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Nabhaas Cloud Consulting profile imageAbhilash Kumar | Oracle ACE ♠
Abhilash Kumar | Oracle ACE ♠ forNabhaas Cloud Consulting

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🚦 Oracle 19c vs PostgreSQL 15 — The Ultimate Parameter Showdown!

🚦 Oracle 19c vs PostgreSQL 15 — The Ultimate Parameter Showdown!

{ Abhilash Kumar Bhattaram :Follow on LinkedIn }

Most cloud or on-prem migrations eventually land at this crossroads: Oracle to Postgres or vice versa. And when they do, you need more than just intuition — you need parameters that match up like long-lost cousins.

I have put together a handy side-by-side checklist comparing 200+ parameters across CPU, Memory, I/O, Connection Management, Autovacuuming (hello, Postgres!), PGA/SGA (hello, Oracle!), WAL vs Redo logs, and a lot more.

Whether you’re:

  • Migrating workloads
  • uning database performance
  • Planning cloud strategies
  • Or just geeking out on system parameters…This checklist helps you decode what maps to what — because guessing shared_buffers isn’t the same as db_cache_size!

Quick Links to each category

CPU Parameters
Memory Parameters
Authentication Parameters
IO Parameters
Other Parameters

NOTE : There could be some parameters which needed in a different category , please feel free to post in the comments.

CPU Parameters

Oracle Parameter (Common in 19c)PostgreSQL Parameter (Common in 15)Description
CPU_COUNTN/A (PostgreSQL assumes available CPUs; can be limited by OS cgroups)Oracle: Informs the database about the number of CPUs available; influencing default parallelism and optimizer decisions.
PARALLEL_MAX_SERVERSmax_worker_processesOracle: Maximum number of parallel execution processes. PostgreSQL: Max number of background worker processes; including those for parallel queries; logical replication; and autovacuum.
PARALLEL_MIN_SERVERSN/A (PostgreSQL workers are spawned on demand)Oracle: Minimum number of parallel execution processes to keep running.
PARALLEL_DEGREE_POLICYmax_parallel_workersOracle: Controls automatic degree of parallelism (DOP); parallel statement queuing; and in-memory parallel execution. Values: MANUAL; AUTO; ADAPTIVE. PostgreSQL: Max number of parallel workers that can be active at any time.
N/Amax_parallel_workers_per_gatherPostgreSQL: Max number of parallel workers that can be started by a single Gather node in a query plan.
PARALLEL_THREADS_PER_CPUN/A (PostgreSQL handles threading internally)Oracle: Describes the number of parallel execution processes or threads that a CPU can handle.
PARALLEL_DEGREE_LIMITmin_parallel_table_scan_sizeOracle: Controls the maximum DOP a statement can have when automatic DOP is in use. PostgreSQL: Threshold for when parallel table scans are considered by the optimizer.
N/Amin_parallel_index_scan_sizePostgreSQL: Threshold for when parallel index scans are considered by the optimizer.
PARALLEL_FORCE_LOCALN/AOracle: Restricts parallel execution to the current Oracle RAC instance.
PARALLEL_MIN_PERCENTN/AOracle: Specifies the minimum percentage of requested parallel execution processes required for parallel execution.
PARALLEL_ADAPTIVE_MULTI_USER (deprecated)N/AOracle: Used to throttle DOP requests to prevent system overload. Replaced by parallel statement queuing and PARALLEL_DEGREE_POLICY = AUTO.
CPU_PER_CALL (via Resource Manager)N/A (OS-level cgroups/resource groups)Oracle: Limits CPU usage per call.
CPU_PER_SESSION (via Resource Manager)N/AOracle: Limits CPU usage per session.
ACTIVE_SESS_POOL_P1 (via Resource Manager)N/AOracle: Limits the number of active sessions in a consumer group.
CPU_COSTING (internal; influenced by OPTIMIZER_MODE)cpu_tuple_costOracle: Optimizer uses CPU costs for plan generation. PostgreSQL: Query planner cost for processing a tuple.
N/Acpu_index_tuple_costPostgreSQL: Query planner cost for processing an index tuple.
N/Acpu_operator_costPostgreSQL: Query planner cost for executing an operator.

