pga superstore

copy of the cursor in the PGA, and at the same time the client will have a statement handle, which are called the cursor, in V$open_ Inside the cursor we can see the currently open cursor and the cached cursor inside the PGA.Session_cached_cursorThis parameter limits the length of the cursor cache list in the PGA session, the cursor cache list is a two-way, LRU list, when a session is intended to close a c

Overview:1.Oracle Memory Management2.Oracle Database startup shutdown3.Oracle parameter file4.Oracle Control files5.Oracle Redo log File6.Oracle Undo Table Space Management7.Oracle normal tablespace and data file8.Oracle Temp Table Space9.Oracle Lock Management10.Oracle User Management 1.Oracle Memory Management1.1 Automatic memory management11g:amm 10G:ASMM1.2 Modifying the SGA sizeSql> alter system set sga_target=1m; System altered. Sql> Show parameter SGA NAME

:① improve application performance;② provides modular program development capabilities;③ has good compatibility;④ allows defining identifiers;⑤ provides a program control structure;⑥ provides exception handling.4. Oracle Memory ArchitectureOracle memory structure can be divided into shared memory and non-shared memory area, the shared memory area is mainly composed of the SGA (System Global area), the non-shared memory is mainly composed of the PGA (P

build input, which is the build table mentioned above, the larger table is B)Create a hash table that can exist in the hash area MemoryThen, we use a large row sources (called probe input, that is, the probe table mentioned above) to test the hash table created earlier.If the hash area memory is not large enough, the hash table cannot be fully stored in the hash area memory.In this case, Oracle splits build input and probe input into multiple unconnected partitions using a hash function in the

The oracle memory structure is composed of two parts: sga (system global area) and pga (program global area ). SGA: allocated when an instance is started. It is an integral part of the instance. PGA: a service process is allocated with one PGA when it is started ). SGA can occupy 80% of the memory linux commands: ipcssga composition: share pool, database buffer c

Automatic Memory Management is configured with two initialization parameters: MEMORY_TARGET: the total size of shared memory that can be used by Oracle when SGA and PGA are dynamically controlled. this parameter is dynamic, therefore, the total amount of memory provided to Oracle can be dynamically increased or decreased. It cannot exceed the value set by the MEMORY_MAX_TARGET parameter. Automatic Memory Management is configured with two initializati

statistic with known issues in the Statspack report (such as low-efficiency SQL statements. Check the index scan to ensure that each scan is necessary and to check the connection sequence of Multi-Table connections. DB_CACHE_SIZE is also the factor that determines the frequency of these waits. Problematic Hash-area connections should appear in PGA memory, but they also consume a large amount of memory, resulting in a large amount of waiting During se

). A partition is a series of consecutive blocks in the data file. By adding a new partition for the segment, the segment will be expanded. These areas must be adjacent, even in a data file. They can be from any data file that is part of the tablespace where the segment is located.Logically, a tablespace can contain multiple segments, and each segment can contain multiple partitions. A zone is a set of continuous Oracle blocks. Physically, data files are composed of multiple operating system bl

sqlid and wait event of the most occupied time within 10 minutesGroup by SQL _id, eventOrder by count (*) desc-- ****************** Buffer hit rate *****************SELECT a. VALUE + B. VALUE logical_reads,C. VALUE phys_reads,Round (100 * (1-c.value/(a. value + B. value), 4) hit_ratioFROM v $ sysstat a, v $ sysstat B, v $ sysstat cWHERE a. NAME = 'db block gets'AND B. NAME = 'consistent gets'AND c. NAME = 'physical reads ';-- ****************** Share pool hit rate *****************Select sum (p

When the Oracle database is started, it starts the Oracle instance based on the parameters provided in the parameter file. These parameters include the database name, sga, pga allocation, and control file location, When the Oracle database is started, it starts the Oracle instance based on the parameters provided in the parameter file. These parameters include the database name, sga, pga allocation, and con

) control structure ). That is to say, this area contains SQL statements that have been analyzed by syntax and are ready to be executed at any time. Dictionary high-speed buffer (data dictionary cache) It is used to store all the information required by the Oracle System Management. This information is the username used to log on to Oracle. These users have database objects and their locations. Svrmgr>; show SGA total system global area 35544188 bytes fixed size 22208 bytes variable size 3376332

as databases. 2) program global zone (PGA) PGA is the memory area used by Oracle. It can only be stored and controlled by a single process at a time, used to store session variables and internal arrays. SGA Oracle memory structure (SGA diagram) § 2. 7.2 Global Program Zone PGA is the memory area used by Oracle. It can only be stored and controlled by a single pr

information of the dump structure. The event set by alter session is only valid for the current session. For the event set by alter system, except for the current session, the event is equally valid for the newly logged-on session, but the session opened before the alter system command is executed is invalid. IMMEDIATE-related events 1. Memory Dumps 1). Global Area Alter session set events 'immediate trace name global_area level n '; 1 Including PGA