Add log_verbosity = 'silent' support to COPY command.

Previously, when the on_error option was set to ignore, the COPY command
would always log NOTICE messages for input rows discarded due to
data type incompatibility. Users had no way to suppress these messages.

This commit introduces a new log_verbosity setting, 'silent',
which prevents the COPY command from emitting NOTICE messages
when on_error = 'ignore' is used, even if rows are discarded.
This feature is particularly useful when processing malformed files
frequently, where a flood of NOTICE messages can be undesirable.

For example, when frequently loading malformed files via the COPY command
or querying foreign tables using file_fdw (with an upcoming patch to
add on_error support for file_fdw), users may prefer to suppress
these messages to reduce log noise and improve clarity.

Author: Atsushi Torikoshi
Reviewed-by: Masahiko Sawada, Fujii Masao
Discussion: https://postgr.es/m/ab59dad10490ea3734cf022b16c24cfd@oss.nttdata.com

doc/src/sgml/ref/copy.sgml

@@ -407,6 +407,8 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
       <literal>verbose</literal>, a <literal>NOTICE</literal> message
       containing the line of the input file and the column name whose input
       conversion has failed is emitted for each discarded row.
+      When it is set to <literal>silent</literal>, no message is emitted
+      regarding ignored rows.
      </para>
     </listitem>
    </varlistentry>
@@ -428,9 +430,11 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
     <listitem>
      <para>
       Specifies the amount of messages emitted by a <command>COPY</command>
-      command: <literal>default</literal> or <literal>verbose</literal>. If
-      <literal>verbose</literal> is specified, additional messages are emitted
-      during processing.
+      command: <literal>default</literal>, <literal>verbose</literal>, or
+      <literal>silent</literal>.
+      If <literal>verbose</literal> is specified, additional messages are
+      emitted during processing.
+      <literal>silent</literal> suppresses both verbose and default messages.
      </para>
      <para>
       This is currently used in <command>COPY FROM</command> command when

src/backend/commands/copy.c

@@ -427,9 +427,11 @@ defGetCopyLogVerbosityChoice(DefElem *def, ParseState *pstate)
 	char	   *sval;
 
 	/*
-	 * Allow "default", or "verbose" values.
+	 * Allow "silent", "default", or "verbose" values.
 	 */
 	sval = defGetString(def);
+	if (pg_strcasecmp(sval, "silent") == 0)
+		return COPY_LOG_VERBOSITY_SILENT;
 	if (pg_strcasecmp(sval, "default") == 0)
 		return COPY_LOG_VERBOSITY_DEFAULT;
 	if (pg_strcasecmp(sval, "verbose") == 0)

src/backend/commands/copyfrom.c

@@ -1320,7 +1320,8 @@ CopyFrom(CopyFromState cstate)
 	error_context_stack = errcallback.previous;
 
 	if (cstate->opts.on_error != COPY_ON_ERROR_STOP &&
-		cstate->num_errors > 0)
+		cstate->num_errors > 0 &&
+		cstate->opts.log_verbosity >= COPY_LOG_VERBOSITY_DEFAULT)
 		ereport(NOTICE,
 				errmsg_plural("%llu row was skipped due to data type incompatibility",
 							  "%llu rows were skipped due to data type incompatibility",

src/bin/psql/tab-complete.c

@@ -2916,7 +2916,7 @@ psql_completion(const char *text, int start, int end)
 
 	/* Complete COPY <sth> FROM filename WITH (LOG_VERBOSITY */
 	else if (Matches("COPY|\\copy", MatchAny, "FROM|TO", MatchAny, "WITH", "(", "LOG_VERBOSITY"))
-		COMPLETE_WITH("default", "verbose");
+		COMPLETE_WITH("silent", "default", "verbose");
 
 	/* Complete COPY <sth> FROM <sth> WITH (<options>) */
 	else if (Matches("COPY|\\copy", MatchAny, "FROM", MatchAny, "WITH", MatchAny))

src/include/commands/copy.h

@@ -45,7 +45,9 @@ typedef enum CopyOnErrorChoice
  */
 typedef enum CopyLogVerbosityChoice
 {
-	COPY_LOG_VERBOSITY_DEFAULT = 0, /* logs no additional messages, default */
+	COPY_LOG_VERBOSITY_SILENT = -1, /* logs none */
+	COPY_LOG_VERBOSITY_DEFAULT = 0, /* logs no additional messages. As this is
+									 * the default, assign 0 */
 	COPY_LOG_VERBOSITY_VERBOSE, /* logs additional messages */
 } CopyLogVerbosityChoice;
 

src/test/regress/expected/copy2.out

@@ -760,6 +760,7 @@ COPY check_ign_err2 FROM STDIN WITH (on_error ignore, log_verbosity verbose);
 NOTICE:  skipping row due to data type incompatibility at line 2 for column "l": null input
 CONTEXT:  COPY check_ign_err2
 NOTICE:  1 row was skipped due to data type incompatibility
+COPY check_ign_err2 FROM STDIN WITH (on_error ignore, log_verbosity silent);
 -- reset context choice
 \set SHOW_CONTEXT errors
 SELECT * FROM check_ign_err;
@@ -774,7 +775,8 @@ SELECT * FROM check_ign_err2;
  n |  m  | k |   l   
 ---+-----+---+-------
  1 | {1} | 1 | 'foo'
-(1 row)
+ 3 | {3} | 3 | 'bar'
+(2 rows)
 
 -- test datatype error that can't be handled as soft: should fail
 CREATE TABLE hard_err(foo widget);

src/test/regress/sql/copy2.sql

@@ -533,6 +533,10 @@ COPY check_ign_err2 FROM STDIN WITH (on_error ignore, log_verbosity verbose);
 1	{1}	1	'foo'
 2	{2}	2	\N
 \.
+COPY check_ign_err2 FROM STDIN WITH (on_error ignore, log_verbosity silent);
+3	{3}	3	'bar'
+4	{4}	4	\N
+\.
 
 -- reset context choice
 \set SHOW_CONTEXT errors