MySQL Bugs: #36059: Support for variable 'have

Bug #36059	Support for variable 'have_falcon'.
Submitted:	14 Apr 2008 14:22	Modified:	15 Apr 2008 10:50
Reporter:	Santo Leto	Email Updates:
Status:	Won't fix	Impact on me:	None
Category:	MySQL Server: Falcon storage engine	Severity:	S4 (Feature request)
Version:	6.0.4-alpha	OS:	Any
Assigned to:	Sergey Vojtovich	CPU Architecture:	Any
Tags:	falcon variables, have_falcon

Description:
Could you please add a variable 'have_falcon'?

Thanks.

How to repeat:
mysql> SHOW VARIABLES LIKE 'have_falcon';
Empty set (0.00 sec)

Suggested fix:
The variable should be similar to 'have_maria' or 'have_innodb':

mysql> SHOW VARIABLES LIKE 'have_maria';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| have_maria    | YES   |
+---------------+-------+
1 row in set (0.00 sec)

mysql> SHOW VARIABLES LIKE 'have_innodb';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| have_innodb   | YES   |
+---------------+-------+
1 row in set (0.00 sec)

Sergey, Do you know how easy this is to do?

Do you know a workaround for this issue?

I was thinking to use the SHOW PLUGIN syntax but it doesn't support a WHERE clause.
So I can't execute a query like

SHOW PLUGINS WHERE `Name` = 'Falcon' and `Status` = 'Active';

I can only do a version comparison: 

if 
	mysql_get_server_version(..) > 60000 
then 
	ok 
else 
	unsupported

This is not a real workaround: it fails if you (later) add the falcon engine in the 5.1.x series.

So the question is: suppose you are connected to a server; is there a way to know if the server has the falcon engine?

If the answer is no, you probably could increase from S4 to S3.

Maybe you can execute

USE information_schema;
SHOW TABLES LIKE 'FAL%';

and then check the recordcount: if > 0 then falcon is supported otherwise isn't supported.

This way is not elegant.

Please advice.
Thank you.

It is rather trivial to add 'have_falcon' variable. But as have_engine variables are not well suited to work with pluggable architecture we would unlikely do that (think about bugs like this are open for every 3-d party engine). And it is very likely that they will get obsoleted some time.

Currently there is a good way to check if an engine is enabled or not by querying information_scema.engines (works for both 5.1 and 6.0):
select * from information_schema.engines where engine='Falcon' and (support='DEFAULT' or support='YES');

Closing this bug as "Won't fix". If you still believe that have_falcon makes sence for you, feel free to reopen this bug.

Thank you for the hint.
I forgot that table.

Rgs.