Greenplum Database New Features - New Server Configuration parameters

Greenplum added a bunch of new server configuration parameters in almost every release. Lets list all server configuration parameter as of GPDB (total 263)  and discuss about some of the parameters specifically mentioned in release notes (GPDB 4.3.3 and GPDB

New Server Configuration parameters (4.3.3 and

1) Append only tables / Append optimized tables 

"Append-Only Tables";"max_appendonly_tables";"10000";"";"postmaster";"configuration file";"0";"2147483647";"Maximum number of different (unrelated) append only tables that can participate in writing data concurrently.";""

"Append-Only Tables";"gp_appendonly_compaction_threshold";"10";"";"user";"default";"0";"100";"Threshold of the ratio of dirty data in a segment file over which the file will be compacted during lazy vacuum.";""

"Append-Only Tables";"gp_default_storage_options";"appendonly=false,blocksize=32768,compresstype=none,checksum=true,orientation=row";"";"user";"default";"";"";"Default options for appendonly storage.";""

2) Client Connection Defaults/Locale and Formatting

"Client Connection Defaults / Locale and Formatting";"lc_collate";"en_US.utf8";"";"internal";"override";"";"";"Shows the collation order locale.";""

"Client Connection Defaults / Locale and Formatting";"lc_numeric";"en_US.utf8";"";"user";"configuration file";"";"";"Sets the locale for formatting numbers.";""

"Client Connection Defaults / Locale and Formatting";"lc_time";"en_US.utf8";"";"user";"configuration file";"";"";"Sets the locale for formatting date and time values.";""

"Client Connection Defaults / Locale and Formatting";"IntervalStyle";"postgres";"";"user";"default";"";"";"Sets the display format for interval values.";""

"Client Connection Defaults / Locale and Formatting";"lc_ctype";"en_US.utf8";"";"internal";"override";"";"";"Shows the character classification and case conversion locale.";""

"Client Connection Defaults / Locale and Formatting";"lc_messages";"en_US.utf8";"";"superuser";"configuration file";"";"";"Sets the language in which messages are displayed.";""

"Client Connection Defaults / Locale and Formatting";"timezone_abbreviations";"Default";"";"user";"command line";"";"";"Selects a file of time zone abbreviations.";""

"Client Connection Defaults / Locale and Formatting";"TimeZone";"US/Eastern";"";"user";"command line";"";"";"Sets the time zone for displaying and interpreting time stamps.";""

"Client Connection Defaults / Locale and Formatting";"extra_float_digits";"0";"";"user";"default";"-15";"2";"Sets the number of digits displayed for floating-point values.";"This affects real, double precision, and geometric data types. The parameter value is added to the standard number of digits (FLT_DIG or DBL_DIG as appropriate)."

"Client Connection Defaults / Locale and Formatting";"DateStyle";"ISO, MDY";"";"user";"session";"";"";"Sets the display format for date and time values.";"Also controls interpretation of ambiguous date inputs."

"Client Connection Defaults / Locale and Formatting";"server_encoding";"UTF8";"";"internal";"override";"";"";"Sets the server (database) character set encoding.";""

"Client Connection Defaults / Locale and Formatting";"client_encoding";"UNICODE";"";"user";"session";"";"";"Sets the client's character set encoding.";""

"Client Connection Defaults / Locale and Formatting";"lc_monetary";"en_US.utf8";"";"user";"configuration file";"";"";"Sets the locale for formatting monetary amounts.";""

"Client Connection Defaults / Other Defaults";"gp_role";"dispatch";"";"superuser";"default";"";"";"Sets the role for the session.";"Valid values are DISPATCH, EXECUTE, and UTILITY."

"Client Connection Defaults / Other Defaults";"update_process_title";"on";"";"superuser";"default";"";"";"Updates the process title to show the active SQL command.";"Enables updating of the process title every time a new SQL command is received by the server."

"Client Connection Defaults / Other Defaults";"tcp_keepalives_count";"9";"";"user";"default";"0";"2147483647";"Maximum number of TCP keepalive retransmits.";"This controls the number of consecutive keepalive retransmits that can be lost before a connection is considered dead. A value of 0 uses the system default."

"Client Connection Defaults / Other Defaults";"tcp_keepalives_idle";"7200";"s";"user";"default";"0";"2147483647";"Seconds between issuing TCP keepalives.";"A value of 0 uses the system default."

"Client Connection Defaults / Other Defaults";"tcp_keepalives_interval";"75";"s";"user";"default";"0";"2147483647";"Seconds between TCP keepalive retransmits.";"A value of 0 uses the system default."

"Client Connection Defaults / Other Defaults";"gp_vmem_idle_resource_timeout";"18000";"ms";"user";"default";"0";"2147483647";"Sets the time a session can be idle (in milliseconds) before we release gangs on the segment DBs to free resources.";"A value of 0 turns off the timeout."

"Client Connection Defaults / Other Defaults";"gp_session_id";"5176";"";"backend";"default";"-2147483648";"2147483647";"Global ID used to uniquely identify a particular session in an Greenplum Database array";""

"Client Connection Defaults / Other Defaults";"gp_connection_send_timeout";"3600";"";"sighup";"default";"0";"2147483647";"Timeout for sending data to unresponsive clients (seconds)";"A value of 0 uses the system default."

"Client Connection Defaults / Other Defaults";"local_preload_libraries";"";"";"backend";"default";"";"";"Lists shared libraries to preload into each backend.";""

"Client Connection Defaults / Other Defaults";"gp_command_count";"8";"";"internal";"default";"0";"2147483647";"Shows the number of commands received from the client in this session.";""

"Client Connection Defaults / Other Defaults";"explain_pretty_print";"on";"";"user";"default";"";"";"Uses the indented output format for EXPLAIN VERBOSE.";""

"Client Connection Defaults / Other Defaults";"dynamic_library_path";"$libdir";"";"superuser";"default";"";"";"Sets the path for dynamically loadable modules.";"If a dynamically loadable module needs to be opened and the specified name does not have a directory component (i.e., the name does not contain a slash), the system will search this path for the specified file."

"Client Connection Defaults / Statement Behavior";"default_transaction_read_only";"off";"";"user";"default";"";"";"Sets the default read-only status of new transactions.";""

"Client Connection Defaults / Statement Behavior";"default_tablespace";"";"";"user";"default";"";"";"Sets the default tablespace to create tables and indexes in.";"An empty string selects the database's default tablespace."

