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Fix some inconsistencies in EXPLAIN output 

06286709e added a SERIALIZE option to EXPLAIN which included showing the
amount of kilobytes serialized.  The calculation to convert bytes into
kilobytes wasn't consistent with how that's done in the rest of EXPLAIN.
Traditionally we round up to the nearest kB, but the new code rounded to
the nearest kB.

To fix this, invent a macro that does the conversion and use that macro
everywhere that requires this conversion.

Additionally, 5de890e36 added EXPLAIN (MEMORY) but included the memory
sizes in bytes.  Convert these values to kilobytes to align with the
other memory related outputs.

In passing, swap out a "long" type in show_hash_info() and use a uint64
instead.  We do support platforms where sizeof(Size) == 8 and
sizeof(long) == 4, so using a long there is questionable.

Reported-by: jian he
Reviewed-by: jian he
Discussion: https://www.postgresql.org/message-id/CACJufxE4Sp7xvgOwhqtFx5hS85AxMKobPWDo-xZHZVTpK3EBjA@mail.gmail.com
This commit is contained in:
David Rowley 2024-05-16 12:50:16 +12:00
parent f01e3ba56f
commit 0de37b5106
2 changed files with 30 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

48
src/backend/commands/explain.c
View File

@ -62,6 +62,12 @@ typedef struct SerializeMetrics
#define X_CLOSE_IMMEDIATE 2
#define X_NOWHITESPACE 4
/*
* Various places within need to convert bytes to kilobytes. Round these up
* to the next whole kilobyte.
*/
#define BYTES_TO_KILOBYTES(b) (((b) + 1023) / 1024)
static void ExplainOneQuery(Query *query, int cursorOptions,
IntoClause *into, ExplainState *es,
const char *queryString, ParamListInfo params,
@ -1120,11 +1126,11 @@ ExplainPrintSerialize(ExplainState *es, SerializeMetrics *metrics)
if (es->timing)
appendStringInfo(es->str, "Serialization: time=%.3f ms output=" UINT64_FORMAT "kB format=%s\n",
1000.0 * INSTR_TIME_GET_DOUBLE(metrics->timeSpent),
(metrics->bytesSent + 512) / 1024,
BYTES_TO_KILOBYTES(metrics->bytesSent),
format);
else
appendStringInfo(es->str, "Serialization: output=" UINT64_FORMAT "kB format=%s\n",
(metrics->bytesSent + 512) / 1024,
BYTES_TO_KILOBYTES(metrics->bytesSent),
format);
if (es->buffers && peek_buffer_usage(es, &metrics->bufferUsage))
@ -1141,7 +1147,7 @@ ExplainPrintSerialize(ExplainState *es, SerializeMetrics *metrics)
1000.0 * INSTR_TIME_GET_DOUBLE(metrics->timeSpent),
3, es);
ExplainPropertyUInteger("Output Volume", "kB",
(metrics->bytesSent + 512) / 1024, es);
BYTES_TO_KILOBYTES(metrics->bytesSent), es);
ExplainPropertyText("Format", format, es);
if (es->buffers)
show_buffer_usage(es, &metrics->bufferUsage);
@ -3275,7 +3281,7 @@ show_hash_info(HashState *hashstate, ExplainState *es)
if (hinstrument.nbatch > 0)
{
long spacePeakKb = (hinstrument.space_peak + 1023) / 1024;
uint64 spacePeakKb = BYTES_TO_KILOBYTES(hinstrument.space_peak);
if (es->format != EXPLAIN_FORMAT_TEXT)
{
@ -3287,15 +3293,15 @@ show_hash_info(HashState *hashstate, ExplainState *es)
hinstrument.nbatch, es);
ExplainPropertyInteger("Original Hash Batches", NULL,
hinstrument.nbatch_original, es);
ExplainPropertyInteger("Peak Memory Usage", "kB",
spacePeakKb, es);
ExplainPropertyUInteger("Peak Memory Usage", "kB",
spacePeakKb, es);
}
else if (hinstrument.nbatch_original != hinstrument.nbatch ||
hinstrument.nbuckets_original != hinstrument.nbuckets)
{
ExplainIndentText(es);
appendStringInfo(es->str,
"Buckets: %d (originally %d) Batches: %d (originally %d) Memory Usage: %ldkB\n",
"Buckets: %d (originally %d) Batches: %d (originally %d) Memory Usage: " UINT64_FORMAT "kB\n",
hinstrument.nbuckets,
hinstrument.nbuckets_original,
hinstrument.nbatch,
@ -3306,7 +3312,7 @@ show_hash_info(HashState *hashstate, ExplainState *es)
{
ExplainIndentText(es);
