…_length > 65535L || int_count > 255) { my_message(ER_TOO_MANY_FIELDS, ER(ER_TOO_MANY_FIELDS), MYF(0)); DBUG_RETURN(1); } Which is, of… 2+strlen(field_name) for each field. Unless you have many columns, and then it’s something else (as in that case… perl code I was able to hit a too many columns error with only 192 columns (i.e. 191 worked): sub cname ($$) { my $c…
Post: Is Synchronous Replication right for your app?
May 14, 2013 By 18 Comments
… solution. But, what they tend not to think too much about is if moving from async to… count = count + 1 where achievement = ‘killed_troll’; How many players might accomplish this achievement at the same time… Example 2, above, how above moving the ‘joined’ column to the users_groups table so we don’…
Post: High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
… this now. You can have the clicks column record the total, and the blue_clicks column record only blue clicks; to find… key columns. And not only will every index be a little narrower, the table will now contain only half as many rows… that read a lot of rows — MySQL can’t handle too many of those at once. Aside from star schemas, another tactic…
Post: MySQL Indexing Best Practices: Webinar Questions Followup
August 16, 2012 By 4 Comments
… to use something else as primary key. Q: How many indexes is too many? A: There is a hard limit on amount of… per table in recent MySQL versions. However it is often too many. Instead of thinking about hard limit of indexes I prefer… index on one column and using order by on another column. do i need to add the index on column using order by…
Post: My Innodb Feature wishes
May 4, 2006 By 30 Comments
… the page if many columns are long strings. I would like to see it at least doing it for indexed columns only or… fit all and for certain workloads 16K is too much while for some others too little. Being able to specify page size… is too bad even with 4 concurrent queries). The problem seems to be at least partially due to global mutexes in many…
Post: Identifying the load with the help of pt-query-digest and Percona Server
December 29, 2011 By 3 Comments
… need to be analyzed and fixed. And there are not too many tools out there that can make your life easy. However… to the times/values reported in the 95% (95th percentile) column as that gives us more accurate understanding. Now, for example… tables involved in the query, probably selecting only the needed columns which could exclude the blob ones. Conclusion The only conclusion…
Post: Quick comparison of MyISAM, Infobright, and MonetDB
September 29, 2009 By 30 Comments
… many columns (the same one Peter wrote about recently). The client’s performance is suffering in part because of the number of columns… (sums of columns), but they’re ad-hoc (can access any columns) and it seems tailor-made for a column-oriented database. I… front-end to it. You can talk XQuery to it, too. I’m not sure if you can talk dirty to…
Post: Find and remove duplicate indexes
June 20, 2012 By 9 Comments
… that means that the secondary keys contains the primary key column. Let’s see the following example: mysql> show create table… index ‘key_name’ includes the primary key so that last column ‘i’ is usually not necessary on the secondary key because… the problem. Conclusion Indexes are good for our queries but too many indexes or duplicate or redundant indexes can hurt the performance…
Post: How innodb_open_files affects performance
November 18, 2009 By 4 Comments
… of test and creating 100.000 tables with single integer column. The process of creating tables took about 45 minutes which… warning messages during recovery: 091118 18:47:44 InnoDB: Warning: too many (67) files stay open while the maximum InnoDB: allowed value… file LRU len 0 091118 18:47:44 InnoDB: Warning: too many (68) files stay open while the maximum InnoDB: allowed value…
Post: Announcing Percona Server 5.1.66-14.2
January 15, 2013 By Leave a Comment
…. Bug fixed #908620 (Ignacio Nin). innodb_fake_changes would allocate too many extents on UPDATE. In some cases this could cause infinite… #1039536 (Alexey Kopytov). In cases where indexes with AUTO_INCREMENT columns where correctly detected, mysqldump prevented all such keys from optimization…
