aBeginning with version 1.2.7.0 and up to version 1.3, the core of JCS (the LRU memory cache, the indexed disk cache, the TCP lateral, and the RMI remote server) requires only two other jars. 开始从版本1.2.7.0和由版本1.3决定, JCS的核心 (LRU存储器高速缓存、被标注的磁盘高速缓存、TCP侧面...
it works well for concurrent applications and scales to any number of processors. It even optimizes the memory layout with respect to the CPU caches to improve[cache locality]and avoid[false sharing].
Create dataset reader cost:创建索引数据读取器的耗时,耗时较高有可能是未命中Cache。 Create split reader cost:打开文件消耗的时间,耗时高则说明文件meta没有命中缓存,IO开销较高。 Get result cost:从Start Query阶段结束开始计算,到所有结果均返回所花费的时间。Get result cost包含Get the first block cost,单位...
UNCACHEABLE SUBQUERY A subquery for which the result cannot be cached and must be re-evaluated for each row of the outer query UNCACHEABLE UNION The second or later select in a UN´ION that belongs to an uncacheable subquery (see UNCACHEABLE SUBQUERY)type...
Implement a Stack computer in Javascript. This is a simple computer that keeps a stack, when a number is entered it goes onto the top of the stack. When an operation is entered, the previous 2 numbers Explain the operations of: i) Cache Memory ii) Associative Memory iii) Virtual Memory ...
Buffers can only be used with the ANALYZE option. PostgreSQL uses a Least Recently Used (LRU) cache to store frequently used data in memory. Buffers display how much of the data comes from a cache, and how much is retrieved from disk. Displays the number of shared, local, and temp ...
The SELECT identifier. This is the sequential number of the SELECT within the query. The value can be NULL if the row refers to the union result of other rows. In this case, the table column shows a value like <unionM,N> to indicate that the row refers to the union of the rows wi...
在使用explain查看执行计划后如果还看不出为什么sql执行慢的原因,此时可以使用show profile,可以更细粒度的查看sql的执行过程,诸如IO,上下文切换,CPU,Memory等等。根据这些开销进一步分析当前SQL瓶颈从而进行优化与调整。 默认情况下,处于关闭状态,并保存最近15次的运行结果 ...
For a "Hello world" program, the kernel must copy the string from the user program memory to the screen memory. Why must the screen's buffer memory be protected? What is the purpose of cache memory? Explain how uncompressed sound files are represented, using bits. ...
configure-memory-usage.md configure-placement-rules.md configure-store-limit.md configure-time-zone.md constraints.md control-execution-plan.md coprocessor-cache.md correlated-subquery-optimization.md cost-model.md credits.md daily-check.md data-type-date-and-time.md data-type-default-values....