Re: Output affected rows in EXPLAIN

2023-11-22 Thread John Naylor 
On Wed, Nov 15, 2023 at 2:17 PM  wrote:
>
> We can check the number of updated rows from execute plan,
> I think there is no need to return the command tag
> when EXPLAIN(ANALYZE) is executed by default.

Given that several people have voiced an opinion against this patch,
I'm marking it rejected.

Re: Output affected rows in EXPLAIN

2023-11-14 Thread kuroda . keisuke 

Hi hackers,

Indeed, I think it is a little confusing that when executing
EXPLAIN(ANALYZE), even though an update is actually occurring,
the commandtag of the update result is not returned.

However, the manual also describes the information that will be
affected when EXPLAIN (ANALYZE) is executed as important information.
https://www.postgresql.org/docs/current/sql-explain.html

Also, in most cases, users who use EXPLAIN(ANALYZE) only want
an execution plan of a statement.
If command tags are not required, this can be controlled using
the QUIET variable, but command tags other than EXPLAIN will also
be omitted, increasing the scope of the effect.
We can check the number of updated rows from execute plan,
I think there is no need to return the command tag
when EXPLAIN(ANALYZE) is executed by default.

## patch and QUIET=off(default)

postgres=# explain (analyze) insert into a values (1);
QUERY PLAN
--
 Insert on a  (cost=0.00..0.01 rows=0 width=0) (actual time=0.227..0.228 
rows=0 loops=1)
   ->  Result  (cost=0.00..0.01 rows=1 width=4) (actual 
time=0.013..0.015 rows=1 loops=1)

 Planning Time: 0.152 ms
 Execution Time: 0.480 ms
(4 rows)

INSERT 0 1

## patch and QUIET=on(psql work quietly)

'INSERT 0 1' is omitted both 'explain(analyze) and 'INSERT'.

postgres=# \set QUIET on
postgres=# explain (analyze) insert into a values (1);
QUERY PLAN
--
 Insert on a  (cost=0.00..0.01 rows=0 width=0) (actual time=0.058..0.059 
rows=0 loops=1)
   ->  Result  (cost=0.00..0.01 rows=1 width=4) (actual 
time=0.004..0.005 rows=1 loops=1)

 Planning Time: 0.059 ms
 Execution Time: 0.117 ms
(4 rows)

postgres=# insert into a values (1);
postgres=#

Best Regards,
Keisuke Kuroda
NTT COMWARE

On 2023-09-07 23:57, Damir Belyalov wrote:

This creates a bug, not fixes one.  It's intentional that "insert
into a"
is shown as returning zero rows, because that's what it did.  If
you'd
written "insert ... returning", you'd have gotten a different
result:


Maybe I didn't understand you correctly, but I didn't touch the number
of affected rows in EXPLAIN output.
It's just a simple patch that adds 1 row after using commands: EXPLAIN
INSERT, EXPLAIN UPDATE, EXPLAIN DELETE.
It was done because the commands INSERT/UPDATE/DELETE return one row
after execution: "UPDATE 7" or "INSERT 0 4".
EXPLAIN (ANALYZE) INSERT/UPDATE/DELETE does the same thing as these
commands, but doesn't output this row. So I added it.

Patch is fixed. There is no row "EXPLAIN" in queries like:

postgres=# explain (analyze) select * from t;
  QUERY PLAN
---
 Seq Scan on t  (cost=0.00..35.50 rows=2550 width=4) (actual
time=0.064..0.075 rows=5 loops=1)
 Planning Time: 1.639 ms
 Execution Time: 0.215 ms
(3 rows)

 EXPLAIN

What is about queries EXPLAIN INSERT/UPDATE/DELETE without ANALYZE?
Now it is outputting a row with 0 affected (inserted) rows at the end:
"INSERT 0 0", "UPDATE 0". Example:
explain update a set n = 2;
 QUERY PLAN

 Update on a  (cost=0.00..35.50 rows=0 width=0)
   ->  Seq Scan on a  (cost=0.00..35.50 rows=2550 width=10)
(2 rows)

UPDATE 0

Regards,
Damir Belyalov
Postgres Professional

Re: Output affected rows in EXPLAIN

2023-09-07 Thread Damir Belyalov 
> This creates a bug, not fixes one.  It's intentional that "insert into a"
> is shown as returning zero rows, because that's what it did.  If you'd
> written "insert ... returning", you'd have gotten a different result:
>
Maybe I didn't understand you correctly, but I didn't touch the number of
affected rows in EXPLAIN output.
It's just a simple patch that adds 1 row after using commands: EXPLAIN
INSERT, EXPLAIN UPDATE, EXPLAIN DELETE.
It was done because the commands INSERT/UPDATE/DELETE return one row after
execution: "UPDATE 7" or "INSERT 0 4".
EXPLAIN (ANALYZE) INSERT/UPDATE/DELETE does the same thing as these
commands, but doesn't output this row. So I added it.


