Marginal comments and docs cleanup.
Fix up some imprecise comments and poor markup from ba79cb5dc
. Also try
to convert the documentation of log_min_duration_sample and friends into
passable English.
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@ -5984,13 +5984,13 @@ local0.* /var/log/postgresql
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<para>
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Causes the duration of each completed statement to be logged
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if the statement ran for at least the specified amount of time.
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If this value is specified without units, it is taken as milliseconds.
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Setting this to zero prints all statement durations.
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Minus-one (the default) disables logging statement durations.
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For example, if you set it to <literal>250ms</literal>
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then all SQL statements that run 250ms or longer will be
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logged. Enabling this parameter can be helpful in tracking down
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unoptimized queries in your applications.
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If this value is specified without units, it is taken as milliseconds.
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Setting this to zero prints all statement durations.
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Minus-one (the default) disables logging statement durations.
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Only superusers can change this setting.
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</para>
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@ -6030,49 +6030,39 @@ local0.* /var/log/postgresql
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</term>
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<listitem>
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<para>
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Allows to sample the logging of the duration of each completed
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statement if the statement ran for at least the specified amount of
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time. If this value is specified without units, it is taken as milliseconds.
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Allows sampling the duration of completed statements that ran for
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at least the specified amount of time. This produces the same
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kind of log entries as
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<xref linkend="guc-log-min-duration-statement"/>, but only for a
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subset of the executed statements, with sample rate controlled by
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<xref linkend="guc-log-statement-sample-rate"/>.
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For example, if you set it to <literal>100ms</literal> then all
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SQL statements that run 100ms or longer will be considered for
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sampling. Enabling this parameter can be helpful when the
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traffic is too high to log all queries.
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If this value is specified without units, it is taken as milliseconds.
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Setting this to zero samples all statement durations.
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Minus-one (the default) disables sampling statement durations.
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For example, if you set it to <literal>250ms</literal>
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then all SQL statements that run 250ms or longer will be considered
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for sampling, with sample rate is controlled by <xref linkend="guc-log-statement-sample-rate"/>.
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Enabling this parameter can be helpful when the traffic too high to
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sample all queries.
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Only superusers can change this setting.
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</para>
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<para>
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This option has lower priority than <xref linkend="guc-log-min-duration-statement"/>,
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meaning that statements with durations exceeding <xref linkend="guc-log-min-duration-statement"/>
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are not subject to sampling and are always logged.
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This setting has lower priority
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than <varname>log_min_duration_statement</varname>, meaning that
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statements with durations
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exceeding <varname>log_min_duration_statement</varname> are not
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subject to sampling and are always logged.
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</para>
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<para>
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For clients using extended query protocol, durations of the Parse,
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Bind, and Execute steps are logged independently.
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Other notes for <varname>log_min_duration_statement</varname>
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apply also to this setting.
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</para>
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<note>
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<para>
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When using this option together with
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<xref linkend="guc-log-statement"/>,
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the text of statements that are logged because of
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<varname>log_statement</varname> will not be repeated in the
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duration log message.
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If you are not using <application>syslog</application>, it is recommended
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that you log the PID or session ID using
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<xref linkend="guc-log-line-prefix"/>
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so that you can link the statement message to the later
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duration message using the process ID or session ID.
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</para>
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</note>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-log-statement-sample-rate" xreflabel="log_statement_sample_rate">
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<term><varname>log_statement_sample_rate</varname> (<type>real</type>)
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<term><varname>log_statement_sample_rate</varname> (<type>floating point</type>)
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<indexterm>
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<primary><varname>log_statement_sample_rate</varname> configuration parameter</primary>
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</indexterm>
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@ -6080,43 +6070,40 @@ local0.* /var/log/postgresql
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<listitem>
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<para>
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Determines the fraction of statements with duration exceeding
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<xref linkend="guc-log-min-duration-sample"/> to be logged.
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This is a statistical parameter, for example <literal>0.5</literal>
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means there is statistically one in two chances to log the statement.
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The default is <literal>1.0</literal>, meaning log all such
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<xref linkend="guc-log-min-duration-sample"/> that will be logged.
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Sampling is stochastic, for example <literal>0.5</literal> means
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there is statistically one chance in two that any given statement
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will be logged.
