Parm Patram

Parm Patram
Phone : (404) 216-4283
Email: ppatram _at_ btsincorporated.com

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Summary
Mr. Patram has been an Oracle DBA/Oracle Apps DBA for more than 5 years and a Linux/Solaris Systems Admin for more than 10 years. He holds the Oracle Certified Professional and Solaris Certified System Administrator credentials and is also very versed in Linux (Redhat).

He has proven ability to improve manageability, stability, security and performance. His analytical, troubleshooting, and creative abilities allow him to adapt to any circumstance quickly, accurately pinpoint root cause, and come up with unique solutions.

Skills Summary
* Oracle 10g/11g
* Recovery Manager (RMAN)
* User and Security Administration
* Export/Import (exp, expdp)
* Logminer
* Streams Replication
* Dataguard Standby Database
* Oracle Enterprise Manager (OEM)
* Oracle EBS
* Performance Tuning
* Materialized Views (Snapshots)
* PL/SQL, sqlplus
* Real Application Clusters (RAC)
* mySQL
* postgresql
* Unix Shell Scripting (bash, ksh)
* PHP/Perl, expect, C Programming
* Code Versioning (svn, fisheye)
* Linux/Solaris (kickstart, LVM/Disksuite RAID, NFS, samba)
* Installation/Configuration (rpm, up2date, yum, apt-get)
* Advanced Network Troubleshooting (ping, ipcalc, arping, tcpdump, nmap)
* Advanced Application Troubleshooting (strace/truss, netstat, ipcs, lsof, ps, jconsole)
* Monitoring (Hyperic, openNMS, SNMP)
* Migration (rsync)
* Change/Configuration Auditing (Tripwire, custom scripting)
* Change Control
* Automation (expect, Perl, C, shell)
* Apache/Tomcat

Work Employment History
Nov 2009 – Present: Linux/Solaris & Oracle Database Administrator at Barnhardt.
* Managed development, stage and production databases and application servers for large manufacturing company’s ERP.
* Install/configure Solaris 9 on Sunfire 280R. Developed method to clone the production server to backup/stage for consistency. Did some hardware work with RSC.
* Updated old documentation and wrote new articles in tech services wiki relating to Linux/Solaris/Oracle.
* Developed and implemented method to permit Oracle 10g Dataguard to compress archivelogs using SSH port forwarding (Linux).
* Wrote custom plugins in Perl/bash/ksh for Hyperic to monitor Oracle Streams, Oracle Dataguard, and certain specific metrics on the application server.
* Developed scripts using expect to test ERP functionality in an automated fashion.
* Helped establish Change Control process.
* Installed ERP on Linux (RHEL 5) for functional/development testing.

* Streamlined Dev refresh process by scripting much of the pieces and creating a checklist of the order to execute those scripts. Project time did not permit a fully automated approach, which was the next progression.
* Updated some of the scripts to use command-line arguments. This allowed the scripts to be exactly the same, but function differently based on arguments.
* Updated the ‘standby monitor’ to perform checks to eliminate false alerts.
* Developed ‘Tango’, which is a way to detect changes to an Oracle database’s settings or object properties. Tango consists of Oracle PL/SQL package and bash/Perl OS scripts.
* Developed method to resize the filesystem used for archive logging without needing to stop the database (Linux).
* Installed monitoring/auditing tools: Tripwire, openNMS, and Hyperic on RHEL 5 systems.
* Helped with securing the ERP platform.
* Identified/corrected performance problems resulting from over-sized SGA. Implemented SQL Profiling to improve performance of certain problem queries (Oracle).

Aug 2005 – Nov 2009: Senior Linux/Oracle Database Consultant at Business Technology Services, Inc.
* Specialized in RHEL, Oracle 10g and Oracle EBS.
* Managed company’s dedicated Linux server which services their website and email needs.
* Worked for many clients of BTS, Inc. in various industries.
* On call support.
* Oracle Dataguard standby database implementation, troubleshooting and tuning.
* Oracle Streams replication.
* General Troubleshooting and problem resolution.
* Custom monitoring for Linux OS and Oracle database.
* Oracle database performance tuning.
* Oracle RAC on Linux (RHEL) implementation and monitoring.
* Oracle EBS (11i and 12i) patch investigation and installation.
* Oracle EBS cloning.

