很显然,如果数据已经在cache中或数据在磁盘上,代价显然是不同的。 参数effective_cache_size就是用来告诉优化器,系统可以提供多大的cache。这里的cache不仅仅是内存的cache,也考虑了文件系统cache、cpu的cache等。effective_cache_size是这些cache的总和。 1 2 3 4 5 6 7 8 9 10 11 12 13 postgres=# create ...
effective_cache_size 便是做这个的,简而言之,此参数用于告诉优化器有多少缓存可以用于查询,包括操作系统的缓存,按照一般经验,推荐设置为 RAM * 0.7 Sets the planner's assumption about the effective size of the disk cache that is available to a single query. 然而官网的解释比较粗糙,其详细原理并没有过...
Share buffers 和 filesystem cache 主要的作用就是缓存数据, 通过缓存数据来满足数据处理时,具体的信息一定在内存中存在. 其实到这里有两点是模糊的, 1 连接到POSTGRESQL的SESSION 是否需要内存, 2 数据的排序和临时表等等的内存释放包含在 effective_cache_size 也就是ORACLE 中的 SGA PGA的含义,在PG中是否有明确...
Share buffers 和 filesystem cache 主要的作用就是缓存数据, 通过缓存数据来满足数据处理时,具体的信息一定在内存中存在. 其实到这里有两点是模糊的, 1 连接到POSTGRESQL的SESSION 是否需要内存, 2 数据的排序和临时表等等的内存释放包含在 effective_cache_size 也就是ORACLE 中的 SGA PGA的含义,在PG中是否有明确...
That is exactly what effective_cache_size is all about. It helps the planner to determine how much cache there really is and helps to adjust the I/O cache. Actually,the explanation I am giving here is already longer than the actual C code in the server. Let's take a look at costsize...
effective_cache_size can have a serious impact on execution plans and change things dramatically. See what kind of difference it can make.
2.) effective_cache_size - from what I read this is the 'total' allowed memory for postgresql to use correct? So, if I am willing to allow 1GB of memory should I make this 1GB? This is the effective amount of caching between the actual postgres ...
DEVICE FOR CACHE COMPRESSION ENGINE INCREASING EFFECTIVE CACHE SIZE BY DATA COMPRESSION OF ON-CHIP CACHEPROBLEM TO BE SOLVED: To provide a device for a cache compression engine increasing an effective cache size by data compression of an on-chip cache. SOLUTION: The compression engine 30 for a ...
I'm developing a public-facing web application that serves high-resolution photos and videos, sometimes exceeding 80MB in size. The application runs in kiosk...
参数effective_cache_size就是用来告诉优化器,系统可以提供多大的cache。这里的cache不仅仅是内存的cache,也考虑了文件系统cache、cpu的cache等。effective_cache_size是这些cache的总和。 postgres=# create table t_random as select id,random() as r from generate_series(1,1000000) as id order by random();...