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The "MemtableThresholds" page has been changed by FlipKromer. The comment on this change is: toc. http://wiki.apache.org/cassandra/MemtableThresholds?action=diff&rev1=15&rev2=16 -------------------------------------------------- + <<TableOfContents>> + == Don't Touch that Dial == The settings described here should only be changed in the face of a quantifiable performance problem. They will affect the cluster quite differently for distinct use cases and workloads, and the defaults were well-chosen. @@ -25, +27 @@ '''Larger memtables do absorb more overwrites''': If your write load sees some rows written more often than others (eg upvotes of a front-page story) a larger memtable absorbs more overwrites, which creates more efficient sstables and thus better read performance. If your write load is batch oriented or if you have a massive row set, rows are not likely to be rewritten for a long time, and so this benefit will pay a smaller dividend. - '''Larger memtables lead to more effective compaction''': Since compaction is tiered, large sstables are prefereable: turning over tons of tiny memtables is bad. Again, this impacts read performance (by improving the overall io-contention weather), but not writes. + '''Larger memtables do lead to more effective compaction''': Since compaction is tiered, large sstables are prefereable: turning over tons of tiny memtables is bad. Again, this impacts read performance (by improving the overall io-contention weather), but not writes. Listed below are the thresholds found in `storage-conf.xml`, along with a description.