Jan 2000 – August 2005: Senior Linux Administrator at Interland, Inc (now Peer1).
* Worked in Dedicated Server Solutions department which offered billable Admin services to company’s Dedicated Server customers.
* DSS also provided Data Center Operations support for company’s Shared Servers in addition to the Dedicated Servers (5000+ total).
* Tier III support for Dedicated Services (non-billable questions and issues).
* Assisted Engineering with build issues by writing work-around scripts and providing diagnostic data.
* Was the leading revenue earner in DSS.
* Some hardware work (HP/Compaq Proliant, Cobalt, white-box).
* Plesk Linux Control Panel SME. Wrote many scripts to manage and migrate Cobalt RAQ, systems with no control panel, and older versions of Plesk to the newest Plesk versions.
* Instituted Clean, Patch, &Lockdown service for customers whose servers had been hacked into.
* Invented ‘Backplane Sharing’ to retrieve data from RAID array on non-booting servers by using the dead system to power up the RAID array so it can be mounted to a running machine in order to perform a data copy.
* Developed unique method of reviving badly hacked servers that fail to boot by booting from CD, chroot, then manual services startup. Used as a stop-gap until a full migration to a new server could be effected.
* Provided excellent sales support for sizing requirements and other technical consulting required for completing the sale.

Miscellaneous Freelance Work
Omega Learning Centers (http://omegalearningcenter.com).
Administer company’s web server and email server.  Maintain and add new functionality to company’s suite of proprietary web-based interfaces used for running their business. Instrumental in scaling the products out to meet their need to franchise. Company now has 3 locations and growing.

3D Cellular (http://omegalearningcenter.com).
Administer company’s web and email server. Manage server firewall.  Responsible for the SSL certificates in use for both the website and email. Implemented VPN between LAN and Internet server. Designed custom scripts for backing up customer’s project files from their local area network to the server as well as designing and implementing an off-site backup plan for the server itself.

Kagan Creative (http://kagancreative.com).
Server administration and migration. Built and configured a dedicated mySQL server for client. Also responsible for about 10 SSL certificates for various websites running on the web server. Configured 3-node load-balanced web server for client.

HPP Christian Hosting  (http://hppchristianhosting.com).
Administered 3 high-traffic and heavily populated web servers totaling about 1000 different websites. Identify and upgrade old vulnerable applications running on the various websites that were being hacked into. Migrated the servers a few times to keep up with growing demand and the need for faster hardware. Assisted with some handover work when client sold the business in September 2007.

Certifications
Oracle Certified Professional (Database and Grids), 2009
Solaris Certified System Administrator, 2003
Microsoft Certified Systems Engineer, 1999

Education
1990, Associates of Arts (Data Processing)

References
Available Upon Request

contents too big for a post see file http://oracle.3dub.com/vdollar.txt

The virtual tables are stored in memory and start with V$ and there are a bunch of them as follows:

select VIEW_NAME from ALL_VIEWS WHERE (view_name like ‘V_$%’ or view_name like ‘V$%’) order by view_name;