"Client Connection Defaults / Statement Behavior";"default_transaction_isolation";"read committed";"";"user";"default";"";"";"Sets the transaction isolation level of each new transaction.";"Each SQL transaction has an isolation level, which can be either "read uncommitted", "read committed", "repeatable read", or "serializable"."

"Client Connection Defaults / Statement Behavior";"check_function_bodies";"on";"";"user";"default";"";"";"Check function bodies during CREATE FUNCTION.";""

"Client Connection Defaults / Statement Behavior";"transaction_read_only";"off";"";"user";"override";"";"";"Sets the current transaction's read-only status.";""

"Client Connection Defaults / Statement Behavior";"transaction_isolation";"read committed";"";"user";"override";"";"";"Sets the current transaction's isolation level.";""

"Client Connection Defaults / Statement Behavior";"vacuum_freeze_min_age";"100000000";"";"user";"default";"0";"1000000000";"Minimum age at which VACUUM should freeze a table row.";""

"Client Connection Defaults / Statement Behavior";"search_path";""$user",public";"";"user";"default";"";"";"Sets the schema search order for names that are not schema-qualified.";""

"Client Connection Defaults / Statement Behavior";"statement_timeout";"0";"ms";"user";"default";"0";"2147483647";"Sets the maximum allowed duration (in milliseconds) of any statement.";"A value of 0 turns off the timeout."

3) Connection and Authentication

"Connections and Authentication / Connection Settings";"bonjour_name";"";"";"postmaster";"default";"";"";"Sets the Bonjour broadcast service name.";""

"Connections and Authentication / Connection Settings";"max_connections";"250";"";"postmaster";"configuration file";"10";"65535";"Sets the maximum number of concurrent connections.";""

"Connections and Authentication / Connection Settings";"unix_socket_group";"";"";"postmaster";"default";"";"";"Sets the owning group of the Unix-domain socket.";"The owning user of the socket is always the user that starts the server."

"Connections and Authentication / Connection Settings";"port";"5432";"";"postmaster";"command line";"1";"65535";"Sets the TCP port the server listens on.";""

"Connections and Authentication / Connection Settings";"superuser_reserved_connections";"3";"";"postmaster";"default";"0";"536870911";"Sets the number of connection slots reserved for superusers.";""

"Connections and Authentication / Connection Settings";"unix_socket_permissions";"511";"";"postmaster";"default";"0";"511";"Sets the access permissions of the Unix-domain socket.";"Unix-domain sockets use the usual Unix file system permission set. The parameter value is expected to be an numeric mode specification in the form accepted by the chmod and umask system calls. (To use the customary octal format the number must start with a (...)"

"Connections and Authentication / Connection Settings";"unix_socket_directory";"";"";"postmaster";"default";"";"";"Sets the directory where the Unix-domain socket will be created.";""

"Connections and Authentication / Connection Settings";"listen_addresses";"*";"";"postmaster";"command line";"";"";"Sets the host name or IP address(es) to listen to.";""

"Connections and Authentication / Security and Authentication";"password_encryption";"on";"";"user";"default";"";"";"Encrypt passwords.";"When a password is specified in CREATE USER or ALTER USER without writing either ENCRYPTED or UNENCRYPTED, this parameter determines whether the password is to be encrypted."

"Connections and Authentication / Security and Authentication";"password_hash_algorithm";"MD5";"";"superuser";"default";"";"";"The cryptograph hash algorithm to apply to passwords before storing them.";"Valid values are MD5, SHA-256 or SHA-256-FIPS (for a FIPS compliant implementation)."

"Connections and Authentication / Security and Authentication";"ssl";"off";"";"postmaster";"default";"";"";"Enables SSL connections.";""

"Connections and Authentication / Security and Authentication";"ssl_ciphers";"ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH";"";"postmaster";"default";"";"";"Sets the list of allowed SSL ciphers.";""

"Connections and Authentication / Security and Authentication";"db_user_namespace";"off";"";"sighup";"default";"";"";"Enables per-database user names.";""

"Connections and Authentication / Security and Authentication";"authentication_timeout";"60";"s";"sighup";"default";"1";"600";"Sets the maximum time in seconds to complete client authentication.";""

"Connections and Authentication / Security and Authentication";"krb_caseins_users";"off";"";"postmaster";"default";"";"";"Sets whether Kerberos user names should be treated as case-insensitive.";""

"Connections and Authentication / Security and Authentication";"krb_server_keyfile";"FILE:/data/pulse2-agent/agents/agent1/work/GPDB-4_3_x-rcbuilds/rhel5_x86_64/";"";"sighup";"default";"";"";"Sets the location of the Kerberos server key file.";""

"Connections and Authentication / Security and Authentication";"krb_srvname";"postgres";"";"sighup";"default";"";"";"Sets the name of the Kerberos service.";""

4) Customized Options

"Customized Options";"pljava_release_lingering_savepoints";"off";"";"superuser";"default";"";"";"If true, lingering savepoints will be released on function exit; if false, they will be rolled back";""

"Customized Options";"pljava_classpath";"";"";"user";"default";"";"";"classpath used by the the JVM";""

"Customized Options";"custom_variable_classes";"";"";"sighup";"default";"";"";"Sets the list of known custom variable classes.";""

"Customized Options";"gp_hadoop_home";"";"";"user";"default";"";"";"The location where Hadoop is installed in each segment.";""

"Customized Options";"pljava_vmoptions";"";"";"superuser";"default";"";"";"Options sent to the JVM when it is created";""

"Customized Options";"pljava_statement_cache_size";"0";"";"superuser";"default";"0";"512";"Size of the prepared statement MRU cache";""

"Customized Options";"gp_hadoop_target_version";"gphd-1.1";"";"user";"default";"";"";"The distro/version of Hadoop that external table is connecting to.";"See release notes or gppkg readme for details."

5) Deprecated Options

"Deprecated Options";"max_work_mem";"1024000";"kB";"superuser";"default";"256";"2147483647";"Sets the maximum value for work_mem setting.";""

"Deprecated Options";"work_mem";"32768";"kB";"user";"default";"256";"2147483647";"Sets the maximum memory to be used for query workspaces.";"This much memory may be used by each internal sort operation and hash table before switching to temporary disk files."

6) Developer Options

"Developer Options";"gp_debug_linger";"0";"s";"user";"default";"0";"3600";"Number of seconds for QD/QE process to linger upon fatal internal error.";"Allows an opportunity to debug the backend process before it terminates."