Memory Parameters

Oracle Parameter (Common in 19c)PostgreSQL Parameter (Common in 15)Description
MEMORY_TARGETN/A (Indirectly controlled by shared_buffers; max_connections; work_mem; etc.)Oracle: Sets the total memory available for the instance (SGA + PGA). Oracle automatically distributes memory between SGA and PGA. PostgreSQL: No single parameter. Total memory usage is the sum of shared_buffers; wal_buffers; and (max_connections * work_mem) plus other process-specific memory.
MEMORY_MAX_TARGETN/AOracle: Sets the maximum limit to which MEMORY_TARGET can be increased without an instance restart.
SGA_TARGETshared_buffersOracle: Target size for the SGA. Oracle automatically tunes DB_CACHE_SIZE; SHARED_POOL_SIZE; LARGE_POOL_SIZE; JAVA_POOL_SIZE; STREAMS_POOL_SIZE within this target. PostgreSQL: shared_buffers is the main shared memory area for caching data pages. Analogous to Oracle's DB_CACHE_SIZE.
DB_CACHE_SIZE(Part of shared_buffers)Oracle: Size of the database block buffer cache within SGA. Used for caching data blocks.
SHARED_POOL_SIZEmax_prepared_transactionsOracle: Used for library cache (parsed SQL; PL/SQL); dictionary cache; and control structures.
max_locks_per_transactionPostgreSQL: Controls server-side memory for various objects (e.g.; prepared transactions; locks).
max_wal_sendersPostgreSQL: Controls server-side memory for various objects (e.g.; WAL senders).
LARGE_POOL_SIZEN/A (depends on specific feature usage)Oracle: Used for large allocations like RMAN I/O buffers; parallel execution message buffers; XA transactions; and session memory for shared server processes.
JAVA_POOL_SIZEN/AOracle: Used for Java objects in the JVM and session memory for Java.
STREAMS_POOL_SIZEN/AOracle: Used for Oracle Streams and GoldenGate.
LOG_BUFFERwal_buffersOracle: Size of the redo log buffer. PostgreSQL: Size of the Write-Ahead Log (WAL) buffer. Both buffer transaction changes before writing to disk.
PGA_AGGREGATE_TARGETwork_memOracle: Target aggregate size for all PGAs across all server processes. Oracle automatically tunes individual work areas (sort; hash-join; bitmap merge; etc.). PostgreSQL: work_mem is the maximum amount of memory to be used by a query operation (sort; hash table) before writing to temporary disk files. This is per operation; not per session.
WORKAREA_SIZE_POLICYN/A (part of work_mem's behavior)Oracle: Set to AUTO to enable automatic PGA management.
SORT_AREA_SIZE (deprecated in AUTO PGA mode)work_memOracle: Max memory for sorts (manual PGA management). PostgreSQL: Sorts use work_mem.
HASH_AREA_SIZE (deprecated in AUTO PGA mode)work_memOracle: Hash joins use work_mem.
TEMP_SPACE_SIZE (indirectly managed by temporary tablespaces)temp_buffersOracle: Temporary segments are allocated within temporary tablespaces. TEMP_SPACE_SIZE is not a direct parameter to configure a pool; but rather indicates usage. PostgreSQL: temp_buffers specifies the max memory used for temporary buffers per session.
N/Atemp_file_limitPostgreSQL: Sets the maximum total size of temporary files used by any one session.
N/Amaintenance_work_memPostgreSQL: Max memory used for maintenance operations like VACUUM; CREATE INDEX; ALTER TABLE ADD FOREIGN KEY. This is used by autovacuum workers and for manual maintenance.
N/A (Oracle's JIT for JVM is internal)jit_providerPostgreSQL: Controls behavior and memory for JIT compilation.
N/Ajit_above_costPostgreSQL: Cost threshold for JIT compilation.
N/Ajit_optimize_distinct_aggsPostgreSQL: Enables JIT optimization for distinct aggregates.
N/Ajit_expressionsPostgreSQL: Enables JIT compilation for expressions.
N/Ajit_inline_above_costPostgreSQL: Inline cost threshold for JIT.
N/Ajit_mem_bytesPostgreSQL: Maximum memory allocated for JIT compilation.
N/Ajit_tuple_deformingPostgreSQL: Enables JIT tuple deforming.