V$OBJECT_USAGE
V$XS_SESSION
V$XS_SESSION_ATTRIBUTE
V$XS_SESSION_ROLE
V$ACCESS
V$ACTIVE_INSTANCES
V$ACTIVE_SERVICES
V$ACTIVE_SESSION_HISTORY
V$ACTIVE_SESS_POOL_MTH
V$ADVISOR_PROGRESS
V$ALERT_TYPES
V$AQ
V$AQ1
V$ARCHIVE
V$ARCHIVED_LOG
V$ARCHIVE_DEST
V$ARCHIVE_DEST_STATUS
V$ARCHIVE_GAP
V$ARCHIVE_PROCESSES
V$ASM_ALIAS
V$ASM_ATTRIBUTE
V$ASM_CLIENT
V$ASM_DISK
V$ASM_DISKGROUP
V$ASM_DISKGROUP_STAT
V$ASM_DISK_IOSTAT
V$ASM_DISK_STAT
V$ASM_FILE
V$ASM_OPERATION
V$ASM_TEMPLATE
V$AW_AGGREGATE_OP
V$AW_ALLOCATE_OP
V$AW_CALC
V$AW_LONGOPS
V$AW_OLAP
V$AW_SESSION_INFO
V$BACKUP
V$BACKUP_ARCHIVELOG_DETAILS
V$BACKUP_ARCHIVELOG_SUMMARY
V$BACKUP_ASYNC_IO
V$BACKUP_CONTROLFILE_DETAILS
V$BACKUP_CONTROLFILE_SUMMARY
V$BACKUP_COPY_DETAILS
V$BACKUP_COPY_SUMMARY
V$BACKUP_CORRUPTION
V$BACKUP_DATAFILE
V$BACKUP_DATAFILE_DETAILS
V$BACKUP_DATAFILE_SUMMARY
V$BACKUP_DEVICE
V$BACKUP_FILES
V$BACKUP_PIECE
V$BACKUP_PIECE_DETAILS
V$BACKUP_REDOLOG
V$BACKUP_SET
V$BACKUP_SET_DETAILS
V$BACKUP_SET_SUMMARY
V$BACKUP_SPFILE
V$BACKUP_SPFILE_DETAILS
V$BACKUP_SPFILE_SUMMARY
V$BACKUP_SYNC_IO
V$BGPROCESS
V$BH
V$BLOCKING_QUIESCE
V$BLOCK_CHANGE_TRACKING
V$BSP
V$BUFFERED_PUBLISHERS
V$BUFFERED_QUEUES
V$BUFFERED_SUBSCRIBERS
V$BUFFER_POOL
V$BUFFER_POOL_STATISTICS
V$CALLTAG
V$CIRCUIT
V$CLASS_CACHE_TRANSFER
V$CLASS_PING
V$CLIENT_RESULT_CACHE_STATS
V$CLIENT_STATS
V$CLUSTER_INTERCONNECTS
V$CONFIGURED_INTERCONNECTS
V$CONTEXT
V$CONTROLFILE
V$CONTROLFILE_RECORD_SECTION
V$COPY_CORRUPTION
V$CORRUPT_XID_LIST
V$CPOOL_CC_INFO
V$CPOOL_CC_STATS
V$CPOOL_STATS
V$CR_BLOCK_SERVER
V$CURRENT_BLOCK_SERVER
V$DATABASE
V$DATABASE_BLOCK_CORRUPTION
V$DATABASE_INCARNATION
V$DATAFILE
V$DATAFILE_COPY
V$DATAFILE_HEADER
V$DATAGUARD_CONFIG
V$DATAGUARD_STATS
V$DATAGUARD_STATUS
V$DATAPUMP_JOB
V$DATAPUMP_SESSION
V$DBFILE
V$DBLINK
V$DB_CACHE_ADVICE
V$DB_OBJECT_CACHE
V$DB_PIPES
V$DB_TRANSPORTABLE_PLATFORM
V$DELETED_OBJECT
V$DETACHED_SESSION
V$DIAG_INFO
V$DISPATCHER
V$DISPATCHER_CONFIG
V$DISPATCHER_RATE
V$DLM_ALL_LOCKS
V$DLM_CONVERT_LOCAL
V$DLM_CONVERT_REMOTE
V$DLM_LATCH
V$DLM_LOCKS
V$DLM_MISC
V$DLM_RESS
V$DLM_TRAFFIC_CONTROLLER
V$DNFS_CHANNELS
V$DNFS_FILES
V$DNFS_SERVERS
V$DNFS_STATS