"Developer Options";"optimizer_control";"on";"";"superuser";"default";"";"";"Allow/disallow turning the optimizer on or off.";""

"Developer Options";"log_count_recovered_files_batch";"1000";"";"postmaster";"default";"0";"2147483647";"Logs the total number of files shipped to the mirror after every batch of size specified by this value";""

"Developer Options";"gp_autostats_mode";"ON_NO_STATS";"";"user";"configuration file";"";"";"Sets the autostats mode.";"Valid values are NONE, ON_CHANGE, ON_NO_STATS. ON_CHANGE requires setting gp_autostats_on_change_threshold."

"Developer Options";"gp_autostats_on_change_threshold";"2147483647";"";"user";"configuration file";"0";"2147483647";"Threshold for number of tuples added to table by CTAS or Insert-to to trigger autostats in on_change mode. See gp_autostats_mode.";""

"Developer Options";"gp_backup_directIO";"off";"";"user";"configuration file";"";"";"Enable direct IO dump";""

"Developer Options";"gp_backup_directIO_read_chunk_mb";"20";"";"user";"configuration file";"1";"200";"Size of read Chunk buffer in directIO dump (in MB)";""

"Developer Options";"gp_reraise_signal";"on";"";"superuser";"default";"";"";"Do we attempt to dump core when a serious problem occurs.";""

"Developer Options";"gp_workfile_compress_algorithm";"none";"";"user";"default";"";"";"Specify the compression algorithm that work files in the query executor use.";"Valid values are "NONE", "ZLIB"."

"Developer Options";"debug_assertions";"off";"";"user";"default";"";"";"Turns on various assertion checks.";"This is a debugging aid."

7) External Tables

"External Tables";"readable_external_table_timeout";"0";"s";"user";"default";"0";"2147483647";"Cancel the query if no data read within N seconds.";"A value of 0 turns off the timeout."

"External Tables";"gp_external_enable_exec";"on";"";"postmaster";"configuration file";"";"";"Enable selecting from an external table with an EXECUTE clause.";""

"External Tables";"gp_initial_bad_row_limit";"1000";"";"user";"default";"0";"2147483647";"Stops processing when number of the first bad rows exceeding this value";""

"External Tables";"gp_max_csv_line_length";"1048576";"";"user";"default";"32768";"4194304";"Maximum allowed length of a csv input data row in bytes";""

"External Tables";"gp_external_max_segs";"64";"";"user";"default";"1";"2147483647";"Maximum number of segments that connect to a single gpfdist URL.";""

"External Tables";"gp_external_grant_privileges";"off";"";"postmaster";"default";"";"";"Enable non superusers to create http or gpfdist external tables.";""

8)  GPDB Error Handling

"GPDB Error Handling";"gp_reject_percent_threshold";"300";"";"user";"default";"0";"2147483647";"Reject limit in percent starts calculating after this number of rows processed";""

9) Greenplum Database / Array Tuning

"Greenplum Database / Array Tuning";"gp_interconnect_timer_period";"5";"ms";"user";"default";"1";"100";"Sets the timer period (in ms) for UDP interconnect";""

"Greenplum Database / Array Tuning";"gp_interconnect_timer_checking_period";"20";"ms";"user";"default";"1";"100";"Sets the timer checking period (in ms) for UDP interconnect";""

"Greenplum Database / Array Tuning";"gp_interconnect_snd_queue_depth";"2";"";"user";"default";"1";"4096";"Sets the maximum size of the send queue for each connection in the UDP interconnect";""

"Greenplum Database / Array Tuning";"gp_interconnect_setup_timeout";"7200";"s";"user";"default";"0";"7200";"Timeout (in seconds) on interconnect setup that occurs at query start";"Used by Interconnect to timeout the setup of the communication fabric."

"Greenplum Database / Array Tuning";"gp_interconnect_queue_depth";"4";"";"user";"default";"1";"4096";"Sets the maximum size of the receive queue for each connection in the UDP interconnect";""

"Greenplum Database / Array Tuning";"gp_filerep_tcp_keepalives_count";"2";"";"user";"default";"0";"2147483647";"Maximum number of TCP keepalive retransmits for FileRep connection.";"This controls the number of consecutive keepalive retransmits that can be lost before a connection is considered dead. A value of 0 uses the system default."

"Greenplum Database / Array Tuning";"gp_filerep_tcp_keepalives_idle";"60";"s";"user";"default";"0";"2147483647";"Seconds between issuing TCP keepalives for FileRep connection.";"A value of 0 uses the system default."

"Greenplum Database / Array Tuning";"gp_filerep_tcp_keepalives_interval";"30";"s";"user";"default";"0";"2147483647";"Seconds between TCP keepalive retransmits for FileRep connection.";"A value of 0 uses the system default."

"Greenplum Database / Array Tuning";"gp_fts_probe_interval";"60";"s";"postmaster";"default";"10";"2147483647";"A complete probe of all segments starts each time a timer with this period expires.";"Used by the fts-probe process. "

"Greenplum Database / Array Tuning";"gp_fts_probe_threadcount";"16";"";"postmaster";"default";"1";"128";"Use this number of threads for probing the segments.";"The number of threads to create at each probe interval expiration."

"Greenplum Database / Array Tuning";"gp_fts_probe_timeout";"20";"s";"user";"default";"0";"2147483647";"Maximum time (in seconds) allowed for FTS to complete probing a segment.";"Used by the fts-probe process."

"Greenplum Database / Array Tuning";"gp_interconnect_min_rto";"20";"ms";"user";"default";"1";"1000";"Sets the min rto (in ms) for UDP interconnect";""

"Greenplum Database / Array Tuning";"gp_connections_per_thread";"64";"";"superuser";"configuration file";"0";"2147483647";"Sets the number of client connections handled in each thread.";""

"Greenplum Database / Array Tuning";"gp_hashjoin_tuples_per_bucket";"5";"";"user";"default";"1";"25";"Target density of hashtable used by Hashjoin during execution";"A smaller value will tend to produce larger hashtables, which increases join performance"

"Greenplum Database / Array Tuning";"gp_udp_bufsize_k";"0";"";"backend";"default";"0";"32768";"Sets recv buf size of UDP interconnect, for testing.";""

"Greenplum Database / Array Tuning";"gp_interconnect_default_rtt";"20";"ms";"user";"default";"1";"1000";"Sets the default rtt (in ms) for UDP interconnect";""

"Greenplum Database / Array Tuning";"gp_interconnect_min_retries_before_timeout";"100";"";"user";"default";"1";"4096";"Sets the min retries before reporting a transmit timeout in the interconnect.";""

"Greenplum Database / Array Tuning";"gp_interconnect_fc_method";"LOSS";"";"user";"default";"";"";"Sets the flow control method used for UDP interconnect.";"Valid values are "capacity" and "loss"."

