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Be more careful about GucSource for internally-driven GUC settings.

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The original advice for hard-wired SetConfigOption calls was to use
PGC_S_OVERRIDE, particularly for PGC_INTERNAL GUCs.  However,
that's really overkill for PGC_INTERNAL GUCs, since there is no
possibility that we need to override a user-provided setting.
Instead use PGC_S_DYNAMIC_DEFAULT in most places, so that the
value will appear with source = 'default' in pg_settings and thereby
not be shown by psql's new \dconfig command.  The one exception is
that when changing in_hot_standby in a hot-standby session, we still
use PGC_S_OVERRIDE, because people felt that seeing that in \dconfig
would be a good thing.

Similarly use PGC_S_DYNAMIC_DEFAULT for the auto-tune value of
wal_buffers (if possible, that is if wal_buffers wasn't explicitly
set to -1), and for the typical 2MB value of max_stack_depth.

In combination these changes remove four not-very-interesting
entries from the typical output of \dconfig, all of which people
fingered as "why is that showing up?" in the discussion thread.

Discussion: https://postgr.es/m/3118455.1649267333@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2022-06-08 13:26:18 -04:00
parent abed46aea4
commit 7ab5b4eb48
9 changed files with 52 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
src/backend/access/transam/xlog.c
View File

@ -4167,7 +4167,7 @@ ReadControlFile(void)
snprintf(wal_segsz_str, sizeof(wal_segsz_str), "%d", wal_segment_size);
SetConfigOption("wal_segment_size", wal_segsz_str, PGC_INTERNAL,
PGC_S_OVERRIDE);
PGC_S_DYNAMIC_DEFAULT);
/* check and update variables dependent on wal_segment_size */
if (ConvertToXSegs(min_wal_size_mb, wal_segment_size) < 2)
@ -4186,7 +4186,7 @@ ReadControlFile(void)
/* Make the initdb settings visible as GUC variables, too */
SetConfigOption("data_checksums", DataChecksumsEnabled() ? "yes" : "no",
PGC_INTERNAL, PGC_S_OVERRIDE);
PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT);
}
/*
@ -4343,13 +4343,22 @@ XLOGShmemSize(void)
* This isn't an amazingly clean place to do this, but we must wait till
* NBuffers has received its final value, and must do it before using the
* value of XLOGbuffers to do anything important.
*
* We prefer to report this value's source as PGC_S_DYNAMIC_DEFAULT.
* However, if the DBA explicitly set wal_buffers = -1 in the config file,
* then PGC_S_DYNAMIC_DEFAULT will fail to override that and we must force
* the matter with PGC_S_OVERRIDE.
*/
if (XLOGbuffers == -1)
{
char buf[32];
snprintf(buf, sizeof(buf), "%d", XLOGChooseNumBuffers());
SetConfigOption("wal_buffers", buf, PGC_POSTMASTER, PGC_S_OVERRIDE);
SetConfigOption("wal_buffers", buf, PGC_POSTMASTER,
PGC_S_DYNAMIC_DEFAULT);
if (XLOGbuffers == -1) /* failed to apply it? */
SetConfigOption("wal_buffers", buf, PGC_POSTMASTER,
PGC_S_OVERRIDE);
}
Assert(XLOGbuffers > 0);

2
src/backend/bootstrap/bootstrap.c
View File

@ -262,7 +262,7 @@ BootstrapModeMain(int argc, char *argv[], bool check_only)
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("-X requires a power of two value between 1 MB and 1 GB")));
SetConfigOption("wal_segment_size", optarg, PGC_INTERNAL,
PGC_S_OVERRIDE);
PGC_S_DYNAMIC_DEFAULT);
}
break;
case 'c':

2
src/backend/postmaster/postmaster.c
View File

@ -921,7 +921,7 @@ PostmasterMain(int argc, char *argv[])
* useful to show, even if one would only expect at least PANIC. LOG
* entries are hidden.
*/
SetConfigOption("log_min_messages", "FATAL", PGC_INTERNAL,
SetConfigOption("log_min_messages", "FATAL", PGC_SUSET,
PGC_S_OVERRIDE);
}

6
src/backend/storage/ipc/ipci.c
View File

@ -334,7 +334,8 @@ InitializeShmemGUCs(void)
size_b = CalculateShmemSize(NULL);
size_mb = add_size(size_b, (1024 * 1024) - 1) / (1024 * 1024);
sprintf(buf, "%zu", size_mb);
SetConfigOption("shared_memory_size", buf, PGC_INTERNAL, PGC_S_OVERRIDE);
SetConfigOption("shared_memory_size", buf,
PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT);
/*
* Calculate the number of huge pages required.
@ -346,6 +347,7 @@ InitializeShmemGUCs(void)
hp_required = add_size(size_b / hp_size, 1);
sprintf(buf, "%zu", hp_required);
SetConfigOption("shared_memory_size_in_huge_pages", buf, PGC_INTERNAL, PGC_S_OVERRIDE);
SetConfigOption("shared_memory_size_in_huge_pages", buf,
PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT);
}
}

6
src/backend/utils/init/miscinit.c
View File

@ -787,7 +787,7 @@ InitializeSessionUserId(const char *rolename, Oid roleid)
PGC_BACKEND, PGC_S_OVERRIDE);
SetConfigOption("is_superuser",
AuthenticatedUserIsSuperuser ? "on" : "off",
PGC_INTERNAL, PGC_S_OVERRIDE);
PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT);
ReleaseSysCache(roleTup);
}
@ -844,7 +844,7 @@ SetSessionAuthorization(Oid userid, bool is_superuser)
SetConfigOption("is_superuser",
is_superuser ? "on" : "off",
PGC_INTERNAL, PGC_S_OVERRIDE);
PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT);
}
/*
@ -901,7 +901,7 @@ SetCurrentRoleId(Oid roleid, bool is_superuser)
SetConfigOption("is_superuser",
is_superuser ? "on" : "off",
PGC_INTERNAL, PGC_S_OVERRIDE);
PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT);
}