Authentication Parameters

Oracle Parameter (Common in 19c)PostgreSQL Parameter (Common in 15)Description
SQLNET.AUTHENTICATION_SERVICESpg_hba.conf (Host-Based Authentication)Oracle: Configures authentication methods (OS; Kerberos; RADIUS; etc.). PostgreSQL: Configuration file that controls client authentication.
REMOTE_OS_AUTHENTpassword_encryptionOracle: Enables/disables remote OS authentication. PostgreSQL: Determines how passwords are encrypted for new users.
N/Agss_authenticationPostgreSQL: Enables GSSAPI authentication.
N/Akrb_srvnamePostgreSQL: Kerberos service principal name.
N/Ascram_iterationsPostgreSQL: Number of iterations for SCRAM password hashing.
N/Amd5_salt_lengthPostgreSQL: Length of salt used for MD5 password hashing.
N/Adata_directory_modePostgreSQL: Permissions of the data_directory.
SQLNET.ENCRYPTION_CLIENTsslOracle: Enables network encryption for client connections. PostgreSQL: Enables SSL connections.
SQLNET.ENCRYPTION_TYPES_CLIENTssl_cert_fileOracle: Specifies encryption algorithms. PostgreSQL: Path to SSL certificate file.
SSL_VERSIONssl_key_fileOracle: Specifies SSL/TLS version. PostgreSQL: Path to SSL private key file.
SSL_CIPHER_SUITESssl_ca_fileOracle: Specifies SSL cipher suites. PostgreSQL: Path to SSL certificate authority (CA) file.
N/Assl_ciphersPostgreSQL: Specifies the list of allowed SSL ciphers.
N/Assl_prefer_server_ciphersPostgreSQL: Server prefers its cipher order over client's.
N/Assl_crl_filePostgreSQL: Path to SSL Certificate Revocation List (CRL) file.
N/Assl_dh_params_filePostgreSQL: Path to Diffie-Hellman parameters file.
N/Assl_ecdh_curvePostgreSQL: Specifies the curve to use for ECDH.
ENCRYPTION_WALLET_LOCATION (for TDE)N/A (Relies on OS/filesystem encryption or external tools)Oracle: Manages the location of the wallet for TDE; encrypting data at rest. PostgreSQL: Doesn't have native TDE. Encryption at rest is typically handled by the underlying operating system; filesystem; or disk encryption.
AUDIT_TRAILlogging_collectorOracle: Controls auditing behavior. PostgreSQL: Enables the logging collector.
AUDIT_SYS_OPERATIONSlog_destinationOracle: Audits privileged operations. PostgreSQL: Where log output is sent (e.g.; stderr; csvlog).
AUDIT_FILE_DESTlog_filenameOracle: Directory for audit trail files. PostgreSQL: File name pattern for log files.
UNIFIED_AUDIT_SGA_SIZElog_rotation_ageOracle: Size of SGA for unified audit trail. PostgreSQL: Time-based log file rotation.
_AUDIT_DDL_ENABLE (internal)log_rotation_sizeOracle: Enables DDL auditing. PostgreSQL: Size-based log file rotation.
N/Alog_min_duration_statementPostgreSQL: Logs statements that run longer than this duration.
N/Alog_connectionsPostgreSQL: Logs connection attempts.
N/Alog_disconnectionsPostgreSQL: Logs disconnections.
N/Alog_lock_waitsPostgreSQL: Logs long lock waits.
N/Alog_temp_filesPostgreSQL: Logs use of temporary files.
PASSWORD_VERIFY_FUNCTION (via profiles)N/A (PostgreSQL handles password expiration and attempts via external tools or custom functions; not core parameters)Oracle: PL/SQL function for password complexity.
PASSWORD_GRACE_TIME (via profiles)N/AOracle: Grace period before password expiry.
FAILED_LOGIN_ATTEMPTS (via profiles)N/AOracle: Number of failed login attempts before account lockout.
PASSWORD_REUSE_TIME (via profiles)N/AOracle: Time before password can be reused.
PASSWORD_REUSE_MAX (via profiles)N/AOracle: Max number of password changes before password can be reused.
VPD (Virtual Private Database)row_security (table level)Oracle: Fine-grained access control based on context. PostgreSQL: Enables/disables RLS for a specific table.