V$DYNAMIC_REMASTER_STATS
V$ENABLEDPRIVS
V$ENCRYPTED_TABLESPACES
V$ENCRYPTION_WALLET
V$ENQUEUE_LOCK
V$ENQUEUE_STAT
V$ENQUEUE_STATISTICS
V$EVENTMETRIC
V$EVENT_HISTOGRAM
V$EVENT_NAME
V$EXECUTION
V$FAST_START_SERVERS
V$FAST_START_TRANSACTIONS
V$FILEMETRIC
V$FILEMETRIC_HISTORY
V$FILESPACE_USAGE
V$FILESTAT
V$FILE_CACHE_TRANSFER
V$FILE_HISTOGRAM
V$FILE_PING
V$FIXED_TABLE
V$FIXED_VIEW_DEFINITION
V$FLASHBACK_DATABASE_LOG
V$FLASHBACK_DATABASE_LOGFILE
V$FLASHBACK_DATABASE_STAT
V$FLASHBACK_TXN_GRAPH
V$FLASHBACK_TXN_MODS
V$FLASH_RECOVERY_AREA_USAGE
V$FOREIGN_ARCHIVED_LOG
V$FS_FAILOVER_HISTOGRAM
V$FS_FAILOVER_STATS
V$GCSHVMASTER_INFO
V$GCSPFMASTER_INFO
V$GC_ELEMENT
V$GC_ELEMENTS_W_COLLISIONS
V$GES_BLOCKING_ENQUEUE
V$GES_ENQUEUE
V$GLOBALCONTEXT
V$GLOBAL_BLOCKED_LOCKS
V$GLOBAL_TRANSACTION
V$HM_CHECK
V$HM_CHECK_PARAM
V$HM_FINDING
V$HM_INFO
V$HM_RECOMMENDATION
V$HM_RUN
V$HS_AGENT
V$HS_PARAMETER
V$HS_SESSION
V$HVMASTER_INFO
V$INCMETER_CONFIG
V$INCMETER_INFO
V$INCMETER_SUMMARY
V$INDEXED_FIXED_COLUMN
V$INSTANCE
V$INSTANCE_CACHE_TRANSFER
V$INSTANCE_LOG_GROUP
V$INSTANCE_RECOVERY
V$IOFUNCMETRIC
V$IOFUNCMETRIC_HISTORY
V$IOSTAT_CONSUMER_GROUP
V$IOSTAT_FILE
V$IOSTAT_FUNCTION
V$IOSTAT_NETWORK
V$IO_CALIBRATION_STATUS
V$IR_FAILURE
V$IR_FAILURE_SET
V$IR_MANUAL_CHECKLIST
V$IR_REPAIR
V$JAVAPOOL
V$JAVA_LIBRARY_CACHE_MEMORY
V$JAVA_POOL_ADVICE
V$KCCDI
V$KCCFE
V$LATCH
V$LATCHHOLDER
V$LATCHNAME
V$LATCH_CHILDREN
V$LATCH_MISSES
V$LATCH_PARENT
V$LIBRARYCACHE
V$LIBRARY_CACHE_MEMORY
V$LICENSE
V$LOADISTAT
V$LOADPSTAT
V$LOBSTAT
V$LOCK
V$LOCKED_OBJECT
V$LOCKS_WITH_COLLISIONS
V$LOCK_ACTIVITY
V$LOCK_ELEMENT
V$LOCK_TYPE
V$LOG
V$LOGFILE
V$LOGHIST
V$LOGMNR_CALLBACK
V$LOGMNR_CONTENTS
V$LOGMNR_DICTIONARY
V$LOGMNR_DICTIONARY_LOAD
V$LOGMNR_LATCH
V$LOGMNR_LOGFILE
V$LOGMNR_LOGS
V$LOGMNR_PARAMETERS
V$LOGMNR_PROCESS
V$LOGMNR_REGION
V$LOGMNR_SESSION
V$LOGMNR_STATS
V$LOGMNR_TRANSACTION
V$LOGSTDBY
V$LOGSTDBY_PROCESS
V$LOGSTDBY_PROGRESS
V$LOGSTDBY_STATE
V$LOGSTDBY_STATS
V$LOGSTDBY_TRANSACTION
V$LOG_HISTORY
V$MANAGED_STANDBY
V$MAP_COMP_LIST
V$MAP_ELEMENT
V$MAP_EXT_ELEMENT
V$MAP_FILE
V$MAP_FILE_EXTENT
V$MAP_FILE_IO_STACK
V$MAP_LIBRARY
V$MAP_SUBELEMENT
V$MAX_ACTIVE_SESS_TARGET_MTH
