Updates for array documentation, from Joe Conway.
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Tom Lane
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<!-- $Header: /cvsroot/pgsql/doc/src/sgml/array.sgml,v 1.29 2003/08/09 22:50:21 tgl Exp $ -->
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<!-- $Header: /cvsroot/pgsql/doc/src/sgml/array.sgml,v 1.30 2003/08/19 06:06:43 tgl Exp $ -->
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<sect1 id="arrays">
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<title>Arrays</title>
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@ -162,7 +162,6 @@ ERROR: multidimensional arrays must have array expressions with matching dimens
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expression syntax is discussed in more detail in <xref
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linkend="sql-syntax-array-constructors">.
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</para>
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</sect2>
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<sect2>
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@ -326,9 +325,9 @@ UPDATE sal_emp SET pay_by_quarter[1:2] = '{27000,27000}'
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<literal>||</literal>.
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<programlisting>
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SELECT ARRAY[1,2] || ARRAY[3,4];
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?column?
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---------------
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{{1,2},{3,4}}
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?column?
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-----------
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{1,2,3,4}
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(1 row)
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SELECT ARRAY[5,6] || ARRAY[[1,2],[3,4]];
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@ -337,27 +336,68 @@ SELECT ARRAY[5,6] || ARRAY[[1,2],[3,4]];
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{{5,6},{1,2},{3,4}}
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(1 row)
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</programlisting>
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</para>
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<para>
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The concatenation operator allows a single element to be pushed on to the
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beginning or end of a one-dimensional array. It also accepts two
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<replaceable>N</>-dimensional arrays, or an <replaceable>N</>-dimensional
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and an <replaceable>N+1</>-dimensional array. In the former case, the two
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<replaceable>N</>-dimension arrays become outer elements of an
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<replaceable>N+1</>-dimensional array. In the latter, the
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<replaceable>N</>-dimensional array is added as either the first or last
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outer element of the <replaceable>N+1</>-dimensional array.
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When extending an array by concatenation, the subscripts of its existing
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elements are preserved. For example, when pushing
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onto the beginning of an array with one-based subscripts, the resulting
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array has zero-based subscripts:
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and an <replaceable>N+1</>-dimensional array.
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</para>
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<para>
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When a single element is pushed on to the beginning of a one-dimensional
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array, the result is an array with a lower bound subscript equal to
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the righthand operand's lower bound subscript, minus one. When a single
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element is pushed on to the end of a one-dimensional array, the result is
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an array retaining the lower bound of the lefthand operand. For example:
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<programlisting>
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SELECT array_dims(1 || ARRAY[2,3]);
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array_dims
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------------
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[0:2]
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(1 row)
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SELECT array_dims(ARRAY[1,2] || 3);
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array_dims
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------------
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[1:3]
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(1 row)
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</programlisting>
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</para>
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<para>
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When two arrays with an equal number of dimensions are concatenated, the
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result retains the lower bound subscript of the lefthand operand's outer
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dimension. The result is an array comprising every element of the lefthand
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operand followed by every element of the righthand operand. For example:
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<programlisting>
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SELECT array_dims(ARRAY[1,2] || ARRAY[3,4,5]);
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array_dims
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------------
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[1:5]
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(1 row)
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SELECT array_dims(ARRAY[[1,2],[3,4]] || ARRAY[[5,6],[7,8],[9,0]]);
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array_dims
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------------
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[1:5][1:2]
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(1 row)
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</programlisting>
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</para>
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<para>
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When an <replaceable>N</>-dimensional array is pushed on to the beginning
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or end of an <replaceable>N+1</>-dimensional array, the result is
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analogous to the element-array case above. Each <replaceable>N</>-dimensional
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sub-array is essentially an element of the <replaceable>N+1</>-dimensional
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array's outer dimension. For example:
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<programlisting>
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SELECT array_dims(ARRAY[1,2] || ARRAY[[3,4],[5,6]]);
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array_dims
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------------
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[0:2][1:2]
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(1 row)
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</programlisting>
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</para>
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@ -386,9 +426,9 @@ SELECT array_append(ARRAY[1,2], 3);
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(1 row)
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SELECT array_cat(ARRAY[1,2], ARRAY[3,4]);
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array_cat
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---------------
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{{1,2},{3,4}}
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array_cat
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-----------
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{1,2,3,4}
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(1 row)
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SELECT array_cat(ARRAY[[1,2],[3,4]], ARRAY[5,6]);
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@ -1,5 +1,5 @@
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<!--
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$Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.167 2003/08/17 04:52:41 momjian Exp $
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$Header: /cvsroot/pgsql/doc/src/sgml/func.sgml,v 1.168 2003/08/19 06:06:43 tgl Exp $
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PostgreSQL documentation
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-->
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@ -7032,7 +7032,7 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
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<para>
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<xref linkend="array-operators-table"> shows the operators
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available for the <type>array</type> types.
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available for <type>array</type> types.
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</para>
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<table id="array-operators-table">
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@ -7093,7 +7093,7 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
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<entry> <literal>||</literal> </entry>
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<entry>array-to-array concatenation</entry>
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<entry><literal>ARRAY[1,2,3] || ARRAY[4,5,6]</literal></entry>
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<entry><literal>{{1,2,3},{4,5,6}}</literal></entry>
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<entry><literal>{1,2,3,4,5,6}</literal></entry>
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</row>
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<row>
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@ -7120,6 +7120,11 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
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</tgroup>
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</table>
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<para>
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See <xref linkend="arrays"> for more details about array operator
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behavior.
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</para>
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<para>
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<xref linkend="array-functions-table"> shows the functions
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available for use with array types. See <xref linkend="arrays">
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@ -7167,7 +7172,7 @@ SELECT pg_type_is_visible('myschema.widget'::regtype);
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for <literal>NULL</literal> inputs
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</entry>
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<entry><literal>array_cat(ARRAY[1,2,3], ARRAY[4,5,6])</literal></entry>
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<entry><literal>{{1,2,3},{4,5,6}}</literal></entry>
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<entry><literal>{1,2,3,4,5,6}</literal></entry>
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</row>
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<row>
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<entry>
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@ -1,5 +1,5 @@
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<!--
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$Header: /cvsroot/pgsql/doc/src/sgml/syntax.sgml,v 1.82 2003/08/14 23:13:27 tgl Exp $
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$Header: /cvsroot/pgsql/doc/src/sgml/syntax.sgml,v 1.83 2003/08/19 06:06:48 tgl Exp $
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-->
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<chapter id="sql-syntax">
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@ -1270,6 +1270,23 @@ SELECT ARRAY[[1,2],[3,4]];
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at the same level must produce sub-arrays of identical dimensions.
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</para>
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<para>
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Multidimensional array constructor elements can be anything yielding
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an array of the proper kind, not only a sub-<literal>ARRAY</> construct.
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For example:
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<programlisting>
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create table arr(f1 int[], f2 int[]);
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CREATE TABLE
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insert into arr values (ARRAY[[1,2],[3,4]],ARRAY[[5,6],[7,8]]);
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INSERT 2635544 1
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select ARRAY[f1, f2, '{{9,10},{11,12}}'::int[]] from arr;
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array
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------------------------------------------------
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{{{1,2},{3,4}},{{5,6},{7,8}},{{9,10},{11,12}}}
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(1 row)
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</programlisting>
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</para>
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<para>
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It is also possible to construct an array from the results of a
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subquery. In this form, the array constructor is written with the
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