Date: Mon, 10 Feb 2025 16:25:08 -0600
From: Nathan Bossart <nathandbossart@gmail.com>
To: Peter Smith <smithpb2250@gmail.com>
Cc: "David G. Johnston" <david.g.johnston@gmail.com>,
	pgsql-hackers@postgresql.org
Subject: Re: describe special values in GUC descriptions more consistently
Message-ID: <Z6p8xOfmPUdo6QmI@nathan>
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On Tue, Feb 11, 2025 at 08:29:28AM +1100, Peter Smith wrote:
> +1 for this. Your wording examples below look good to me..

Okay, how does this look?

-- 
nathan

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	filename="v2-0001-Describe-special-values-in-GUC-descriptions-more-.patch"

From 25f62fa18e5e6ffd0fbd48e9f9bdd5474caaf23c Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nathan@postgresql.org>
Date: Fri, 7 Feb 2025 16:06:18 -0600
Subject: [PATCH v2 1/1] Describe special values in GUC descriptions more
 consistently.

---
 src/backend/utils/misc/guc_tables.c | 139 ++++++++++++++--------------
 1 file changed, 70 insertions(+), 69 deletions(-)

diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index ce7534d4d23..8dc8a912c19 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -2109,7 +2109,7 @@ struct config_int ConfigureNamesInt[] =
 		{"archive_timeout", PGC_SIGHUP, WAL_ARCHIVING,
 			gettext_noop("Sets the amount of time to wait before forcing a "
 						 "switch to the next WAL file."),
-			NULL,
+			gettext_noop("0 disables the timeout."),
 			GUC_UNIT_S
 		},
 		&XLogArchiveTimeout,
@@ -2186,7 +2186,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"geqo_pool_size", PGC_USERSET, QUERY_TUNING_GEQO,
 			gettext_noop("GEQO: number of individuals in the population."),
-			gettext_noop("Zero selects a suitable default value."),
+			gettext_noop("0 means use a suitable default value."),
 			GUC_EXPLAIN
 		},
 		&Geqo_pool_size,
@@ -2196,7 +2196,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"geqo_generations", PGC_USERSET, QUERY_TUNING_GEQO,
 			gettext_noop("GEQO: number of iterations of the algorithm."),
-			gettext_noop("Zero selects a suitable default value."),
+			gettext_noop("0 means use a suitable default value."),
 			GUC_EXPLAIN
 		},
 		&Geqo_generations,
@@ -2219,7 +2219,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"max_standby_archive_delay", PGC_SIGHUP, REPLICATION_STANDBY,
 			gettext_noop("Sets the maximum delay before canceling queries when a hot standby server is processing archived WAL data."),
-			NULL,
+			gettext_noop("-1 means wait forever."),
 			GUC_UNIT_MS
 		},
 		&max_standby_archive_delay,
@@ -2230,7 +2230,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"max_standby_streaming_delay", PGC_SIGHUP, REPLICATION_STANDBY,
 			gettext_noop("Sets the maximum delay before canceling queries when a hot standby server is processing streamed WAL data."),
-			NULL,
+			gettext_noop("-1 means wait forever."),
 			GUC_UNIT_MS
 		},
 		&max_standby_streaming_delay,
@@ -2263,7 +2263,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"wal_receiver_timeout", PGC_SIGHUP, REPLICATION_STANDBY,
 			gettext_noop("Sets the maximum wait time to receive data from the sending server."),
-			NULL,
+			gettext_noop("0 disables the timeout."),
 			GUC_UNIT_MS
 		},
 		&wal_receiver_timeout,
@@ -2354,7 +2354,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"shared_memory_size_in_huge_pages", PGC_INTERNAL, PRESET_OPTIONS,
 			gettext_noop("Shows the number of huge pages needed for the main shared memory area."),
-			gettext_noop("-1 indicates that the value could not be determined."),
+			gettext_noop("-1 means the value could not be determined."),
 			GUC_NOT_IN_SAMPLE | GUC_DISALLOW_IN_FILE | GUC_RUNTIME_COMPUTED
 		},
 		&shared_memory_size_in_huge_pages,
