mirror of
https://github.com/postgres/postgres.git
synced 2025-07-28 23:42:10 +03:00
Require that array literals produce "rectangular" arrays, i.e. all the
subarrays of a given dimension have the same number of elements/subarrays. Also repair a longstanding undocumented (as far as I can see) ability to explicitly set array bounds in the array literal syntax. It now can deal properly with negative array indicies. Modify array_out so that arrays with non-standard lower bounds (i.e. not 1) are output with the expicit dimension syntax. This fixes a longstanding issue whereby arrays with non-default lower bounds had them changed to default after a dump/reload cycle. Modify regression tests and docs to suit, and add some minimal documentation regarding the explicit dimension syntax.
This commit is contained in:
Joe Conway
@ -1,4 +1,4 @@
|
||||
<!-- $PostgreSQL: pgsql/doc/src/sgml/array.sgml,v 1.35 2004/06/07 04:04:47 tgl Exp $ -->
|
||||
<!-- $PostgreSQL: pgsql/doc/src/sgml/array.sgml,v 1.36 2004/08/05 03:29:11 joe Exp $ -->
|
||||
|
||||
<sect1 id="arrays">
|
||||
<title>Arrays</title>
|
||||
@ -121,12 +121,23 @@ CREATE TABLE tictactoe (
|
||||
INSERT INTO sal_emp
|
||||
VALUES ('Bill',
|
||||
'{10000, 10000, 10000, 10000}',
|
||||
'{{"meeting", "lunch"}, {}}');
|
||||
'{{"meeting", "lunch"}, {"meeting"}}');
|
||||
ERROR: multidimensional arrays must have array expressions with matching dimensions
|
||||
</programlisting>
|
||||
|
||||
Note that multidimensional arrays must have matching extents for each
|
||||
dimension. A mismatch causes an error report.
|
||||
|
||||
<programlisting>
|
||||
INSERT INTO sal_emp
|
||||
VALUES ('Bill',
|
||||
'{10000, 10000, 10000, 10000}',
|
||||
'{{"meeting", "lunch"}, {"training", "presentation"}}');
|
||||
|
||||
INSERT INTO sal_emp
|
||||
VALUES ('Carol',
|
||||
'{20000, 25000, 25000, 25000}',
|
||||
'{{"talk", "consult"}, {"meeting"}}');
|
||||
'{{"breakfast", "consulting"}, {"meeting", "lunch"}}');
|
||||
</programlisting>
|
||||
</para>
|
||||
|
||||
@ -138,59 +149,31 @@ INSERT INTO sal_emp
|
||||
</para>
|
||||
|
||||
<para>
|
||||
This can lead to surprising results. For example, the result of the
|
||||
previous two inserts looks like this:
|
||||
The result of the previous two inserts looks like this:
|
||||
<programlisting>
|
||||
SELECT * FROM sal_emp;
|
||||
name | pay_by_quarter | schedule
|
||||
-------+---------------------------+--------------------
|
||||
Bill | {10000,10000,10000,10000} | {{meeting},{""}}
|
||||
Carol | {20000,25000,25000,25000} | {{talk},{meeting}}
|
||||
name | pay_by_quarter | schedule
|
||||
-------+---------------------------+-------------------------------------------
|
||||
Bill | {10000,10000,10000,10000} | {{meeting,lunch},{training,presentation}}
|
||||
Carol | {20000,25000,25000,25000} | {{breakfast,consulting},{meeting,lunch}}
|
||||
(2 rows)
|
||||
</programlisting>
|
||||
Because the <literal>[2][2]</literal> element of
|
||||
<structfield>schedule</structfield> is missing in each of the
|
||||
<command>INSERT</command> statements, the <literal>[1][2]</literal>
|
||||
element is discarded.
|
||||
</para>
|
||||
|
||||
<note>
|
||||
<para>
|
||||
Fixing this is on the to-do list.
|
||||
</para>
|
||||
</note>
|
||||
|
||||
<para>
|
||||
The <literal>ARRAY</literal> expression syntax may also be used:
|
||||
<programlisting>
|
||||
INSERT INTO sal_emp
|
||||
VALUES ('Bill',
|
||||
ARRAY[10000, 10000, 10000, 10000],
|
||||
ARRAY[['meeting', 'lunch'], ['','']]);
|
||||
ARRAY[['meeting', 'lunch'], ['training', 'presentation']]);
|
||||
|
||||
INSERT INTO sal_emp
|
||||
VALUES ('Carol',
|
||||
ARRAY[20000, 25000, 25000, 25000],
|
||||
ARRAY[['talk', 'consult'], ['meeting', '']]);
|
||||
SELECT * FROM sal_emp;
|
||||
name | pay_by_quarter | schedule
|
||||
-------+---------------------------+-------------------------------
|
||||
Bill | {10000,10000,10000,10000} | {{meeting,lunch},{"",""}}
|
||||
Carol | {20000,25000,25000,25000} | {{talk,consult},{meeting,""}}
|
||||
(2 rows)
|
||||
ARRAY[['breakfast', 'consulting'], ['meeting', 'lunch']]);
|
||||
</programlisting>
|
||||
Note that with this syntax, multidimensional arrays must have matching
|
||||
extents for each dimension. A mismatch causes an error report, rather than
|
||||
silently discarding values as in the previous case.