Label SecurityCREATE POLICY (policy level)Oracle: Security based on data labels. PostgreSQL: Defines rules for row-level access.
OS_AUTHENT_PREFIXallow_system_table_modsOracle: Prefix for OS authenticated users. PostgreSQL: Should be off to prevent direct modification of catalog tables.
SPFILE (binary; managed by DB)OS file permissions for postgresql.confOracle: Binary parameter file; internally managed and protected. PostgreSQL: Text configuration file; relies on OS permissions.
N/AOS file permissions for pg_hba.confPostgreSQL: Text authentication configuration file; relies on OS permissions.
N/AOS file permissions for pg_ident.confPostgreSQL: Text identity mapping configuration file; relies on OS permissions.
Oracle Parameter (Common in 19c)PostgreSQL Parameter (Common in 15)Description
LISTENER.ORA (PORT)listen_addressesOracle: Configures the Oracle Listener port. PostgreSQL: Specifies the TCP/IP addresses on which the server is to listen.
LISTENER.ORA (HOST)portOracle: Configures the Oracle Listener host. PostgreSQL: The TCP port number the server listens on.
LISTENER.ORA (INBOUND_CONNECT_TIMEOUT)N/AOracle: Timeout for connections to the listener.
LISTENER.ORA (DEFAULT_SERVICE)N/AOracle: Default service for the listener.
PROCESSESmax_connectionsOracle: Maximum number of OS user processes that can connect. PostgreSQL: Maximum number of concurrent client connections.
SESSIONSsuperuser_reserved_connectionsOracle: Maximum number of user sessions. PostgreSQL: Number of connections reserved for superusers; preventing lockout.
SQLNET.ORA (DEFAULT_SDU_SIZE)tcp_keepalives_idleOracle: Session Data Unit size. PostgreSQL: Time before sending keepalive probes.
SQLNET.ORA (RECV_BUF_SIZE)tcp_keepalives_intervalOracle: Receive buffer size. PostgreSQL: Time between keepalive probes.
SQLNET.ORA (SEND_BUF_SIZE)tcp_keepalives_countOracle: Send buffer size. PostgreSQL: Number of failed keepalive probes before connection is dropped.
SQLNET.ORA (DISABLE_OOB)N/AOracle: Disables out-of-band breaks.
SQLNET.ORA (NAMES.DIRECTORY_PATH)N/AOracle: Specifies name resolution methods.
SQLNET.ORA (SQLNET.ALLOWED_LOGON_VERSION_CLIENT)N/AOracle: Controls minimum allowed client logon version.
SQLNET.ORA (SQLNET.COMPRESSION)N/AOracle: Enables/disables network compression.
LOG_ARCHIVE_CONFIG (for Data Guard)max_wal_sendersOracle: Configures Data Guard archiving. PostgreSQL: Maximum number of concurrent WAL sender processes.
STANDBY_FILE_MANAGEMENT (for Data Guard)wal_keep_segmentsOracle: Manages datafiles on standby. PostgreSQL: Number of past WAL file segments to retain in the pg_wal directory.
N/Ahot_standbyPostgreSQL: Enables connections to the standby server during recovery.
N/Ahot_standby_feedback"PostgreSQL: Enables feedback from hot standby to primary to prevent ""snapshot too old"" errors."
N/Aprimary_conninfoPostgreSQL: Connection string for the primary server from the standby.
N/Arestore_commandPostgreSQL: Shell command for retrieving archived WAL files during recovery.
N/Arecovery_target_timelinePostgreSQL: Specifies the timeline to recover to.
N/Asynchronous_standby_namesPostgreSQL: Specifies which standbys must confirm WAL receipt for synchronous commit.
N/A (Oracle primarily uses TCP/IP for local connections)unix_socket_directoriesPostgreSQL: Directories for Unix domain sockets.
N/Aunix_socket_groupPostgreSQL: Group ownership for Unix domain sockets.
N/Aunix_socket_permissionsPostgreSQL: Permissions for Unix domain sockets.

