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Improve ON CONFLICT documentation.

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Author: Peter Geoghegan and Andres Freund
Discussion: CAM3SWZScpWzQ-7EJC77vwqzZ1GO8GNmURQ1QqDQ3wRn7AbW1Cg@mail.gmail.com
Backpatch: 9.5, where ON CONFLICT was introduced
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Andres Freund 2015-11-10 00:02:49 +01:00
parent 6f8519d130
commit af85779bf7
1 changed files with 354 additions and 341 deletions
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doc/src/sgml/ref/insert.sgml
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@ -99,7 +99,8 @@ INSERT INTO <replaceable class="PARAMETER">table_name</replaceable> [ AS <replac
<para> <para>
You must have <literal>INSERT</literal> privilege on a table in You must have <literal>INSERT</literal> privilege on a table in
order to insert into it. If <literal>ON CONFLICT DO UPDATE</> is order to insert into it. If <literal>ON CONFLICT DO UPDATE</> is
present the <literal>UPDATE</literal> privilege is also required. present, <literal>UPDATE</literal> privilege on the table is also
required.
</para> </para>
<para> <para>
@ -126,366 +127,378 @@ INSERT INTO <replaceable class="PARAMETER">table_name</replaceable> [ AS <replac
<refsect1> <refsect1>
<title>Parameters</title> <title>Parameters</title>
<variablelist> <refsect2 id="SQL-INSERTING-PARAMS">
<varlistentry> <title id="sql-inserting-params-title">Inserting</title>
<term><replaceable class="parameter">with_query</replaceable></term>
<listitem>
<para>
The <literal>WITH</literal> clause allows you to specify one or more
subqueries that can be referenced by name in the <command>INSERT</>
query. See <xref linkend="queries-with"> and <xref linkend="sql-select">
for details.
</para>
<para>
It is possible for the <replaceable class="parameter">query</replaceable>
(<command>SELECT</command> statement)
to also contain a <literal>WITH</literal> clause. In such a case both
sets of <replaceable>with_query</replaceable> can be referenced within
the <replaceable class="parameter">query</replaceable>, but the
second one takes precedence since it is more closely nested.
</para>
</listitem>
</varlistentry>
<varlistentry> <para>
<term><replaceable class="PARAMETER">table_name</replaceable></term> This section covers parameters that may be used when only
<listitem> inserting new rows. Parameters <emphasis>exclusively</emphasis>
<para> used with the <literal>ON CONFLICT</literal> clause are described
The name (optionally schema-qualified) of an existing table. separately.
</para> </para>
</listitem>
</varlistentry>
<varlistentry> <variablelist>
<term><replaceable class="parameter">alias</replaceable></term> <varlistentry>
<listitem> <term><replaceable class="parameter">with_query</replaceable></term>
<para> <listitem>
A substitute name for the target table. When an alias is provided, it <para>
completely hides the actual name of the table. This is particularly The <literal>WITH</literal> clause allows you to specify one or more
useful when using <literal>ON CONFLICT DO UPDATE</literal> into a table subqueries that can be referenced by name in the <command>INSERT</>
named <literal>excluded</literal> as that's also the name of the query. See <xref linkend="queries-with"> and <xref linkend="sql-select">
pseudo-relation containing the proposed row. for details.
</para> </para>
</listitem> <para>
</varlistentry> It is possible for the <replaceable class="parameter">query</replaceable>
(<command>SELECT</command> statement)
to also contain a <literal>WITH</literal> clause. In such a case both
sets of <replaceable>with_query</replaceable> can be referenced within
the <replaceable class="parameter">query</replaceable>, but the
second one takes precedence since it is more closely nested.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">table_name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of an existing table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">alias</replaceable></term>
<listitem>
<para>
A substitute name for <replaceable
class="PARAMETER">table_name</replaceable>. When an alias is
provided, it completely hides the actual name of the table.
This is particularly useful when <literal>ON CONFLICT DO
UPDATE</literal> targets a table named excluded, since that's
also the name of the special table representing rows proposed
for insertion.
