MySQL Bugs: #21607: cached statement handles not released

Bug #21607	cached statement handles not released
Submitted:	13 Aug 2006 4:05	Modified:	7 Sep 2006 15:07
Reporter:	Kolbe Kegel	Email Updates:
Status:	Duplicate	Impact on me:	None
Category:	Connectors: DBD::mysql ( Perl )	Severity:	S3 (Non-critical)
Version:	3.0006_1	OS:	Linux (Linux)
Assigned to:	Bugs System	CPU Architecture:	Any
Tags:	dbd::mysql dbi perl prepared statement handle cached finish

Description:
Statement handles obtained using prepare_cached are not properly cleaned up when all of the results have been fetched from the handle.

According to DBI documentation:

When all the data has been fetched from a "SELECT" statement, the driver should automatically call "finish" for you. So you should not normally need to call it explicitly except when you know that you’ve not fetched all the data from a statement handle.  The most common example is when you only want to fetch one row, but in that case the "selectrow_*" methods are usually better anyway.  Adding calls to "finish" after each fetch loop is a common mistake, don’t do it, it can mask genuine problems like uncaught fetch errors.

How to repeat:
my ($stmt,$sth,$r);

$stmt = 'show variables';
$sth = $dbh->prepare_cached($stmt);
$sth->execute();

$r = $sth->fetchall_arrayref;

$sth = $dbh->prepare_cached($stmt);

Generates the following warning:

prepare_cached(show variables) statement handle DBI::st=HASH(0x8dbc10) still Active at sth_finish.pl line 21

Suggested fix:
"finish" should be called for cached prepared statement handles after all results have been fetched.

duplicate of 19874, which the fix for will be released this week

Patrick, that reference is wrong, please note the currect bug#.