Patch is fixed. There is no row "EXPLAIN" in queries like:
postgres=# explain (analyze) select * from t;
  QUERY PLAN
---
 Seq Scan on t  (cost=0.00..35.50 rows=2550 width=4) (actual
time=0.064..0.075 rows=5 loops=1)
 Planning Time: 1.639 ms
 Execution Time: 0.215 ms
(3 rows)

EXPLAIN


What is about queries EXPLAIN INSERT/UPDATE/DELETE without ANALYZE?
Now it is outputting a row with 0 affected (inserted) rows at the end:
"INSERT 0 0", "UPDATE 0". Example:
explain update a set n = 2;
 QUERY PLAN

 Update on a  (cost=0.00..35.50 rows=0 width=0)
   ->  Seq Scan on a  (cost=0.00..35.50 rows=2550 width=10)
(2 rows)

UPDATE 0

Regards,
Damir Belyalov
Postgres Professional
From c6cbc6fa9ddf24f29bc19ff115224dd76e351db1 Mon Sep 17 00:00:00 2001
From: Damir Belyalov 
Date: Tue, 5 Sep 2023 15:04:01 +0300
Subject: [PATCH 1/2] Output affected rows in EXPLAIN.

---
 src/backend/commands/explain.c | 10 +-
 src/backend/tcop/cmdtag.c  |  2 +-
 src/backend/tcop/pquery.c  |  8 +++-
 src/backend/tcop/utility.c | 27 ++-
 src/bin/psql/common.c  |  5 +++--
 src/include/commands/explain.h |  3 ++-
 src/include/tcop/cmdtag.h  |  1 +
 src/include/tcop/cmdtaglist.h  |  3 +++
 src/interfaces/libpq/fe-exec.c |  4 +++-
 9 files changed, 55 insertions(+), 8 deletions(-)

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 8570b14f62..453e545ba5 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -162,7 +162,7 @@ static void escape_yaml(StringInfo buf, const char *str);
  */
 void
 ExplainQuery(ParseState *pstate, ExplainStmt *stmt,
-			 ParamListInfo params, DestReceiver *dest)
+			 ParamListInfo params, DestReceiver *dest, uint64 *processed)
 {
 	ExplainState *es = NewExplainState();
 	TupOutputState *tstate;
@@ -173,6 +173,9 @@ ExplainQuery(ParseState *pstate, ExplainStmt *stmt,
 	bool		timing_set = false;
 	bool		summary_set = false;
 
+	if (processed)
+		*processed = 0;
+
 	/* Parse options list. */
 	foreach(lc, stmt->options)
 	{
@@ -311,6 +314,9 @@ ExplainQuery(ParseState *pstate, ExplainStmt *stmt,
 	end_tup_output(tstate);
 
 	pfree(es->str->data);
+
+	if (processed)
+		*processed = es->es_processed;
 }
 
 /*
@@ -649,6 +655,8 @@ ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
 	 */
 	INSTR_TIME_SET_CURRENT(starttime);
 
+	es->es_processed += queryDesc->estate->es_processed;
+
 	ExecutorEnd(queryDesc);
 
 	FreeQueryDesc(queryDesc);
diff --git a/src/backend/tcop/cmdtag.c b/src/backend/tcop/cmdtag.c
index 4bd713a0b4..9e6fdbd8af 100644
--- a/src/backend/tcop/cmdtag.c
+++ b/src/backend/tcop/cmdtag.c
@@ -146,7 +146,7 @@ BuildQueryCompletionString(char *buff, const QueryCompletion *qc,
 	 */
 	if (command_tag_display_rowcount(tag) && !nameonly)
 	{
-		if (tag == CMDTAG_INSERT)
+		if (tag == CMDTAG_INSERT || tag == CMDTAG_EXPLAIN_INSERT)
 		{
 			*bufp++ = ' ';
 			*bufp++ = '0';
diff --git a/src/backend/tcop/pquery.c b/src/backend/tcop/pquery.c
index 5565f200c3..ba0b33cc67 100644
--- a/src/backend/tcop/pquery.c
+++ b/src/backend/tcop/pquery.c
@@ -775,7 +775,13 @@ PortalRun(Portal portal, long count, bool isTopLevel, bool run_once,
 if (qc && portal->qc.commandTag != CMDTAG_UNKNOWN)
 {
 	CopyQueryCompletion(qc, >qc);
-	qc->nprocessed = nprocessed;
+	if (portal->qc.commandTag == CMDTAG_EXPLAIN ||
+		portal->qc.commandTag == CMDTAG_EXPLAIN_INSERT ||
+		portal->qc.commandTag == CMDTAG_EXPLAIN_UPDATE ||
+		portal->qc.commandTag == CMDTAG_EXPLAIN_DELETE)
+		qc->nprocessed = portal->qc.nprocessed;
+	else
+		qc->nprocessed = nprocessed;
 }
 