</para>
</listitem>
</varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">column_name</replaceable></term> <term><replaceable class="PARAMETER">column_name</replaceable></term>
<listitem> <listitem>
<para> <para>
The name of a column in the table named by <replaceable class="PARAMETER">table_name</replaceable>. The name of a column in the table named by <replaceable
The column name can be qualified with a subfield name or array class="PARAMETER">table_name</replaceable>. The column name
subscript, if needed. (Inserting into only some fields of a can be qualified with a subfield name or array subscript, if
composite column leaves the other fields null.) When needed. (Inserting into only some fields of a composite
referencing a column with <literal>ON CONFLICT DO UPDATE</>, do column leaves the other fields null.) When referencing a
not include the table's name in the specification of a target column with <literal>ON CONFLICT DO UPDATE</>, do not include
column. For example, <literal>INSERT ... ON CONFLICT DO UPDATE the table's name in the specification of a target column. For
tab SET table_name.col = 1</> is invalid (this follows the general example, <literal>INSERT ... ON CONFLICT DO UPDATE tab SET
behavior for <command>UPDATE</>). table_name.col = 1</> is invalid (this follows the general
</para> behavior for <command>UPDATE</>).
</listitem> </para>
</varlistentry> </listitem>
</varlistentry>
<varlistentry> <varlistentry>
<term><literal>DEFAULT VALUES</literal></term> <term><literal>DEFAULT VALUES</literal></term>
<listitem> <listitem>
<para> <para>
All columns will be filled with their default values. All columns will be filled with their default values.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">expression</replaceable></term> <term><replaceable class="PARAMETER">expression</replaceable></term>
<listitem> <listitem>
<para> <para>
An expression or value to assign to the corresponding column. An expression or value to assign to the corresponding column.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><literal>DEFAULT</literal></term> <term><literal>DEFAULT</literal></term>
<listitem> <listitem>
<para> <para>
The corresponding column will be filled with The corresponding column will be filled with
its default value. its default value.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">query</replaceable></term> <term><replaceable class="PARAMETER">query</replaceable></term>
<listitem> <listitem>
<para> <para>
A query (<command>SELECT</command> statement) that supplies the A query (<command>SELECT</command> statement) that supplies the
rows to be inserted. Refer to the rows to be inserted. Refer to the
<xref linkend="sql-select"> <xref linkend="sql-select">
statement for a description of the syntax. statement for a description of the syntax.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">output_expression</replaceable></term> <term><replaceable class="PARAMETER">output_expression</replaceable></term>
<listitem> <listitem>
<para> <para>
An expression to be computed and returned by the <command>INSERT</> An expression to be computed and returned by the
command after each row is inserted (not updated). The <command>INSERT</> command after each row is inserted or
expression can use any column names of the table named by updated. The expression can use any column names of the table
<replaceable class="PARAMETER">table_name</replaceable>. named by <replaceable
Write <literal>*</> to return all columns of the inserted row(s). class="PARAMETER">table_name</replaceable>. Write
</para> <literal>*</> to return all columns of the inserted or updated
</listitem> row(s).
</varlistentry> </para>
</listitem>
</varlistentry>
<varlistentry> <varlistentry>
<term><literal>conflict_target</literal></term> <term><replaceable class="PARAMETER">output_name</replaceable></term>
<listitem> <listitem>
<para> <para>
Specify which conflicts <literal>ON CONFLICT</literal> refers to. A name to use for a returned column.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
</variablelist>
</refsect2>
<varlistentry> <refsect2 id="sql-on-conflict">
<term><literal>conflict_action</literal></term> <title id="sql-on-conflict-title"><literal>ON CONFLICT</literal> Clause</title>
<listitem> <indexterm zone="SQL-INSERT">
<para> <primary>UPSERT</primary>
<literal>DO NOTHING</literal> or <literal>DO UPDATE </indexterm>
SET</literal> clause specifying the action to be performed in <indexterm zone="SQL-INSERT">
case of a conflict. <primary>ON CONFLICT</primary>
</para> </indexterm>
</listitem> <para>
</varlistentry> The optional <literal>ON CONFLICT</literal> clause specifies an
alternative action to raising a unique violation or exclusion
constraint violation error. For each individual row proposed for
insertion, either the insertion proceeds, or, if an
<emphasis>arbiter</emphasis> constraint or index specified by
<parameter>conflict_target</parameter> is violated, the
alternative <parameter>conflict_action</parameter> is taken.