@@ -2376,7 +2376,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"commit_timestamp_buffers", PGC_POSTMASTER, RESOURCES_MEM,
 			gettext_noop("Sets the size of the dedicated buffer pool used for the commit timestamp cache."),
-			gettext_noop("Specify 0 to have this value determined as a fraction of \"shared_buffers\"."),
+			gettext_noop("0 means use a fraction of \"shared_buffers\"."),
 			GUC_UNIT_BLOCKS
 		},
 		&commit_timestamp_buffers,
@@ -2431,7 +2431,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"subtransaction_buffers", PGC_POSTMASTER, RESOURCES_MEM,
 			gettext_noop("Sets the size of the dedicated buffer pool used for the subtransaction cache."),
-			gettext_noop("Specify 0 to have this value determined as a fraction of \"shared_buffers\"."),
+			gettext_noop("0 means use a fraction of \"shared_buffers\"."),
 			GUC_UNIT_BLOCKS
 		},
 		&subtransaction_buffers,
@@ -2442,7 +2442,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"transaction_buffers", PGC_POSTMASTER, RESOURCES_MEM,
 			gettext_noop("Sets the size of the dedicated buffer pool used for the transaction status cache."),
-			gettext_noop("Specify 0 to have this value determined as a fraction of \"shared_buffers\"."),
+			gettext_noop("0 means use a fraction of \"shared_buffers\"."),
 			GUC_UNIT_BLOCKS
 		},
 		&transaction_buffers,
@@ -2626,7 +2626,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"autovacuum_vacuum_cost_limit", PGC_SIGHUP, VACUUM_AUTOVACUUM,
 			gettext_noop("Vacuum cost amount available before napping, for autovacuum."),
-			NULL
+			gettext_noop("-1 means use \"vacuum_cost_limit\".")
 		},
 		&autovacuum_vac_cost_limit,
 		-1, -1, 10000,
@@ -2682,7 +2682,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"statement_timeout", PGC_USERSET, CLIENT_CONN_STATEMENT,
 			gettext_noop("Sets the maximum allowed duration of any statement."),
-			gettext_noop("A value of 0 turns off the timeout."),
+			gettext_noop("0 disables the timeout."),
 			GUC_UNIT_MS
 		},
 		&StatementTimeout,
@@ -2693,7 +2693,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"lock_timeout", PGC_USERSET, CLIENT_CONN_STATEMENT,
 			gettext_noop("Sets the maximum allowed duration of any wait for a lock."),
-			gettext_noop("A value of 0 turns off the timeout."),
+			gettext_noop("0 disables the timeout."),
 			GUC_UNIT_MS
 		},
 		&LockTimeout,
@@ -2704,7 +2704,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"idle_in_transaction_session_timeout", PGC_USERSET, CLIENT_CONN_STATEMENT,
 			gettext_noop("Sets the maximum allowed idle time between queries, when in a transaction."),
-			gettext_noop("A value of 0 turns off the timeout."),
+			gettext_noop("0 disables the timeout."),
 			GUC_UNIT_MS
 		},
 		&IdleInTransactionSessionTimeout,
@@ -2715,7 +2715,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"transaction_timeout", PGC_USERSET, CLIENT_CONN_STATEMENT,
 			gettext_noop("Sets the maximum allowed duration of any transaction within a session (not a prepared transaction)."),
-			gettext_noop("A value of 0 turns off the timeout."),
+			gettext_noop("0 disables the timeout."),
 			GUC_UNIT_MS
 		},
 		&TransactionTimeout,
@@ -2726,7 +2726,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"idle_session_timeout", PGC_USERSET, CLIENT_CONN_STATEMENT,
 			gettext_noop("Sets the maximum allowed idle time between queries, when not in a transaction."),
-			gettext_noop("A value of 0 turns off the timeout."),
+			gettext_noop("0 disables the timeout."),
 			GUC_UNIT_MS
 		},
 		&IdleSessionTimeout,
@@ -2940,7 +2940,7 @@ struct config_int ConfigureNamesInt[] =
 			gettext_noop("Write a message to the server log if checkpoints "
 						 "caused by the filling of WAL segment files happen more "
 						 "frequently than this amount of time. "
