAMETER">cond_expr</REPLACEABLE> is the same
as specified for the WHERE clause.
<Para>
HAVING specifies a grouped table derived by the elimination
of groups from the result of the previously specified clause
that do not meet the <REPLACEABLE CLASS="PARAMETER">cond_expr</REPLACEABLE>.
<Para>
Each column referenced in <REPLACEABLE CLASS="PARAMETER">cond_expr</REPLACEABLE> shall unambiguously
reference a grouping column.
</PARA>
</REFSECT2>
<REFSECT2 ID="R2-SQL-ORDERBYCLAUSE-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
ORDER BY clause
</TITLE>
<PARA>
<Synopsis>
ORDER BY <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> [ASC | DESC] [, ...]
</Synopsis>
<PARA>
<REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> can be either a column
name or an ordinal number.
<PARA>
The ordinal numbers refers to the ordinal (left-to-right) position
of the column. This feature makes it possible to define an ordering
on the basis of a column that does not have a proper name.
This is never absolutely necessary because it is always possible assign a name
to a calculated column using the AS clause, e.g.:
<ProgramListing>
SELECT title, date_prod + 1 AS newlen FROM films ORDER BY newlen;
</ProgramListing>
<PARA>
The columns in the ORDER BY must appear in the SELECT clause.
Thus the following statement is illegal:
<ProgramListing>
SELECT name FROM distributors ORDER BY code;
</ProgramListing>
<PARA>
Optionally one may add the keyword DESC (descending)
or ASC (ascending) after each column name in the ORDER BY clause.
If not specified, ASC is assumed by default.
</REFSECT2>
<REFSECT2 ID="R2-SQL-UNION-2">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
UNION clause
</TITLE>
<PARA>
<Synopsis>
<REPLACEABLE CLASS="PARAMETER">table_query</REPLACEABLE> UNION [ALL] <REPLACEABLE CLASS="PARAMETER">table_query</REPLACEABLE>
[ORDER BY <REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> [ASC | DESC] [, ...] ]
</Synopsis>
where
<REPLACEABLE CLASS="PARAMETER">table_query</REPLACEABLE>
specifies any select expression without an ORDER BY clause.
<PARA>
The UNION operator specifies a table derived from a Cartesian product.
The two tables that represent the direct operands of the UNION must
have the same number of columns, and corresponding columns must be
of compatible data types.
<PARA>
By default, the result of UNION does not contain any duplicate rows
unless the ALL clause is specified.
<Para>
Multiple UNION operators in the same SELECT statement are evaluated left to right.
Note that the ALL keyword is not global in nature, being applied only for the current pair of
table results.
</REFSECT2>
<REFSECT1 ID="R1-SQL-SELECT-2">
<TITLE>
Usage
</TITLE>
<PARA>
</PARA>
<ProgramListing>
--Join table films with their distributors:
--
SELECT f.title, f.did, d.name, f.date_prod, f.kind
FROM distributors d, films f
WHERE f.did = d.did;
title |did|name | date_prod|kind
-------------------------+---+----------------+----------+----------
The Third Man |101|British Lion |1949-12-23|Drama
The African Queen |101|British Lion |1951-08-11|Romantic
Une Femme est une Femme |102|Jean Luc Godard |1961-03-12|Romantic
Vertigo |103|Paramount |1958-11-14|Action
Becket |103|Paramount |1964-02-03|Drama
48 Hrs |103|Paramount |1982-10-22|Action
War and Peace |104|Mosfilm |1967-02-12|Drama
West Side Story |105|United Artists |1961-01-03|Musical
Bananas |105|United Artists |1971-07-13|Comedy
Yojimbo |106|Toho |1961-06-16|Drama
There's a Girl in my Soup|107|Columbia |1970-06-11|Comedy
Taxi Driver |107|Columbia |1975-05-15|Action
Absence of Malice |107|Columbia |1981-11-15|Action
Storia di una donna |108|Westward |1970-08-15|Romantic
The King and I |109|20th Century Fox|1956-08-11|Musical
Das Boot |110|Bavaria Atelier |1981-11-11|Drama
Bed Knobs and Broomsticks|111|Walt Disney | |Musical
</ProgramListing>
<ProgramListing>
--sum column "len" of all films group by "kind":
--
SELECT kind, SUM(len) AS total FROM films GROUP BY kind;
kind |total
----------+------
Action | 07:34
Comedy | 02:58
Drama | 14:28
Musical | 06:42
Romantic | 04:38
</ProgramListing>
<ProgramListing>
--sum column length of all films group by "kind"
--having total duration < 5 hours:
--
SELECT kind, SUM(len) AS total
FROM films
GROUP BY kind
HAVING SUM(len) < INTERVAL '5 hour';
kind |total
----------+------
Comedy | 02:58
Romantic | 04:38
</ProgramListing>
<ProgramListing>
--The following two examples are identicals:
--
SELECT * FROM distributors ORDER BY name;
SELECT * FROM distributors ORDER BY 2;
did|name
---+----------------
109|20th Century Fox
110|Bavaria Atelier
101|British Lion
107|Columbia
102|Jean Luc Godard
113|Luso films
104|Mosfilm
103|Paramount
106|Toho
105|United Artists
111|Walt Disney
112|Warner Bros.