V$MEMORY_CURRENT_RESIZE_OPS
V$MEMORY_DYNAMIC_COMPONENTS
V$MEMORY_RESIZE_OPS
V$MEMORY_TARGET_ADVICE
V$METRIC
V$METRICGROUP
V$METRICNAME
V$METRIC_HISTORY
V$MTTR_TARGET_ADVICE
V$MUTEX_SLEEP
V$MUTEX_SLEEP_HISTORY
V$MVREFRESH
V$MYSTAT
V$NFS_CLIENTS
V$NFS_LOCKS
V$NFS_OPEN_FILES
V$NLS_PARAMETERS
V$NLS_VALID_VALUES
V$OBJECT_DEPENDENCY
V$OBJECT_PRIVILEGE
V$OBSOLETE_PARAMETER
V$OFFLINE_RANGE
V$OPEN_CURSOR
V$OPTION
V$OSSTAT
V$PARALLEL_DEGREE_LIMIT_MTH
V$PARAMETER
V$PARAMETER2
V$PARAMETER_VALID_VALUES
V$PERSISTENT_PUBLISHERS
V$PERSISTENT_QUEUES
V$PERSISTENT_SUBSCRIBERS
V$PGASTAT
V$PGA_TARGET_ADVICE
V$PGA_TARGET_ADVICE_HISTOGRAM
V$PQ_SESSTAT
V$PQ_SLAVE
V$PQ_SYSSTAT
V$PQ_TQSTAT
V$PROCESS
V$PROCESS_GROUP
V$PROCESS_MEMORY
V$PROCESS_MEMORY_DETAIL
V$PROCESS_MEMORY_DETAIL_PROG
V$PROPAGATION_RECEIVER
V$PROPAGATION_SENDER
V$PROXY_ARCHIVEDLOG
V$PROXY_ARCHIVELOG_DETAILS
V$PROXY_ARCHIVELOG_SUMMARY
V$PROXY_COPY_DETAILS
V$PROXY_COPY_SUMMARY
V$PROXY_DATAFILE
V$PWFILE_USERS
V$PX_BUFFER_ADVICE
V$PX_INSTANCE_GROUP
V$PX_PROCESS
V$PX_PROCESS_SYSSTAT
V$PX_SESSION
V$PX_SESSTAT
V$QUEUE
V$QUEUEING_MTH
V$RECOVERY_FILE_DEST
V$RECOVERY_FILE_STATUS
V$RECOVERY_LOG
V$RECOVERY_PROGRESS
V$RECOVERY_STATUS
V$RECOVER_FILE
V$REDO_DEST_RESP_HISTOGRAM
V$REPLPROP
V$REPLQUEUE
V$REQDIST
V$RESERVED_WORDS
V$RESOURCE
V$RESOURCE_LIMIT
V$RESTORE_POINT
V$RESULT_CACHE_DEPENDENCY
V$RESULT_CACHE_MEMORY
V$RESULT_CACHE_OBJECTS
V$RESULT_CACHE_STATISTICS
V$RESUMABLE
V$RFS_THREAD
V$RMAN_BACKUP_JOB_DETAILS
V$RMAN_BACKUP_SUBJOB_DETAILS
V$RMAN_BACKUP_TYPE
V$RMAN_COMPRESSION_ALGORITHM
V$RMAN_CONFIGURATION
V$RMAN_ENCRYPTION_ALGORITHMS
V$RMAN_OUTPUT
V$RMAN_STATUS
V$ROLLNAME
V$ROLLSTAT
V$ROWCACHE
V$ROWCACHE_PARENT
V$ROWCACHE_SUBORDINATE
V$RSRCMGRMETRIC
V$RSRCMGRMETRIC_HISTORY
V$RSRC_CONSUMER_GROUP
V$RSRC_CONSUMER_GROUP_CPU_MTH
V$RSRC_CONS_GROUP_HISTORY
V$RSRC_PLAN
V$RSRC_PLAN_CPU_MTH
V$RSRC_PLAN_HISTORY
V$RSRC_SESSION_INFO
V$RULE
V$RULE_SET
V$RULE_SET_AGGREGATE_STATS
V$SCHEDULER_RUNNING_JOBS
V$SECUREFILE_TIMER
V$SEGMENT_STATISTICS
V$SEGSTAT
V$SEGSTAT_NAME
V$SERVICEMETRIC
V$SERVICEMETRIC_HISTORY
V$SERVICES
V$SERVICE_EVENT
V$SERVICE_STATS
V$SERVICE_WAIT_CLASS