"Greenplum Database / Array Tuning";"gp_interconnect_transmit_timeout";"3600";"s";"user";"default";"1";"7200";"Timeout (in seconds) on interconnect to transmit a packet";"Used by Interconnect to timeout packet transmission."

"Greenplum Database / Array Tuning";"gp_interconnect_type";"UDPIFC";"";"backend";"configuration file";"";"";"Sets the protocol used for inter-node communication.";"Valid values are "tcp", "udp" and "udpifc"."

"Greenplum Database / Array Tuning";"gp_max_packet_size";"8192";"";"backend";"default";"512";"65507";"Sets the max packet size for the Interconnect.";""

"Greenplum Database / Array Tuning";"gp_cached_segworkers_threshold";"5";"";"user";"default";"0";"2147483647";"Sets the maximum number of segment workers to cache between statements.";""

"Greenplum Database / Array Tuning";"gp_interconnect_hash_multiplier";"2";"";"superuser";"default";"1";"256";"Sets the number of hash buckets used by the UDP interconnect to track connections (the number of buckets is given by the product of the segment count and the hash multipliers).";""

"Greenplum Database / Array Tuning";"gp_segment_connect_timeout";"600";"s";"user";"configuration file";"0";"2147483647";"Maximum time (in seconds) allowed for a new worker process to start or a mirror to respond.";"0 indicates 'wait forever'."

"Greenplum Database / Array Tuning";"gp_interconnect_cache_future_packets";"on";"";"user";"default";"";"";"Control whether future packets are cached.";""

"Lock Management";"deadlock_timeout";"1000";"ms";"sighup";"default";"0";"2147483647";"The time in milliseconds to wait on lock before checking for deadlock.";""

10) Lock Management

"Lock Management";"max_locks_per_transaction";"128";"";"postmaster";"default";"10";"2147483647";"Sets the maximum number of locks per transaction.";"The shared lock table is sized on the assumption that at most max_locks_per_transaction * max_connections distinct objects will need to be locked at any one time."

11) Preset options

"Preset Options";"server_version_num";"80215";"";"internal";"default";"80215";"80215";"Shows the server version as an integer.";""

"Preset Options";"block_size";"32768";"";"internal";"default";"32768";"32768";"Shows size of a disk block";""

"Preset Options";"max_function_args";"100";"";"internal";"default";"100";"100";"Shows the maximum number of function arguments.";""

"Preset Options";"max_identifier_length";"63";"";"internal";"default";"63";"63";"Shows the maximum identifier length";""

"Preset Options";"max_index_keys";"32";"";"internal";"default";"32";"32";"Shows the maximum number of index keys.";""

"Preset Options";"integer_datetimes";"on";"";"internal";"default";"";"";"Datetimes are integer based.";""

"Preset Options";"gp_contentid";"-1";"";"postmaster";"command line";"-2147483648";"2147483647";"The contentid used by this server.";""

"Preset Options";"gp_standby_dbid";"0";"";"postmaster";"command line";"-2147483648";"32767";"Sets DBID of standby master.";""

"Preset Options";"gp_dbid";"1";"";"postmaster";"command line";"-2147483648";"2147483647";"The dbid used by this server.";""

"Preset Options";"gp_num_contents_in_cluster";"2";"";"postmaster";"command line";"-2147483648";"2147483647";"Sets the number of segments in the cluster.";""

"Preset Options";"server_version";"8.2.15";"";"internal";"default";"";"";"Shows the server version.";""

12) Query Tuning

"Query Tuning / Other Planner Options";"from_collapse_limit";"20";"";"user";"default";"1";"2147483647";"Sets the FROM-list size beyond which subqueries are not collapsed.";"The planner will merge subqueries into upper queries if the resulting FROM list would have no more than this many items."

"Query Tuning / Other Planner Options";"join_collapse_limit";"20";"";"user";"default";"1";"2147483647";"Sets the FROM-list size beyond which JOIN constructs are not flattened.";"The planner will flatten explicit JOIN constructs into lists of FROM items whenever a list of no more than this many items would result."

"Query Tuning / Other Planner Options";"gp_enable_predicate_propagation";"on";"";"user";"default";"";"";"When two expressions are equivalent (such as with equijoined keys) then the planner applies predicates on one expression to the other expression.";"If false, planner does not copy predicates."

"Query Tuning / Other Planner Options";"gp_workfile_checksumming";"on";"";"user";"default";"";"";"Enable checksumming on the executor work files in order to catch possible faulty writes caused by your disk drivers.";""

"Query Tuning / Other Planner Options";"gp_enable_fast_sri";"on";"";"user";"default";"";"";"Enable single-slice single-row inserts.";""

"Query Tuning / Other Planner Options";"cursor_tuple_fraction";"1";"";"user";"default";"0";"1";"Sets the planner's estimate of the fraction of a cursor's rows that will be retrieved.";""

"Query Tuning / Planner Cost Constants";"effective_cache_size";"16384";"32kB";"user";"default";"1";"2147483647";"Sets the planner's assumption about size of the disk cache.";"That is, the portion of the kernel's disk cache that will be used for PostgreSQL data files. This is measured in disk pages, which are normally 8 kB each."

"Query Tuning / Planner Cost Constants";"cpu_tuple_cost";"0.01";"";"user";"default";"0";"1.79769e+308";"Sets the planner's estimate of the cost of processing each tuple (row).";""

"Query Tuning / Planner Cost Constants";"cpu_index_tuple_cost";"0.005";"";"user";"default";"0";"1.79769e+308";"Sets the planner's estimate of the cost of processing each index entry during an index scan.";""

"Query Tuning / Planner Cost Constants";"cpu_operator_cost";"0.0025";"";"user";"default";"0";"1.79769e+308";"Sets the planner's estimate of the cost of processing each operator or function call.";""

"Query Tuning / Planner Cost Constants";"gp_motion_cost_per_row";"0";"";"user";"default";"0";"1.79769e+308";"Sets the planner's estimate of the cost of moving a row between worker processes.";"If >0, the planner uses this value -- instead of double the cpu_tuple_cost -- for Motion operator cost estimation."

"Query Tuning / Planner Cost Constants";"gp_segments_for_planner";"0";"";"user";"default";"0";"2147483647";"If >0, number of segment dbs for the planner to assume in its cost and size estimates.";"If 0, estimates are based on the actual number of segment dbs."