-						 "Zero turns off the warning."),
+						 "0 disables the warning."),
 			GUC_UNIT_S
 		},
 		&CheckPointWarning,
@@ -2951,7 +2951,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"checkpoint_flush_after", PGC_SIGHUP, WAL_CHECKPOINTS,
 			gettext_noop("Number of pages after which previously performed writes are flushed to disk."),
-			NULL,
+			gettext_noop("0 disables forced writeback."),
 			GUC_UNIT_BLOCKS
 		},
 		&checkpoint_flush_after,
@@ -2962,7 +2962,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"wal_buffers", PGC_POSTMASTER, WAL_SETTINGS,
 			gettext_noop("Sets the number of disk-page buffers in shared memory for WAL."),
-			gettext_noop("Specify -1 to have this value determined as a fraction of \"shared_buffers\"."),
+			gettext_noop("-1 means use a fraction of \"shared_buffers\"."),
 			GUC_UNIT_XBLOCKS
 		},
 		&XLOGbuffers,
@@ -3029,7 +3029,8 @@ struct config_int ConfigureNamesInt[] =
 			gettext_noop("Sets the maximum WAL size that can be reserved by replication slots."),
 			gettext_noop("Replication slots will be marked as failed, and segments released "
 						 "for deletion or recycling, if this much space is occupied by WAL "
-						 "on disk."),
+						 "on disk. "
+						 "-1 means no maximum."),
 			GUC_UNIT_MB
 		},
 		&max_slot_wal_keep_size_mb,
@@ -3089,7 +3090,7 @@ struct config_int ConfigureNamesInt[] =
 			gettext_noop("Sets the minimum execution time above which "
 						 "a sample of statements will be logged."
 						 " Sampling is determined by \"log_statement_sample_rate\"."),
-			gettext_noop("Zero logs a sample of all queries. -1 turns this feature off."),
+			gettext_noop("-1 disables sampling. 0 means sample all statements."),
 			GUC_UNIT_MS
 		},
 		&log_min_duration_sample,
@@ -3101,7 +3102,7 @@ struct config_int ConfigureNamesInt[] =
 		{"log_min_duration_statement", PGC_SUSET, LOGGING_WHEN,
 			gettext_noop("Sets the minimum execution time above which "
 						 "all statements will be logged."),
-			gettext_noop("Zero prints all queries. -1 turns this feature off."),
+			gettext_noop("-1 disables logging statement durations. 0 means log all statement durations."),
 			GUC_UNIT_MS
 		},
 		&log_min_duration_statement,
@@ -3113,7 +3114,7 @@ struct config_int ConfigureNamesInt[] =
 		{"log_autovacuum_min_duration", PGC_SIGHUP, LOGGING_WHAT,
 			gettext_noop("Sets the minimum execution time above which "
 						 "autovacuum actions will be logged."),
-			gettext_noop("Zero prints all actions. -1 turns autovacuum logging off."),
+			gettext_noop("-1 disables logging autovacuum actions. 0 means log all autovacuum actions."),
 			GUC_UNIT_MS
 		},
 		&Log_autovacuum_min_duration,
@@ -3125,7 +3126,7 @@ struct config_int ConfigureNamesInt[] =
 		{"log_parameter_max_length", PGC_SUSET, LOGGING_WHAT,
 			gettext_noop("Sets the maximum length in bytes of data logged for bind "
 						 "parameter values when logging statements."),
-			gettext_noop("-1 to print values in full."),
+			gettext_noop("-1 means log values in full."),
 			GUC_UNIT_BYTE
 		},
 		&log_parameter_max_length,
@@ -3137,7 +3138,7 @@ struct config_int ConfigureNamesInt[] =
 		{"log_parameter_max_length_on_error", PGC_USERSET, LOGGING_WHAT,
 			gettext_noop("Sets the maximum length in bytes of data logged for bind "
 						 "parameter values when logging statements, on error."),
-			gettext_noop("-1 to print values in full."),
+			gettext_noop("-1 means log values in full."),
 			GUC_UNIT_BYTE
 		},
 		&log_parameter_max_length_on_error,
@@ -3159,7 +3160,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"bgwriter_lru_maxpages", PGC_SIGHUP, RESOURCES_BGWRITER,
 			gettext_noop("Background writer maximum number of LRU pages to flush per round."),
-			NULL
+			gettext_noop("0 disables background writing.")
