…. Writing a core file Segmentation fault (core dumped) Note the end of this message – you should see Segmentation fault(core dumped) after…. If core file was not written you will just have “Segmentation fault” with no “core dumped” attached to it. If you…
Comment: Fix of InnoDB/XtraDB scalability of rollback segment
February 25, 2010 By 9 Comments
Just ran into a pileup created by contention on the rollback segment mutex. The thread holding it is blocked on disk IO to read a page from the rollback segment. It doesn’t give up the rollback segment mutex while waiting for IO to complete. That won’t scale. Thanks for finding this.
Comment: Fix of InnoDB/XtraDB scalability of rollback segment
January 25, 2009 By 9 Comments
…. My group has recommended may times in increasing the rollback segments, but my concern is that in a mixed server environment… will not recover from the new segments defined. Also, giving my.cnf parameter to control segments gives some flexibility but also increases…
Post: How much space does empty Innodb table take ?
December 16, 2008 By 7 Comments
… happening here. According to documentation each index should get 2 segments one for non-leaf an one for leaf pages. However… whole 32 pages allocated. In the case above no single segment should require more than 32 pages so It is surprising…) What is clear however is what if some pages from segment are allocated it goes in the interesting space regarding space…
Post: My Innodb Feature wishes
May 4, 2006 By 30 Comments
…’m not mistaken blobs are stored each in its own “segment” which means having many blobs in the same row is… and store on the same segment and ie only store blobs over 1M in their own segments. Clustering. I love Innodb’s…
Post: Profiling MySQL Memory Usage With Valgrind Massif
January 9, 2013 By 3 Comments
… before compiling. An often bumped up setting is VG_N_SEGMENTS in coregrind/m_aspacemgr/aspacemgr-linux.c (when you see ‘Valgrind: FATAL: VG_N_SEGMENTS is too low’) Newer releases [better] support newer hardware and…
Comment: Should we give a MySQL Query Cache a second chance ?
April 10, 2011 By 64 Comments
… bit, say using breaking the cache into 16 segments and choosing a cache segment on hash of sql mod 16 or some…
Comment: Should we give a MySQL Query Cache a second chance ?
April 10, 2011 By 64 Comments
… bit, say using breaking the cache into 16 segments and choosing a cache segment on hash of sql mod 16 or some…
Comment: Using Multiple Key Caches for MyISAM Scalability
April 29, 2010 By 8 Comments
… particular master on. We took the time to examine and segment the tables that were candidates for giving their own key… you can throw at your writes, the further you can segment your key caches. Obviously there will be upper bounds but…
Post: Tuning for heavy writing workloads
October 14, 2009 By 9 Comments
… (it is rseg->mutex). The mutex is for each rollback segments, so we can increase the rsegs to solve the contention… size. The value is the number of entries in rollback segment. The entries are used for consistent reading of the older…
