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Search Results for: select row

Online Advertiser Intent Media Selects TokuDB over InnoDB and NoSQL for Big Data Ad-Hoc Analysis

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Intent Media Issue addressed: Ad hoc analytics on clickstream data arriving too fast for InnoDB or NoSQL to handle. TokuDB powers an online advertising application The Company: Headquartered in New York, Intent Media is a …

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Debugging problems with row based replication

MySQL 5.1 introduces row based binary logging. In fact, the default binary logging format in GA versions of MySQL 5.1 is ‘MIXED’ STATEMENT*;   The binlog_format  variable can still be changed per sessions which means …

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When the subselect runs faster

A few weeks ago, we had a query optimization request from one of our customer. The query was very simple like:

This column in the table is looks like this:

The table have …

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Faster MySQL failover with SELECT mirroring

One of my favorite MySQL configurations for high availability is master-master replication, which is just like normal master-slave replication except that you can fail over in both directions. Aside from MySQL Cluster, which is more …

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Missing Data – rows used to generate result set

As Baron writes it is not the number of rows returned by the query but number of rows accessed by the query will most likely be defining query performance. Of course not all row accessed …

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To SQL_CALC_FOUND_ROWS or not to SQL_CALC_FOUND_ROWS?

When we optimize clients’ SQL queries I pretty often see a queries with SQL_CALC_FOUND_ROWS option used. Many people think, that it is faster to use this option than run two separate queries: one – to …

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Using index for ORDER BY vs restricting number of rows.

One interesting problem with MySQL Optimizer I frequently run into is making poor decision when it comes to choosing between using index for ORDER BY or using index for restriction. Consider we’re running web site …

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SELECT LOCK IN SHARE MODE and FOR UPDATE

Baron wrote nice article comparing locking hints in MySQL and SQL Server. In MySQL/Innodb LOCK IN SHARE MODE and SELECT FOR UPDATE are more than hints. Behavior will be different from normal SELECT statements. Here …

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INSERT INTO … SELECT Performance with Innodb tables.

Everyone using Innodb tables probably got use to the fact Innodb tables perform non locking reads, meaning unless you use some modifiers such as LOCK IN SHARE MODE or FOR UPDATE, SELECT statements will not …

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Join Optimizations in MySQL 5.6 and MariaDB 5.5

This is the third blog post in the series of blog posts leading up to the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. This blog post is targeted at the join …

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