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Displaying posts with tag: Hints and tips (reset)

Access Shard-Query with the MySQL client without using MySQL proxy
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One of the great features of Shard-Query is the ability to use MySQL proxy to access resultsets transparently. While this is a great tool, many people have expressed reservations about using MySQL Proxy, an alpha component in their production environment.

I recognize that this is a valid concern, and have implemented an alternate method of retrieving resultsets directly in the MySQL client, without using a proxy. This means that any node can easily act as the “head” node without any extra daemon, instead of having to run many proxies.

The sq_helper() routine has been checked into the git …

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Shard-Query loader gets a facelift and now Amazon S3 support too
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Shard-Query (source) now supports the MySQL “LOAD DATA INFILE” command.

When you use LOAD DATA LOCAL INFILE a single threaded load from the current process will be performed.  You can specify a path to a file anywhere readable by the PHP script.  This allows loading without using the Gearman workers and without using a shared filesystem.

If you do not specify LOCAL, then the Gearman based loader is used.  You must not specify a path to the file when you omit the LOCAL keyword.  This …

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Shard-Query supports background jobs, query parallelism, and all SELECT syntax
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SkySQL just blogged about a tool to schedule long running MySQL jobs, prevent too many queries from running simultaneously, and stores the results in tables.  It even uses Gearman.  You will note that the article says that it uses PAQU, which uses Shard-Query.

I think PAQU was created for two reasons.  A) Shard-Query lacked support for fast aggregation of STDDEV and VARIANCE (this has been fixed), and B) their data set requires “cross-shard queries”.  From what I can see though, their type of cross-shard queries can be solved using subqueries in the FROM clause using Shard-Query, instead …

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Tips for working with append-only databases using sharding and log structured tables
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This post is structured like a series of questions and answers in a conversation.  I recently had a number of conversations that all pretty much went this same way.  If you, like others, have many basic questions about how to proceed when faced with an append-only store for the first time, well then hopefully this post will help provide some answers for you.  The post focuses on column stores, the most common append-only store, but there are others.

Why do I want to use a column store? Column stores are optimal for OLAP analysis

Column stores offer substantial performance …

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Showing entries 1 to 4

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