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Showing entries 1 to 10 of 56 10 Older Entries

Displaying posts with tag: MySQL 5.1 (reset)

MySQL in Oracle Critical Patch Update Advisory January 2014
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Oracle has released the Critical Patch Update (CPU) advisory for January 2014.

The affected MySQL products are:

  • Oracle MySQL Enterprise Monitor, versions 2.3, 3.0 
  • Oracle MySQL Server, versions 5.1, 5.5, 5.6

So this means that you should consider updating MySQL. For MySQL Enterprise the updates should be available on My Oracle Support and for the Community version the new versions are on the …




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Implications of Metadata Locking Changes in MySQL 5.5
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While most of the talk recently has mostly been around the new changes in MySQL 5.6 (and that is understandable), I have had lately some very interesting cases to deal with, with respect to the Metadata Locking related changes that were introduced in MySQL 5.5.3. It appears that the implications of Metadata Locking have not been covered well, and since there are still a large number of MySQL 5.0 and 5.1 installations that would upgrade or are in the process of upgrading to MySQL 5.5, I thought it necessary to discuss what these implications …

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mysqldiskusage – to see database disk usage by MySQL Workbench
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As we know, MySQL workbench is excellent GUI tool for managing MySQL DB servers, creating ERDs (Data Modelling) and for sql development. But with this GUI tool, we are getting some command-line utilities too like mysqldiskusage, mysqlindexcheck, mysqlfailover, mysqldiff, mysqldbcompare etc., Here, I’m describing mysqldiskusage utility, which is not only displays mysql db usage but … Continue Reading

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mysqlslap – to check client load in MySQL 5.1
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mysqlslap is native mysql utility to check client load in MySQL server. It’s introduced in MySQl 5.1. It seems very useful as it has lots of options to check load of your server by running different kind of queries with specific iterations, specific concurrency. Output will give you how much max/min/avg  time has been taken … Continue Reading

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slow_log and general_log tables in MySQL 5.1
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“Server log tables” is one of the finest feature in MySQL 5.1 version but It looks like people are not using this feature regularly or perhaps they are happy with files only. Here, I’m explaining how we can enable that feature, use it and how it will be helpful for filtering the required statements in … Continue Reading

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Event scheduler in MySQL 5.1
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I just recently used Event scheduler which was the major feature in MySQL 5.1 version. Its very much similar to the linux crontab functionality. MySQL Event is nothing but a bunch of statements which we can run on specific schedule. When you will create any event, its just a database object like table, view or … Continue Reading

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When EXPLAIN estimates can go wrong!
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This is the title of my first blog post on MySQL Performance Blog. It deals with a customer case where the customer was facing a peculiar problem where the rows column in the EXPLAIN output of the query was totally off. The actual number of rows was 18 times more than the number of rows reported by MySQL in the output of EXPLAIN. Now this can be a real pain as MySQL uses “the number of rows” estimation to pick and choose indexes and it could really be picking up a wrong index simply because of the wrong estimate. You...

The post …

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Found a nasty COALESCE() related bug in 5.5.6-rc
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Seeing as it looks like 5.5 is shortly about to go GA I thought I’d give it a run and see how well it works. The only way really to test it is to give it a bit of load and look for things which break. That I did with the 5.5.6-rc community rpms, compared to the 5.1 advanced rpms I usually run.

My colleagues, Ben and Peter, found a horrible problem which means that I can’t use this even for any real usage on my real servers. See: bug#57095 for all the gory details. Thanks to them both for finding the problem and then digging down and figuring out the real cause. Sometimes …

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MySQL 5.1 and InnoDB Hot Backup Gotcha
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Recently while we were building a slave with a newer version of MySQL 5.1 from an InnoDB Hot backup, the following error occurred when we ran mysql_upgrade:

mysql.time_zone                                    OK
mysql.time_zone_leap_second                        OK
mysql.time_zone_name                               OK
mysql.time_zone_transition                         OK
mysql.time_zone_transition_type                    OK
mysql.user                                         OK
Running 'mysql_fix_privilege_tables'...
ERROR 13 (HY000) at line 311: Can't get stat of './mysql/general_log.CSV' (Errcode: 2)
ERROR 13 (HY000) at line 316: Can't get stat of …
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Don’t put a NULL in the IN clause in 5.1
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There seems to be an optimizer problem in 5.1, if you put a NULL in the IN clause of a SELECT. For example, given the following table:

CREATE TABLE foo (
    a INT NOT NULL AUTO_INCREMENT,
    PRIMARY KEY (a)
);

Compare these two EXPLAINs:

mysql> EXPLAIN * FROM foo WHERE a IN (160000, 160001, 160002)\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: foo
         type: range
possible_keys: PRIMARY
          key: PRIMARY
      key_len: 4
          ref: NULL
         rows: 3
        Extra: Using where
1 row in set (0.06 sec)

mysql> EXPLAIN SELECT * FROM foo WHERE a IN …
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Showing entries 1 to 10 of 56 10 Older Entries

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