… a number between 0.0 and 1.0, which is multiplied by the current fc_limit (adjusted by the above calculation if… global wsrep_provider_options=”gcs.fc_limit=500; gcs.fc_master_slave=YES; gcs.fc_factor=1.0″; Working with flow control… cost of increasing the fc_limit Keeping the fc_limit small has two three purposes: It limits the amount of delay any node…
Post: Understanding the maximum number of columns in a MySQL table
April 8, 2013 By 5 Comments
… 4096. This, however, is not the true limit. To find out what the actual limit is, we must delve further into the…_FIELDS), MYF(0)); DBUG_RETURN(1); } Which is, of course, obvious! Various parts of this limit are: info_length is roughly 2… limit of 1,000 columns. This is the code from ha_innodb.cc that enforces that limit: if (form->s->fields > 1000) { /* The limit…
Comment: Can't Create Thread: Errno 11 (A Tale of Two Ulimits)
April 17, 2013 By 10 Comments
… mysql2 restart [linko@g4 ~]$ ps -ax | grep mysql 35328 pts/1 S 0:00 /bin/sh /usr/bin/mysqld_safe –defaults… –user=mysql –log-error=/var/log/mysqld2.log –open-files-limit=32768 –pid-file=/var/lib/mysql2/g4.dmz.local.pid… cat /proc/35967/limits Limit Soft Limit Hard Limit Units Max processes 1024 unlimited processes Next time i do another. 1. ssh to server and…
Post: More on MySQL transaction descriptors optimization
April 26, 2013 By Leave a Comment
… mutex protecting the list of transactions, its applicability is quite limited. Namely, it requires the list of transactions to be either…-only cow and throw some data updates into the mix, limitations of read-only transactions become obvious. In the following test…-engine=INNODB –mysql-socket=/tmp/mysql.sock –oltp-point-selects=1 –oltp-simple-ranges=0 –oltp-sum-ranges=0 –oltp-order…
Post: MySQL 5.6 Compatible Percona Toolkit 2.2 Released
March 25, 2013 By 2 Comments
… working despite recoverable errors and such. Whereas pt-osc 2.1 only retries certain operations, pt-osc 2.2 retries every… JSON structure. Version check is on by default In 2.1.4, released September/October 2012, we introduced a feature called… forever by default, so specify –iterations or –run-time to limit how long they run. There are more changes in addition…
Post: Is Synchronous Replication right for your app?
May 14, 2013 By 18 Comments
… rows that are updated heavily “hotspots”. Examples of hotspots Example 1: Your application is an online game and you keep track… with a statement like this: UPDATE achievements SET count = count + 1 where achievement = ‘killed_troll’; How many players might accomplish this… specified by this variable (default is 1 retry). This means more waiting, and after the limit is exceeded you will still get…
Post: The write cache: Swap insanity tome III
April 19, 2013 By 5 Comments
… backup size is about 28GB and the file upload size limit is 5GB. So, about 28GB was written to disk in… st Fri Mar 22 10:03:22 UTC 2013 2 1 291992 224892 138848 7254284 0 0 148504 476 24190 24233… 0 Fri Mar 22 10:03:24 UTC 2013 2 1 291992 222228 138848 7258064 0 0 194040 96 22443 20425… 0 Fri Mar 22 10:03:26 UTC 2013 3 1 291992 224088 138852 7260196 0 0 172386 156 27143 27637…
Comment: Using index for ORDER BY vs restricting number of rows.
April 11, 2013 By 8 Comments
… trouble。。。。 the table: ID my_id follow 1 1 16 2 1 15 3 1 14 4 1 14 I just want to find out… FROM wp_fans GROUP BY follow order by NUM desc limit 5 Follow was index。 the explain: type:index，Extra:Using…
Post: Percona Toolkit for MySQL Webinar Followup Questions
April 5, 2013 By 1 Comment
… locally with the root user. And you can sometimes have limitations. For instance, you won’t be able to have access… are included in the slides. My setup was the following: 1 instance installed by the package manager, with the sakila database 1 master and 2 slaves installed with MySQL Sandbox, with the …
Post: Memory allocators: MySQL performance improvements in Percona Server 5.5.30-30.2
April 15, 2013 By
… the next transaction. There are two aspects of this problem: 1) memory allocation is an costly operation and if memory allocator….30 – throughput of MySQL 5.5.30 with glibc is limited first of all by inefficiency of transaction list handling (see…
