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May
2
comment Any script to auto test tune and benchmark mysql config?
Thanks, @RickJames. I think vote early and vote often only works in Chicago. I've always felt the "disable it" advice about the query cache to be a bit extreme, sort of a knee-jerk reaction, since my experience is that there are millions of tiny gains it provides over time, which add up in its favor -- at least on workloads typical in my environments. Still, I've edited to soften the stance on the query cache a bit, explain some limitations, and add a link to a fairly recent Percona blog post that seems relevant (no affiliation).
Apr
16
comment XAMPP: MySQL not starting
That is not at all what this error is saying. InnoDB is trying but faiing to initialize successfully because of a corrupt file. Unknown/unsupported storage engine: InnoDB is a side effect of the failure of InnoDB to properly start up, because of the prior (actual) error.
Apr
10
comment mysql replication takes 6 seconds
Let us continue this discussion in chat.
Apr
10
comment mysql replication takes 6 seconds
A network error between VMs on the same host? Yikes. It certainly does give that impression, but I smell another rat here that I can't put my finger on. There are no other slaves connecting, right? And SELECT @@net_read_timeout, @@net_write_timeout; gives the normal values of 30 and 60, yeah?. I would be inclined to break out a packet sniffer and plan for some manual analysis of the hex dumps of the protocol streams at this point, though I have a nagging sense that you have some kind of non-obvious misconfiguration. Does normal async replication work?
Apr
9
comment mysql replication takes 6 seconds
Oh... heh, is Failed reading log event, reconnecting to retry, log 'binlog-3306.000001' at position 3483 a recurring message with identical content? Or is the position advancing?
Apr
9
comment mysql replication takes 6 seconds
The magic number error is counterintuitive until you understand the most important words there are the least obvious: it's "Read ... error." The actual message the author seems to have intended to convey (from looking at the source) is "error while trying to read data at the appropriate offset for the byte position where the semisync magic number should be found in the incoming stream" -- not that the number is wrong, but that trying to read it failed.
Apr
9
comment mysql replication takes 6 seconds
Does SELECT @@SERVER_ID, @@SERVER_UUID; give different values for each variable when compared across instances (i.e. are the two vms' server_id values different from each other, and are their server_uuid values different from each other)?
Apr
3
comment MySQL BETWEEN command - performance (order)
1) Technically they are stored ordered by primary key in InnoDB, since that's always the clustered index, although that still doesn't matter, for the other reasons, which you correctly stated. Indeed, it's a simplification but a reasonable one to say that a fundamental purpose of an index is to prevent the server from scanning through the table sequentially, regardless of what "sequentially" actually happens to mean.
Mar
27
comment How to convert .ibd files to .sql
I'm voting to close this question as off-topic because it appears to be essentially the same question you asked three hours ago: dba.stackexchange.com/questions/133472/… ... please don't do that. It's unnecessary, and isn't going to get a faster response.
Mar
27
comment Database as it is raw content
Important questions, before you can figure out what -- if anything -- can be done with this tar file: does each .ibd file have a matching .cfg file of the same name? Do you know what version of MySQL Server this file came from? Is there a file included called ibdata1?
Mar
25
comment Slow Join queries using Spider-Storage-Engine on MariaDB
Is there something in the docs that leads you to believe that this is possible with Spider? With ordinary FEDERATED tables, the way this is done is by creating a view on the remote server that incorporates the join, then declaring a federated table with fake indexes on the appropriate columns, on the local server, pointing to the remote view as though it were a table.
Mar
24
comment MySQL Too Many Connections (Max Connections Limit Not Reached)
The most useful thing to do, first, is to capture the exact wording of the error, including error number and sqlstate code if possible. Also, how exactly are you finding the "highest connection count?"
Mar
21
comment Give third-party access to AWS hosted MySQL
If this is RDS then give 'em access to a read replica. They not only can't modify your database, they also can't impair its performance with badly written queries, which is always a risk.
Mar
20
comment How to verify galera is synced
@jerichorivera it should equal the number of nodes, but if it isn't, that does not necessarily mean this node has a problem. With 3 nodes, if "node x" suddenly returns a value of "2" here, then "node x" would actually be one of the good nodes... So, while useful information, it doesn't really give you any new information about this node.
Mar
20
comment How to verify galera is synced
@Som3guy yes, 'Synced' is correct.
Mar
19
comment Select query on an index column with gap locking
A SELECT query run in isolation wouldn't need to lock the gap, but you're building a derived table with the select and using it to join into the update. That's a different scenario entirely.
Mar
19
comment MySQL Server won't start
This log isn't useful. You need to find the real one, possibly at /var/log/mysql/$(hostname).err...
Mar
19
comment Setting up a redis or memcached slave table with a MySQL (or other traditional database) as the master
InnoDB tries to work in memory. Of course all changes have to be written to disk immediately, otherwise you'd have no ACID but yes, the InnoDB buffer pool is an underappreciated aspect of InnoDB.
Mar
19
comment Setting up a redis or memcached slave table with a MySQL (or other traditional database) as the master
It really depends on why you are wanting this -- what specific problem does it solve? It's usually best to ask about the problem rather than about your attempted solution. InnoDB in MySQL is all-memory-based, disk-backed, given a system with sufficient memory for the data and correct provisioning... and InnoDB can be queried with a memcache client, for pretty blazing speed, since the SQL parser is bypassed when this feature is enabled and used. dev.mysql.com/doc/refman/5.6/en/innodb-memcached-setup.html
Mar
5
comment Preventing MySQL index corruption
ANALYZE TABLE would probably also "fix" it. This doesn't look like "corruption," merely inaccurate index statistics.