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Search Results for: index slower than table

Importing big tables with large indexes with Myloader MySQL tool

Mydumper is known as the faster (much faster) mysqldump alternative. So, if you take a logical backup you will choose Mydumper instead of mysqldump. But what about the restore? Well, who needs to restore a …

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Introducing TokuMX Clustering Indexes for MongoDB

Since introducing TokuMX, we’ve discussed benefits that TokuMX has for existing MongoDB applications that require no changes. In this post, I introduce an extension we’ve made to the indexing API: clustering indexes, a tool that …

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MySQL 5.6.10 Optimizer Limitations: Index Condition Pushdown

While preparing the webinar I will deliver this Friday, I ran into a quite interesting (although not very impacting) optimizer issue: a “SELECT *” taking half the time to execute than the same “SELECT one_indexed_column” …

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Full table scan vs full index scan performance

Earlier this week, Cédric blogged about how easy we can get confused between a covering index and a full index scan in the EXPLAIN output. While a covering index (seen with EXPLAIN as Extra: Using …

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MySQL Indexing Best Practices: Webinar Questions Followup

I had a lot of questions on my MySQL Indexing: Best Practices Webinar (both recording and slides are available now) We had lots of questions. I did not have time to answer some and others …

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Improved InnoDB fast index creation

One of the serious limitations in the fast index creation feature introduced in the InnoDB plugin is that it only works when indexes are explicitly created using ALTER TABLE or CREATE INDEX. Peter has already …

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table_cache negative scalability

Couple of months ago there was a post by FreshBooks on getting great performance improvements by lowering table_cache variable. So I decided to investigate what is really happening here. The “common sense” approach to tuning …

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Statistics of InnoDB tables and indexes available in xtrabackup

If you ever wondered how big is that or another index in InnoDB … you had to calculate it yourself by multiplying size of row (which I should add is harder in the case of …

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How clustering indexes sometimes help UPDATE and DELETE performance

I recently posted a blog entry on clustering indexes, which are good for speeding up queries. Eric Day brought up the concern that clustering indexes might degrade update performance. This is often true, since any …

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Performance gotcha of MySQL memory tables

One performance gotcha with MEMORY tables you might know about comes from the fact it is the only MySQL storage engine which defaults to HASH index type by default, instead of BTREE which makes indexes …

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