从磁盘上读取的数据量,单位Bytes,当Query没有命中缓存Cache时,则需要去磁盘读取数据。 Read bytes Query读取的总字节大小,单位Bytes,包括物理读(Physical Read)和从内存Cache中读取的数据大小。反映Query执行获取的数据量的大小。 Affected rows DML影响的行数,只有DML才会展示该指标。 Dag instance count 查询计划DAG...
The machine RAM says 64 MB, but why does the total memory display only 5x or even 4x MB? The answer is all kinds of, unable to agree on which is right: Built-in software, background programs, boot services and procedures, system cache or buffer pool, the memory occupied by the core...
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 block...
In-memory package cache Package cache event monitor name The procedure searches for the section in the given location. An executable ID uniquely and consistently identifies a section. The executable ID is an opaque, binary token generated at the data server for each section that has been executed...
Services: There are multiple layers of cache in a service. If the data is not cached in the CPU cache, the service will try to retrieve the data from memory. Sometimes the service has a second-level cache to store data on disk.
If the duration is long, the cache may not be hit. Create split reader cost: the duration that is taken to open a file. If the duration is long, the metadata of the file does not hit the cache. If this occurs, the I/O overhead is high. Get result cost: the duration from ...
Sorts are expensive operations especially on large tables where the rows do not fit in memory and spill to disk. By default sort blocks are placed into the buffer cache. This may result in aging out of other blocks that may be reread by other processes. To avoid this you can use the pa...
| Source:PLAN_CACHE | | TemplateId: 5819c807 EXPLAIN EXECUTE语句:表示下推SQL在MySQL的执行情况,这个语句和MySQL的explain语句同义。通过该语句可以查看下推SQL在DN上有没有使用索引,有没有做全表扫描。 EXPLAINEXECUTEselect count(*) from lineitem group byL_ORDERKEY; ...
Inside subQuery1, there can be zero (as in this case) or more DFEChunkLocalSubQuery or DFELoopSubQuery operators that encapsulate a part of the pushed execution plan that is executed in a memory-bounded mechanism. A DFEChunkLocalSubQuery contains one SolutionInjection that is used as an input...
UNCACHEABLE UNIONUNION中第二个或之后的SELECT,属于无法缓存的子查询 DEPENDENT 意味着使用了关联子查询。 3. table 查询的表名。不一定是实际存在的表名。 可以为如下的值: <unionM,N>: 引用id为M和N UNION后的结果。 <derivedN>: 引用id为N的结果派生出的表。派生表可以是一个结果集,例如派生自FROM中...