pga purse

When creating an Oracle database, you should see this option in the database creation assistant wizard, which is the connection mode of the database. In Oracle9i or 10g, we can see two connection modes: a dedicated server connection (dedicated server) and a shared server connection (Shared Server ). Next we will classify the differences between the two connection methods. Dedicated server mode means that each time you access Oracle, the listener of the Oracle server will get this access reques

When creating an Oracle database, you should see this option in the database creation assistant wizard, which is the connection mode of the database. In Oracle9i or 10g, we can see two connection modes: a dedicated server connection (dedicated server) and a shared server connection (Shared Server ). Next we will classify the differences between the two connection methods. Dedicated server mode means that each time you access Oracle, the listener of the Oracle server will get this access reques

Oracle memory structure, oracle Structure The memory structure of Oracle is divided into SGA and PGA. SGA is dynamically allocated. It is configured by the sga_max_size parameter and allocated when the oracle database instance is started, share an SGA for all session connections; For PGA, each user creates a PAG memory zone for session connections. Shared Pool: stores the execution structure (Execution Pla

When creating an Oracle database, you should see this option in the database creation assistant wizard, which is the connection mode of the database. In Oracle9i or 10g, we can see two connection modes: a dedicated server connection (dedicated server) and a shared server connection (shared server ). Next we will classify the differences between the two connection methods. Dedicated server mode means that each time you access Oracle, the Listener of the Oracle server will get this access request

, which may be necessary to recover from a media failure.◆ Password File: Authenticate which users have the permission to start and close Oracle routines. 2. Logical Structure tablespaces, segments, partitions, and blocks)◆ Tablespace: it is the basic logical structure in the database and a collection of data files.◆ Segment: the space occupied by objects in the database.◆ Zone: A large storage space reserved for data at one time.◆ Block: the most basic storage unit of ORACLE, which is specified

database cache and a data dictionary cache. The size of the Shared Pool directly affects the database performance. Data Buffer Zone It is used to store the data read from the disk data file, which is shared by all users. The server process saves the read data in the data buffer. When subsequent requests need the data, they can be found in the memory and no longer need to read the data from the disk, improving the reading speed. The size of the data buffer has a direct impact on the reading spee

read data in the data buffer. When subsequent requests need the data, they can be found in the memory and no longer need to read the data from the disk, improving the reading speed. The size of the data buffer has a direct impact on the reading speed of the database. Log Buffer Logs record all modification information of the database. The log information is first generated in the log buffer zone. When the number of log data in the log buffer reaches a certain level, the background process

files and redo log files, a database requires at least one control file Data files: File redo log files that store data: Records of changes made to the database so that data recovery can be enabled in the event of a failure. A database requires at least two redo log file parameter files: Defines the attributes of an Oracle routine, such as a parameter archive that adjusts the size of some memory structures in the SGA: an offline copy of the redo log files that may be necessary for recovery from

database requires at least one control file Data files: Files that store data Redo log file: Contains a record of changes made to the database so that data recovery can be enabled in the event of a failure. A database requires at least two redo log files Parameter file: Defines the attributes of an Oracle routine, for example, it contains parameters to resize some memory structures in the SGA Archive: An offline copy of the redo log files that may be necessary for recovery from media failure. P

------Shared Memory segments-------- key shmid owner perms bytes nattch status 0x36010028 425995 Oracle 640 287309824 ------semaphore Arrays-------- Key semid owner perms nsems 0x7df2e688 98304 Oracle 640 154 ------message queues-------- key msqid owner perms used-bytes Messages 2. There is a stack of Oracle processes that are started: Oracle database startup has two large memory structure

the CentOS version under Kernel2.6 to carry out the experiment. [Oracle@361way ~]$ Uname-r2.6.18-128.el5At this point, the Oracle instance is 11GR2 (11.2.0.3), running in AMM memory management mode. The shared memory segment information is as follows. [Oracle@361way ~]$ Ipcs-m------Shared Memory Segments--------Key shmid owner perms bytes nattch Status0x00000000 32768 Oracle 640 4096 00x00000000 65537 Oracle 640 4096 00X01606D30 98306 Oracle 640 4096 0[Oracle@361way ~]$ grep huge/proc/meminfo

Area: A large storage space reserved for data one-time Block: Oracle's most basic storage unit, specified when establishing a database 3. Memory allocation (SGA and PGA) SGA: The memory area that is used to store database information that is shared by the database process. It contains data and control information for the Oracle server, which is allocated in real memory on the computer where the Oracle server resides, if the actual memory is not enou

storage space that is reserved for data at one one-time.Block: Oracle's most basic storage unit, specified when establishing a database. 3. Memory allocation (SGA and PGA) SGA: The memory area that is used to store database information that is shared by the database process. It contains data and control information for the Oracle server, which is allocated in real memory on the computer where the Oracle server resides, if the actual memory is not eno

database. Area: A large storage space that is reserved for data at one one-time. Block: Oracle's most basic storage unit, specified when establishing a database. 3. Memory allocation (SGA and PGA) SGA: The memory area that is used to store database information that is shared by the database process. It contains data and control information for the Oracle server, which is allocated in real memory on the computer where the Oracle server resides, if

of data file collection. Segment: Is the space occupied by the object in the database: a large chunk of storage space reserved for data: Oracle's most basic storage unit, specifying 3, memory allocation (SGA and PGA) SGA when building databases: is the memory area used to store database information, This information is shared by the database process. It contains data and control information for the Oracle server, which is allocated in real memory on

corresponding server process to it. There is also a structure for the shared server, this structure is not a user process corresponding to a server process, will be coordinated through the scheduler processing, about the shared server connection, this article is not redundant.3. Server process and instance process interaction4. Instance and database process interactionThe above describes what the approximate interaction process is when we are doing database connection operations. Let's take a l

$sesstat S 6 WHERE N.NAME = ' session cursor cache count ' 7 and s.statistic# = n.statistic#), 8 (SELECT VALUE from v$parameter WHERE NAME = ' session_cached_cursors ') /c4> 9 UNION All Ten SELECT ' open_cursors ', Lpad (VALUE, 5), To_char (+ * used/value, ' 990 ') | | '% ' From (SELECT MAX (SUM (s.value)) used From v$statname N, V$sesstat S The WHERE N.NAME in (' opened Cursors current ', ' session cursor cache count ') s.statistic# = n.statistic# GROU

Tags: Oracle architecture user ManagementDatabase architectureDefined:The composition of the database, the working process, the composition and management mechanism of the data in the database.Compositioninstances, user processes, server processes, database files,Other files (parameter files, password files, archive files).Oracle's concept:Program Global Zone (PGA):Defined:A piece of memory that the server process uses to contain data and control info

Recently listened to Bosenry teacher's MySQL optimization Open class, this is my notes.Now let's talk about the two features of MySQL memory and I/O.First, MySQL Memory Features:1. There is also global memory and memory per session (each session is similar to Oracle's SGA and PGA), but for each session of memory, we do not assign it too large. If the memory allocated to each session is too large, it can cause the oom to occur. In high concurrency, inc

When it comes to query theory, you first need to know the architecture of Oracle. The database service consists of two parts: an instance and a database file. The examples section includes the SGA (System Global area) and the PGA (Progam Global Area) and the background process composition. Examples include: data files, control files, log files, parameter files, and so on.When the user writes the SQL statement to start the query, the first entry to the