Provide FORCE_NULL * and FORCE_NOT_NULL * options for COPY FROM

These options already exist, but you need to specify a column list for
them, which can be cumbersome. We already have the possibility of all
columns for FORCE QUOTE, so this is simply extending that facility to
FORCE_NULL and FORCE_NOT_NULL.

Author: Zhang Mingli
Reviewed-By: Richard Guo, Kyatoro Horiguchi, Michael Paquier.

Discussion: https://postgr.es/m/CACJufxEnVqzOFtqhexF2+AwOKFrV8zHOY3y=p+gPK6eB14pn_w@mail.gmail.com

Author: adunstan

doc/src/sgml/ref/copy.sgml

@@ -41,8 +41,8 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
     QUOTE '<replaceable class="parameter">quote_character</replaceable>'
     ESCAPE '<replaceable class="parameter">escape_character</replaceable>'
     FORCE_QUOTE { ( <replaceable class="parameter">column_name</replaceable> [, ...] ) | * }
-    FORCE_NOT_NULL ( <replaceable class="parameter">column_name</replaceable> [, ...] )
-    FORCE_NULL ( <replaceable class="parameter">column_name</replaceable> [, ...] )
+    FORCE_NOT_NULL { ( <replaceable class="parameter">column_name</replaceable> [, ...] ) | * }
+    FORCE_NULL { ( <replaceable class="parameter">column_name</replaceable> [, ...] ) | * }
     ENCODING '<replaceable class="parameter">encoding_name</replaceable>'
 </synopsis>
  </refsynopsisdiv>
@@ -350,6 +350,7 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
       In the default case where the null string is empty, this means that
       empty values will be read as zero-length strings rather than nulls,
       even when they are not quoted.
+      If <literal>*</literal> is specified, the option will be applied to all columns.
       This option is allowed only in <command>COPY FROM</command>, and only when
       using <literal>CSV</literal> format.
      </para>
@@ -364,6 +365,7 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
       if it has been quoted, and if a match is found set the value to
       <literal>NULL</literal>. In the default case where the null string is empty,
       this converts a quoted empty string into NULL.
+      If <literal>*</literal> is specified, the option will be applied to all columns.
       This option is allowed only in <command>COPY FROM</command>, and only when
       using <literal>CSV</literal> format.
      </para>

src/backend/commands/copy.c

@@ -512,9 +512,11 @@ ProcessCopyOptions(ParseState *pstate,
 		}
 		else if (strcmp(defel->defname, "force_not_null") == 0)
 		{
-			if (opts_out->force_notnull)
+			if (opts_out->force_notnull || opts_out->force_notnull_all)
 				errorConflictingDefElem(defel, pstate);
-			if (defel->arg && IsA(defel->arg, List))
+			if (defel->arg && IsA(defel->arg, A_Star))
+				opts_out->force_notnull_all = true;
+			else if (defel->arg && IsA(defel->arg, List))
 				opts_out->force_notnull = castNode(List, defel->arg);
 			else
 				ereport(ERROR,
@@ -525,9 +527,11 @@ ProcessCopyOptions(ParseState *pstate,
 		}
 		else if (strcmp(defel->defname, "force_null") == 0)
 		{
-			if (opts_out->force_null)
+			if (opts_out->force_null || opts_out->force_null_all)
 				errorConflictingDefElem(defel, pstate);
-			if (defel->arg && IsA(defel->arg, List))
+			if (defel->arg && IsA(defel->arg, A_Star))
+				opts_out->force_null_all = true;
+			else if (defel->arg && IsA(defel->arg, List))
 				opts_out->force_null = castNode(List, defel->arg);
 			else
 				ereport(ERROR,

src/backend/commands/copyfrom.c

@@ -1393,7 +1393,9 @@ BeginCopyFrom(ParseState *pstate,
 
 	/* Convert FORCE_NOT_NULL name list to per-column flags, check validity */
 	cstate->opts.force_notnull_flags = (bool *) palloc0(num_phys_attrs * sizeof(bool));
-	if (cstate->opts.force_notnull)
+	if (cstate->opts.force_notnull_all)
+		MemSet(cstate->opts.force_notnull_flags, true, num_phys_attrs * sizeof(bool));
+	else if (cstate->opts.force_notnull)
 	{
 		List	   *attnums;
 		ListCell   *cur;
@@ -1416,7 +1418,9 @@ BeginCopyFrom(ParseState *pstate,
 
