Tweak docs for log_statement_sample_rate

Author: Justin Pryzby, partly after a suggestion from Masahiko Sawada
Discussion: https://postgr.es/m/20190328135918[email protected]
Discussion: https://postgr.es/m/CAD21AoB9+y8N4+Fan-ne-_7J5yTybPttxeVKfwUocKp4zT1vNQ@mail.gmail.com

diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index 915296310ce30aed6f5b5dd146b33d806004f370..4cbcc7a8e516579c5a40a8e3aa4d98c0cabe9ef7 100644 (file)
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -5821,11 +5821,12 @@ local0.*    /var/log/postgresql
          Causes the duration of each completed statement to be logged
          if the statement ran for at least the specified number of
          milliseconds, modulated by log_statement_sample_rate.
-         Setting this to zero prints all statement durations. Minus-one (the default)
-         disables logging statement durations. For example, if you set it to
-         250ms then all SQL statements that run 250ms or longer
-         will be logged. Enabling this parameter can be helpful in tracking down
-         unoptimized queries in your applications.
+         Setting this to zero prints all statement durations.
+         -1 (the default) disables logging statements due to
+         exceeding duration threshold; for example, if you set it to
+         250ms, then all SQL statements that run 250ms or
+         longer will be logged. Enabling this parameter can be helpful in
+         tracking down unoptimized queries in your applications.
          Only superusers can change this setting.
         
 
@@ -5859,14 +5860,15 @@ local0.*    /var/log/postgresql
       
        
         
-         Determines the fraction of the statements that exceed
-          which to log.
-         The default is 1, meaning log to all such
+         Determines the fraction of statements that exceed
+          to be logged.
+         The default is 1, meaning log all such
          statements.
-         Setting this to zero disables logging, same as setting
-         log_min_duration_statement
-         to minus-one. log_statement_sample_rate
-         is helpful when the traffic is too high to log all queries.
+         Setting this to zero disables logging by duration, same as setting
+         log_min_duration_statement to
+         -1.
+         log_statement_sample_rate is helpful when the
+         traffic is too high to log all queries.
         
        
       
@@ -6144,7 +6146,7 @@ local0.*    /var/log/postgresql
 
        
         
-         The difference between setting this option and setting
+         The difference between enabling log_duration and setting
           to zero is that
          exceeding log_min_duration_statement forces the text of
          the query to be logged, but this option doesn't.  Thus, if

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 83a9fc2b4c6968ae3955a38ec766874f89e7292d..0806a340f8d60d5a451519c79ca515db9e8dab5d 100644 (file)
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -3378,8 +3378,8 @@ static struct config_real ConfigureNamesReal[] =
 
    {
        {"log_statement_sample_rate", PGC_SUSET, LOGGING_WHEN,
-           gettext_noop("Fraction of statements over log_min_duration_statement to log."),
-           gettext_noop("If you only want a sample, use a value between 0 (never "
+           gettext_noop("Fraction of statements exceeding log_min_duration_statement to be logged."),
+           gettext_noop("If you only want a sample, use a value between 0.0 (never "
                         "log) and 1.0 (always log).")
        },
        &log_statement_sample_rate,

diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index f31d419f79552ba36e9093d500cc6406a09313fa..bbbeb4bb155db2c518890fec493fec71740f5abd 100644 (file)
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -491,9 +491,9 @@
                    # 0 logs all statement, > 0 logs only statements running at
                    # least this number of milliseconds.
 
-#log_statement_sample_rate = 1 # Fraction of logged statements over
-                   # log_min_duration_statement. 1.0 logs all statements,
-                   # 0 never logs.
+#log_statement_sample_rate = 1.0   # Fraction of logged statements exceeding
+                   # log_min_duration_statement to be logged.
+                   # 1.0 logs all such statements, 0.0 never logs.
 
 #log_transaction_sample_rate = 0.0 # Fraction of transactions whose statements
                    # are logged regardless of their duration. 1.0 logs all