Add xheader_width pset option to psql

The setting controls tha maximum length of the header line in expanded
format output. Possible settings are full, column, page, or an integer.
the default is full, the current behaviour, and in this case the header
line is the length of the widest line of output. column causes the
header to be truncated to the width of the first column, page causes it
to be truncated to the width of the terminal page, and an integer causes
it to be truncated to that value. If the full value is less than the
page or integer value no truncation occurs. If given without an argument
this option prints its current setting.

Platon Pronko, somewhat modified by me.

Discussion: https://postgr.es/m/f03d38a3-db96-a56e-d1bc-dbbc80bbde4d@gmail.com

doc/src/sgml/ref/psql-ref.sgml

@@ -2842,6 +2842,39 @@ lo_import 152801
           </listitem>
           </varlistentry>
 
+          <varlistentry>
+          <term><literal>xheader_width</literal></term>
+          <listitem>
+          <para>
+           Sets the maximum width of the header for expanded output to one of
+           <literal>full</literal> (the default value),
+           <literal>column</literal>, <literal>page</literal>, or an
+           <replaceable class="parameter">integer value</replaceable>.
+          </para>
+
+          <para>
+           <literal>full</literal>: the expanded header is not truncated,
+           and will be as wide as the widest output
+           line.
+          </para>
+
+          <para>
+           <literal>column</literal>: truncate the header line at the
+           width of the first column.
+          </para>
+
+          <para>
+           <literal>page</literal>: truncate the the header line at the terminal
+           width.
+          </para>
+
+          <para>
+           <replaceable class="parameter">integer value</replaceable>: specify
+           the exact maximum width of the header line.
+          </para>
+          </listitem>
+          </varlistentry>
+
           <varlistentry>
           <term><literal>fieldsep</literal></term>
           <listitem>

src/bin/psql/command.c

@@ -2244,6 +2244,7 @@ exec_command_pset(PsqlScanState scan_state, bool active_branch)
 				"unicode_border_linestyle",
 				"unicode_column_linestyle",
 				"unicode_header_linestyle",
+				"xheader_width",
 				NULL
 			};
 
@@ -4369,6 +4370,29 @@ do_pset(const char *param, const char *value, printQueryOpt *popt, bool quiet)
 			popt->topt.expanded = !popt->topt.expanded;
 	}
 
+	/* header line width in expanded mode */
+	else if (strcmp(param, "xheader_width") == 0)
+	{
+		if (! value)
+			;
+		else if (pg_strcasecmp(value, "full") == 0)
+			popt->topt.expanded_header_width_type = PRINT_XHEADER_FULL;
+		else if (pg_strcasecmp(value, "column") == 0)
+			popt->topt.expanded_header_width_type = PRINT_XHEADER_COLUMN;
+		else if (pg_strcasecmp(value, "page") == 0)
+			popt->topt.expanded_header_width_type = PRINT_XHEADER_PAGE;
+		else
+		{
+			popt->topt.expanded_header_width_type = PRINT_XHEADER_EXACT_WIDTH;
+			popt->topt.expanded_header_exact_width = atoi(value);
+			if (popt->topt.expanded_header_exact_width == 0)
+			{
+				pg_log_error("\\pset: allowed xheader_width values are full (default), column, page, or a number specifying the exact width.");
+				return false;
+			}
+		}
+	}
+
 	/* field separator for CSV format */
 	else if (strcmp(param, "csv_fieldsep") == 0)
 	{
@@ -4561,6 +4585,19 @@ printPsetInfo(const char *param, printQueryOpt *popt)
 			printf(_("Expanded display is off.\n"));
 	}
 