 		},
 		&bgwriter_lru_maxpages,
 		100, 0, INT_MAX / 2,	/* Same upper limit as shared_buffers */
@@ -3169,7 +3170,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"bgwriter_flush_after", PGC_SIGHUP, RESOURCES_BGWRITER,
 			gettext_noop("Number of pages after which previously performed writes are flushed to disk."),
-			NULL,
+			gettext_noop("0 disables forced writeback."),
 			GUC_UNIT_BLOCKS
 		},
 		&bgwriter_flush_after,
@@ -3182,7 +3183,7 @@ struct config_int ConfigureNamesInt[] =
 			PGC_USERSET,
 			RESOURCES_ASYNCHRONOUS,
 			gettext_noop("Number of simultaneous requests that can be handled efficiently by the disk subsystem."),
-			NULL,
+			gettext_noop("0 disables simultaneous requests."),
 			GUC_EXPLAIN
 		},
 		&effective_io_concurrency,
@@ -3196,7 +3197,7 @@ struct config_int ConfigureNamesInt[] =
 			PGC_USERSET,
 			RESOURCES_ASYNCHRONOUS,
 			gettext_noop("A variant of \"effective_io_concurrency\" that is used for maintenance work."),
-			NULL,
+			gettext_noop("0 disables simultaneous requests."),
 			GUC_EXPLAIN
 		},
 		&maintenance_io_concurrency,
@@ -3223,7 +3224,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"backend_flush_after", PGC_USERSET, RESOURCES_ASYNCHRONOUS,
 			gettext_noop("Number of pages after which previously performed writes are flushed to disk."),
-			NULL,
+			gettext_noop("0 disables forced writeback."),
 			GUC_UNIT_BLOCKS
 		},
 		&backend_flush_after,
@@ -3283,7 +3284,7 @@ struct config_int ConfigureNamesInt[] =
 		{"log_rotation_age", PGC_SIGHUP, LOGGING_WHERE,
 			gettext_noop("Sets the amount of time to wait before forcing "
 						 "log file rotation."),
-			NULL,
+			gettext_noop("0 disables time-based creation of new log files."),
 			GUC_UNIT_MIN
 		},
 		&Log_RotationAge,
@@ -3295,7 +3296,7 @@ struct config_int ConfigureNamesInt[] =
 		{"log_rotation_size", PGC_SIGHUP, LOGGING_WHERE,
 			gettext_noop("Sets the maximum size a log file can reach before "
 						 "being rotated."),
-			NULL,
+			gettext_noop("0 disables size-based creation of new log files."),
 			GUC_UNIT_KB
 		},
 		&Log_RotationSize,
@@ -3397,7 +3398,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"wal_summary_keep_time", PGC_SIGHUP, WAL_SUMMARIZATION,
 			gettext_noop("Time for which WAL summary files should be kept."),
-			NULL,
+			gettext_noop("0 disables automatic summary file deletion."),
 			GUC_UNIT_MIN,
 		},
 		&wal_summary_keep_time,
@@ -3428,8 +3429,8 @@ struct config_int ConfigureNamesInt[] =
 	},
 	{
 		{"autovacuum_vacuum_max_threshold", PGC_SIGHUP, VACUUM_AUTOVACUUM,
-			gettext_noop("Maximum number of tuple updates or deletes prior to vacuum, or -1 to disable maximum threshold."),
-			NULL
+			gettext_noop("Maximum number of tuple updates or deletes prior to vacuum."),
+			gettext_noop("-1 disables the maximum threshold.")
