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Display explain buffers measurements in memory units rather than blocks. Also show "Total Buffer Usage" to hint that these are totals not averages per loop

This commit is contained in:
Greg Stark 2010-02-15 02:36:26 +00:00
parent f8c183a1ac
commit 34ebccddcd
1 changed files with 74 additions and 24 deletions
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98
src/backend/commands/explain.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994-5, Regents of the University of California * Portions Copyright (c) 1994-5, Regents of the University of California
* *
* IDENTIFICATION * IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.200 2010/02/01 15:43:35 rhaas Exp $ * $PostgreSQL: pgsql/src/backend/commands/explain.c,v 1.201 2010/02/15 02:36:26 stark Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -98,6 +98,7 @@ static void ExplainJSONLineEnding(ExplainState *es);
static void ExplainYAMLLineStarting(ExplainState *es); static void ExplainYAMLLineStarting(ExplainState *es);
static void escape_json(StringInfo buf, const char *str); static void escape_json(StringInfo buf, const char *str);
static void escape_yaml(StringInfo buf, const char *str); static void escape_yaml(StringInfo buf, const char *str);
static double normalize_memory(double amount, char **unit, int *precision);
/* /*
@ -1081,47 +1082,63 @@ ExplainNode(Plan *plan, PlanState *planstate,
if (has_shared || has_local || has_temp) if (has_shared || has_local || has_temp)
{ {
appendStringInfoSpaces(es->str, es->indent * 2); appendStringInfoSpaces(es->str, es->indent * 2);
appendStringInfoString(es->str, "Buffers:"); appendStringInfoString(es->str, "Total Buffer Usage:");
if (has_shared) 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"); appendStringInfoString(es->str, " shared");
if (usage->shared_blks_hit > 0) appendStringInfo(es->str, " hit=%.*f%s",
appendStringInfo(es->str, " hit=%ld", hit_prec, hit_mem, hit_unit);
usage->shared_blks_hit);
if (usage->shared_blks_read > 0) if (usage->shared_blks_read > 0)
appendStringInfo(es->str, " read=%ld", appendStringInfo(es->str, " read=%.*f%s",
usage->shared_blks_read); read_prec, read_mem, read_unit);
if (usage->shared_blks_written > 0) if (usage->shared_blks_written > 0)
appendStringInfo(es->str, " written=%ld", appendStringInfo(es->str, " written=%.*f%s",
usage->shared_blks_written); written_prec, written_mem, written_unit);
if (has_local || has_temp) if (has_local || has_temp)
appendStringInfoChar(es->str, ','); appendStringInfoChar(es->str, ',');
} }
if (has_local) if (has_local)
{ {
appendStringInfoString(es->str, " local"); char *hit_unit, *read_unit, *written_unit;
if (usage->local_blks_hit > 0) int hit_prec, read_prec, written_prec;
appendStringInfo(es->str, " hit=%ld", double hit_mem = normalize_memory((double)usage->local_blks_hit * BLCKSZ, &hit_unit, &hit_prec);
usage->local_blks_hit); double read_mem = normalize_memory((double)usage->local_blks_read * BLCKSZ, &read_unit, &read_prec);
if (usage->local_blks_read > 0) double written_mem = normalize_memory((double)usage->local_blks_written * BLCKSZ, &written_unit, &written_prec);
appendStringInfo(es->str, " read=%ld",
usage->local_blks_read); appendStringInfoString(es->str, " local");
if (usage->local_blks_written > 0) if (usage->local_blks_hit > 0)
appendStringInfo(es->str, " written=%ld", appendStringInfo(es->str, " hit=%.*f%s",
usage->local_blks_written); 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) if (has_temp)
appendStringInfoChar(es->str, ','); appendStringInfoChar(es->str, ',');
} }
if (has_temp) 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"); appendStringInfoString(es->str, " temp");
if (usage->temp_blks_read > 0) if (usage->temp_blks_read > 0)
appendStringInfo(es->str, " read=%ld", appendStringInfo(es->str, " read=%.*f%s",
usage->temp_blks_read); read_prec, read_mem, read_unit);
if (usage->temp_blks_written > 0) if (usage->temp_blks_written > 0)
appendStringInfo(es->str, " written=%ld", appendStringInfo(es->str, " written=%.*f%s",
usage->temp_blks_written); written_prec, written_mem, written_unit);
} }
appendStringInfoChar(es->str, '\n'); appendStringInfoChar(es->str, '\n');
} }
@ -2153,3 +2170,36 @@ escape_yaml(StringInfo buf, const char *str)
appendStringInfo(buf, "%s", str); 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;
}