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Jan
20
answered what does !! as an operator in mysql?
Jan
14
comment mysql multi-source replication to single slave from Debian repo's?
It's helpful if you post the exact error message. SELECT @@VERSION; to confirm that the version running on the server is what you expect it to be.
Jan
12
comment How to properly kill MySQL?
@Pacerier I guess it's a combination of intense study of the documentation (reading it before I needed to know something, rather than just looking up the answers to specific issues, I've discovered a lot of interesting things I didn't know I was missing), occasional dives into the source code (there are a lot of interesting and sometimes amusing comments there, too), combined with curiosity and experience.
Jan
12
comment What should be done before upgrading MySQL?
@Pacerier you don't technically have to do most of these steps. The FLUSH operations are something I like to do because it tends to speed things up. My own adminstration philosophy is that I don't want to "1-click" anything. The more I understand what's really going on, the better equipped I feel like I can be to notice something out of the ordinary and handle the unexpected.
Jan
11
comment MySQL over total memory allocated usage? memory leak?
Either your server is not using the actual my.cnf file that you think it is, or your post represents at least two different states of the server's operating environment over time. innodb-buffer-pool-size = 64M does not match Buffer pool size, bytes 268419072 ... it's off by a factor of about 4, and I see no explanation for this. Any ideas? You should perhaps SHOW GLOBAL VARIABLES LIKE 'innodb_buffer_pool_size'; (or thread_cache_size, or anything else you change) and be certain the changes you believe you are making... are actually happening.
Jan
10
comment MySQL blob removes last bites when selecting in some strings
To start, try SELECT HEX(blobcolumn) AS c1 FROM t1... to see a hex representation of what's stored, with the conversion done by the server. This should help you discover whether the data is actually there but not being shown, or whether the data was not properly inserted. The next step would likely depend on what you find here.
Jan
10
comment MySQL over total memory allocated usage? memory leak?
Try setting thread_cache_size to 0 or at least a much smaller value, such as 8. There is no such thing as a maximum memory usage in MySQL. The server daemon will use as much memory as the workload requires. The mysqltuner script uses an old formula that is essentially meaningless unless it shows an extremely large number, which implies that you've set one or more parameters to an unreasonable value.
Jan
9
answered How do I report progress of a long running transaction in MySQL?
Jan
9
comment Check for table lock in conditional statement
@clickstefan I don't know why they designed some of the SHOW statements the way they did and didn't put the same things in information_schema. If you or someone you know is proficient in C, it's actually possible to create a custom storage engine in MySQL that could expose this information via an SQL interface, as a queryable table. I've contemplated writing one for SHOW SLAVE STATUS but haven't gotten around to it (and you can discover some attributes about the slave status from information_schema.processlist).
Jan
9
comment Check for table lock in conditional statement
@clickstefan there are some other possibilities, like the innodb_trx table in information_schema or even the processlist table that could potentially give you programmatically accessible and useful information when deciding to proceed, but you don't want to be overly aggressive in querying them because some information_schema queries can be relatively resource-intensive.
Jan
8
comment Check for table lock in conditional statement
@ypercube thanks. And thanks, again. :) Among other things, I find this very useful with recurring jobs in the event scheduler. If another thread holds my lock I know the previous run of the event is still going, so I shouldn't proceed. I use a simple wrapper procedure that I call get_lock_or_die() that returns if the lock is yours, or throws a fatal error with SIGNAL SQLSTATE 45000 ... otherwise. Errors thrown inside scheduled events go to the MySQL error log, so as a side effect, I get a log entry to let me know the previous execution of the scheduled event ran longer than it should.
Jan
8
answered Check for table lock in conditional statement
Jan
8
answered Local MySQL instance running extremely slow compared to remote version
Jan
8
answered Is it possble to replicate MySQL server on Azure virtual machines
Jan
8
comment Check for table lock in conditional statement
This seems like potentially a bit of XY. What are you actually trying to accomplish with this? You can't do it directly, of course, but depending on the motivation, there might be a viable alternative. Also, what version of MySQL Server?
Jan
8
comment MySQL explain query: Using temporary table vs more rows examined
Remember, when trying to compare performance between variant queries, you need to use SELECT SQL_NO_CACHE so that you get a better sense of how long the server actually takes to process them. 0.00 sec seems pretty low.
Jan
8
comment Can MySql cause a Windows server to shutdown unexpectedly?
I am extremely skeptical that MySQL Server is causing Windows to completely shut down without leaving a trace. If it is, then Windows Server is an even worse platform than I already suspected. The more likely explanation is that the hosting provider doesn't understand the nature of the problem... therefore, according to them, there is no problem.
Jan
6
comment Database design what are your thoughts
en.m.wikipedia.org/wiki/Object-relational_impedance_mismatch is where you should start reading about why not to try this. If it doesn't keep you busy, then contemplate how you'd handle the discrepancies between release families of just one rdbms, and then think about what subset of which SQL standard you'll support, since you can't be fully cross-platform unless every target platform has a way to do everything you want to try to support through your abstraction interface.
Jan
2
answered mysql replication master 5.5 slave 5.1 error on create database
Jan
2
revised Foreign key set to cascading but fails to update - why?
blockquote quotation from documentation