 		},
 		&autovacuum_vac_max_thresh,
 		100000000, -1, INT_MAX,
@@ -3437,8 +3438,8 @@ struct config_int ConfigureNamesInt[] =
 	},
 	{
 		{"autovacuum_vacuum_insert_threshold", PGC_SIGHUP, VACUUM_AUTOVACUUM,
-			gettext_noop("Minimum number of tuple inserts prior to vacuum, or -1 to disable insert vacuums."),
-			NULL
+			gettext_noop("Minimum number of tuple inserts prior to vacuum."),
+			gettext_noop("-1 disables insert vacuums.")
 		},
 		&autovacuum_vac_ins_thresh,
 		1000, -1, INT_MAX,
@@ -3530,7 +3531,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"autovacuum_work_mem", PGC_SIGHUP, RESOURCES_MEM,
 			gettext_noop("Sets the maximum memory to be used by each autovacuum worker process."),
-			NULL,
+			gettext_noop("-1 means use \"maintenance_work_mem\"."),
 			GUC_UNIT_KB
 		},
 		&autovacuum_work_mem,
@@ -3541,7 +3542,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"tcp_keepalives_idle", PGC_USERSET, CONN_AUTH_TCP,
 			gettext_noop("Time between issuing TCP keepalives."),
-			gettext_noop("A value of 0 uses the system default."),
+			gettext_noop("0 means use the system default."),
 			GUC_UNIT_S
 		},
 		&tcp_keepalives_idle,
@@ -3552,7 +3553,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"tcp_keepalives_interval", PGC_USERSET, CONN_AUTH_TCP,
 			gettext_noop("Time between TCP keepalive retransmits."),
-			gettext_noop("A value of 0 uses the system default."),
+			gettext_noop("0 means use the system default."),
 			GUC_UNIT_S
 		},
 		&tcp_keepalives_interval,
@@ -3575,8 +3576,8 @@ struct config_int ConfigureNamesInt[] =
 		{"tcp_keepalives_count", PGC_USERSET, CONN_AUTH_TCP,
 			gettext_noop("Maximum number of TCP keepalive retransmits."),
 			gettext_noop("Number of consecutive keepalive retransmits that can be "
-						 "lost before a connection is considered dead. A value of 0 uses the "
-						 "system default."),
+						 "lost before a connection is considered dead. "
+						 "0 means use the system default."),
 		},
 		&tcp_keepalives_count,
 		0, 0, INT_MAX,
@@ -3586,8 +3587,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"gin_fuzzy_search_limit", PGC_USERSET, CLIENT_CONN_OTHER,
 			gettext_noop("Sets the maximum allowed result for exact search by GIN."),
-			NULL,
-			0
+			gettext_noop("0 means no limit."),
 		},
 		&GinFuzzySearchLimit,
 		0, 0, INT_MAX,
@@ -3643,7 +3643,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"log_temp_files", PGC_SUSET, LOGGING_WHAT,
 			gettext_noop("Log the use of temporary files larger than this number of kilobytes."),
-			gettext_noop("Zero logs all files. The default is -1 (turning this feature off)."),
+			gettext_noop("-1 disables temporary file logs. 0 means log all files."),
 			GUC_UNIT_KB
 		},
 		&log_temp_files,
@@ -3676,7 +3676,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"tcp_user_timeout", PGC_USERSET, CONN_AUTH_TCP,
 			gettext_noop("TCP user timeout."),
-			gettext_noop("A value of 0 uses the system default."),
+			gettext_noop("0 means use the system default."),
 			GUC_UNIT_MS
 		},
 		&tcp_user_timeout,
@@ -3687,7 +3687,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"huge_page_size", PGC_POSTMASTER, RESOURCES_MEM,
 			gettext_noop("The size of huge page that should be requested."),
-			NULL,
+			gettext_noop("0 means use the system default."),
 			GUC_UNIT_KB
 		},
 		&huge_page_size,
@@ -3698,7 +3698,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"debug_discard_caches", PGC_SUSET, DEVELOPER_OPTIONS,
 			gettext_noop("Aggressively flush system caches for debugging purposes."),
-			NULL,
+			gettext_noop("0 means use normal caching behavior."),
