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MySQL Newsletter January 2003
Author: MySql | Monday January 27, 2003
MySQL Newsletter January 2003 - Recieved by email.
Articles in this newsletter:
PRODUCTS
* MySQL 4.0.9 (Gamma) is released
* MyODBC 3.51.05 (gamma) is released
* MySQL 3.23.55 is released
FEATURES
* Tuning MySQL Server 4.0 Query cache.
TRAINING
* Upcoming MySQL Training courses
PARTNER CORNER
* The Kompany partners with MySQL AB to offer Rekall Pro for MySQL
LATEST NEWS
* Latest MySQL News
--------------------------------------------------
PRODUCTS
MySQL 4.0.9 (Gamma) is released
MySQL 4.0.9, a new version of the world's most
popular Open Source Database, has been released.
It is now available in source and binary form for
a number of platforms from our download pages at
http://www.mysql.com/downloads/
and mirror sites.
Note that all mirrors may not be up to date; If
you can't find this version on some mirror, please
retry later or try another mirror.
This is a new gamma release, fixing some recently
discovered bugs.
You can see the changes for 4.0.9 at the changelog
at
http://www.mysql.com/doc/en/News-4.0.9.html
MyODBC 3.51.05 (gamma) is released
As you might have already noticed from our web
site, the MyODBC 3.51.05 - Gamma is released. It
is now available in source and binary form for a
number of platforms from our download pages at
http://www.mysql.com/downloads/api-myodbc-3.51.html
and mirror sites.
This is the gamma release of MyODBC 3.51.05. This
should be the final release in the development
series before making the stable announcement
unless if there is any critical bugs from this
version.
OpenOffice users must upgrade to this version on
all platforms, as this
includes number of fixes, and this version is
pre-tested from the Open
Office team before the release.
So, please test this, and let us know the status
back.
Here is the list of changes:
-- Fix for the thread-safe library core dumps when
the driver is built with the debug options.
-- Fix for OpenOffice to return valid list of
catalog names SQLTables along with a valid catalog
name.
-- Fixed SQLTablePrivileges and
SQLColumnPrivileges to return each
privilege type in a individual rows.
-- Fixed the time conversion format error from
SQL_TIME_STRUCT.
(Thanks to Ocke Janssen for
the above 3 bugs from OpenOffice team).
-- Fixed SQLSpecialColumns coredump on HP-UX
(threaded library)
-- Fixed SQLGetTypeInfo to return individual rows
for auto_increment
status for all numeric types. (Request from Gerry
Sweeney )
-- Fixed to return an error when the conversion is
from SQL_C_NUMERIC as the driver is not capable to
handle SQL_NUMERIC_STRUCT conversion due to lack
of descriptors support. (Request from Michael
Thomas from Microsoft
ODBC team)
-- Added missed ROWS_FETCH_PTR status to SQLFetch
and SQLExtendedFetch as that of SQLFetchScroll
along with PARAMS_PROCESSED_PTR.
-- Fixed to not to set the default attributes for
the new DSN when the attributes are set through
the config APIs (Windows specific).
-- Added to return the DRIVER name when there is
no DSN is specified (Unix only fix).
-- Support for the new autoconf tools along with
few new configuration
options.
-- Lot of cleanups to configure script to work on
all Unix platforms
along with gcc 3.x compatibility.
-- Added distribution utility scripts under
scripts sub-directory.
* Binary distribution support for all platforms
* Snapshot source distribution
-- Minor fix-ups to work with native compilers.
Recommended upgrade to earlier versions on all
platforms.
For more information about MyODBC 3.51.05, refer
to the following
(updated):
FAQ :
http://www.mysql.com/products/myodbc/faq_toc.html
(updated with new style, with a split on
individual chapters).
Manual :
http://www.mysql.com/products/myodbc/manual_toc.html
Release notes, Changelog and downloads:
http://www.mysql.com/downloads/api-myodbc-3.51.html
MySQL 3.23.55 is released
MySQL 3.23.55, a new version of the popular Open
Source Database, has been released. It is now
available in source and binary form for a number
of platforms from our download pages at
http://www.mysql.com/downloads/
and mirror sites.
Note that not all mirror sites may be up to date
at this point of time - if you can't find this
version on some mirror, please try again later or
choose another download site.
This is a bugfix release for the current stable
tree. Users who use MySQL in an untrusted
multi-user environment should consider upgrading
to this version, which also fixes a bug that
enabled valid local users to crash mysqld by using
a specially modified mysql client application.
You can see the changes for 3.23.55 at the
changelog at
http://www.mysql.com/doc/en/News-3.23.55.html
--------------------------------------------------
FEATURES
Tuning MySQL Server 4.0 Query cache.
Peter Zaitsev
It is always a challenging job to tune database
for the best performance. There are plenty of
options, which you can set to provide the balance,
which provides the best performance for exactly
your application. MySQL 4.0 adds more tools to
this job by introducing Query Cache, which can
also be tuned.
What is the MySQL Query Cache?
