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Search Results for: update delete

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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An Updated Description of Clustering Keys for TokuDB

Covering indexes can result in orders of magnitude performance improvements for queries. Bradley’s presentation on covering indexes describes what a covering index is, how it can effect performance, and why it works. However, the definition of …

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What’s new in TokuMX 1.4, Part 3: Optimized updates

We just released version 1.4.0 of TokuMX, our high-performance distribution of MongoDB. There are a lot of improvements in this version (release notes), the most of any release yet. In this series of blog posts, …

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TokuDB Fast Update Benchmark

Last month my colleague Rich Prohaska covered the technical details of our “Fast Update” feature which we added to TokuDB in version 6.6.  The message based architecture of Fractal Tree Indexes allows us to defer certain operations …

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STOP: DELETE IGNORE on Tables with Foreign Keys Can Break Replication

DELETE IGNORE suppresses errors and downgrades them as warnings, if you are not aware how IGNORE behaves on tables with FOREIGN KEYs, you could be in for a surprise. Let’s take a table with data as example, …

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Why “insert … on duplicate key update” May Be Slow, by Incurring Disk Seeks

In my post on June 18th, I explained why the semantics of normal ad-hoc insertions with a primary key are expensive because they require disk seeks on large data sets. I previously explained why it …

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Making Updates Fast, by Avoiding Disk Seeks

The analysis that shows how to make deletions really fast by using clustering keys and TokuDB’s fractal tree based engine also applies to make updates really fast. (I left it out of the last post …

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How Fast Can Updates Run?

Last time, I introduced the notion of strict and lenient updates. Now it’s time to see what the performance characteristics are of each. Just to rehash, we are focusing on the storage engine (a la …

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Updates & Discipline

So far, I’ve analyzed point and range queries. Now it’s time to talk about insertions and deletions. We’ll call the combination updates. Updates come in two flavors, and today we’ll cover both. Depending on the …

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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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