V$SERVMOD_ACT_STATS
V$SESSION
V$SESSION_CONNECT_INFO
V$SESSION_CURSOR_CACHE
V$SESSION_EVENT
V$SESSION_FIX_CONTROL
V$SESSION_LONGOPS
V$SESSION_OBJECT_CACHE
V$SESSION_WAIT
V$SESSION_WAIT_CLASS
V$SESSION_WAIT_HISTORY
V$SESSMETRIC
V$SESSTAT
V$SESS_IO
V$SESS_TIME_MODEL
V$SES_OPTIMIZER_ENV
V$SGA
V$SGAINFO
V$SGASTAT
V$SGA_CURRENT_RESIZE_OPS
V$SGA_DYNAMIC_COMPONENTS
V$SGA_DYNAMIC_FREE_MEMORY
V$SGA_RESIZE_OPS
V$SGA_TARGET_ADVICE
V$SHARED_POOL_ADVICE
V$SHARED_POOL_RESERVED
V$SHARED_SERVER
V$SHARED_SERVER_MONITOR
V$SORT_SEGMENT
V$SORT_USAGE
V$SPPARAMETER
V$SQL
V$SQLAREA
V$SQLAREA_PLAN_HASH
V$SQLFN_ARG_METADATA
V$SQLFN_METADATA
V$SQLSTATS
V$SQLTEXT
V$SQLTEXT_WITH_NEWLINES
V$SQL_BIND_CAPTURE
V$SQL_BIND_DATA
V$SQL_BIND_METADATA
V$SQL_CS_HISTOGRAM
V$SQL_CS_SELECTIVITY
V$SQL_CS_STATISTICS
V$SQL_CURSOR
V$SQL_FEATURE
V$SQL_FEATURE_DEPENDENCY
V$SQL_FEATURE_HIERARCHY
V$SQL_HINT
V$SQL_JOIN_FILTER
V$SQL_MONITOR
V$SQL_OPTIMIZER_ENV
V$SQL_PLAN
V$SQL_PLAN_MONITOR
V$SQL_PLAN_STATISTICS
V$SQL_PLAN_STATISTICS_ALL
V$SQL_REDIRECTION
V$SQL_SHARED_CURSOR
V$SQL_SHARED_MEMORY
V$SQL_WORKAREA
V$SQL_WORKAREA_ACTIVE
V$SQL_WORKAREA_HISTOGRAM
V$SSCR_SESSIONS
V$STANDBY_APPLY_SNAPSHOT
V$STANDBY_LOG
V$STATISTICS_LEVEL
V$STATNAME
V$STREAMS_APPLY_COORDINATOR
V$STREAMS_APPLY_READER
V$STREAMS_APPLY_SERVER
V$STREAMS_CAPTURE
V$STREAMS_MESSAGE_TRACKING
V$STREAMS_POOL_ADVICE
V$STREAMS_TRANSACTION
V$SUBCACHE
V$SUBSCR_REGISTRATION_STATS
V$SYSAUX_OCCUPANTS
V$SYSMETRIC
V$SYSMETRIC_HISTORY
V$SYSMETRIC_SUMMARY
V$SYSSTAT
V$SYSTEM_CURSOR_CACHE
V$SYSTEM_EVENT
V$SYSTEM_FIX_CONTROL
V$SYSTEM_PARAMETER
V$SYSTEM_PARAMETER2
V$SYSTEM_WAIT_CLASS
V$SYS_OPTIMIZER_ENV
V$SYS_TIME_MODEL
V$TABLESPACE
V$TEMPFILE
V$TEMPORARY_LOBS
V$TEMPSTAT
V$TEMP_CACHE_TRANSFER
V$TEMP_EXTENT_MAP
V$TEMP_EXTENT_POOL
V$TEMP_PING
V$TEMP_SPACE_HEADER
V$THREAD
V$THRESHOLD_TYPES
V$TIMER
V$TIMEZONE_FILE
V$TIMEZONE_NAMES
V$TRANSACTION
V$TRANSACTION_ENQUEUE
V$TRANSPORTABLE_PLATFORM
V$TSM_SESSIONS
V$TYPE_SIZE
V$UNDOSTAT
V$UNUSABLE_BACKUPFILE_DETAILS
V$VERSION
V$VPD_POLICY
V$WAITCLASSMETRIC
V$WAITCLASSMETRIC_HISTORY
V$WAITSTAT
V$WAIT_CHAINS
V$WALLET
V$WORKLOAD_REPLAY_THREAD
V$XML_AUDIT_TRAIL
V$_LOCK

