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Commitbfda0a0

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Doc: improve documentation for UNNEST().
Per a user question, spell out that UNNEST() returns array elementsin storage order; also provide an example to clarify the behavior formulti-dimensional arrays.While here, also clarify the SELECT reference page's description ofWITH ORDINALITY. These details were already given in 7.2.1.4, buta reference page should not omit details.Back-patch to v13; there's not room in the table in older versions.Discussion:https://postgr.es/m/FF1FB31F-0507-4F18-9559-2DE6E07E3B43@gmail.com
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‎doc/src/sgml/func.sgml

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@@ -17926,14 +17926,25 @@ SELECT NULLIF(value, '(none)') ...
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<returnvalue>setof anyelement</returnvalue>
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</para>
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<para>
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Expands an array to a set of rows.
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Expands an array into a set of rows.
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The array's elements are read out in storage order.
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</para>
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<para>
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<literal>unnest(ARRAY[1,2])</literal>
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<returnvalue></returnvalue>
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<programlisting>
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1
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2
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</programlisting>
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</para>
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<para>
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<literal>unnest(ARRAY[['foo','bar'],['baz','quux']])</literal>
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<returnvalue></returnvalue>
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<programlisting>
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foo
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bar
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baz
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quux
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</programlisting>
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</para></entry>
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</row>
@@ -17944,10 +17955,10 @@ SELECT NULLIF(value, '(none)') ...
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<returnvalue>setof anyelement, anyelement [, ... ]</returnvalue>
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</para>
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<para>
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Expands multiple arrays (possibly of different data types)to a set of
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Expands multiple arrays (possibly of different data types)into a set of
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rows. If the arrays are not all the same length then the shorter ones
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are padded with <literal>NULL</literal>s. This is only allowed in a
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query's FROM clause; see <xref linkend="queries-tablefunctions"/>.
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are padded with <literal>NULL</literal>s. Thisformis only allowed
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in aquery's FROM clause; see <xref linkend="queries-tablefunctions"/>.
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</para>
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<para>
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<literal>select * from unnest(ARRAY[1,2], ARRAY['foo','bar','baz']) as x(a,b)</literal>

‎doc/src/sgml/ref/select.sgml

Lines changed: 12 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -476,18 +476,25 @@ TABLE [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ]
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result sets, but any function can be used.) This acts as
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though the function's output were created as a temporary table for the
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duration of this single <command>SELECT</command> command.
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When the optional <command>WITH ORDINALITY</command> clause is
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added to the function call, a new column is appended after
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all the function's output columns with numbering for each row.
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If the function's result type is composite (including the case of a
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function with multiple <literal>OUT</literal> parameters), each
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attribute becomes a separate column in the implicit table.
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</para>
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<para>
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When the optional <command>WITH ORDINALITY</command> clause is added
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to the function call, an additional column of type <type>bigint</type>
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will be appended to the function's result column(s). This column
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numbers the rows of the function's result set, starting from 1.
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By default, this column is named <literal>ordinality</literal>.
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</para>
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<para>
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An alias can be provided in the same way as for a table.
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If an alias is written, a column
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alias list can also be written to provide substitute names for
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one or more attributes of the function's composite return
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type, including the column added by <literal>ORDINALITY</literal>
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if present.
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type, including the ordinality column if present.
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</para>
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<para>

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