explain-units-c.diff

*** a/src/backend/commands/explain.c
--- b/src/backend/commands/explain.c
***************
*** 98,104 **** static void ExplainJSONLineEnding(ExplainState *es);
  static void ExplainYAMLLineStarting(ExplainState *es);
  static void escape_json(StringInfo buf, const char *str);
  static void escape_yaml(StringInfo buf, const char *str);
! 
  
  /*
   * ExplainQuery -
--- 98,104 ----
  static void ExplainYAMLLineStarting(ExplainState *es);
  static void escape_json(StringInfo buf, const char *str);
  static void escape_yaml(StringInfo buf, const char *str);
! static double normalize_memory(double amount, char **unit, int *precision);
  
  /*
   * ExplainQuery -
***************
*** 1081,1127 **** ExplainNode(Plan *plan, PlanState *planstate,
  			if (has_shared || has_local || has_temp)
  			{
  				appendStringInfoSpaces(es->str, es->indent * 2);
! 				appendStringInfoString(es->str, "Buffers:");
  
  				if (has_shared)
  				{
  					appendStringInfoString(es->str, " shared");
! 					if (usage->shared_blks_hit > 0)
! 						appendStringInfo(es->str, " hit=%ld",
! 							usage->shared_blks_hit);
  					if (usage->shared_blks_read > 0)
! 						appendStringInfo(es->str, " read=%ld",
! 							usage->shared_blks_read);
  					if (usage->shared_blks_written > 0)
! 						appendStringInfo(es->str, " written=%ld",
! 							usage->shared_blks_written);
  					if (has_local || has_temp)
  						appendStringInfoChar(es->str, ',');
  				}
  				if (has_local)
  				{
! 					appendStringInfoString(es->str, " local");
! 					if (usage->local_blks_hit > 0)
! 						appendStringInfo(es->str, " hit=%ld",
! 							usage->local_blks_hit);
! 					if (usage->local_blks_read > 0)
! 						appendStringInfo(es->str, " read=%ld",
! 							usage->local_blks_read);
! 					if (usage->local_blks_written > 0)
! 						appendStringInfo(es->str, " written=%ld",
! 							usage->local_blks_written);
  					if (has_temp)
  						appendStringInfoChar(es->str, ',');
  				}
  				if (has_temp)
  				{
  					appendStringInfoString(es->str, " temp");
  					if (usage->temp_blks_read > 0)
! 						appendStringInfo(es->str, " read=%ld",
! 							usage->temp_blks_read);
! 					if (usage->temp_blks_written > 0)
! 						appendStringInfo(es->str, " written=%ld",
! 							usage->temp_blks_written);
  				}
  				appendStringInfoChar(es->str, '\n');
  			}
--- 1081,1143 ----
  			if (has_shared || has_local || has_temp)
  			{
  				appendStringInfoSpaces(es->str, es->indent * 2);
! 				appendStringInfoString(es->str, "Total Buffer Usage:");
  
  				if (has_shared)
  				{
+ 					char *hit_unit, *read_unit, *written_unit;
+ 					int   hit_prec,  read_prec,  written_prec;
+ 					double hit_mem      = normalize_memory((double)usage->shared_blks_hit      * BLCKSZ, &hit_unit,      &hit_prec);
+ 					double read_mem     = normalize_memory((double)usage->shared_blks_read     * BLCKSZ, &read_unit,     &read_prec);
+ 					double written_mem  = normalize_memory((double)usage->shared_blks_written  * BLCKSZ, &written_unit,  &written_prec);
+ 
  					appendStringInfoString(es->str, " shared");
! 						appendStringInfo(es->str, " hit=%.*f%s", 
! 										 hit_prec, hit_mem, hit_unit);
  					if (usage->shared_blks_read > 0)
! 						appendStringInfo(es->str, " read=%.*f%s",
! 										 read_prec, read_mem, read_unit);
  					if (usage->shared_blks_written > 0)
! 						appendStringInfo(es->str, " written=%.*f%s",
! 										 written_prec, written_mem, written_unit);
  					if (has_local || has_temp)
  						appendStringInfoChar(es->str, ',');
  				}
  				if (has_local)
  				{
! 					char *hit_unit, *read_unit, *written_unit;
! 					int   hit_prec,  read_prec,  written_prec;
! 					double hit_mem      = normalize_memory((double)usage->local_blks_hit      * BLCKSZ, &hit_unit,      &hit_prec);
! 					double read_mem     = normalize_memory((double)usage->local_blks_read     * BLCKSZ, &read_unit,     &read_prec);
! 					double written_mem  = normalize_memory((double)usage->local_blks_written  * BLCKSZ, &written_unit,  &written_prec);
! 
!  					appendStringInfoString(es->str, " local");
!  					if (usage->local_blks_hit > 0)
! 						appendStringInfo(es->str, " hit=%.*f%s", 
! 										 hit_prec, hit_mem, hit_unit);
!  					if (usage->local_blks_read > 0)
! 						appendStringInfo(es->str, " read=%.*f%s",
! 										 read_prec, read_mem, read_unit);
!  					if (usage->local_blks_written > 0)
! 						appendStringInfo(es->str, " written=%.*f%s",
! 										 written_prec, written_mem, written_unit);
  					if (has_temp)
  						appendStringInfoChar(es->str, ',');
  				}
  				if (has_temp)
  				{
+ 					char *read_unit, *written_unit;
+ 					int   read_prec,  written_prec;
+ 					double read_mem     = normalize_memory((double)usage->temp_blks_read     * BLCKSZ, &read_unit,     &read_prec);
+ 					double written_mem  = normalize_memory((double)usage->temp_blks_written  * BLCKSZ, &written_unit,  &written_prec);
+ 
  					appendStringInfoString(es->str, " temp");
  					if (usage->temp_blks_read > 0)
! 						appendStringInfo(es->str, " read=%.*f%s",
! 										 read_prec, read_mem, read_unit);
!  					if (usage->temp_blks_written > 0)
! 						appendStringInfo(es->str, " written=%.*f%s",
! 										 written_prec, written_mem, written_unit);
  				}
  				appendStringInfoChar(es->str, '\n');
  			}
***************
*** 2153,2155 **** escape_yaml(StringInfo buf, const char *str)
--- 2169,2204 ----
  
  	appendStringInfo(buf, "%s", str);
  }
+ 
+ /*
+  * For a quantity of bytes pick a reasonable display unit for it and
+  * return the quantity in that unit. Also return the unit name and a
+  * reasonable precision via the reference parameters.
+  */
+ 
+ static double normalize_memory(double amount, char **unit, int *precision)
+ {
+ 	static char *units[] = {"bytes", "kB", "MB", "GB", "TB", "PB"};
+ 	char **u = units, **last = units + (sizeof(units)/sizeof(*units)-1);
+ 
+ 	while (amount > 1024.0 && u < last)
+ 	{
+ 		amount /= 1024.0;
+ 		u += 1;
+ 	}
+ 
+ 	*unit = *u;
+ 
+ 	/* if it's bytes or kB then don't print decimals since that's less
+ 	 * than blocksize, otherwise always print 3 significant digits */
+ 	if (u == units || u == units+1 )
+ 		*precision = 0;
+ 	else if (amount < 10)
+ 		*precision = 2;
+ 	else if (amount < 100)
+ 		*precision = 1;
+ 	else
+ 		*precision = 0;
+ 
+ 	return amount;
+ }