+	/* show xheader width value */
+	else if (strcmp(param, "xheader_width") == 0)
+	{
+		if (popt->topt.expanded_header_width_type == PRINT_XHEADER_FULL)
+			printf(_("Expanded header width is 'full'.\n"));
+		else if (popt->topt.expanded_header_width_type == PRINT_XHEADER_COLUMN)
+			printf(_("Expanded header width is 'column'.\n"));
+		else if (popt->topt.expanded_header_width_type == PRINT_XHEADER_PAGE)
+			printf(_("Expanded header width is 'page'.\n"));
+		else if (popt->topt.expanded_header_width_type == PRINT_XHEADER_EXACT_WIDTH)
+			printf(_("Expanded header width is %d.\n"), popt->topt.expanded_header_exact_width);
+	}
+
 	/* show field separator for CSV format */
 	else if (strcmp(param, "csv_fieldsep") == 0)
 	{
@@ -4881,6 +4918,23 @@ pset_value_string(const char *param, printQueryOpt *popt)
 		return pstrdup(_unicode_linestyle2string(popt->topt.unicode_column_linestyle));
 	else if (strcmp(param, "unicode_header_linestyle") == 0)
 		return pstrdup(_unicode_linestyle2string(popt->topt.unicode_header_linestyle));
+	else if (strcmp(param, "xheader_width") == 0)
+	{
+		if (popt->topt.expanded_header_width_type == PRINT_XHEADER_FULL)
+			return(pstrdup("full"));
+		else if (popt->topt.expanded_header_width_type == PRINT_XHEADER_COLUMN)
+			return(pstrdup("column"));
+		else if (popt->topt.expanded_header_width_type == PRINT_XHEADER_PAGE)
+			return(pstrdup("page"));
+		else
+		{
+			/* must be PRINT_XHEADER_EXACT_WIDTH */
+			char wbuff[32];
+			snprintf(wbuff, sizeof(wbuff), "%d",
+					 popt->topt.expanded_header_exact_width);
+			return pstrdup(wbuff);
+		}
+	}
 	else
 		return pstrdup("ERROR");
 }

src/bin/psql/tab-complete.c

@@ -4654,13 +4654,16 @@ psql_completion(const char *text, int start, int end)
 						 "tableattr", "title", "tuples_only",
 						 "unicode_border_linestyle",
 						 "unicode_column_linestyle",
-						 "unicode_header_linestyle");
+						 "unicode_header_linestyle",
+						 "xheader_width");
 	else if (TailMatchesCS("\\pset", MatchAny))
 	{
 		if (TailMatchesCS("format"))
 			COMPLETE_WITH_CS("aligned", "asciidoc", "csv", "html", "latex",
 							 "latex-longtable", "troff-ms", "unaligned",
 							 "wrapped");
+		else if (TailMatchesCS("xheader_width"))
+			COMPLETE_WITH_CS("full", "column", "page");
 		else if (TailMatchesCS("linestyle"))
 			COMPLETE_WITH_CS("ascii", "old-ascii", "unicode");
 		else if (TailMatchesCS("pager"))

src/fe_utils/print.c

@@ -1222,15 +1222,16 @@ cleanup:
 
 
 static void
-print_aligned_vertical_line(const printTextFormat *format,
+print_aligned_vertical_line(const printTableOpt *topt,
-							const unsigned short opt_border,
 							unsigned long record,
 							unsigned int hwidth,
 							unsigned int dwidth,
+							int output_columns,
 							printTextRule pos,
 							FILE *fout)
 {
-	const printTextLineFormat *lformat = &format->lrule[pos];
+	const printTextLineFormat *lformat = &get_line_style(topt)->lrule[pos];
+	const unsigned short opt_border = topt->border;
 	unsigned int i;
 	int			reclen = 0;
 
@@ -1259,8 +1260,18 @@ print_aligned_vertical_line(const printTextFormat *format,
 		if (reclen-- <= 0)
 			fputs(lformat->hrule, fout);
 		if (reclen-- <= 0)
-			fputs(lformat->midvrule, fout);
+		{
-		if (reclen-- <= 0)
+			if (topt->expanded_header_width_type == PRINT_XHEADER_COLUMN)
+			{
+				fputs(lformat->rightvrule, fout);
+			}
+			else
+			{
+				fputs(lformat->midvrule, fout);
+			}
+		}
+		if (reclen-- <= 0
+			&& topt->expanded_header_width_type != PRINT_XHEADER_COLUMN)
 			fputs(lformat->hrule, fout);
 	}
 	else
@@ -1268,12 +1279,43 @@ print_aligned_vertical_line(const printTextFormat *format,
 		if (reclen-- <= 0)
 			fputc(' ', fout);
 	}
-	if (reclen < 0)
+
-		reclen = 0;
+	if (topt->expanded_header_width_type != PRINT_XHEADER_COLUMN)
-	for (i = reclen; i < dwidth; i++)
+	{
-		fputs(opt_border > 0 ? lformat->hrule : " ", fout);
+		if (topt->expanded_header_width_type == PRINT_XHEADER_PAGE
-	if (opt_border == 2)
+			|| topt->expanded_header_width_type == PRINT_XHEADER_EXACT_WIDTH)
-		fprintf(fout, "%s%s", lformat->hrule, lformat->rightvrule);
+		{
+			if (topt->expanded_header_width_type == PRINT_XHEADER_EXACT_WIDTH)
+			{
+				output_columns = topt->expanded_header_exact_width;
+			}
+			if (output_columns > 0)
+			{
+				if (opt_border == 0)
+					dwidth = Min(dwidth, Max(0, (int) (output_columns - hwidth)));
+				if (opt_border == 1)
+					dwidth = Min(dwidth, Max(0, (int) (output_columns - hwidth - 3)));
+				/*
+				 * Handling the xheader width for border=2 doesn't make
+				 * much sense because this format has an additional
+				 * right border, but keep this for consistency.
+				 */
+				if (opt_border == 2)
+					dwidth = Min(dwidth, Max(0, (int) (output_columns - hwidth - 7)));
+			}
+		}
+
+		if (reclen < 0)
+			reclen = 0;
+		if (dwidth < reclen)
+			dwidth = reclen;
+
+		for (i = reclen; i < dwidth; i++)
+			fputs(opt_border > 0 ? lformat->hrule : " ", fout);
+		if (opt_border == 2)
+			fprintf(fout, "%s%s", lformat->hrule, lformat->rightvrule);
+	}
+
 	fputc('\n', fout);
 }
 
