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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
19
answered How to select users that doesn't in the role
Jun
19
answered Mysql Replication - How it works offline?
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
answered Will frequent small select queries slow down frequent write queries in InnoDB table in MySQL?
May
29
answered MySQL binlog limitations
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.
May
19
comment Converting MySQL master-master replication to master-standby
... in fact, the master should not only be stopped, but also RESET SLAVE; to be safe... else you risk dropping and reloading tables on the master, while you are rebuilding the slave.
May
19
comment Delete and Recreate Indexes in MySQL to reduce table size for copying the db to a new server?
If mysqldump isn't working, then you are doing something wrong, and you should consider posting a new question, to figure out why, assuming there is not already an answer here that addresses the problem. It is the standard tool for this task, and is by far the safest approach.
May
9
comment Best configuration for MySQL? InnoDB and MyISAM
You should remove all of those settings except innodb_buffer_pool_size. Don't depart from the defaults unless you have a specific reason to, and verify the impact of each change, separately. Tweaking parameters like this can have unintended consequences and most "tuning" advice you will find is not helpful.
May
7
comment Intermittent “access denied” (1045) message from MySQL
SET GLOBAL LOG_WARNINGS = 2; and try again. Then check the MySQL error log.
May
6
comment Get data faster from databasse
That is not really a query. It would be better to get the actual SQL being generated by that construct... and then use EXPLAIN SELECT ... to review the server's query plan... but certainly WHERE column LIKE '%search_string%' is always going to be a slower query because indexes provide very little benefit. The % at the beginning prevents any index on the referenced column from being used, if there is one.