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The default is <literal>1.0</literal>, meaning to log all sampled
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statements.
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Setting this to zero disables sampling logging, same as setting
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Setting this to zero disables sampled statement-duration logging,
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the same as setting
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<varname>log_min_duration_sample</varname> to
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<literal>-1</literal>.
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<varname>log_statement_sample_rate</varname> is helpful when the
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traffic is too high to log all queries.
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Only superusers can change this setting.
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</para>
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<note>
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<para>
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Like all statement-logging options, this option can add significant
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overhead.
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</para>
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</note>
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</listitem>
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</varlistentry>
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<varlistentry id="guc-log-transaction-sample-rate" xreflabel="log_transaction_sample_rate">
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<term><varname>log_transaction_sample_rate</varname> (<type>real</type>)
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<term><varname>log_transaction_sample_rate</varname> (<type>floating point</type>)
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<indexterm>
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<primary><varname>log_transaction_sample_rate</varname> configuration parameter</primary>
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</indexterm>
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</term>
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<listitem>
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<para>
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Set the fraction of transactions whose statements are all logged,
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Sets the fraction of transactions whose statements are all logged,
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in addition to statements logged for other reasons. It applies to
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each new transaction regardless of its statements' durations.
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The default is <literal>0</literal>, meaning not to log statements
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from any additional transaction. Setting this to <literal>1</literal>
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logs all statements for all transactions.
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<varname>log_transaction_sample_rate</varname> is helpful to track a
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sample of transaction.
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Sampling is stochastic, for example <literal>0.1</literal> means
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there is statistically one chance in ten that any given transaction
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will be logged.
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<varname>log_transaction_sample_rate</varname> can be helpful to
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construct a sample of transactions.
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The default is <literal>0</literal>, meaning not to log
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statements from any additional transactions. Setting this
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to <literal>1</literal> logs all statements of all transactions.
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Only superusers can change this setting.
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</para>
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<note>
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@ -6632,9 +6619,9 @@ log_line_prefix = '%m [%p] %q%u@%d/%a '
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<para>
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Controls whether bind parameters are logged when a statement is logged
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as a result of <xref linkend="guc-log-min-error-statement"/>.
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It adds some overhead, as postgres will compute and store textual
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representations of parameter values in memory for all statements,
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even if they eventually do not get logged.
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It adds some overhead, as <productname>PostgreSQL</productname> will
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compute and store textual representations of parameter values in
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memory for all statements, even if they eventually do not get logged.
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This setting has no effect on statements logged due to
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<xref linkend="guc-log-min-duration-statement"/> or
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<xref linkend="guc-log-statement"/> settings, as they are always logged
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@ -262,16 +262,16 @@ RestoreParamList(char **start_address)
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/*
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* BuildParamLogString
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* Return a string that represent the parameter list, for logging.
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* Return a string that represents the parameter list, for logging.
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*
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* If caller already knows textual representations for some parameters, it can
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* pass an array of exactly params->numParams values as knownTextValues, which
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* can contain NULLs for any unknown individual values. NULL can be given if
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* no parameters are known.
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*
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* If maxlen is not zero, that's the maximum number of characters of the
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* input string printed; an ellipsis is added if more characters exist.
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* (Added quotes are not considered.)
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* If maxlen is not zero, that's the maximum number of bytes of any one
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* parameter value to be printed; an ellipsis is added if the string is
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* longer. (Added quotes are not considered in this calculation.)
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*/
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char *
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BuildParamLogString(ParamListInfo params, char **knownTextValues, int maxlen)
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/*
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* NB: think not of returning params->paramValuesStr! It may have been
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* generated with a different maxlen, and so unsuitable.
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* generated with a different maxlen, and so be unsuitable. Besides that,
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* this is the function used to create that string.
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*/
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/*
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@ -26,7 +26,7 @@
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/*
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* appendStringInfoStringQuoted
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*
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* Append up to maxlen characters from s to str, or the whole input string if
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* Append up to maxlen bytes from s to str, or the whole input string if
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* maxlen <= 0, adding single quotes around it and doubling all single quotes.
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* Add an ellipsis if the copy is incomplete.
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*/
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