<literal>ON CONFLICT DO NOTHING</literal> simply avoids inserting
a row as its alternative action. <literal>ON CONFLICT DO
UPDATE</literal> updates the existing row that conflicts with the
row proposed for insertion as its alternative action.
</para>
<varlistentry> <para>
<term><replaceable class="PARAMETER">output_name</replaceable></term> <parameter>conflict_target</parameter> can perform
<listitem> <emphasis>unique index inference</emphasis>. When performing
<para> inference, it consists of one or more <replaceable
A name to use for a returned column. class="PARAMETER">column_name_index</replaceable> columns and/or
</para> <replaceable class="PARAMETER">expression_index</replaceable>
</listitem> expressions, and an optional <replaceable class="PARAMETER">
</varlistentry> index_predicate</replaceable>. All <replaceable
class="PARAMETER">table_name</replaceable> unique indexes that,
without regard to order, contain exactly the
<parameter>conflict_target</parameter>-specified
columns/expressions are inferred (chosen) as arbiter indexes. If
an <replaceable class="PARAMETER">index_predicate</replaceable> is
specified, it must, as a further requirement for inference,
satisfy arbiter indexes. Note that this means a non-partial
unique index (a unique index without a predicate) will be inferred
(and thus used by <literal>ON CONFLICT</literal>) if such an index
satisfying every other criteria is available. If an attempt at
inference is unsuccessful, an error is raised.
</para>
<varlistentry> <para>
<term><replaceable class="PARAMETER">column_name_index</replaceable></term> <literal>ON CONFLICT DO UPDATE</literal> guarantees an atomic
<listitem> <command>INSERT</command> or <command>UPDATE</command> outcome;
<para> provided there is no independent error, one of those two outcomes
The name of a <replaceable is guaranteed, even under high concurrency. This is also known as
class="PARAMETER">table_name</replaceable> column. Part of a <firstterm>UPSERT</firstterm> &mdash; <quote>UPDATE or
unique index inference clause. Follows <command>CREATE INSERT</quote>.
INDEX</command> format. <literal>SELECT</> privilege on </para>
<replaceable class="PARAMETER">column_name_index</replaceable>
is required.
</para>
</listitem>
</varlistentry>
<varlistentry> <variablelist>
<term><replaceable class="PARAMETER">expression_index</replaceable></term> <varlistentry>
<listitem> <term><literal>conflict_target</literal></term>
<para> <listitem>
Similar to <replaceable <para>
class="PARAMETER">column_name_index</replaceable>, but used to Specifies which conflicts <literal>ON CONFLICT</literal> takes
infer expressions on <replaceable the alternative action on by choosing <firstterm>arbiter
class="PARAMETER">table_name</replaceable> columns appearing indexes</firstterm>. Either performs <emphasis>unique index
within index definitions (not simple columns). Part of unique inference</emphasis>, or names a constraint explicitly. For
index inference clause. Follows <command>CREATE INDEX</command> <literal>ON CONFLICT DO NOTHING</literal>, it is optional to
format. <literal>SELECT</> privilege on any column appearing specify a <parameter>conflict_target</parameter>; when
within <replaceable omitted, conflicts with all usable constraints (and unique
class="PARAMETER">expression_index</replaceable> is required. indexes) are handled. For <literal>ON CONFLICT DO
</para> UPDATE</literal>, a <parameter>conflict_target</parameter>
</listitem> <emphasis>must</emphasis> be provided.
</varlistentry> </para>
</listitem>
</varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">collation</replaceable></term> <term><literal>conflict_action</literal></term>
<listitem> <listitem>
<para> <para>
When specified, mandates that corresponding <replaceable <parameter>conflict_action</parameter> specifies an
class="PARAMETER">column_name_index</replaceable> or alternative <literal>ON CONFLICT</literal> action. It can be
<replaceable class="PARAMETER">expression_index</replaceable> use a either <literal>DO NOTHING</literal>, or a <literal>DO
particular collation in order to be matched in the inference clause. UPDATE</literal> clause specifying the exact details of the
Typically this is omitted, as collations usually do not affect whether or <literal>UPDATE</literal> action to be performed in case of a
not a constraint violation occurs. Follows <command>CREATE conflict. The <literal>SET</literal> and
INDEX</command> format. <literal>WHERE</literal> clauses in <literal>ON CONFLICT DO
</para> UPDATE</literal> have access to the existing row using the
</listitem> table's name (or an alias), and to rows proposed for insertion
</varlistentry> using the special <varname>excluded</varname> table.