"Query Tuning / Planner Cost Constants";"seq_page_cost";"1";"";"user";"default";"0";"1.79769e+308";"Sets the planner's estimate of the cost of a sequentially fetched disk page.";""

"Query Tuning / Planner Cost Constants";"random_page_cost";"100";"";"user";"default";"0";"1.79769e+308";"Sets the planner's estimate of the cost of a nonsequentially fetched disk page.";""

"Query Tuning / Planner Method Configuration";"enable_hashagg";"on";"";"user";"default";"";"";"Enables the planner's use of hashed aggregation plans.";""

"Query Tuning / Planner Method Configuration";"gp_idf_deduplicate";"auto";"";"user";"default";"";"";"Sets the mode to control inverse distribution function's de-duplicate strategy.";"Valid values are AUTO, NONE, and FORCE."

"Query Tuning / Planner Method Configuration";"gp_enable_sort_limit";"on";"";"user";"default";"";"";"Enable LIMIT operation to be performed while sorting.";"Sort more efficiently when plan requires the first <n> rows at most."

"Query Tuning / Planner Method Configuration";"gp_enable_sort_distinct";"on";"";"user";"default";"";"";"Enable duplicate removal to be performed while sorting.";"Reduces data handling when plan calls for removing duplicates from sorted rows."

"Query Tuning / Planner Method Configuration";"optimizer";"on";"";"user";"database";"";"";"Enable the new optimizer.";""

"Query Tuning / Planner Method Configuration";"gp_statistics_pullup_from_child_partition";"on";"";"user";"default";"";"";"This guc enables the planner to utilize statistics from partitions in planning queries on the parent.";""

"Query Tuning / Planner Method Configuration";"gp_statistics_use_fkeys";"on";"";"user";"default";"";"";"This guc enables the planner to utilize statistics derived from foreign key relationships.";""

"Query Tuning / Planner Method Configuration";"enable_hashjoin";"on";"";"user";"default";"";"";"Enables the planner's use of hash join plans.";""

"Query Tuning / Planner Method Configuration";"gp_enable_adaptive_nestloop";"on";"";"user";"default";"";"";"Enables the planner's use of the Adaptive Join Choice operator.";"During query execution, actual outer row count determines choice of Nested or Hash Join."

"Query Tuning / Planner Method Configuration";"gp_enable_sequential_window_plans";"on";"";"user";"default";"";"";"Experimental feature: Enable non-parallel window plans.";"The planner will evaluate window functions associated with separate window specifications sequentially rather that in parallel."

"Query Tuning / Planner Method Configuration";"enable_indexscan";"on";"";"user";"default";"";"";"Enables the planner's use of index-scan plans.";""

"Query Tuning / Planner Method Configuration";"enable_mergejoin";"off";"";"user";"default";"";"";"Enables the planner's use of merge join plans.";""

"Query Tuning / Planner Method Configuration";"gp_adjust_selectivity_for_outerjoins";"on";"";"user";"default";"";"";"Adjust selectivity of null tests over outer joins.";""

"Query Tuning / Planner Method Configuration";"gp_enable_preunique";"on";"";"user";"default";"";"";"Enable 2-phase duplicate removal.";"If true, planner may 

choose to remove duplicates in two phases--before and after redistribution."

"Query Tuning / Planner Method Configuration";"enable_nestloop";"off";"";"user";"default";"";"";"Enables the planner's use of nested-loop join plans.";""

"Query Tuning / Planner Method Configuration";"enable_seqscan";"on";"";"user";"default";"";"";"Enables the planner's use of sequential-scan plans.";""

"Query Tuning / Planner Method Configuration";"enable_sort";"on";"";"user";"default";"";"";"Enables the planner's use of explicit sort steps.";""

"Query Tuning / Planner Method Configuration";"gp_enable_groupext_distinct_pruning";"on";"";"user";"default";"";"";"Enable 3-phase aggregation and join to compute distinct-qualified aggregates on grouping extention queries.";""

"Query Tuning / Planner Method Configuration";"enable_tidscan";"on";"";"user";"default";"";"";"Enables the planner's use of TID scan plans.";""

"Query Tuning / Planner Method Configuration";"gp_enable_groupext_distinct_gather";"on";"";"user";"default";"";"";"Enable gathering data to a single node to compute distinct-qualified aggregates on grouping extention queries.";""

"Query Tuning / Planner Method Configuration";"gp_enable_agg_distinct";"on";"";"user";"default";"";"";"Enable 2-phase aggregation to compute a single distinct-qualified aggregate.";""

"Query Tuning / Planner Method Configuration";"gp_enable_agg_distinct_pruning";"on";"";"user";"default";"";"";"Enable 3-phase aggregation and join to compute distinct-qualified aggregates.";""

"Query Tuning / Planner Method Configuration";"gp_enable_direct_dispatch";"on";"";"user";"default";"";"";"Enable dispatch for single-row-insert targetted mirror-pairs.";"Don't involve the whole cluster if it isn't needed."

"Query Tuning / Planner Method Configuration";"enable_groupagg";"on";"";"user";"default";"";"";"Enables the planner's use of grouping aggregation plans.";""

"Query Tuning / Planner Method Configuration";"enable_bitmapscan";"on";"";"user";"default";"";"";"Enables the planner's use of bitmap-scan plans.";""

"Query Tuning / Planner Method Configuration";"gp_enable_fallback_plan";"on";"";"user";"default";"";"";"Plan types which are not enabled may be used when a query would be infeasible without them.";"If false, planner rejects queries that cannot be satisfied using only the enabled plan types."

"Query Tuning / Planner Method Configuration";"gp_enable_multiphase_agg";"on";"";"user";"default";"";"";"Enables the planner's use of two- or three-stage parallel aggregation plans.";"Allows partial aggregation before motion."