|
||||
For example:
|
||||
<programlisting>
|
||||
INSERT INTO sal_emp
|
||||
VALUES ('Carol',
|
||||
ARRAY[20000, 25000, 25000, 25000],
|
||||
ARRAY[['talk', 'consult'], ['meeting']]);
|
||||
ERROR: multidimensional arrays must have array expressions with matching dimensions
|
||||
</programlisting>
|
||||
Also notice that the array elements are ordinary SQL constants or
|
||||
Notice that the array elements are ordinary SQL constants or
|
||||
expressions; for instance, string literals are single quoted, instead of
|
||||
double quoted as they would be in an array literal. The <literal>ARRAY</>
|
||||
expression syntax is discussed in more detail in <xref
|
||||
@ -247,9 +230,9 @@ SELECT pay_by_quarter[3] FROM sal_emp;
|
||||
<programlisting>
|
||||
SELECT schedule[1:2][1:1] FROM sal_emp WHERE name = 'Bill';
|
||||
|
||||
schedule
|
||||
--------------------
|
||||
{{meeting},{""}}
|
||||
schedule
|
||||
------------------------
|
||||
{{meeting},{training}}
|
||||
(1 row)
|
||||
</programlisting>
|
||||
|
||||
@ -266,9 +249,10 @@ SELECT schedule[1:2][1] FROM sal_emp WHERE name = 'Bill';
|
||||
is specified, as in this example:
|
||||
<programlisting>
|
||||
SELECT schedule[1:2][2] FROM sal_emp WHERE name = 'Bill';
|
||||
schedule
|
||||
---------------------------
|
||||
{{meeting,lunch},{"",""}}
|
||||
|
||||
schedule
|
||||
-------------------------------------------
|
||||
{{meeting,lunch},{training,presentation}}
|
||||
(1 row)
|
||||
</programlisting>
|
||||
</para>
|
||||
@ -546,6 +530,47 @@ SELECT * FROM sal_emp WHERE 10000 = ALL (pay_by_quarter);
|
||||
up to the next right brace or delimiter is taken as the item value.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
By default, the lower bound index value of an array's dimensions is
|
||||
set to one. If any of an array's dimensions has a lower bound index not
|
||||
equal to one, an additional decoration that indicates the actual
|
||||
array dimensions will precede the array structure decoration.
|
||||
The decoration consists of square braces (<literal>[</> and <literal>]</>)
|
||||
around each array dimension's lower and upper bound indicies, plus
|
||||
a colon (<literal>:</>) delimiter character inbetween. Delimiting the
|
||||
array dimension decoration from the array structure decoration is a
|
||||
single assignment operator (<literal>=</>). For example:
|
||||
<programlisting>
|
||||
SELECT 1 || ARRAY[2,3] AS array;
|
||||
|
||||
array
|
||||
---------------
|
||||
[0:2]={1,2,3}
|
||||
(1 row)
|
||||
|
||||
SELECT ARRAY[1,2] || ARRAY[[3,4]] AS array;
|
||||
|
||||
array
|
||||
--------------------------
|
||||
[0:1][1:2]={{1,2},{3,4}}
|
||||
(1 row)
|
||||
</programlisting>
|
||||
</para>
|
||||
|
||||
<para>
|
||||
In a similar fashion, an array with non-default indicies may be specified
|
||||
using the same literal syntax. For example:
|
||||
<programlisting>
|
||||
SELECT f1[1][-2][3] AS e1, f1[1][-1][5] AS e2
|
||||
FROM (SELECT '[1:1][-2:-1][3:5]={{{1,2,3},{4,5,6}}}'::int[] AS f1) AS ss;
|
||||
|
||||
e1 | e2
|
||||
----+----
|
||||
1 | 6
|
||||
(1 row)
|
||||
</programlisting>
|
||||
</para>
|
||||
|
||||
<para>
|
||||
As shown previously, when writing an array value you may write double
|
||||
quotes around any individual array
|
||||
|
||||
Reference in New Issue
Block a user