Query Cache is an intelligent MySQL feature, which
allows to greatly improving the speed of the
frequently executed queries by caching query
response and returning it to the client instead of
real query execution.
In order to adjust Query Cache settings you need
to understand how does the query cache work. Let
us explain this briefly. As the query arrives to
MySQL server it performs a textual comparison with
the queries in the Query Cache. This means "SELECT
* FROM a" and "Select * From a" will be recognized
as different queries. If a query matches one
stored in the cache, the cached result is
returned. If not, then the query is executed and
if parameters allow the query result is stored in
the query cache. When a table is modified, queries
stored in the cache using the modified table, are
removed from query cache.
There are 3 main variables, which can be used to
tune Query Cache settings. They are
query_cache_size, query_cache_limit and
query_cache_type.
query_cache_size:
Setting proper query_cache_size is the most
complex task. It sets the amount of memory used
for the query cache. One should find the right
balance between the benefit you get from query
cache and that non-cached queries slow down a bit,
basicly due to less amount of memory available for
other caches and buffers. Only benchmarking can
point out the exactly best balance, but there are
some guidelines, how to set this variable. Basic
idea is that the more benefit query cache
potentially gives you, the more memory it might be
worth to allocate for it. Qcache_inserts will show
you how many queries are added to query cache
while qcache_hits will show you how many query
results are taken directly from the query cache
instead of executing them. You should compare
qcache_hits value to total number of your select
queries to see what is your current hit rate. You
may increase or degrease query_cache_size to find
the value, which provides best performance for
you. Note that as the query cache content gets
invalidated with update queries, amount of memory
which query cache can use is not unbound.
Qcache_free_memory shows amount of free memory in
query cache, which is not used at the moment. If
this value stays constantly high during the load
it might be good idea to decrease the query cache
size, i.e. to free some memory from the query
cache to other caches and buffers.
query_cache_limit:
This variable sets the maximum result size, which
would be stored in the query cache. The reason to
have this variable is to limit queries having very
large result sets to overwrite all the queries in
the query set. The way to set this variable is to
determine, what is the largest result set size of
the queries you wish to cache? In most cases you
can find the answer easily. In some cases there
are queries of any possible size. In such case you
might want to compare benefit from caching this
large query with benefit of having in the cache
smaller queries, the large query overwrites to
make the decision. Examining cache query hit rate
is also a good help here. A rule of thumb to start
tuning the parameter might be setting
query_cache_limit 1/100 to 1/10 of
query_cache_size.
query_cache_type:
There are two ways how query cache can be enabled.
Setting this variable "on" will attempt to cache
all select queries. It is a good setting if you do
not want to make any changes in your application,
but you want it to start using query cache. Thus
this setting allows you later to mark queries you
do not want to be cached with SQL_NO_CACHE.
Setting query_cache_type value to "DEMAND" is a
good solution if in your application most of the
queries will not benefit from the caching, as they
never repeat or result is invalidated before the
query is repeated. With this option you can select
those queries, which will benefit from caching by
using the SQL_CACHE option.
--------------------------------------------------
TRAINING
Upcoming MySQL Training courses
MySQL AB is holding numerous training courses in
the following countries: USA, Germany, Canada,
France, UK, Australia, and Sweden. Check out dates
and locations at
http://www.mysql.com/training/
--------------------------------------------------
PARTNER CORNER
The Kompany partners with MySQL AB to offer Rekall
Pro for MySQL
TheKompany provides a line of powerful,
multi-platform tools for developers and desktop
users, a number of which are database centric such
as Rekall and DataArchitect, which is what led to
this partnership. Rekall is a RAD DBMS centric
tool for Linux, Windows and Mac OS X (to be
released soon). Rekall provides a full compliment
of widgets and tools for rapidly prototyping,
creating and deploying applications on top of
MySQL. Scripting on widgets and events is
accomplished using the popular Python object
oriented scripting language for which there is
even an embedded debugger. DataArchitect is the
emerging enterprise tool for designing databases,
reverse engineering and creating ERD's, at all
levels of an organization.
Learn more and order at:
http://www.thekompany.com/products/dataarchitect/
--------------------------------------------------
LATEST NEWS
Latest MySQL News
MySQL Adds Subselects, Upgrades Performance and
Security
http://www.mysql.com/press/release_2003_05.html
MySQL AB Hosts First MySQL Users Conference &
Expo
http://www.mysql.com/press/release_2003_04.html
MySQL Named "Swedish IT Product of the Year"
http://www.mysql.com/press/release_2003_03.html
MySQL Database Available on IBM eServer zSeries
http://www.mysql.com/press/release_2003_02.html
Enhanced MySQL Software for Mac OS X Available
from MySQL AB
http://www.mysql.com/press/release_2002_18.html
Westone Amplifies Database Performance with
MySQL
http://www.mysql.com/press/user_stories/westone.html
MySQL Releases Database Upgrade with Major
Security, Stability Enhancements
http://www.mysql.com/press/release_2002_17.html
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