pga ps4

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

-information of Rman backup is recorded show parameter spfile; -- pfile and SPFile convert each other Create pfile='/home/oracle/pfile.ora'from spfile ; -- Storage location dump; (*) Logical storage structure Tablespace: A table space can have multiple data files Segment segment: A table is a segment, a table segment, and an index segment Zone extent: the smallest unit of allocated space Block: Minimum storage unit 8k -- the size of the Block Show parameter db_block_size; (2) Process st

Memory Statistics~~~~~~~~~~~~~~~~~ Begin End------------ ------------Host Mem (MB): 16,338.5 16,338.5SGA Use (MB): 3,072.0 3,072.0PGA Use (MB): 805.1 861.7% Host Mem used for sga+pga:23.73 24.08Exception response:Physical read (blocks): 35,368.4 3,067.3Physical Write (Blocks): 6.8 0.6 Tota wait% DB Event Waits time Avg (ms) time wait Class ------------------------------------------------- -------------------- Direct Path read 912,622 306.336 79.2 Us

Tags: using IPCRM to clear the database HP UX memory utilization issuesTo account for the environment, is the real-time production database host network. HP-UX 11.31+oracle 10.2.0.4.0 RAC cluster.Two machines outdoor rac,essdb3 and ESSDB4 two machines.Physical memory 128g,sga allocated 64G,PGA 5G. Morning found ESSDB4 host glance run only 6G of free memory.Use the following command for a simple analysis:Sql> select distinct SID from V$mystat; Gets the

centralized data dictionary that users can use to build their own applications. Orcale represents data in the form of a two-dimensional table and provides SQL (Structured Query language) to perform basic database management functions such as querying, manipulating, defining, and controlling data. Orcale has a good portability, through its communication function, the microcomputer program can be the same as small or large computer orcale, and can pass data to each other. In addition, Orcale also

Label:Oracle performs SQL processing: syntax checking, semantic checking, parsing of SQL statements, execution of SQL, and return of results. The PGA is an area of memory that is independent of the SGA, and when the user process connects to the Oracle server, the Oracle server assigns the appropriate PGA to each server process, and when the server process finishes, Oracle automatically releases the memory s

Linux.Action: Refer to documentation for a list of supported operating systems. Or, size/dev/shm to be at least the SGA_MAX_SIZE on each Oracle instance running on the system. You can also use the search function of the official document to search for error codes and find corresponding explanations and solutions. Setting Memory Target at Instance Startup on LinuxStarting with Oracle Database 11g Release 1 (11.1), Oracle provides the option of automatically managing SGA and