<literal>SELECT</> privilege is required on any column in the
target table where corresponding <varname>excluded</varname>
columns are read.
</para>
<para>
Note that the effects of all per-row <literal>BEFORE
INSERT</literal> triggers are reflected in
<varname>excluded</varname> values, since those effects may
have contributed to the row being excluded from insertion.
</para>
</listitem>
</varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">opclass</replaceable></term> <term><replaceable class="PARAMETER">column_name_index</replaceable></term>
<listitem> <listitem>
<para> <para>
When specified, mandates that corresponding <replaceable The name of a <replaceable
class="PARAMETER">column_name_index</replaceable> or class="PARAMETER">table_name</replaceable> column. Used to
<replaceable class="PARAMETER">expression_index</replaceable> use infer arbiter indexes. Follows <command>CREATE
particular operator class in order to be matched by the inference INDEX</command> format. <literal>SELECT</> privilege on
clause. Sometimes this is omitted because the <replaceable class="PARAMETER">column_name_index</replaceable>
<emphasis>equality</emphasis> semantics are often equivalent across a is required.
type's operator classes anyway, or because it's sufficient to trust that </para>
the defined unique indexes have the pertinent definition of equality. </listitem>
Follows <command>CREATE INDEX</command> format. </varlistentry>
</para>
</listitem>
</varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">index_predicate</replaceable></term> <term><replaceable class="PARAMETER">expression_index</replaceable></term>
<listitem> <listitem>
<para> <para>
Used to allow inference of partial unique indexes. Any indexes Similar to <replaceable
that satisfy the predicate (which need not actually be partial class="PARAMETER">column_name_index</replaceable>, but used to
indexes) can be matched by the rest of the inference clause. infer expressions on <replaceable
Follows <command>CREATE INDEX</command> format. class="PARAMETER">table_name</replaceable> columns appearing
<literal>SELECT</> privilege on any column appearing within within index definitions (not simple columns). Follows
<replaceable class="PARAMETER">index_predicate</replaceable> is <command>CREATE INDEX</command> format. <literal>SELECT</>
required. privilege on any column appearing within <replaceable
</para> class="PARAMETER">expression_index</replaceable> is required.
</listitem> </para>
</varlistentry> </listitem>
</varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">constraint_name</replaceable></term> <term><replaceable class="PARAMETER">collation</replaceable></term>
<listitem> <listitem>
<para> <para>
Explicitly specifies an arbiter <emphasis>constraint</emphasis> When specified, mandates that corresponding <replaceable
by name, rather than inferring a constraint or index. This is class="PARAMETER">column_name_index</replaceable> or
mostly useful for exclusion constraints, that cannot be chosen <replaceable class="PARAMETER">expression_index</replaceable>
in the conventional way (with an inference clause). use a particular collation in order to be matched during
</para> inference. Typically this is omitted, as collations usually
</listitem> do not affect whether or not a constraint violation occurs.
</varlistentry> Follows <command>CREATE INDEX</command> format.
</para>
</listitem>
</varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">condition</replaceable></term> <term><replaceable class="PARAMETER">opclass</replaceable></term>
<listitem> <listitem>
<para> <para>
An expression that returns a value of type <type>boolean</type>. Only When specified, mandates that corresponding <replaceable
rows for which this expression returns <literal>true</literal> will be class="PARAMETER">column_name_index</replaceable> or
updated, although all rows will be locked when the <replaceable class="PARAMETER">expression_index</replaceable>
<literal>ON CONFLICT DO UPDATE</> action is taken. use particular operator class in order to be matched during
</para> inference. Typically this is omitted, as the
</listitem> <emphasis>equality</emphasis> semantics are often equivalent
</varlistentry> across a type's operator classes anyway, or because it's
</variablelist> sufficient to trust that the defined unique indexes have the
</refsect1> pertinent definition of equality. Follows <command>CREATE
INDEX</command> format.