How to use the data dictionary

The data dictionary is perhaps the equivalent of the ‘mysql’ database — it stores specific information about the logical and physical layout of the database, users in that database, perms, etc. It is automatically created and updated by oracle. It is readonly to all users — only oracle can write to it (similar to /proc filesystem in Linux).

A schema is a collection of database objects. It is owned by a database user and has the same name as that user. Schema objects are the logical structures that directly relate to the data in the database. There is NO relation between tablespace and schema.

Schema Objects:

1. Tables
   - contains rows and colums (just like mysql).
2. Indexes
   - just like mysql indexes — speeds up searches.
3. Views
   - can be thought of as stored query. You can do most operations (select, insert..) on a view. If the view is ‘updateable’ then the operations affect the actual data used to create the view.
4. Clusters
   - groups of one or more tables that are stored together because they share common columns.
5. Synonyms
   - a user-defined name or any ‘nameable’ object in the database. Do not actually take up storage except in the ‘data dictionary’.

1. Blocks
   - similar to a filesystem block. Controllable via the DB_BLOCK_SIZE initialization parameter.
2. Extents
   - a certain number of contiguous blocks used to store the same piece of data.
3. Segments
   - collection of extents. Some of the extents making up the segment may belong to different physical datafiles, but are all part of the same tablespace (below).
4. Tablespaces
   - each database is divided into logical storage units called ‘tablespaces’. The default is to have many small files (smallfile tablespace) to store the tablespace data, but you can also create ‘bigfile’ tablespaces so all of the tablespace data is stored in a single LARGE file.
   - a tablespace can be ‘readonly’ or taken offline independently of the rest of the database.

These are the files (7) that make up the physical database:

1. Datafiles
   - a datafile can only be associated with one database
   - datafiles can be defined to ‘grow’
   - one or more datafiles form a logical unit of database storage called a ‘tablespace’.
2. Control Files
   - the control files store the locations of the datafiles and redo log files
   - also stores the database name and time of creation.
   - oracle can ‘multiplex’ the control files (keep many copies) to safeguard their contents.
3. Online Redo Log Files
   - ‘transaction log’ — keeps track of all changes to the data (kept in memory)
4. Archived Redo Log Files
   - once the online redo logs are written to disk they are now ‘archived’. The parameter ARCHIVELOG is how oracle will automatically archive the redo logs. You can store the archives on separate drives for protection.
5. Parameter Files
   - pfiles (parameter) and spfiles (server parameters) control the config options for the database and instance.
6. Alert and Trace Log Files
   - alert files = errors and warnings. Trace = used by background processes to dump diagnostic data.
7. Backup Files