… 76 GB of the buffer pool, due to some weird memory mapping issue and a continuous block of 76 GB not being…. Apparenly OpenSUSE defaults are set in proportion to physical memory to keep the memory-hungry applications from taking the system down. On… physical memory, 2 GB swap it decided to set the virtual memory ulimit (-v) to 77.27 GB, and the physical memory (-m…
Post: Read Buffers, mmap, malloc and MySQL Performance
September 12, 2007 By 8 Comments
… – o_profile (often together with strace) are great tools for MySQL Performance analyses. Too many people end tuning on plans and…. Indeed allocating with mmap is much slower than allocating from memory memory pool which process already “owns” and in real life it… 10 times slow down over time as memory becomes fragmented with 50.000+ of memory areas mapped. As the gap in the process…
Post: Thoughts on MySQL Replication
July 7, 2006 By 18 Comments
… Memory is much faster than disk and you generally want to have data you’re accessing to be cached in memory by MySQL… of cache memory you have. Using memcached or similar solutions on the top of things for caching as well as mapping of… replication ? – Small database size. Small meaning working set fits in memory. This reduces waste of storage, removes problem with cache duplication…
Post: Distributed Set Processing with Shard-Query
May 14, 2011 By 27 Comments
…-Query works on sets, and features pluggable partition mapping, it allows partitioning resources to any depth …any limitation in resources in a cluster (cpu, memory, disk, power,etc) then split the problem …resource which speaks SQL, but right now only MySQL storage nodes are supported. Amdahl’s law …
Post: Quick comparison of MyISAM, Infobright, and MonetDB
September 29, 2009 By 30 Comments
…, but I had trouble with MonetDB — there was not enough memory for this. I didn’t do anything fancy with the… underlying language. An abstracted front-end is a great idea; MySQL abstracts the storage backend, but why not do both? Last… in an hour, I believe it uses memory-mapped files to hold the data in-memory. If this is true, it explains why…
Post: fadvise - may be not what you expect
April 2, 2010 By 7 Comments
… in reloading of the memory contents from the underlying mapped file or zero-fill-in-demand pages for mappings without an underlying file…
Post: What MySQL buffer cache hit rate should you target
June 29, 2006 By 5 Comments
…example – you have some script doing small (in memory) data processing on your server doing some traversing…you would not see otherwise. The bad luck is – MySQL currently does not provide this information (it exists… reads etc) but you would probably have trouble mapping them to particular objects and…
Post: The new cool MySQL patch has landed! Check your queries performance!
October 31, 2007 By 16 Comments
…: 56 Rows_examined: 1113 LOGGING OF THE REPLICATED STATEMENTS Normally MySQL will not write into slow log any queries executed by… that table must be created on disk instead of in memory, in such case Disk_tmp_table will state that. Filesort… entire buffer pool, because it could take a lot of memory to map all the pages. The inaccuracy grows with the number…
Post: Talking MySQL to Sphinx
April 19, 2009 By 4 Comments
… – Sphinx executes GROUP BY in fixed memory which means results may be approximate – … | 2735703 | +————+——–+———-+———–+———+ 10 rows in set (32.47 sec) MySQL mysql> select max(forum_id) as m,…The good thing is the query execution maps to the same execution engine which …
Post: State of MySQL Market and will Replication live ?
April 9, 2008 By 29 Comments
… see as response to these requirements ? From MySQL side we have further development of MySQL Cluster to be more usable for web… Wave is appliances – you can see Violin Memory appliance which can be used with MySQL to get very fast IO and so… Scalability on the scale of Big Table with Map Reduce. Indeed I think MySQL Replication usage will reduce, but I would not…
