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Jul
28
comment Mysql backup bug
Please post the exact error you get, omitting no details or punctuation. Errors can be cryptic to the untrained eye and obvious to experienced DBAs, and there are easy ways to examine large files using sed or perl or other tools, but we need more info. Also the output of mysqldump -V and the query SELECT @@VERSION;.
Jul
19
comment Active-active Cluster In MySQL
@tesla747 you are correct.
Jul
19
comment Active-active Cluster In MySQL
NDB Cluster is synchronous, but it's its own different product, it's not "Standard MySQL behavior + Synchronous Replication" which is what PXC and MariaDB essentially provide, with Galera. There are arguments on both sides of the MariaDB/Percona preference debate, which are not on topic here, but I suggest that of those two is more likely to fit what you want than NDB, because unlike them, NDB is not a drop-in replacement for MySQL Server, and has a smaller set of applications and environments to which it is suited.
Jul
12
comment restoring a EC2 snapshot on RDS
The phrase "restore our database snapshot on ec2 directly on RDS" does not really explain what you are trying to do. Please edit the question to clarify exactly what you are trying to do, and why.
Jul
10
comment Best way to backup mysql database?
Rsync? Of the actual MySQL data files from a running server? That's not an acceptable method of backup.
Jul
9
comment Cannot Start mySQL Daemon with Error “mysqld from pid file … ended”
$ ps auwwx | grep mysqld | grep -v grep ... does that return anything?
Jul
2
comment RDS Replication Error (Apply Error 1406 / Truncation)
You made schema changes on the replica, directly?
Jun
29
comment mysql query choosing an incorrect execution plan
You may not have noticed, based on the boxes you drew, but the optimizer has actually swapped the order of the last 2 tables in the query plan.
Jun
29
comment MySQL is inserting “” as 0 in decimal fields. How to stop that?
Empty string is no more like NULL than it is like 0 and arguably even less so. If you want null, why exactly would you not insert null?
Jun
24
comment MySQL - Add index to low cardinality text column?
@gview There is no intention to imply that indexes are somehow without cost. Indexes, of course, require space to exist and resources to maintain. The example is an attempt to dispel the pervasive myth that low cardinality indexes in MySQL are not worth their cost because the optimizer won't use them... and for exactly that reason, it is a deliberately extreme example, with an index "less useful" than OP's question contemplates. Yes, indexes consume space in the InnoDB buffer pool, but that memory is not shared with the query cache, which is the only place MySQL caches actual result sets.
Jun
24
comment DB Schema design : single table with more columns vs multiple tables with fewer colomns
...Or indexes, covering indexes, index scans?
Jun
23
comment MySQL trigger after insert with insert and delete instructions does not work properly
@RickJames there shouldn't be: NOW() returns a constant time that indicates the time at which the statement began to execute. (Within a stored function or trigger, NOW() returns the time at which the function or triggering statement began to execute.) This differs from the behavior for SYSDATE(), which returns the exact time at which it executes.
Jun
23
comment Mysql Replication - How it works offline?
You can create additional tables on a slave server without causing a problem, as long as there are no conflicting table names, and you never modify the replicated tables directly on the slave. You could use the MySQL event scheduler (again, only on the replica) to populate the tables. It's not entirely clear what you are trying to accomplish but it sounds viable.
Jun
20
comment Killing a process without login to MySQL
It does nothing of the sort. It's harmless, but all it does is clear the host cache, primarily used to relieve the condition where a host is being denied access because of too many errors ... Not too many connections. dev.mysql.com/doc/refman/5.6/en/flush.html
Jun
19
comment Mysql Replication - How it works offline?
N.B. do not try to replicate only certain schemas or tables. Replicate everything. Partial replication has very complex rules. Replicating everything is much simpler.
Jun
17
comment Is there a tool to check if my database is normalized to the third normal form?
@Drewverlee it seems, at first, like you're correct, based on the phrasing I chose, here. It's been so long ago that I don't recall precisely what I intended. My intention was to craft an unrealistic scenario where the table -- which I suggest is not in 3NF with realistic data -- would have been clearly in at least 3NF as it was. If student were the primary key, though, the answer still seems to be correct as it is, with instructor and subject being dependent only on student and not each other. I would, of course, welcome any edits that improve the quality or clarity of this answer.
Jun
3
comment INET6_ATON returns NULL for input parameter
Not necessarily a bug... SHOW WARNINGS; upon receiving the NULL response might also have provided you with some useful info.
May
29
comment MySQL binlog limitations
"a binlog tailer" is... what, specifically?
May
27
comment Qcache_free_memory not full yet I get alot of Qcache_lowmem_prunes
@aland that is a very good point. No, I should have been using the default value of 4096. It looks as if the query cache trims the block down to the smallest possible power of two after filling it, leaving the free space at the end, so that 7/8ths of the entire 4096 bytes originally allocated aren't stranded. I'll have to dig more deeply into this.
May
19
comment Converting MySQL master-master replication to master-standby
And to be clear, the RESET SLAVE; would be done on the master to prevent it from receiving further updates from the slave.