Clean up some inconsistencies with GUC declarations

This is similar to 7d25958, and this commit takes care of all the
remaining inconsistencies between the initial value used in the C
variable associated to a GUC and its default value stored in the GUC
tables (as of pg_settings.boot_val).

Some of the initial values of the GUCs updated rely on a compile-time
default.  These are refactored so as the GUC table and its C declaration
use the same values.  This makes everything consistent with other
places, backend_flush_after, bgwriter_flush_after, port,
checkpoint_flush_after doing so already, for example.

Extracted from a larger patch by Peter Smith.  The spots updated in the
modules are from me.

Author: Peter Smith, Michael Paquier
Reviewed-by: Nathan Bossart, Tom Lane, Justin Pryzby
Discussion: https://postgr.es/m/CAHut+PtHE0XSfjjRQ6D4v7+dqzCw=d+1a64ujra4EX8aoc_Z+w@mail.gmail.com

Author: michaelpq

contrib/auth_delay/auth_delay.c

@@ -21,7 +21,7 @@
 PG_MODULE_MAGIC;
 
 /* GUC Variables */
-static int	auth_delay_milliseconds;
+static int	auth_delay_milliseconds = 0;
 
 /* Original Hook */
 static ClientAuthentication_hook_type original_client_auth_hook = NULL;

contrib/pg_prewarm/autoprewarm.c

@@ -103,7 +103,7 @@ static AutoPrewarmSharedState *apw_state = NULL;
 
 /* GUC variables. */
 static bool autoprewarm = true; /* start worker? */
-static int	autoprewarm_interval;	/* dump interval */
+static int	autoprewarm_interval = 300; /* dump interval */
 
 /*
  * Module load callback.

contrib/pg_stat_statements/pg_stat_statements.c

@@ -283,11 +283,12 @@ static const struct config_enum_entry track_options[] =
 	{NULL, 0, false}
 };
 
-static int	pgss_max;			/* max # statements to track */
-static int	pgss_track;			/* tracking level */
-static bool pgss_track_utility; /* whether to track utility commands */
-static bool pgss_track_planning;	/* whether to track planning duration */
-static bool pgss_save;			/* whether to save stats across shutdown */
+static int	pgss_max = 5000;	/* max # statements to track */
+static int	pgss_track = PGSS_TRACK_TOP;	/* tracking level */
+static bool pgss_track_utility = true;	/* whether to track utility commands */
+static bool pgss_track_planning = false;	/* whether to track planning
+											 * duration */
+static bool pgss_save = true;	/* whether to save stats across shutdown */
 
 
 #define pgss_enabled(level) \

contrib/pg_trgm/trgm_op.c

@@ -68,7 +68,7 @@ _PG_init(void)
 							 "Sets the threshold used by the % operator.",
 							 "Valid range is 0.0 .. 1.0.",
 							 &similarity_threshold,
-							 0.3,
+							 0.3f,
 							 0.0,
 							 1.0,
 							 PGC_USERSET,
@@ -80,7 +80,7 @@ _PG_init(void)
 							 "Sets the threshold used by the <% operator.",
 							 "Valid range is 0.0 .. 1.0.",
 							 &word_similarity_threshold,
-							 0.6,
+							 0.6f,
 							 0.0,
 							 1.0,
 							 PGC_USERSET,
@@ -92,7 +92,7 @@ _PG_init(void)
 							 "Sets the threshold used by the <<% operator.",
 							 "Valid range is 0.0 .. 1.0.",
 							 &strict_word_similarity_threshold,
-							 0.5,
+							 0.5f,
 							 0.0,
 							 1.0,
 							 PGC_USERSET,

contrib/sepgsql/hooks.c

@@ -57,7 +57,7 @@ static sepgsql_context_info_t sepgsql_context_info;
 /*
  * GUC: sepgsql.permissive = (on|off)
  */
-static bool sepgsql_permissive;
+static bool sepgsql_permissive = false;
 
 bool
 sepgsql_get_permissive(void)
@@ -68,7 +68,7 @@ sepgsql_get_permissive(void)
 /*
  * GUC: sepgsql.debug_audit = (on|off)
  */
-static bool sepgsql_debug_audit;
+static bool sepgsql_debug_audit = false;
 
 bool
 sepgsql_get_debug_audit(void)

src/backend/access/transam/xact.c

@@ -75,7 +75,7 @@
  *	User-tweakable parameters
  */
 int			DefaultXactIsoLevel = XACT_READ_COMMITTED;
-int			XactIsoLevel;
+int			XactIsoLevel = XACT_READ_COMMITTED;
 
 bool		DefaultXactReadOnly = false;
 bool		XactReadOnly;

src/backend/access/transam/xlog.c

@@ -131,7 +131,7 @@ bool		wal_init_zero = true;
 bool		wal_recycle = true;
 bool		log_checkpoints = true;
 int			sync_method = DEFAULT_SYNC_METHOD;
-int			wal_level = WAL_LEVEL_MINIMAL;
+int			wal_level = WAL_LEVEL_REPLICA;
 int			CommitDelay = 0;	/* precommit delay in microseconds */
 int			CommitSiblings = 5; /* # concurrent xacts needed to sleep */
 int			wal_retrieve_retry_interval = 5000;

src/backend/libpq/be-secure.c

@@ -58,8 +58,8 @@ char	   *SSLECDHCurve;
 /* GUC variable: if false, prefer client ciphers */
 bool		SSLPreferServerCiphers;
 
-int			ssl_min_protocol_version;
-int			ssl_max_protocol_version;
+int			ssl_min_protocol_version = PG_TLS1_2_VERSION;
+int			ssl_max_protocol_version = PG_TLS_ANY;
 
 /* ------------------------------------------------------------ */
 /*			 Procedures common to all secure sessions			*/

src/backend/postmaster/postmaster.c

@@ -196,7 +196,7 @@ BackgroundWorker *MyBgworkerEntry = NULL;
 
 
 /* The socket number we are listening for connections on */
-int			PostPortNumber;
+int			PostPortNumber = DEF_PGPORT;
 
 /* The directory names for Unix socket(s) */
 char	   *Unix_socket_directories;

src/backend/storage/buffer/bufmgr.c

@@ -142,22 +142,22 @@ bool		track_io_timing = false;
  * for buffers not belonging to tablespaces that have their
  * effective_io_concurrency parameter set.
  */
-int			effective_io_concurrency = 0;
+int			effective_io_concurrency = DEFAULT_EFFECTIVE_IO_CONCURRENCY;
 
 /*
  * Like effective_io_concurrency, but used by maintenance code paths that might
  * benefit from a higher setting because they work on behalf of many sessions.
  * Overridden by the tablespace setting of the same name.
  */
-int			maintenance_io_concurrency = 0;
+int			maintenance_io_concurrency = DEFAULT_MAINTENANCE_IO_CONCURRENCY;
 
 /*
  * GUC variables about triggering kernel writeback for buffers written; OS
  * dependent defaults are set via the GUC mechanism.
  */
-int			checkpoint_flush_after = 0;
-int			bgwriter_flush_after = 0;
-int			backend_flush_after = 0;
+int			checkpoint_flush_after = DEFAULT_CHECKPOINT_FLUSH_AFTER;
+int			bgwriter_flush_after = DEFAULT_BGWRITER_FLUSH_AFTER;
+int			backend_flush_after = DEFAULT_BACKEND_FLUSH_AFTER;
 
 /* local state for StartBufferIO and related functions */
 static BufferDesc *InProgressBuf = NULL;