 /* Mark portal not active */
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index e3ccf6c7f7..8975d046f9 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -867,7 +867,32 @@ standard_ProcessUtility(PlannedStmt *pstmt,

Re: Output affected rows in EXPLAIN

2023-09-06 Thread Tom Lane 
Damir Belyalov  writes:
> I create a patch that outputs affected rows in EXPLAIN that occur by
> INSERT/UPDATE/DELETE.
> Despite the fact that commands in EXPLAIN ANALYZE query are executed as
> usual, EXPLAIN doesn't show outputting affected rows as in these commands.
> The patch fixes this problem.

This creates a bug, not fixes one.  It's intentional that "insert into a"
is shown as returning zero rows, because that's what it did.  If you'd
written "insert ... returning", you'd have gotten a different result:

=# explain analyze insert into a values (1);
QUERY PLAN  
  
--
 Insert on a  (cost=0.00..0.01 rows=0 width=0) (actual time=0.015..0.016 rows=0 
loops=1)
   ->  Result  (cost=0.00..0.01 rows=1 width=4) (actual time=0.001..0.001 
rows=1 loops=1)
 Planning Time: 0.015 ms
 Execution Time: 0.027 ms
(4 rows)

=# explain analyze insert into a values (1) returning *;
QUERY PLAN  
  
--
 Insert on a  (cost=0.00..0.01 rows=1 width=4) (actual time=0.026..0.028 rows=1 
loops=1)
   ->  Result  (cost=0.00..0.01 rows=1 width=4) (actual time=0.003..0.003 
rows=1 loops=1)
 Planning Time: 0.031 ms
 Execution Time: 0.051 ms
(4 rows)

Now admittedly, if you want to know the number of rows that went to disk,
you have to infer that from the number of rows emitted by the
ModifyTable's child plan.  But that's a matter for documentation
(and I'm pretty sure it's documented someplace).

regards, tom lane

Re: Output affected rows in EXPLAIN

2023-09-06 Thread Daniel Gustafsson 
> On 6 Sep 2023, at 14:49, Damir Belyalov  wrote

> The patch fixes this problem.

Given that EXPLAIN ANALYZE has worked like for a very long time, which problem
is it you have identified?

I'm also not convinced that the added "EXPLAIN" in the below plan is an
improvement in any way.

postgres=# explain (analyze) select * from t;
  QUERY PLAN
---
 Seq Scan on t  (cost=0.00..35.50 rows=2550 width=4) (actual time=0.064..0.075 
rows=5 loops=1)
 Planning Time: 1.639 ms
 Execution Time: 0.215 ms
(3 rows)

EXPLAIN
postgres=#

--
Daniel Gustafsson

Output affected rows in EXPLAIN

2023-09-06 Thread Damir Belyalov 
I create a patch that outputs affected rows in EXPLAIN that occur by
INSERT/UPDATE/DELETE.
Despite the fact that commands in EXPLAIN ANALYZE query are executed as
usual, EXPLAIN doesn't show outputting affected rows as in these commands.
The patch fixes this problem.

Examples:
explain analyze insert into a values (1);
QUERY PLAN

--
 Insert on a  (cost=0.00..0.01 rows=0 width=0) (actual time=0.076..0.077
rows=0 loops=1)
   ->  Result  (cost=0.00..0.01 rows=1 width=4) (actual time=0.002..0.002
rows=1 loops=1)
 Planning Time: 0.025 ms
 Execution Time: 0.412 ms
(4 rows)

INSERT 0 1

  QUERY PLAN

--
 Update on a  (cost=0.00..35.50 rows=0 width=0) (actual time=0.059..0.060
rows=0 loops=1)
   ->  Seq Scan on a  (cost=0.00..35.50 rows=2550 width=10) (actual
time=0.012..0.013 rows=7 loops=1)
 Planning Time: 0.142 ms
 Execution Time: 0.666 ms
(4 rows)

