array [] vs {}
Hi,
I am attempting to use arrays in a db for the first time and am having
strife:
[] notation work only on non-empty initialized arrays. Is this
a feature/bug I should know about? For example:
create table test (
myname varchar(50),
myarray int[]
);
INSERT INTO test (myname) values ('bobo');
UPDATE test SET myarray[1] = 5;
SELECT * FROM TEST;
myname | myarray
--------+---------
bobo |
(1 row)
-- An empty array column is not what I'd expect
-- but curly brackets work
UPDATE test SET myarray = '{5}';
SELECT * FROM TEST;
myname | myarray
--------+---------
bobo | {5}
(1 row)
-- However If I revert to [] notation I can do as I please:
UPDATE test SET myarray[2] = 50;
SELECT * FROM TEST;
myname | myarray
--------+---------
bobo | {5,50}
(1 row)
- [] works as expected?
Any tips for getting myarray[1] to behave?
Sean
Sean Mullen wrote:
Any tips for getting myarray[1] to behave?
You are trying to *append* an element to a NULL array, not an empty
array. It is analogous to doing this:
regression=# select NULL || 'hello';
?column?
----------
(1 row)
However, at least for 7.3.x and earlier, there is no way to append an
element to an empty array either. In either case, by setting the column
to a non-NULL and non-empty array, you can then append elements
successfully.
Appending to an empty array is fixed as of a patch recently submitted
and will hopefully be included in 7.4 when it is released:
regression=# create table test (myname text, myarray int[]);
CREATE TABLE
regression=# INSERT INTO test (myname) values ('bobo');
INSERT 1218925 1
regression=# UPDATE test SET myarray[1] = 5;
UPDATE 1
regression=# SELECT * FROM TEST;
myname | myarray
--------+---------
bobo |
(1 row)
regression=# UPDATE test SET myarray = '{}';
UPDATE 1
regression=# UPDATE test SET myarray[2] = 50;
UPDATE 1
regression=# SELECT * FROM TEST;
myname | myarray
--------+---------
bobo | {50}
(1 row)
HTH,
Joe