IO Parameters

Category [IO]Oracle Parameter (Common in 19c)PostgreSQL Parameter (Common in 15)Description
Asynchronous I/O & Direct I/ODISK_ASYNCH_IOeffective_io_concurrencyOracle: Enables/disables asynchronous I/O for datafiles. PostgreSQL: Informs the optimizer about the number of concurrent disk I/O operations that can be executed. While not a direct on/off switch for async I/O; it influences how many I/O operations the planner assumes can be performed in parallel. PostgreSQL uses posix_fadvise() and O_DIRECT implicitly where available and beneficial.
Asynchronous I/O & Direct I/OFILESYSTEMIO_OPTIONSN/AOracle: Controls I/O options for filesystem files; e.g.; SETALL (direct I/O; async I/O) or DIRECTIO (direct I/O only).
Multi-Block ReadsDB_FILE_MULTIBLOCK_READ_COUNT(Indirectly influenced by effective_io_concurrency)Oracle: Number of blocks read in a single I/O operation during full table scans.
I/O Processes/WorkersDB_WRITER_PROCESSESbgwriter_delayOracle: Number of database writer processes (DBWn) that write modified data blocks from buffer cache to data files. PostgreSQL: Delay between runs of the background writer.
I/O Processes/WorkersN/Abgwriter_lru_maxpagesPostgreSQL: Max number of dirty pages to write per bgwriter run.
I/O Processes/WorkersN/Abgwriter_lru_multiplierPostgreSQL: Multiplier for bgwriter_lru_maxpages.
I/O Processes/WorkersN/Awal_writer_delayPostgreSQL: Delay between flushes of the WAL buffers to disk.
I/O Processes/WorkersN/Amax_parallel_io_workers (PostgreSQL 16+)PostgreSQL: Maximum number of background workers that can be used for parallel I/O.
Optimizer I/O CostingIO_CALIBRATION_ENABLEDrandom_page_costOracle: Allows the database to calibrate I/O performance to improve optimizer decisions. PostgreSQL: Cost estimate for a non-sequentially accessed disk page.
Optimizer I/O CostingIO_MEGABYTES_PER_SECseq_page_costOracle: I/O calibration parameter. PostgreSQL: Cost estimate for a sequentially accessed disk page.
Optimizer I/O CostingMAX_IOPSN/AOracle: I/O calibration parameter.
Temporary File Limits(Controlled by temporary tablespace size)temp_file_limitOracle: Temporary segments are managed within temporary tablespaces. PostgreSQL: Maximum amount of disk space a session can use for temporary files.
Redo/WAL SyncCOMMIT_LOG_BUFFER (internal; controlled by LOG_BUFFER)synchronous_commitOracle: How redo entries are written to disk during commit. PostgreSQL: Controls whether transaction commits wait for WAL to be flushed to disk (on; off; local; remote_write;remote_apply` ). Critical for durability.