"Query Tuning / Planner Method Configuration";"gp_dynamic_partition_pruning";"on";"";"user";"default";"";"";"This guc enables plans that can dynamically eliminate scanning of partitions.";""

13) Reporting and Logging

"Reporting and Logging";"gp_connectemc_mode";"on";"";"postmaster";"default";"";"";"control connectemc functionality";"If 'on' send connectemc messages and log them locally, if 'local' log connectemc message locally only, if 'remote' send connectemc messages only, if 'off', no connectemc messages"

"Reporting and Logging";"gp_email_connect_avoid_duration";"7200";"";"superuser";"default";"300";"86400";"Sets the amount of time (in secs) to avoid connecting to SMTP server";""

"Reporting and Logging";"gp_email_connect_failures";"5";"";"superuser";"default";"3";"100";"Sets the number of consecutive connect failures before declaring SMTP server as unavailable";""

"Reporting and Logging";"gp_email_connect_timeout";"15";"";"superuser";"default";"10";"120";"Sets the amount of time (in secs) after which SMTP sockets would timeout";""

"Reporting and Logging";"gp_email_from";"";"";"superuser";"default";"";"";"Sets email address of the sender of email alerts (our e-mail id).";""

"Reporting and Logging";"gp_email_smtp_password";"";"";"superuser";"default";"";"";"Sets the password used for the SMTP server, if required.";""

"Reporting and Logging";"gp_email_smtp_server";"localhost:25";"";"superuser";"default";"";"";"Sets the SMTP server and port used to send e-mail alerts.";""

"Reporting and Logging";"gpperfmon_log_alert_level";"warning";"";"user";"configuration file";"";"";"Specify the log alert level used by gpperfmon.";"Valid values are 'none', 'warning', 'error', 'fatal', 'panic'."

"Reporting and Logging";"gp_email_smtp_userid";"";"";"superuser";"default";"";"";"Sets the userid used for the SMTP server, if required.";""

"Reporting and Logging";"gp_email_to";"";"";"superuser";"default";"";"";"Sets email address(es) to send alerts to. Maybe be multiple email addresses.";""

"Reporting and Logging";"gp_snmp_use_inform_or_trap";"trap";"";"superuser";"default";"";"";"If 'inform', we send alerts as SNMP v2c inform messages, if 'trap', we use SNMP v2 trap messages..";""

"Reporting and Logging";"gp_snmp_monitor_address";"";"";"superuser";"default";"";"";"Sets the network address to send SNMP alerts (inform or trap messages) to.";""

"Reporting and Logging";"gp_snmp_community";"public";"";"superuser";"default";"";"";"Sets SNMP community name to send alerts (inform or trap messages) to.";""

"Reporting and Logging / What to Log";"log_autostats";"off";"";"superuser";"configuration file";"";"";"Logs details of auto-stats issued ANALYZEs.";""

"Reporting and Logging / What to Log";"log_connections";"off";"";"backend";"default";"";"";"Logs each successful connection.";""

"Reporting and Logging / What to Log";"debug_print_slice_table";"off";"";"user";"default";"";"";"Prints the slice table to server log.";""

"Reporting and Logging / What to Log";"debug_print_rewritten";"off";"";"user";"default";"";"";"Prints the parse tree after rewriting to server log.";""

"Reporting and Logging / What to Log";"debug_print_prelim_plan";"off";"";"user";"default";"";"";"Prints the preliminary execution plan to server log.";""

"Reporting and Logging / What to Log";"log_disconnections";"off";"";"backend";"default";"";"";"Logs end of a session, including duration.";""

"Reporting and Logging / What to Log";"debug_print_plan";"off";"";"user";"default";"";"";"Prints the execution plan to server log.";""

"Reporting and Logging / What to Log";"log_timezone";"US/Eastern";"";"sighup";"command line";"";"";"Sets the time zone to use in log messages.";""

"Reporting and Logging / What to Log";"application_name";"pgAdmin III - Query Tool";"";"user";"client";"";"";"Sets the application name to be reported in statistics and logs.";""

"Reporting and Logging / What to Log";"log_hostname";"off";"";"sighup";"default";"";"";"Logs the host name in the connection logs.";"By default, connection logs only show the IP address of the connecting host. If you want them to show the host name you can turn this on, but depending on your host name resolution setup it might impose a non-negligible performance penalty."

"Reporting and Logging / What to Log";"debug_pretty_print";"off";"";"user";"default";"";"";"Indents parse and plan tree displays.";""

"Reporting and Logging / What to Log";"gp_gpperfmon_send_interval";"1";"";"user";"default";"1";"3600";"Interval in seconds between sending messages to gpperfmon.";""

"Reporting and Logging / What to Log";"log_duration";"off";"";"superuser";"default";"";"";"Logs the duration of each completed SQL statement.";""

"Reporting and Logging / What to Log";"log_statement";"all";"";"superuser";"configuration file";"";"";"Sets the type of statements logged.";"Valid values are "none", "ddl", "mod", and "all"."

"Reporting and Logging / What to Log";"debug_print_parse";"off";"";"user";"default";"";"";"Prints the parse tree to the server log.";""

"Reporting and Logging / When to Log";"log_min_messages";"warning";"";"superuser";"default";"";"";"Sets the message levels that are logged.";"Valid values are DEBUG5, DEBUG4, DEBUG3, DEBUG2, DEBUG1, INFO, NOTICE, WARNING, ERROR, LOG, FATAL, and PANIC. Each level includes all the levels that follow it."

"Reporting and Logging / When to Log";"log_min_error_statement";"error";"";"superuser";"default";"";"";"Causes all statements generating error at or above this level to be logged.";"All SQL statements that cause an error of the specified level or a higher level are logged."

"Reporting and Logging / When to Log";"log_min_duration_statement";"-1";"ms";"superuser";"default";"-1";"2147483";"Sets the minimum execution time in milliseconds above which statements will be logged.";"Zero prints all queries. The default is -1 (turning this feature off)."

"Reporting and Logging / When to Log";"log_error_verbosity";"default";"";"superuser";"default";"";"";"Sets the verbosity of logged messages.";"Valid values are "terse", "default", and "verbose"."

"Reporting and Logging / When to Log";"client_min_messages";"notice";"";"user";"session";"";"";"Sets the message levels that are sent to the client.";"Valid values are DEBUG5, DEBUG4, DEBUG3, DEBUG2, DEBUG1, LOG, NOTICE, WARNING, and ERROR. Each level includes all the levels that follow it. The later the level, the fewer messages are sent."

"Reporting and Logging / When to Log";"optimizer_minidump";"onerror";"";"user";"default";"";"";"Generate optimizer minidump.";"Valid values are onerror, always"

"Reporting and Logging / Where to Log";"log_truncate_on_rotation";"off";"";"sighup";"default";"";"";"Truncate existing log files of same name during log rotation.";""

"Reporting and Logging / Where to Log";"log_rotation_size";"0";"kB";"sighup";"default";"0";"2097151";"Automatic log file rotation will occur after N kilobytes";""

"Reporting and Logging / Where to Log";"log_rotation_age";"1440";"min";"sighup";"default";"0";"35791394";"Automatic log file rotation will occur after N minutes";""

"Reporting and Logging / Where to Log";"gp_log_format";"csv";"";"postmaster";"default";"";"";"Sets the format for log files.";"Valid values are TEXT, CSV."

