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Showing entries 1 to 7

Displaying posts with tag: tables (reset)

pstop – a top-like program for MySQL (based on performance_schema)
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I have been working with MySQL for some time and it has changed significantly from what I was using in 5.0 to what we have now in 5.6. One of the biggest handicap we’ve had in the past is to not be able to see what MySQL is doing or why.

MySQL 5.5 introduced us to performance_schema. It was a good start but quite crude. MySQL 5.6 gave us a significant increase in stuff that allows you to see what is going on inside MySQL. That’s great, except it’s hard to read, the documentation is good, but not oriented at the DBA but more at the MySQL developer (that’s what it seems like at least). So most of us have ignored it. Others …

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InnoDB Temporary Tables just got faster
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It all started with a goal to make InnoDB temporary tables more effective. Temporary table semantics are blessed with some important characteristics that can help us simplify lot of operations.

  • Temporary tables are not visible across connections
  • Temporary tables lifetime is limited to connection lifetime (unless user explicitly drops it).

What does this means in to InnoDB ?

  • REDO logging can be avoided for temporary tables and related objects since temporary tables do not survive a shutdown or crash.
  • Temporary table definitions can be maintained in-memory without persisting to the …
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MySQL and InnoDB comments…
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Hello everyone, here we go for a new blog post and now treating about InnoDB inside MySQL 5.5 and as you should now, this new version uses InnoDB Plugin version 1.1 which one has a lot of new adjustable resources. What most caught my attention was the impressed way that users could adjust it to have [...]

What is this MySQL file used for?
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MySQL keeps many different files, some contain real data, some contain meta data. Witch ones are important? Witch can your throw away?

This is my attempt to create a quick reference of all the files used by MySQL, whats in them, what can you do if they are missing, what can you do with them.

When I was working for Dell doing Linux support my first words to a customer where “DO YOU HAVE COMPLETE AND VERIFIED BACKUP?” Make one now before you think about doing anything I suggest here.

You should always try to manage your data through a MySQL client.  If things have gone very bad this may not be possible. MySQL may not start. If …

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Federated Tables
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Your searching for how to create a join across two databases on two different servers and it can’t be done directly.   select  d1.a, d2.b from db1@server1 join db2@server2 where db1.c = db2.c; does not work.

You learn about federated databases.  The federated storage engine allows accesses data in tables of remote databases.  Now how do you make it work?

1) Check if the federated storage engine is supported.  Federation is OFF by default!

mysql> show engines;
+------------+---------+----------------------------------------------------------------+
| Engine     | Support | …
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mg_hot_replace_table.pl
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Do you have MyISAM tables you reload with new data?

Do your queries, using that table, get blocked because the table is locked?

Do the waiting queries create idle connections slowing down the table load?

Do you wish you could just replace the table?

Years ago I was told you can replace CSV tables by simply replacing the CSV file. I figured this would also be true of a MyISAM file and it is. I use this perl script to replace MyISAM tables forcast and current observation weather data. The processing and tables are created on another computer. Weather forecasting …

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MySQL Performance: Use counter tables
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I guess many of you know, that using SELECT count(*) FROM table is problematic and slow when using Innodb tables.
This actually only applies to COUNT(*) queries without WHERE a clause as mentioned in the MySQL Performance Blog.

But if you got some slow count query in your application the best way to increase its performance is to replace / remove it.

So if you are going do to "SELECT count(*) FROM products" the best way, is to have a separated table
that stores the number of products. If you're inserting a row increment the …


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Showing entries 1 to 7

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