UPDATE 7

explain analyze delete from a where n = 1;
QUERY PLAN

---
 Delete on a  (cost=0.00..41.88 rows=0 width=0) (actual time=0.147..0.147
rows=0 loops=1)
   ->  Seq Scan on a  (cost=0.00..41.88 rows=13 width=6) (actual
time=0.120..0.123 rows=7 loops=1)
 Filter: (n = 1)
 Planning Time: 1.073 ms
 Execution Time: 0.178 ms
(5 rows)

DELETE 7

EXPLAIN queries without ANALYZE don't affect rows, so the output number is
0.

explain update a set n = 2;
 QUERY PLAN

 Update on a  (cost=0.00..35.50 rows=0 width=0)
   ->  Seq Scan on a  (cost=0.00..35.50 rows=2550 width=10)
(2 rows)

UPDATE 0

Maybe there is no need to add this row when EXPLAIN has no ANALYZE. So it
is a discussion question.
Also haven't fixed regress tests yet.

Regards,
Damir Belyalov
Postgres Professional
From c6cbc6fa9ddf24f29bc19ff115224dd76e351db1 Mon Sep 17 00:00:00 2001
From: Damir Belyalov 
Date: Tue, 5 Sep 2023 15:04:01 +0300
Subject: [PATCH] Output affected rows in EXPLAIN.

---
 src/backend/commands/explain.c | 10 +-
 src/backend/tcop/cmdtag.c  |  2 +-
 src/backend/tcop/pquery.c  |  8 +++-
 src/backend/tcop/utility.c | 27 ++-
 src/bin/psql/common.c  |  5 +++--
 src/include/commands/explain.h |  3 ++-
 src/include/tcop/cmdtag.h  |  1 +
 src/include/tcop/cmdtaglist.h  |  3 +++
 src/interfaces/libpq/fe-exec.c |  4 +++-
 9 files changed, 55 insertions(+), 8 deletions(-)

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 8570b14f62..453e545ba5 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -162,7 +162,7 @@ static void escape_yaml(StringInfo buf, const char *str);
  */
 void
 ExplainQuery(ParseState *pstate, ExplainStmt *stmt,
-			 ParamListInfo params, DestReceiver *dest)
+			 ParamListInfo params, DestReceiver *dest, uint64 *processed)
 {
 	ExplainState *es = NewExplainState();
 	TupOutputState *tstate;
@@ -173,6 +173,9 @@ ExplainQuery(ParseState *pstate, ExplainStmt *stmt,
 	bool		timing_set = false;
 	bool		summary_set = false;
 
+	if (processed)
+		*processed = 0;
+
 	/* Parse options list. */
 	foreach(lc, stmt->options)
 	{
@@ -311,6 +314,9 @@ ExplainQuery(ParseState *pstate, ExplainStmt *stmt,
 	end_tup_output(tstate);
 
 	pfree(es->str->data);
+
+	if (processed)
+		*processed = es->es_processed;
 }
 
 /*
@@ -649,6 +655,8 @@ ExplainOnePlan(PlannedStmt *plannedstmt, IntoClause *into, ExplainState *es,
 	 */
 	INSTR_TIME_SET_CURRENT(starttime);
 
+	es->es_processed += queryDesc->estate->es_processed;
+
 	ExecutorEnd(queryDesc);
 
 	FreeQueryDesc(queryDesc);
diff --git a/src/backend/tcop/cmdtag.c b/src/backend/tcop/cmdtag.c
index 4bd713a0b4..9e6fdbd8af 100644
--- a/src/backend/tcop/cmdtag.c
+++ b/src/backend/tcop/cmdtag.c
@@ -146,7 +146,7 @@ BuildQueryCompletionString(char *buff, const QueryCompletion *qc,
 	 */
 	if (command_tag_display_rowcount(tag) && !nameonly)
 	{
-		if (tag == CMDTAG_INSERT)
+		if (tag == CMDTAG_INSERT || tag == CMDTAG_EXPLAIN_INSERT)
 		{
 			*bufp++ = ' ';
 			*bufp++ = '0';
diff --git a/src/backend/tcop/pquery.c b/src/backend/tcop/pquery.c
index 5565f200c3..ba0b33cc67 100644
--- a/src/backend/tcop/pquery.c
+++ b/src/backend/tcop/pquery.c
@@ -775,7 +775,13 @@ PortalRun(Portal portal, long count, bool isTopLevel, bool run_once,
 if (qc && portal->qc.commandTag != CMDTAG_UNKNOWN)
 {
 	CopyQueryCompletion(qc, >qc);
-	qc->nprocessed = nprocessed;
+	if (portal->qc.commandTag == CMDTAG_EXPLAIN ||
+		portal->qc.commandTag == CMDTAG_EXPLAIN_INSERT ||
+