14) Resource Usage

"Resource Usage";"gp_workfile_limit_per_query";"0";"";"user";"default";"0";"1.80144e+16";"Maximum disk space (in KB) used for workfiles per query per segment.";"0 for no limit. Current query is terminated when limit is exceeded."

"Resource Usage";"gp_workfile_limit_per_segment";"0";"";"postmaster";"default";"0";"1.80144e+16";"Maximum disk space (in KB) used for workfiles per segment.";"0 for no limit. Current query is terminated when limit is exceeded."

"Resource Usage";"max_prepared_transactions";"250";"";"postmaster";"configuration file";"1";"1000";"Sets the maximum number of simultaneously prepared transactions.";""

"Resource Usage";"gp_safefswritesize";"0";"";"backend";"default";"0";"2147483647";"Minimum FS safe write size.";""

"Resource Usage";"gp_subtrans_warn_limit";"16777216";"";"postmaster";"default";"0";"2147483647";"Sets the warning limit on number of subtransactions in a transaction.";""

"Resource Usage";"gp_workfile_limit_files_per_query";"100000";"";"user";"default";"0";"2147483647";"Maximum number of workfiles allowed per query per segment.";"0 for no limit. Current query is terminated when limit is exceeded."

"Resource Usage";"vacuum_cost_delay";"0";"ms";"user";"default";"0";"1000";"Vacuum cost delay in milliseconds.";""

"Resource Usage";"vacuum_cost_page_hit";"1";"";"user";"default";"0";"10000";"Vacuum cost for a page found in the buffer cache.";""

"Resource Usage";"vacuum_cost_page_dirty";"20";"";"user";"default";"0";"10000";"Vacuum cost for a page dirtied by vacuum.";""

"Resource Usage";"vacuum_cost_page_miss";"10";"";"user";"default";"0";"10000";"Vacuum cost for a page not found in the buffer cache.";""

"Resource Usage";"vacuum_cost_limit";"200";"";"user";"default";"1";"10000";"Vacuum cost amount available before napping.";""

"Resource Usage / Free Space Map";"max_fsm_relations";"1000";"";"postmaster";"default";"100";"2147483647";"Sets the maximum number of tables and indexes for which free space is tracked.";""

"Resource Usage / Free Space Map";"max_fsm_pages";"200000";"";"postmaster";"configuration file";"1000";"2147483647";"Sets the maximum number of disk pages for which free space is tracked.";""

"Resource Usage / Kernel Resources";"max_files_per_process";"1000";"";"postmaster";"default";"25";"2147483647";"Sets the maximum number of simultaneously open files for each server process.";""

"Resource Usage / Kernel Resources";"shared_preload_libraries";"";"";"postmaster";"default";"";"";"Lists shared libraries to preload into server.";""

"Resource Usage / Kernel Resources";"gp_set_proc_affinity";"off";"";"postmaster";"default";"";"";"On postmaster startup, attempt to bind postmaster to a processor";""

"Resource Usage / Memory";"gp_vmem_protect_limit";"8192";"";"postmaster";"configuration file";"0";"1073741823";"Virtual memory limit (in MB) of Greenplum memory protection.";""

"Resource Usage / Memory";"max_statement_mem";"2048000";"kB";"superuser";"default";"32768";"2147483647";"Sets the maximum value for statement_mem setting.";""

"Resource Usage / Memory";"max_stack_depth";"2048";"kB";"superuser";"environment variable";"100";"2147483647";"Sets the maximum stack depth, in kilobytes.";""

"Resource Usage / Memory";"gp_vmem_protect_segworker_cache_limit";"500";"";"postmaster";"default";"1";"1073741823";"Max virtual memory limit (in MB) for a segworker to be cachable.";""

"Resource Usage / Memory";"explain_memory_verbosity";"suppress";"";"user";"default";"";"";"Experimental feature: show memory account usage in EXPLAIN ANALYZE.";"Valid values are SUPPRESS, SUMMARY, and DETAIL."

"Resource Usage / Memory";"maintenance_work_mem";"65536";"kB";"user";"default";"1024";"2147483647";"Sets the maximum memory to be used for maintenance operations.";"This includes operations such as VACUUM and CREATE INDEX."

"Resource Usage / Memory";"statement_mem";"128000";"kB";"user";"default";"1000";"2147483647";"Sets the memory to be reserved for a statement.";""

"Resource Usage / Memory";"shared_buffers";"4000";"32kB";"postmaster";"configuration file";"16";"1073741823";"Sets the number of shared memory buffers used by the server.";""

"Resource Usage / Memory";"gp_max_plan_size";"0";"kB";"superuser";"default";"0";"2147483647";"Sets the maximum size of a plan to be dispatched.";""

"Resource Usage / Memory";"temp_buffers";"1024";"32kB";"user";"default";"100";"1073741823";"Sets the maximum number of temporary buffers used by each session.";""

"Resource Usage / Memory";"gp_max_databases";"16";"";"postmaster";"default";"8";"256";"Sets the maximum number of databases.";""

"Resource Usage / Memory";"gp_max_filespaces";"8";"";"postmaster";"default";"8";"256";"Sets the maximum number of filespaces.";""

"Resource Usage / Memory";"gp_max_local_distributed_cache";"1024";"";"postmaster";"default";"0";"2147483647";"Sets the number of local-distributed transactions to cache for optimizing visibility processing by backends.";""

"Resource Usage / Memory";"runaway_detector_activation_percent";"90";"";"postmaster";"default";"0";"100";"The runaway detector activates if the used vmem exceeds this percentage of the vmem quota. Set to 100 to disable runaway detection.";""

"Resource Usage / Memory";"gp_max_tablespaces";"16";"";"postmaster";"default";"8";"2048";"Sets the maximum number of tablespaces.";""

"Resource Usage / Resources Management";"resource_cleanup_gangs_on_wait";"on";"";"user";"default";"";"";"Enable idle gang cleanup before resource lockwait.";""

"Resource Usage / Resources Management";"gp_resqueue_priority";"on";"";"postmaster";"default";"";"";"Enables priority scheduling.";""

"Resource Usage / Resources Management";"gp_resqueue_priority_cpucores_per_segment";"4";"";"postmaster";"default";"0.1";"512";"Number of processing units associated with a segment.";""

"Resource Usage / Resources Management";"gp_resqueue_memory_policy";"eager_free";"";"superuser";"configuration file";"";"";"Sets the policy for memory allocation of queries.";"Valid values are NONE, AUTO, EAGER_FREE."

