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Showing entries 1 to 10 of 58 10 Older Entries

Displaying posts with tag: indexing (reset)

Why Unique Indexes are Bad
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Before creating a unique index in TokuMX or TokuDB, ask yourself, “does my application really depend on the database enforcing uniqueness of this key?” If the answer is ANYTHING other than yes, do not declare the index to be unique. Why? Because unique indexes may kill your write performance. In this post, I’ll explain why.

Unique indexes are a strange beast: they have no impact on standard databases that use B-Trees, such as MongoDB and MySQL, but may be horribly painful for databases that use write optimized data structures, like TokuMX’s Fractal Tree(R) indexes. How? They

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Purging old rows with QueryScript: three use cases
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Problem: you need to purge old rows from a table. This may be your weekly/monthly cleanup task. The table is large, the amount of rows to be deleted is large, and doing so in one big DELETE is too heavy.

You can use oak-chunk-update or pt-archiver to accomplish the task. You can also use server side scripting with QueryScript, offering a very simple syntax with no external scripting, dependencies and command line options.

I wish to present three cases of row deletion, with three different solutions. In all cases we assume some TIMESTAMP column

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532x Multikey Index Insertion Performance Increase for MongoDB with Fractal Tree Indexes
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In my three previous MongoDB blogs I wrote about our implementation of Fractal Tree(R) indexes on MongoDB, showing a 10x insertion performance increase, a 268x query performance increase, and a comparison of covered indexes and clustered indexes. These benchmarks show the difference that rich and efficient indexing can make to your MongoDB workload.

Given the high performance of Fractal Tree Indexes, we’ve created a new

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My Talk Next Week at HighLoad++
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Next week I’ll be visiting Moscow to talk at Highload++. The conference will take place during Monday 22nd and Tuesday 23rd at the Radisson hotel. I will be giving my personal version of an indexing talk that my colleagues have given in meetups and conferences in the US.

Highload++ conference is targeted to address the issues of complex high traffic web properties. Most of these sites depend on databases to deliver their content, record the traffic and report the application activities in real time. As I learned early in my career at MySQL, the database schema and in particular the indexing strategy, are critical to achieve the highest possible performance out of the

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Looking for MongoDB users to test Fractal Tree Indexing
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In my three previous blogs I wrote about our implementation of Fractal Tree Indexes on MongoDB, showing a 10x insertion performance increase, a 268x query performance increase, and a comparison of covered indexes and clustered indexes. The benchmarks show the difference that rich and efficient indexing can make to your MongoDB workload.

It’s one thing for us to benchmark MongoDB + TokuDB and another to measure real world performance. If you are looking for a way to improve the performance or

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MongoDB Index Shootout: Covered Indexes vs. Clustered Fractal Tree Indexes
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In my two previous blogs I wrote about our implementation of Fractal Tree Indexes on MongoDB, showing a 10x insertion performance increase and a 268x query performance increase. MongoDB’s covered indexes can provide some performance benefits over a regular MongoDB index, as they reduce the amount of IO required to satisfy certain queries.  In essence, when all of the fields you are requesting are present in the index key, then MongoDB does not have to go back to the main storage heap to

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How common_schema split()s tables - internals
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This post exposes some of the internals, and the SQL behind QueryScript's split. common_schema/QueryScript 1.1 introduces the split statement, which auto-breaks a "large" query (one which operates on large tables as a whole or without keys) into smaller queries, and executes them in sequence.

This makes for easier transactions, less locks held, potentially (depending on the user) more idle time released back to the database. split has similar concepts to oak-chunk-update and

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Table split(...) for the masses
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(pun intended)

common_schema's new split statement (see release announcement) auto-splits complex queries over large tables into smaller ones: instead of issuing one huge query, split breaks one's query into smaller queries, each working on a different set of rows (a chunk).

Thus, it is possible to avoid holding locks for long times, allowing for smaller transactions. It also makes for breathing space for the RDBMS, at times boosting operation speed, and at times prolonging operation speed at will.

In this post I show how split exposes itself to the user, should the user wish so.

split can

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Webinar: Understanding Indexing
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Three rules on making indexes around queries to provide good performance

Application performance often depends on how fast a query can respond and query performance almost always depends on good indexing. So one of the quickest and least expensive ways to increase application performance is to optimize the indexes. This talk presents three simple and effective rules on how to construct indexes around queries that result in good performance.


Time: 2PM EDT / 11AM PDT

This webinar is a general discussion applicable to all databases using indexes and is not specific to any particular MySQL® storage engine


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Fractal Tree Indexing and Filesystems – HotStorage 2012
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Modern file systems are well equipped to deal with large writes. One area that remains challenging however is to efficiently write out “microdata”, such as metadata and small portions of large files, while showing good I/O utilization when the data is read back. This challenge is evident with mount options like “noatime” which disables updating file access time on reads. This kind of solution avoids the problem altogether. Another approach, delayed allocation, is meant to coalesce small writes in memory as long as possible before writing it out to disk. Filesystems like ext4 and Btrfs use delayed allocation to make a best-effort at reducing fragmentation and random I/O.

Isn’t there a way to fundamentally solve filesystem fragmentation and random I/O?

This week, I’ll be speaking at

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Showing entries 1 to 10 of 58 10 Older Entries

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