 			GUC_NOT_IN_SAMPLE
 		},
 		&debug_discard_caches,
@@ -3721,7 +3721,7 @@ struct config_int ConfigureNamesInt[] =
 	{
 		{"client_connection_check_interval", PGC_USERSET, CONN_AUTH_TCP,
 			gettext_noop("Sets the time interval between checks for disconnection while running queries."),
-			NULL,
+			gettext_noop("0 disables connection checks."),
 			GUC_UNIT_MS
 		},
 		&client_connection_check_interval,
@@ -3733,7 +3733,7 @@ struct config_int ConfigureNamesInt[] =
 		{"log_startup_progress_interval", PGC_SIGHUP, LOGGING_WHEN,
 			gettext_noop("Time between progress updates for "
 						 "long-running startup operations."),
-			gettext_noop("0 turns this feature off."),
+			gettext_noop("0 disables progress updates."),
 			GUC_UNIT_MS,
 		},
 		&log_startup_progress_interval,
@@ -3964,7 +3964,7 @@ struct config_real ConfigureNamesReal[] =
 	{
 		{"autovacuum_vacuum_cost_delay", PGC_SIGHUP, VACUUM_AUTOVACUUM,
 			gettext_noop("Vacuum cost delay in milliseconds, for autovacuum."),
-			NULL,
+			gettext_noop("-1 means use \"vacuum_cost_delay\"."),
 			GUC_UNIT_MS
 		},
 		&autovacuum_vac_cost_delay,
@@ -4055,7 +4055,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"archive_library", PGC_SIGHUP, WAL_ARCHIVING,
 			gettext_noop("Sets the library that will be called to archive a WAL file."),
-			gettext_noop("An empty string indicates that \"archive_command\" should be used.")
+			gettext_noop("An empty string means \"archive_command\" should be used.")
 		},
 		&XLogArchiveLibrary,
 		"",
@@ -4183,7 +4183,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"log_line_prefix", PGC_SIGHUP, LOGGING_WHAT,
 			gettext_noop("Controls information prefixed to each log line."),
-			gettext_noop("If blank, no prefix is used.")
+			gettext_noop("An empty string means no prefix.")
 		},
 		&Log_line_prefix,
 		"%m [%p] ",
@@ -4226,7 +4226,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"default_tablespace", PGC_USERSET, CLIENT_CONN_STATEMENT,
 			gettext_noop("Sets the default tablespace to create tables and indexes in."),
-			gettext_noop("An empty string selects the database's default tablespace."),
+			gettext_noop("An empty string means use the database's default tablespace."),
 			GUC_IS_NAME
 		},
 		&default_tablespace,
@@ -4237,7 +4237,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"temp_tablespaces", PGC_USERSET, CLIENT_CONN_STATEMENT,
 			gettext_noop("Sets the tablespace(s) to use for temporary tables and sort files."),
-			NULL,
+			gettext_noop("An empty string means use the database's default tablespace."),
 			GUC_LIST_INPUT | GUC_LIST_QUOTE
 		},
 		&temp_tablespaces,
@@ -4249,7 +4249,7 @@ struct config_string ConfigureNamesString[] =
 		{"createrole_self_grant", PGC_USERSET, CLIENT_CONN_STATEMENT,
 			gettext_noop("Sets whether a CREATEROLE user automatically grants "
 						 "the role to themselves, and with which options."),
-			NULL,
+			gettext_noop("An empty string disables automatic self grants."),
 			GUC_LIST_INPUT
 		},
 		&createrole_self_grant,
@@ -4285,7 +4285,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"bonjour_name", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
 			gettext_noop("Sets the Bonjour service name."),
-			NULL
+			gettext_noop("An empty string means use the computer name.")
 		},
 		&bonjour_name,
 		"",
@@ -4295,7 +4295,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"lc_messages", PGC_SUSET, CLIENT_CONN_LOCALE,
 			gettext_noop("Sets the language in which messages are displayed."),
-			NULL
+			gettext_noop("An empty string means use the system setting.")