6
src/backend/utils/init/postinit.c
View File

@ -391,7 +391,7 @@ CheckMyDatabase(const char *name, bool am_superuser, bool override_allow_connect
SetDatabaseEncoding(dbform->encoding);
/* Record it as a GUC internal option, too */
SetConfigOption("server_encoding", GetDatabaseEncodingName(),
PGC_INTERNAL, PGC_S_OVERRIDE);
PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT);
/* If we have no other source of client_encoding, use server encoding */
SetConfigOption("client_encoding", GetDatabaseEncodingName(),
PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
@ -470,8 +470,8 @@ CheckMyDatabase(const char *name, bool am_superuser, bool override_allow_connect
}
/* Make the locale settings visible as GUC variables, too */
SetConfigOption("lc_collate", collate, PGC_INTERNAL, PGC_S_OVERRIDE);
SetConfigOption("lc_ctype", ctype, PGC_INTERNAL, PGC_S_OVERRIDE);
SetConfigOption("lc_collate", collate, PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT);
SetConfigOption("lc_ctype", ctype, PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT);
check_strxfrm_bug();

5
src/backend/utils/misc/guc-file.l
View File

@ -401,9 +401,8 @@ ProcessConfigFileInternal(GucContext context, bool applySettings, int elevel)
* be run only after initialization is complete.
*
* XXX this is an unmaintainable crock, because we have to know how to set
* (or at least what to call to set) every variable that could potentially
* have PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR source. However, there's no
* time to redesign it for 9.1.
* (or at least what to call to set) every non-PGC_INTERNAL variable that
* could potentially have PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR source.
*/
if (context == PGC_SIGHUP && applySettings)
{

34
src/backend/utils/misc/guc.c
View File

@ -5939,6 +5939,8 @@ InitializeGUCOptionsFromEnvironment(void)
* rlimit isn't exactly an "environment variable", but it behaves about
* the same. If we can identify the platform stack depth rlimit, increase
* default stack depth setting up to whatever is safe (but at most 2MB).
* Report the value's source as PGC_S_DYNAMIC_DEFAULT if it's 2MB, or as
* PGC_S_ENV_VAR if it's reflecting the rlimit limit.
*/
stack_rlimit = get_stack_depth_rlimit();
if (stack_rlimit > 0)
@ -5947,12 +5949,19 @@ InitializeGUCOptionsFromEnvironment(void)
if (new_limit > 100)
{
GucSource source;
char limbuf[16];
new_limit = Min(new_limit, 2048);
sprintf(limbuf, "%ld", new_limit);
if (new_limit < 2048)
source = PGC_S_ENV_VAR;
else
{
new_limit = 2048;
source = PGC_S_DYNAMIC_DEFAULT;
}
snprintf(limbuf, sizeof(limbuf), "%ld", new_limit);
SetConfigOption("max_stack_depth", limbuf,
PGC_POSTMASTER, PGC_S_ENV_VAR);
PGC_POSTMASTER, source);
}
}
}
@ -6776,12 +6785,16 @@ BeginReportingGUCOptions(void)
reporting_enabled = true;
/*
* Hack for in_hot_standby: initialize with the value we're about to send.
* Hack for in_hot_standby: set the GUC value true if appropriate. This
* is kind of an ugly place to do it, but there's few better options.
*
* (This could be out of date by the time we actually send it, in which
* case the next ReportChangedGUCOptions call will send a duplicate
* report.)
*/
in_hot_standby = RecoveryInProgress();
if (RecoveryInProgress())
SetConfigOption("in_hot_standby", "true",
PGC_INTERNAL, PGC_S_OVERRIDE);
/* Transmit initial values of interesting variables */
for (i = 0; i < num_guc_variables; i++)
@ -6822,15 +6835,8 @@ ReportChangedGUCOptions(void)
* transition from false to true.
*/
if (in_hot_standby && !RecoveryInProgress())
{
struct config_generic *record;
record = find_option("in_hot_standby", false, false, ERROR);
Assert(record != NULL);
record->status |= GUC_NEEDS_REPORT;
report_needed = true;
in_hot_standby = false;
}
SetConfigOption("in_hot_standby", "false",
PGC_INTERNAL, PGC_S_OVERRIDE);
/* Quick exit if no values have been changed */
if (!report_needed)

8
src/include/utils/guc.h
View File

@ -83,8 +83,7 @@ typedef enum
* override the postmaster command line.) Tracking the source allows us
* to process sources in any convenient order without affecting results.
* Sources <= PGC_S_OVERRIDE will set the default used by RESET, as well
* as the current value. Note that source == PGC_S_OVERRIDE should be
* used when setting a PGC_INTERNAL option.
* as the current value.
*
* PGC_S_INTERACTIVE isn't actually a source value, but is the
* dividing line between "interactive" and "non-interactive" sources for
@ -99,6 +98,11 @@ typedef enum
* shouldn't throw hard errors in this case, at most NOTICEs, since the
* objects might exist by the time the setting is used for real.
*
* When setting the value of a non-compile-time-constant PGC_INTERNAL option,
* source == PGC_S_DYNAMIC_DEFAULT should typically be used so that the value
* will show as "default" in pg_settings. If there is a specific reason not
* to want that, use source == PGC_S_OVERRIDE.
*
* NB: see GucSource_Names in guc.c if you change this.
*/
typedef enum