Other Parameters

Category [Others]Oracle Parameter (Common in 19c)PostgreSQL Parameter (Common in 15)Description
Query OptimizerOPTIMIZER_MODEdefault_statistics_targetOracle: Controls optimizer behavior (e.g.; ALL_ROWS; FIRST_ROWS). PostgreSQL: Controls the level of detail collected by ANALYZE.
Query OptimizerOPTIMIZER_FEATURES_ENABLEgeqoOracle: Enables/disables optimizer features for specific database versions. PostgreSQL: Enables Genetic Query Optimization for complex joins.
Query OptimizerOPTIMIZER_DYNAMIC_SAMPLINGgeqo_thresholdOracle: Controls dynamic sampling for statistics gathering. PostgreSQL: Number of tables in a join before GEQO is considered.
Query OptimizerSTAR_TRANSFORMATION_ENABLEDgeqo_effortOracle: Enables/disables star transformation for star schemas. PostgreSQL: Effort level for GEQO.
Query OptimizerQUERY_REWRITE_ENABLEDfrom_collapse_limitOracle: Enables/disables query rewrite for materialized views. PostgreSQL: Number of FROM-list items that can be collapsed into a single JOIN expression.
Query OptimizerSTATISTICS_LEVELjoin_collapse_limitOracle: Controls the level of statistics collected (e.g.; BASIC; TYPICAL; ALL). PostgreSQL: Number of FROM-list items that can be collapsed into a single JOIN expression for join reordering.
Query OptimizerDB_CACHE_ADVICEenable_seqscanOracle: Enables/disables buffer cache advisory statistics. PostgreSQL: Allows/disallows sequential scans.
Query OptimizerN/Aenable_indexscanPostgreSQL: Allows/disallows index scans.
Query OptimizerN/Aenable_bitmapscanPostgreSQL: Allows/disallows bitmap scans.
Query OptimizerN/Aenable_hashjoinPostgreSQL: Allows/disallows hash joins.
Query OptimizerN/Aenable_mergejoinPostgreSQL: Allows/disallows merge joins.
Query OptimizerN/Aconstraint_exclusionPostgreSQL: Enables/disables constraint exclusion for partitioning.
Query OptimizerN/Aplan_cache_modePostgreSQL: Controls how prepared statements' plans are cached.
Query OptimizerN/Asearch_pathPostgreSQL: Specifies the order in which schemas are searched for unqualified object names.
Session & Transaction ManagementOPEN_CURSORSmax_locks_per_transactionOracle: Maximum number of open cursors per session. PostgreSQL: Maximum number of locks per transaction.
Session & Transaction ManagementCURSOR_SHARINGidle_in_transaction_session_timeoutOracle: Controls how SQL statements are shared in the shared pool. PostgreSQL: Disconnects sessions that have been idle in a transaction for longer than this duration.
Session & Transaction ManagementTRANSACTIONSstatement_timeoutOracle: Maximum number of concurrent transactions. PostgreSQL: Aborts any statement that runs longer than this duration.
Session & Transaction ManagementN/Alock_timeoutPostgreSQL: Aborts any statement that waits longer than this duration for a lock.
Session & Transaction ManagementN/Alog_lock_waitsPostgreSQL: Logs when a session waits for a lock longer than log_min_duration_statement.
Background Processes / WorkersBACKGROUND_DUMP_DESTmax_worker_processesOracle: Directory for background process trace files. PostgreSQL: Overall maximum number of background worker processes.
Background Processes / WorkersCORE_DUMP_DESTmax_parallel_workersOracle: Directory for core dump files. PostgreSQL: Maximum number of parallel workers.
Background Processes / WorkersUSER_DUMP_DESTmax_parallel_maintenance_workersOracle: Directory for user process trace files. PostgreSQL: Maximum number of parallel workers for maintenance operations.
Background Processes / WorkersDIAGNOSTIC_DESTmax_logical_replication_workersOracle: Base directory for all diagnostic files (ADR Home). PostgreSQL: Maximum number of logical replication worker processes.
N/Amax_background_workersPostgreSQL: Generic background worker processes.
Error Logging & DiagnosticsLOG_ARCHIVE_DEST (also for errors)log_destinationOracle: Archiver log destinations. PostgreSQL: Where log output is sent.
Error Logging & DiagnosticsLOG_ARCHIVE_FORMAT (also for errors)logging_collectorOracle: Format of archived logs. PostgreSQL: Enables the logging collector process.
Error Logging & DiagnosticsAUDIT_FILE_DESTlog_directoryOracle: Directory for audit files. PostgreSQL: Directory for log files.
Error Logging & DiagnosticsN/Alog_filenamePostgreSQL: File name pattern for log files.
Error Logging & DiagnosticsN/Alog_file_modePostgreSQL: Permissions for log files.
Error Logging & DiagnosticsN/Alog_rotation_agePostgreSQL: Time-based log file rotation.
Error Logging & DiagnosticsN/Alog_rotation_sizePostgreSQL: Size-based log file rotation.
Error Logging & DiagnosticsN/Alog_timezonePostgreSQL: Timezone for log timestamps.
Error Logging & DiagnosticsN/Aclient_min_messagesPostgreSQL: Minimum message level for clients.
Error Logging & DiagnosticsN/Alog_error_verbosityPostgreSQL: Verbosity of logged error messages.
TimeoutsINBOUND_CONNECT_TIMEOUT_listener_nameconnect_timeout (client-side; not server)Oracle: Timeout for connections to the listener. PostgreSQL: Not a server parameter; typically handled by client drivers.
TimeoutsSQLNET.EXPIRE_TIMEstatement_timeoutOracle: Dead connection detection. PostgreSQL: Aborts long-running statements.
TimeoutsN/Alock_timeoutPostgreSQL: Aborts statements waiting for locks.
TimeoutsN/Aidle_in_transaction_session_timeoutPostgreSQL: Disconnects idle-in-transaction sessions.
Character SetsNLS_CHARACTERSETclient_encodingOracle: Database character set for CHAR/VARCHAR2. PostgreSQL: Character set for client connections.
Character SetsNLS_NCHAR_CHARACTERSETserver_encoding (set at database creation)Oracle: National character set for NCHAR/NVARCHAR2. PostgreSQL: Character set of the database cluster (set at initdb).
Character SetsNLS_LENGTH_SEMANTICSN/AOracle: Specifies how VARCHAR2 length is interpreted (byte or character).
System Statistics CollectionSTATISTICS_LEVELtrack_activitiesOracle: Controls the level of statistics collection (e.g.; for AWR). PostgreSQL: Enables/disables tracking of current commands for pg_stat_activity.
System Statistics CollectionTIMED_STATISTICStrack_countsOracle: Enables/disables collection of timed statistics. PostgreSQL: Enables/disables collection of tuple-level statistics (inserts; updates; deletes; scans).
System Statistics CollectionN/Atrack_io_timingPostgreSQL: Enables/disables tracking of I/O timing statistics.

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