 		},
 		&locale_messages,
 		"",
@@ -4305,7 +4305,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"lc_monetary", PGC_USERSET, CLIENT_CONN_LOCALE,
 			gettext_noop("Sets the locale for formatting monetary amounts."),
-			NULL
+			gettext_noop("An empty string means use the system setting.")
 		},
 		&locale_monetary,
 		"C",
@@ -4315,7 +4315,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"lc_numeric", PGC_USERSET, CLIENT_CONN_LOCALE,
 			gettext_noop("Sets the locale for formatting numbers."),
-			NULL
+			gettext_noop("An empty string means use the system setting.")
 		},
 		&locale_numeric,
 		"C",
@@ -4325,7 +4325,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"lc_time", PGC_USERSET, CLIENT_CONN_LOCALE,
 			gettext_noop("Sets the locale for formatting date and time values."),
-			NULL
+			gettext_noop("An empty string means use the system setting.")
 		},
 		&locale_time,
 		"C",
@@ -4504,7 +4504,8 @@ struct config_string ConfigureNamesString[] =
 		{"unix_socket_group", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
 			gettext_noop("Sets the owning group of the Unix-domain socket."),
 			gettext_noop("The owning user of the socket is always the user "
-						 "that starts the server.")
+						 "that starts the server. "
+						 "An empty string means use the user's default group.")
 		},
 		&Unix_socket_group,
 		"",
@@ -4630,7 +4631,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"ssl_ca_file", PGC_SIGHUP, CONN_AUTH_SSL,
 			gettext_noop("Location of the SSL certificate authority file."),
-			NULL
+			gettext_noop("An empty string disables client certificate validation.")
 		},
 		&ssl_ca_file,
 		"",
@@ -4640,7 +4641,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"ssl_crl_file", PGC_SIGHUP, CONN_AUTH_SSL,
 			gettext_noop("Location of the SSL certificate revocation list file."),
-			NULL
+			gettext_noop("An empty string means don't load CRL file unless \"ssl_crl_dir\" is set.")
 		},
 		&ssl_crl_file,
 		"",
@@ -4650,7 +4651,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"ssl_crl_dir", PGC_SIGHUP, CONN_AUTH_SSL,
 			gettext_noop("Location of the SSL certificate revocation list directory."),
-			NULL
+			gettext_noop("An empty string means don't use CRLs unless \"ssl_crl_file\" is set.")
 		},
 		&ssl_crl_dir,
 		"",
@@ -4681,7 +4682,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"ssl_tls13_ciphers", PGC_SIGHUP, CONN_AUTH_SSL,
 			gettext_noop("Sets the list of allowed TLSv1.3 cipher suites (leave blank for default)."),
-			NULL,
+			gettext_noop("An empty string means use the default cipher suites."),
 			GUC_SUPERUSER_ONLY
 		},
 		&SSLCipherSuites,
@@ -4722,7 +4723,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"ssl_dh_params_file", PGC_SIGHUP, CONN_AUTH_SSL,
 			gettext_noop("Location of the SSL DH parameters file."),
-			NULL,
+			gettext_noop("An empty string means use compiled-in default parameters."),
 			GUC_SUPERUSER_ONLY
 		},
 		&ssl_dh_params_file,
@@ -4733,7 +4734,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"ssl_passphrase_command", PGC_SIGHUP, CONN_AUTH_SSL,
 			gettext_noop("Command to obtain passphrases for SSL."),
-			NULL,
+			gettext_noop("An empty string means use the built-in prompting mechanism."),
 			GUC_SUPERUSER_ONLY
 		},
 		&ssl_passphrase_command,
@@ -4799,7 +4800,7 @@ struct config_string ConfigureNamesString[] =
 	{
 		{"debug_io_direct", PGC_POSTMASTER, DEVELOPER_OPTIONS,
 			gettext_noop("Use direct I/O for file access."),
-			NULL,
+			gettext_noop("An empty string disables direct I/O."),
 			GUC_LIST_INPUT | GUC_NOT_IN_SAMPLE
 		},
 		&debug_io_direct_string,
-- 
2.39.5 (Apple Git-154)


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