</para>
</listitem>
</varlistentry>
<refsect1 id="sql-on-conflict"> <varlistentry>
<title id="sql-on-conflict-title"><literal>ON CONFLICT</literal> Clause</title> <term><replaceable class="PARAMETER">index_predicate</replaceable></term>
<indexterm zone="SQL-INSERT"> <listitem>
<primary>UPSERT</primary> <para>
</indexterm> Used to allow inference of partial unique indexes. Any
<indexterm zone="SQL-INSERT"> indexes that satisfy the predicate (which need not actually be
<primary>ON CONFLICT</primary> partial indexes) can be inferred. Follows <command>CREATE
</indexterm> INDEX</command> format. <literal>SELECT</> privilege on any
<para> column appearing within <replaceable
The optional <literal>ON CONFLICT</literal> clause specifies an class="PARAMETER">index_predicate</replaceable> is required.
alternative action to raising a unique violation or exclusion </para>
constraint violation error. For each individual row proposed for </listitem>
insertion, either the insertion proceeds, or, if a constraint </varlistentry>
specified by the <parameter>conflict_target</parameter> is
violated, the alternative <parameter>conflict_action</parameter> is
taken.
</para>
<para> <varlistentry>
<parameter>conflict_target</parameter> describes which conflicts <term><replaceable class="PARAMETER">constraint_name</replaceable></term>
are handled by the <literal>ON CONFLICT</literal> clause. Either a <listitem>
<emphasis>unique index inference</emphasis> clause or an explicitly <para>
named constraint can be used. For <literal>ON CONFLICT DO Explicitly specifies an arbiter
NOTHING</literal>, it is optional to specify a <emphasis>constraint</emphasis> by name, rather than inferring
<parameter>conflict_target</parameter>; when omitted, conflicts a constraint or index.
with all usable constraints (and unique indexes) are handled. For </para>
<literal>ON CONFLICT DO UPDATE</literal>, a conflict target </listitem>
<emphasis>must</emphasis> be specified. </varlistentry>
Every time an insertion without <literal>ON CONFLICT</literal> <varlistentry>
would ordinarily raise an error due to violating one of the <term><replaceable class="PARAMETER">condition</replaceable></term>
inferred (or explicitly named) constraints, a conflict (as in <listitem>
<literal>ON CONFLICT</literal>) occurs, and the alternative action, <para>
as specified by <parameter>conflict_action</parameter> is taken. An expression that returns a value of type
This happens on a row-by-row basis. <type>boolean</type>. Only rows for which this expression
</para> returns <literal>true</literal> will be updated, although all
rows will be locked when the <literal>ON CONFLICT DO UPDATE</>
action is taken. Note that
<replaceable>condition</replaceable> is evaluated last, after
a conflict has been identified as a candidate to update.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
Note that exclusion constraints are not supported as arbiters with
<literal>ON CONFLICT DO UPDATE</literal>. In all cases, only
<literal>NOT DEFERRABLE</literal> constraints and unique indexes
are supported as arbiters.
</para>
<para> <para>
A <emphasis>unique index inference</emphasis> clause consists of <command>INSERT</command> with an <literal>ON CONFLICT DO UPDATE</>
one or more <replaceable clause is a <quote>deterministic</quote> statement. This means
class="PARAMETER">column_name_index</replaceable> columns and/or that the command will not be allowed to affect any single existing
<replaceable class="PARAMETER">expression_index</replaceable> row more than once; a cardinality violation error will be raised
expressions, and an optional <replaceable class="PARAMETER"> when this situation arises. Rows proposed for insertion should
index_predicate</replaceable>. not duplicate each other in terms of attributes constrained by an
</para> arbiter index or constraint. Note that exclusion constraints are
not supported with <literal>ON CONFLICT DO UPDATE</literal>.
