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Allow assignment to array elements not contiguous with those already

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present; intervening positions are filled with nulls.  This behavior
is required by SQL99 but was not implementable before 8.2 due to lack
of support for nulls in arrays.  I have only made it work for the
one-dimensional case, which is all that SQL99 requires.  It seems quite
complex to get it right in higher dimensions, and since we never allowed
extension at all in higher dimensions, I think that must count as a
future feature addition not a bug fix.
This commit is contained in:
Tom Lane
2006-09-29 21:22:21 +00:00
parent 673a573dcc
commit 352a56ba68
4 changed files with 269 additions and 93 deletions
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13
doc/src/sgml/array.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/array.sgml,v 1.51 2006/05/09 23:12:54 momjian Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/array.sgml,v 1.52 2006/09/29 21:22:21 tgl Exp $ -->
<sect1 id="arrays">
<title>Arrays</title>
@ -350,11 +350,12 @@ UPDATE sal_emp SET pay_by_quarter[1:2] = '{27000,27000}'
</para>
<para>
A stored array value can be enlarged by assigning to an element adjacent to
those already present, or by assigning to a slice that is adjacent
to or overlaps the data already present. For example, if array
<literal>myarray</> currently has 4 elements, it will have five
elements after an update that assigns to <literal>myarray[5]</>.
A stored array value can be enlarged by assigning to element(s) not already
present. Any positions between those previously present and the newly
assigned element(s) will be filled with nulls. For example, if array
<literal>myarray</> currently has 4 elements, it will have six
elements after an update that assigns to <literal>myarray[6]</>,
and <literal>myarray[5]</> will contain a null.
Currently, enlargement in this fashion is only allowed for one-dimensional
arrays, not multidimensional arrays.
</para>