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Displaying posts with tag: RocksDB (reset)
Peter Zaitsev webinar January 27th: Compression In Open Source Databases

Percona invites you to attend a webinar Wednesday, January 27th, with CEO Peter Zaitsev: Compression In Open Source Databases. Register now!

Data growth has been tremendous in the last decade and shows no signs of stopping. To deal with this trend database technologies have implemented a number of approaches, and data compression is by far the most common and important. Compression in open source databases is complicated, and there are a lot of different approaches – each with their own implications.

In this talk we will perform a survey of compression in some of the most popular open source database engines including: Innodb, TokuDB, MongoDB, WiredTiger, RocksDB, and PostgreSQL.

Important information: …

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Checkpoint strikes back

In my recent benchmarks for MongoDB, we can see that the two engines WiredTiger and TokuMX struggle from periodical drops in throughput, which is clearly related to a checkpoint interval – and therefore I correspond it to a checkpoint activity.

The funny thing is that I thought we solved checkpointing issues in InnoDB once and for good. There are bunch of posts on this issue in InnoDB, dated some 4 years ago.  We did a lot of research back then working on a fix for Percona Server

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Using Cgroups to Limit MySQL and MongoDB memory usage

Quite often, especially for benchmarks, I am trying to limit available memory for a database server (usually for MySQL, but recently for MongoDB also). This is usually needed to test database performance in scenarios with different memory limits. I have physical servers with the usually high amount of memory (128GB or more), but I am interested to see how a database server will perform, say if only 16GB of memory is available.

And while InnoDB usually respects the setting of innodb_buffer_pool_size in O_DIRECT mode (OS cache is not being used in this case), more engines (TokuDB for MySQL, MMAP, WiredTiger, RocksDB for MongoDB) usually get benefits from OS cache, and Linux kernel by default is generous enough to allocate as much memory as available. There I should note that while TokuDB (and TokuMX for MongoDB) supports DIRECT mode (that is bypass OS cache), we found there is a performance gain if OS cache is used for compressed pages.

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