</para>
<tip>
<para>
It is often preferable to use unique index inference rather than
naming a constraint directly using <literal>ON CONFLICT ON
CONSTRAINT</literal> <replaceable class="PARAMETER">
constraint_name</replaceable>. Inference will continue to work
correctly when the underlying index is replaced by another more
or less equivalent index in an overlapping way, for example when
using <literal>CREATE UNIQUE INDEX ... CONCURRENTLY</literal>
before dropping the index being replaced.
</para>
</tip>
<para> </refsect2>
All the <replaceable class="PARAMETER">table_name</replaceable>
unique indexes that, without regard to order, contain exactly the
specified columns/expressions and, if specified, whose predicate
implies the <replaceable class="PARAMETER">
index_predicate</replaceable> are chosen as arbiter indexes. Note
that this means an index without a predicate will be used if a
non-partial index matching every other criteria happens to be
available.
</para>
<para>
If no index matches the inference clause (nor is there a constraint
explicitly named), an error is raised. Deferred constraints are
not supported as arbiters.
</para>
<para>
<parameter>conflict_action</parameter> defines the action to be
taken in case of conflict. <literal>ON CONFLICT DO
NOTHING</literal> simply avoids inserting a row as its alternative
action. <literal>ON CONFLICT DO UPDATE</literal> updates the
existing row that conflicts with the row proposed for insertion as
its alternative action.
<literal>ON CONFLICT DO UPDATE</literal> guarantees an atomic
<command>INSERT</command> or <command>UPDATE</command> outcome - provided
there is no independent error, one of those two outcomes is guaranteed,
even under high concurrency. This feature is also known as
<firstterm>UPSERT</firstterm>.
Note that exclusion constraints are not supported with
<literal>ON CONFLICT DO UPDATE</literal>.
</para>
<para>
<literal>ON CONFLICT DO UPDATE</literal> optionally accepts
a <literal>WHERE</literal> clause <replaceable>condition</replaceable>.
When provided, the statement only proceeds with updating if
the <replaceable>condition</replaceable> is satisfied. Otherwise, unlike a
conventional <command>UPDATE</command>, the row is still locked for update.
Note that the <replaceable>condition</replaceable> is evaluated last, after
a conflict has been identified as a candidate to update.
</para>
<para>
The <literal>SET</literal> and <literal>WHERE</literal> clauses in
<literal>ON CONFLICT UPDATE</literal> have access to the existing
row, using the table's name, and to the row
proposed for insertion, using the <varname>excluded</varname>
alias. The <varname>excluded</varname> alias requires
<literal>SELECT</> privilege on any column whose values are read.
Note that the effects of all per-row <literal>BEFORE INSERT</literal>
triggers are reflected in <varname>excluded</varname> values, since those
effects may have contributed to the row being excluded from insertion.
</para>
<para>
<command>INSERT</command> with an <literal>ON CONFLICT DO UPDATE</>
clause is a <quote>deterministic</quote> statement. This means
that the command will not be allowed to affect any single existing
row more than once; a cardinality violation error will be raised
when this situation arises. Rows proposed for insertion should not
duplicate each other in terms of attributes constrained by the
conflict-arbitrating unique index.
</para>
</refsect1> </refsect1>
<refsect1> <refsect1>
@ -617,12 +630,12 @@ INSERT INTO employees_log SELECT *, current_timestamp FROM upd;
<para> <para>
Insert or update new distributors as appropriate. Assumes a unique Insert or update new distributors as appropriate. Assumes a unique
index has been defined that constrains values appearing in the index has been defined that constrains values appearing in the
<literal>did</literal> column. Note that an <varname>EXCLUDED</> <literal>did</literal> column. Note that the special
expression is used to reference values originally proposed for <varname>excluded</> table is used to reference values originally
insertion: proposed for insertion:
<programlisting> <programlisting>
INSERT INTO distributors (did, dname) INSERT INTO distributors (did, dname)
VALUES (5, 'Gizmo transglobal'), (6, 'Associated Computing, inc') VALUES (5, 'Gizmo Transglobal'), (6, 'Associated Computing, Inc')
ON CONFLICT (did) DO UPDATE SET dname = EXCLUDED.dname; ON CONFLICT (did) DO UPDATE SET dname = EXCLUDED.dname;
</programlisting> </programlisting>
</para> </para>