 	/* Convert FORCE_NULL name list to per-column flags, check validity */
 	cstate->opts.force_null_flags = (bool *) palloc0(num_phys_attrs * sizeof(bool));
-	if (cstate->opts.force_null)
+	if (cstate->opts.force_null_all)
+		MemSet(cstate->opts.force_null_flags, true, num_phys_attrs * sizeof(bool));
+	else if (cstate->opts.force_null)
 	{
 		List	   *attnums;
 		ListCell   *cur;

src/backend/commands/copyto.c

@@ -582,10 +582,7 @@ BeginCopyTo(ParseState *pstate,
 	cstate->opts.force_quote_flags = (bool *) palloc0(num_phys_attrs * sizeof(bool));
 	if (cstate->opts.force_quote_all)
 	{
-		int			i;
-
-		for (i = 0; i < num_phys_attrs; i++)
-			cstate->opts.force_quote_flags[i] = true;
+		MemSet(cstate->opts.force_quote_flags, true, num_phys_attrs * sizeof(bool));
 	}
 	else if (cstate->opts.force_quote)
 	{

src/backend/parser/gram.y

@@ -3419,10 +3419,18 @@ copy_opt_item:
 				{
 					$$ = makeDefElem("force_not_null", (Node *) $4, @1);
 				}
+			| FORCE NOT NULL_P '*'
+				{
+					$$ = makeDefElem("force_not_null", (Node *) makeNode(A_Star), @1);
+				}
 			| FORCE NULL_P columnList
 				{
 					$$ = makeDefElem("force_null", (Node *) $3, @1);
 				}
+			| FORCE NULL_P '*'
+				{
+					$$ = makeDefElem("force_null", (Node *) makeNode(A_Star), @1);
+				}
 			| ENCODING Sconst
 				{
 					$$ = makeDefElem("encoding", (Node *) makeString($2), @1);

src/include/commands/copy.h

@@ -56,8 +56,10 @@ typedef struct CopyFormatOptions
 	bool		force_quote_all;	/* FORCE_QUOTE *? */
 	bool	   *force_quote_flags;	/* per-column CSV FQ flags */
 	List	   *force_notnull;	/* list of column names */
+	bool		force_notnull_all;	/* FORCE_NOT_NULL *? */
 	bool	   *force_notnull_flags;	/* per-column CSV FNN flags */
 	List	   *force_null;		/* list of column names */
+	bool		force_null_all; /* FORCE_NULL *? */
 	bool	   *force_null_flags;	/* per-column CSV FN flags */
 	bool		convert_selectively;	/* do selective binary conversion? */
 	List	   *convert_select; /* list of column names (can be NIL) */

src/test/regress/expected/copy2.out

@@ -520,6 +520,50 @@ BEGIN;
 COPY forcetest (d, e) FROM STDIN WITH (FORMAT csv, FORCE_NULL(b));
 ERROR:  FORCE_NULL column "b" not referenced by COPY
 ROLLBACK;
+-- should succeed with no effect ("b" remains an empty string, "c" remains NULL)
+BEGIN;
+COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NOT_NULL *, FORCE_NULL *);
+COMMIT;
+SELECT b, c FROM forcetest WHERE a = 4;
+ b |  c   
+---+------
+   | NULL
+(1 row)
+
+-- should succeed with effect ("b" remains an empty string)
+BEGIN;
+COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NOT_NULL *);
+COMMIT;
+SELECT b, c FROM forcetest WHERE a = 5;
+ b | c 
+---+---
+   | 
+(1 row)
+
+-- should succeed with effect ("c" remains NULL)
+BEGIN;
+COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NULL *);
+COMMIT;
+SELECT b, c FROM forcetest WHERE a = 6;
+ b |  c   
+---+------
+ b | NULL
+(1 row)
+
+-- should fail with "conflicting or redundant options" error
+BEGIN;
+COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NOT_NULL *, FORCE_NOT_NULL(b));
+ERROR:  conflicting or redundant options
+LINE 1: ...c) FROM STDIN WITH (FORMAT csv, FORCE_NOT_NULL *, FORCE_NOT_...
+                                                             ^
+ROLLBACK;
+-- should fail with "conflicting or redundant options" error
+BEGIN;
+COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NULL *, FORCE_NULL(b));
+ERROR:  conflicting or redundant options
+LINE 1: ... b, c) FROM STDIN WITH (FORMAT csv, FORCE_NULL *, FORCE_NULL...
+                                                             ^
+ROLLBACK;
 \pset null ''
 -- test case with whole-row Var in a check constraint
 create table check_con_tbl (f1 int);

src/test/regress/sql/copy2.sql

@@ -344,6 +344,36 @@ ROLLBACK;
 BEGIN;
 COPY forcetest (d, e) FROM STDIN WITH (FORMAT csv, FORCE_NULL(b));
 ROLLBACK;
+-- should succeed with no effect ("b" remains an empty string, "c" remains NULL)
+BEGIN;
+COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NOT_NULL *, FORCE_NULL *);
+4,,""
+\.
+COMMIT;
+SELECT b, c FROM forcetest WHERE a = 4;
+-- should succeed with effect ("b" remains an empty string)
+BEGIN;
+COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NOT_NULL *);
+5,,""
+\.
+COMMIT;
+SELECT b, c FROM forcetest WHERE a = 5;
+-- should succeed with effect ("c" remains NULL)
+BEGIN;
+COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NULL *);
+6,"b",""
+\.
+COMMIT;
+SELECT b, c FROM forcetest WHERE a = 6;
+-- should fail with "conflicting or redundant options" error
+BEGIN;
+COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NOT_NULL *, FORCE_NOT_NULL(b));
+ROLLBACK;
+-- should fail with "conflicting or redundant options" error
+BEGIN;
+COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NULL *, FORCE_NULL(b));
+ROLLBACK;
+
 \pset null ''
 
 -- test case with whole-row Var in a check constraint