"Resource Usage / Resources Management";"gp_resqueue_priority_sweeper_interval";"1000";"";"postmaster";"default";"500";"15000";"Frequency (in ms) at which sweeper process re-evaluates CPU shares.";""

"Resource Usage / Resources Management";"max_resource_portals_per_transaction";"64";"";"postmaster";"default";"0";"2147483647";"Maximum number of resource queues.";""

"Resource Usage / Resources Management";"resource_select_only";"off";"";"postmaster";"default";"";"";"Enable resource locking of SELECT only.";""

"Resource Usage / Resources Management";"max_resource_queues";"9";"";"postmaster";"default";"0";"2147483647";"Maximum number of resource queues.";""

15) Statistics

"Statistics / ANALYZE Database Contents";"default_statistics_target";"25";"";"user";"default";"1";"1000";"Sets the default statistics target.";"This applies to table columns that have not had a column-specific target set via ALTER TABLE SET STATISTICS."

"Statistics / ANALYZE Database Contents";"optimizer_analyze_root_partition";"on";"";"user";"configuration file";"";"";"Enable statistics collection on root partitions during ANALYZE";""

"Statistics / ANALYZE Database Contents";"gp_analyze_relative_error";"0.25";"";"user";"default";"0";"1";"target relative error fraction for row sampling during analyze";""

"Statistics / Monitoring";"log_statement_stats";"off";"";"superuser";"default";"";"";"Writes cumulative performance statistics to the server log.";""

"Statistics / Monitoring";"log_planner_stats";"off";"";"superuser";"default";"";"";"Writes planner performance statistics to the server log.";""

"Statistics / Monitoring";"log_executor_stats";"off";"";"superuser";"default";"";"";"Writes executor performance statistics to the server log.";""

"Statistics / Monitoring";"log_dispatch_stats";"off";"";"superuser";"default";"";"";"Writes dispatcher performance statistics to the server log.";""

"Statistics / Monitoring";"log_parser_stats";"off";"";"superuser";"default";"";"";"Writes parser performance statistics to the server log.";""

"Statistics / Query and Index Statistics Collector";"track_activities";"on";"";"superuser";"default";"";"";"Collects information about executing commands.";"Enables the collection of information on the currently executing command of each session, along with the time at which that command began execution."

"Statistics / Query and Index Statistics Collector";"track_counts";"off";"";"superuser";"default";"";"";"Collects statistics on database activity.";""

"Statistics / Query and Index Statistics Collector";"stats_queue_level";"off";"";"superuser";"default";"";"";"Collects resource queue-level statistics on database activity.";""

16) Ungrouped

"Ungrouped";"gp_enable_gpperfmon";"on";"";"postmaster";"configuration file";"";"";"Enable gpperfmon monitoring.";""

"Ungrouped";"gpperfmon_port";"8888";"";"postmaster";"configuration file";"1024";"65535";"Sets the port number of gpperfmon.";""

"Ungrouped";"pgstat_track_activity_query_size";"1024";"";"postmaster";"default";"1024";"2147483647";"Maximum length of the query to be displayed in pg_stat_activity";""

17) Version and Platform Compatability

"Version and Platform Compatibility";"gp_create_table_random_default_distribution";"off";"";"user";"default";"";"";"Set the default distribution of a table to RANDOM.";""

"Version and Platform Compatibility / Other Platforms and Clients";"transform_null_equals";"off";"";"user";"default";"";"";"Treats "expr=NULL" as "expr IS NULL".";"When turned on, expressions of the form expr = NULL (or NULL = expr) are treated as expr IS NULL, that is, they return true if expr evaluates to the null value, and false otherwise. The correct behavior of expr = NULL is to always return null (unknown)."

"Version and Platform Compatibility / Previous PostgreSQL Versions";"standard_conforming_strings";"off";"";"user";"default";"";"";"'...' strings treat backslashes literally.";""

"Version and Platform Compatibility / Previous PostgreSQL Versions";"array_nulls";"on";"";"user";"default";"";"";"Enable input of NULL elements in arrays.";"When turned on, unquoted NULL in an array input value means a null value; otherwise it is taken literally."

"Version and Platform Compatibility / Previous PostgreSQL Versions";"backslash_quote";"safe_encoding";"";"user";"default";"";"";"Sets whether "\'" is allowed in string literals.";"Valid values are ON, OFF, and SAFE_ENCODING."

"Version and Platform Compatibility / Previous PostgreSQL Versions";"regex_flavor";"advanced";"";"user";"default";"";"";"Sets the regular expression "flavor".";"This can be set to advanced, extended, or basic."

"Version and Platform Compatibility / Previous PostgreSQL Versions";"add_missing_from";"off";"";"user";"default";"";"";"Automatically adds missing table references to FROM clauses.";""

"Version and Platform Compatibility / Previous PostgreSQL Versions";"escape_string_warning";"on";"";"user";"default";"";"";"Warn about backslash escapes in ordinary string literals.";""

18) WAL Replication

"WAL Replication";"replication_timeout";"60000";"ms";"superuser";"default";"0";"2147483647";"Sets the maximum time to wait for WAL replication (Master Mirroring)";""

"WAL Replication";"wal_receiver_status_interval";"10";"s";"superuser";"default";"0";"2147483";"Sets the maximum interval between WAL receiver status reports to the primary. (Master Mirroring)";""

"WAL Replication";"repl_catchup_within_range";"1";"";"superuser";"default";"0";"63";"Sets the maximum number of xlog segments allowed to lag when the backends can start blocking despite the WAL sender being in catchup phase. (Master Mirroring)";""

19) WAL Settings

"Write-Ahead Log / Settings";"wal_buffers";"8";"32kB";"postmaster";"default";"4";"2147483647";"Sets the number of disk-page buffers in shared memory for WAL.";""

New Server Configuration Parameters in 4.3 for Master Mirroring

New Server Configuration Parameters in 4.3 for Append-Optimized Tables

New Server Configuration Parameter in 4.3.3

New Server Configuration Parameter in gp_appendonly_compaction_threshhold

Specifies the threshold ratio (as a percentage) of hidden rows to total rows that triggers compaction of the segment file when VACUUM is run without the FULL option (a lazy vacuum). If the ratio of hidden rows in a segment file on a segment is less than this threshold, the segment file is not compacted, and a log message is issued.