@@ -1570,11 +1612,12 @@ print_aligned_vertical(const printTableContent *cont,
 				lhwidth++;		/* for newline indicators */
 
 			if (!opt_tuples_only)
-				print_aligned_vertical_line(format, opt_border, record++,
+				print_aligned_vertical_line(cont->opt, record++,
-											lhwidth, dwidth, pos, fout);
+											lhwidth, dwidth, output_columns,
+											pos, fout);
 			else if (i != 0 || !cont->opt->start_table || opt_border == 2)
-				print_aligned_vertical_line(format, opt_border, 0, lhwidth,
+				print_aligned_vertical_line(cont->opt, 0, lhwidth,
-											dwidth, pos, fout);
+											dwidth, output_columns, pos, fout);
 		}
 
 		/* Format the header */
@@ -1760,8 +1803,8 @@ print_aligned_vertical(const printTableContent *cont,
 	if (cont->opt->stop_table)
 	{
 		if (opt_border == 2 && !cancel_pressed)
-			print_aligned_vertical_line(format, opt_border, 0, hwidth, dwidth,
+			print_aligned_vertical_line(cont->opt, 0, hwidth, dwidth,
-										PRINT_RULE_BOTTOM, fout);
+										output_columns, PRINT_RULE_BOTTOM, fout);
 
 		/* print footers */
 		if (!opt_tuples_only && cont->footers != NULL && !cancel_pressed)

src/include/fe_utils/print.h

@@ -66,6 +66,15 @@ typedef enum printTextLineWrap
 	PRINT_LINE_WRAP_NEWLINE		/* Newline in data */
 } printTextLineWrap;
 
+typedef enum printXheaderWidthType
+{
+	/* Expanded header line width variants */
+	PRINT_XHEADER_FULL, /* do not truncate header line (this is the default) */
+	PRINT_XHEADER_COLUMN, /* only print header line above the first column */
+	PRINT_XHEADER_PAGE, /* header line must not be longer than terminal width */
+	PRINT_XHEADER_EXACT_WIDTH, /* explicitly specified width */
+} printXheaderWidthType;
+
 typedef struct printTextFormat
 {
 	/* A complete line style */
@@ -101,6 +110,8 @@ typedef struct printTableOpt
 	enum printFormat format;	/* see enum above */
 	unsigned short int expanded;	/* expanded/vertical output (if supported
 									 * by output format); 0=no, 1=yes, 2=auto */
+	printXheaderWidthType	expanded_header_width_type; /* width type for header line in expanded mode */
+	int				expanded_header_exact_width; /* explicit width for header line in expanded mode */
 	unsigned short int border;	/* Print a border around the table. 0=none,
 								 * 1=dividing lines, 2=full */
 	unsigned short int pager;	/* use pager for output (if to stdout and

src/test/regress/expected/psql.out

@@ -317,6 +317,7 @@ tuples_only              off
 unicode_border_linestyle single
 unicode_column_linestyle single
 unicode_header_linestyle single
+xheader_width            full
 -- test multi-line headers, wrapping, and newline indicators
 -- in aligned, unaligned, and wrapped formats
 prepare q as select array_to_string(array_agg(repeat('x',2*n)),E'\n') as "ab

src/tools/pgindent/typedefs.list

@@ -3569,6 +3569,7 @@ printTextFormat
 printTextLineFormat
 printTextLineWrap
 printTextRule
+printXheaderWidthType
 printfunc
 priv_map
 process_file_callback_t