108|Westward
</ProgramListing>
<ProgramListing>
--union of table distributors and table actors:
-- (only those that begin with letter W):
--
-- distributors: actors:
-- did|name id|name
-- ---+------------ --+--------------
-- 108|Westward 1|Woody Allen
-- 111|Walt Disney 2|Warren Beatty
-- 112|Warner Bros. 3|Walter Matthau
-- ... ...
--
--select only distinct rows (without ALL):
--
SELECT distributors.name
FROM distributors
WHERE distributors.name LIKE 'W%'
UNION
SELECT actors.name
FROM actors
WHERE actors.name LIKE 'W%';
name
--------------
Walt Disney
Walter Matthau
Warner Bros.
Warren Beatty
Westward
Woody Allen
</ProgramListing>
</REFSECT1>
<REFSECT1 ID="R1-SQL-SELECT-3">
<TITLE>
Compatibility
</TITLE>
<PARA>
</PARA>
<REFSECT2 ID="R2-SQL-SELECT-4">
<REFSECT2INFO>
<DATE>1998-04-15</DATE>
</REFSECT2INFO>
<TITLE>
<Acronym>SQL92</Acronym>
</TITLE>
<PARA>
</PARA>
<REFSECT3 ID="R3-SQL-SELECT-1">
<REFSECT3INFO>
<DATE>1998-04-15</DATE>
</REFSECT3INFO>
<TITLE>
SELECT clause
</TITLE>
<PARA>
In the <Acronym>SQL92</Acronym> standard, the optional keyword "AS" is just noise and can be
omitted without affecting the meaning.
The <ProductName>Postgres</ProductName> parser requires this keyword when
renaming columns because the type extensibility features lead to parsing ambiguities
in this context.
<PARA>
In the <Acronym>SQL92</Acronym> standard, the new column name specified in an
"AS" clause may be referenced in GROUP BY and HAVING clauses. This is not currently
allowed in <ProductName>Postgres</ProductName>.
</PARA>
</REFSECT3>
<REFSECT3 ID="R3-SQL-UNION-1">
<REFSECT3INFO>
<DATE>1998-04-15</DATE>
</REFSECT3INFO>
<TITLE>
UNION clause
</TITLE>
<PARA>
The <Acronym>SQL92</Acronym> syntax for UNION allows an additional CORRESPONDING BY clause:
<Synopsis>
<REPLACEABLE CLASS="PARAMETER">table_query</REPLACEABLE> UNION [ALL]
[CORRESPONDING [BY (<REPLACEABLE CLASS="PARAMETER">column</REPLACEABLE> [,...])]]
<REPLACEABLE CLASS="PARAMETER">table_query</REPLACEABLE>
</Synopsis>
<Para>
The CORRESPONDING BY clause is not supported by <ProductName>Postgres</ProductName>.
</PARA>
</REFSECT3>
</REFSECT2>
</REFSECT1>
</REFENTRY>
<!--
<REPLACEABLE CLASS="PARAMETER">
</REPLACEABLE>
<ReturnValue></ReturnValue>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>&bull;
</TERM>
<LISTITEM>
<PARA>
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
<PARA>
</PARA>
-->