[#ZF-5295] Failure on Oracle database - Zend Framework Issue Tracker

Zend Framework

Failure on Oracle database

Created: 17/Dec/08 02:02 AM Updated: 18/Jun/09 07:41 PM Resolved: 18/Jun/09 07:41 PM

Component/s:

Zend_Paginator

Affects Version/s:

1.7.1

Fix Version/s:

1.8.4

Time Tracking:

Not Specified

Description

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The DbSelect adapter fails under Oracle, because Oracle does not support statements like:

SELECT COUNT(DISTINCT column1, column2, column3) FROM table_name

Instead, in Oracle, the statement should be:

SELECT COUNT(DISTINCT column1||column2||column3) FROM table_name

I made a quick fix by changing Zend/Paginator/Adapter/DbSelect.php, but then this would only support Oracle(which is no problem in my case)
The fix is not perfect, there is a chance of failure, but I suppose the '###' string could be changed to something unique.

187,188d186
<           //ORACLE COUNT(DISTINCT col1||col2..) fix
<           $groupPart = str_replace(",", "||'###'||", $groupPart);

Sample code:

$select = new Zend_Db_Select($this->db);

$select->from("product_transfers", 
				array(
					"quantity" => "SUM(quantity)",
					"product_id",
					"name",
					"batch_number"));

$select->group(array(
				"product_id",
				"name",
				"batch_number"));

$paginator = Zend_Paginator::factory($select);

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Mickael Perraud added a comment - 17/Dec/08 02:07 AM

Please, could you provide a complete reproduce code?

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Mickael Perraud added a comment - 21/Dec/08 09:39 AM

I understood the problem but your fix could have problem:

create table foo(
    bar number(3) not null,
    baz varchar2(50)
);
insert into foo( 1, '0abc');
insert into foo( 10, 'abc');
select count(distinct bar || baz) from foo;
// this will return 1 because '||' will concat the 2 columns and won't apply a real distinct

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Mickael Perraud added a comment - 23/Dec/08 01:06 AM

If we want something independent of the DBMS, we must use a request like:

SELECT COUNT(*) FROM (SELECT DISTINCT column1, column2, column3 FROM table_name)

Note: Problem also occurs with DB2

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Jurrien Stutterheim added a comment - 23/Dec/08 01:14 AM

I'd prefer to avoid subqueries if possible because they're a lot slower than regular queries. Wouldn't a GROUP BY on the multiple columns provide the same result?

SELECT COUNT(DISTINCT column1, column2, column3) FROM table_name

would become

SELECT COUNT(*) FROM table_name GROUP BY column1, column2, column3

Feel free to slap me if I'm saying stupid things atm... I need more coffee!

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Mickael Perraud added a comment - 23/Dec/08 01:25 AM

No, this wouldn't function
I f you take my example above, you will receive 2 lines of result.
I understand though the problem of performance.
Take a coffee

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Jurrien Stutterheim added a comment - 23/Dec/08 11:08 AM

Hehe, coffee taken ; )
We could probably detect these problematic queries and create subqueries if there are no other nice ways of supporting them. The solution would preferably work on every DB. If we go for subqueries, we should make an entry in the manual saying these kind of queries are better off with a custom COUNT query (also supported by the DbSelect adapter).

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Jurrien Stutterheim added a comment - 30/May/09 08:44 PM

This thread: http://www.dbasupport.com/forums/showthread.php?t=11349 might have a solution. The Paginator Adapter solution would check the no. of columns. If there's one column, we keep doing things the way they're done now. If there are multiple columns, we apply the suggestion from that forum thread. Currently haven't got time to fully investigate this, so feedback is welcome : )

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Matthew Ratzloff added a comment - 08/Jun/09 02:23 PM

This isn't a blocking issue, so I'm lowering priority to critical. An alternative exists: passing a query to setRowCount().

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Jurrien Stutterheim added a comment - 18/Jun/09 07:41 PM

Resolved in r16149 and merged to release-1.8 in r16150