appendStringInfo(es->str,
"Buckets: %d Batches: %d Memory Usage: %ldkB\n",
"Buckets: %d Batches: %d Memory Usage: " UINT64_FORMAT "kB\n",
hinstrument.nbuckets, hinstrument.nbatch,
spacePeakKb);
}
@ -3376,9 +3382,9 @@ show_memoize_info(MemoizeState *mstate, List *ancestors, ExplainState *es)
* when mem_peak is 0.
*/
if (mstate->stats.mem_peak > 0)
memPeakKb = (mstate->stats.mem_peak + 1023) / 1024;
memPeakKb = BYTES_TO_KILOBYTES(mstate->stats.mem_peak);
else
memPeakKb = (mstate->mem_used + 1023) / 1024;
memPeakKb = BYTES_TO_KILOBYTES(mstate->mem_used);
if (es->format != EXPLAIN_FORMAT_TEXT)
{
@ -3427,7 +3433,7 @@ show_memoize_info(MemoizeState *mstate, List *ancestors, ExplainState *es)
* MemoizeInstrumentation.mem_peak field for us. No need to do the
* zero checks like we did for the serial case above.
*/
memPeakKb = (si->mem_peak + 1023) / 1024;
memPeakKb = BYTES_TO_KILOBYTES(si->mem_peak);
if (es->format == EXPLAIN_FORMAT_TEXT)
{
@ -3464,7 +3470,7 @@ static void
show_hashagg_info(AggState *aggstate, ExplainState *es)
{
Agg *agg = (Agg *) aggstate->ss.ps.plan;
int64 memPeakKb = (aggstate->hash_mem_peak + 1023) / 1024;
int64 memPeakKb = BYTES_TO_KILOBYTES(aggstate->hash_mem_peak);
if (agg->aggstrategy != AGG_HASHED &&
agg->aggstrategy != AGG_MIXED)
@ -3545,7 +3551,7 @@ show_hashagg_info(AggState *aggstate, ExplainState *es)
continue;
hash_disk_used = sinstrument->hash_disk_used;
hash_batches_used = sinstrument->hash_batches_used;
memPeakKb = (sinstrument->hash_mem_peak + 1023) / 1024;
memPeakKb = BYTES_TO_KILOBYTES(sinstrument->hash_mem_peak);
if (es->workers_state)
ExplainOpenWorker(n, es);
@ -3942,22 +3948,22 @@ show_wal_usage(ExplainState *es, const WalUsage *usage)
static void
show_memory_counters(ExplainState *es, const MemoryContextCounters *mem_counters)
{
int64 memUsedkB = BYTES_TO_KILOBYTES(mem_counters->totalspace -
mem_counters->freespace);
int64 memAllocatedkB = BYTES_TO_KILOBYTES(mem_counters->totalspace);
if (es->format == EXPLAIN_FORMAT_TEXT)
{
ExplainIndentText(es);
appendStringInfo(es->str,
"Memory: used=%lld bytes allocated=%lld bytes",
(long long) (mem_counters->totalspace - mem_counters->freespace),
(long long) mem_counters->totalspace);
"Memory: used=" INT64_FORMAT "kB allocated=" INT64_FORMAT "kB",
memUsedkB, memAllocatedkB);
appendStringInfoChar(es->str, '\n');
}
else
{
ExplainPropertyInteger("Memory Used", "bytes",
mem_counters->totalspace - mem_counters->freespace,
es);
ExplainPropertyInteger("Memory Allocated", "bytes",
mem_counters->totalspace, es);
ExplainPropertyInteger("Memory Used", "kB", memUsedkB, es);
ExplainPropertyInteger("Memory Allocated", "kB", memAllocatedkB, es);
}
}

6
src/test/regress/expected/explain.out
View File

@ -345,14 +345,14 @@ select explain_filter('explain (memory) select * from int8_tbl i8');
explain_filter
---------------------------------------------------------
Seq Scan on int8_tbl i8 (cost=N.N..N.N rows=N width=N)
Memory: used=N bytes allocated=N bytes
Memory: used=NkB allocated=NkB
(2 rows)
select explain_filter('explain (memory, analyze) select * from int8_tbl i8');
explain_filter
-----------------------------------------------------------------------------------------------
Seq Scan on int8_tbl i8 (cost=N.N..N.N rows=N width=N) (actual time=N.N..N.N rows=N loops=N)
Memory: used=N bytes allocated=N bytes
Memory: used=NkB allocated=NkB
Planning Time: N.N ms
Execution Time: N.N ms
(4 rows)
@ -413,7 +413,7 @@ select explain_filter('explain (memory) execute int8_query');
explain_filter
---------------------------------------------------------
Seq Scan on int8_tbl i8 (cost=N.N..N.N rows=N width=N)
Memory: used=N bytes allocated=N bytes
Memory: used=NkB allocated=NkB
(2 rows)
-- Test EXPLAIN (GENERIC_PLAN) with partition pruning