Extend pg_stat_statements_reset to reset statistics specific to a

particular user/db/query.

The function pg_stat_statements_reset() is extended to accept userid, dbid,
and queryid as input parameters.  Now, it can discard the statistics
gathered so far by pg_stat_statements corresponding to the specified
userid, dbid, and queryid.  If no parameter is specified or all the
specified parameters have default value aka 0, it will discard all
statistics as per the old behavior.

The new behavior is useful to get the fresh statistics for a specific
user/database/query without resetting all the existing statistics.

Author: Haribabu Kommi, with few additional changes by me
Reviewed-by: Michael Paquier, Amit Kapila and Fujii Masao
Discussion: https://postgr.es/m/CAJrrPGcyh-gkFswyc6C661K6cknL0XkNqVT0sQt2mFNMR4HRKA@mail.gmail.com

contrib/pg_stat_statements/Makefile

@@ -4,10 +4,10 @@ MODULE_big = pg_stat_statements
 OBJS = pg_stat_statements.o $(WIN32RES)
 
 EXTENSION = pg_stat_statements
-DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.5--1.6.sql \
-	pg_stat_statements--1.4--1.5.sql pg_stat_statements--1.3--1.4.sql \
-	pg_stat_statements--1.2--1.3.sql pg_stat_statements--1.1--1.2.sql \
-	pg_stat_statements--1.0--1.1.sql \
+DATA = pg_stat_statements--1.4.sql pg_stat_statements--1.6--1.7.sql \
+	pg_stat_statements--1.5--1.6.sql pg_stat_statements--1.4--1.5.sql \
+	pg_stat_statements--1.3--1.4.sql pg_stat_statements--1.2--1.3.sql \
+	pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
 	pg_stat_statements--unpackaged--1.0.sql
 PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
 

contrib/pg_stat_statements/expected/pg_stat_statements.out

@@ -395,4 +395,202 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
  SELECT pg_stat_statements_reset()         |     1 |    1
 (8 rows)
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+SET ROLE regress_stats_user1;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+SELECT 1 AS "ONE";
+ ONE 
+-----
+   1
+(1 row)
+
+SELECT 1+1 AS "TWO";
+ TWO 
+-----
+   2
+(1 row)
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+               query               | calls | rows 
+-----------------------------------+-------+------
+ CREATE ROLE regress_stats_user1   |     1 |    0
+ CREATE ROLE regress_stats_user2   |     1 |    0
+ RESET ROLE                        |     2 |    0
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1 AS "ONE"                |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT $1+$2 AS "TWO"             |     1 |    1
+ SELECT pg_stat_statements_reset() |     1 |    1
+ SET ROLE regress_stats_user1      |     1 |    0
+ SET ROLE regress_stats_user2      |     1 |    0
+(10 rows)
+
+--
+-- Don't reset anything if any of the parameter is NULL
+--
+SELECT pg_stat_statements_reset(NULL);
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                    query                                     | calls | rows 
+------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                              |     1 |    0
+ CREATE ROLE regress_stats_user2                                              |     1 |    0
+ RESET ROLE                                                                   |     2 |    0
+ SELECT $1 AS "ONE"                                                           |     1 |    1
+ SELECT $1 AS "ONE"                                                           |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                        |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                        |     1 |    1
+ SELECT pg_stat_statements_reset($1)                                          |     1 |    1
+ SELECT pg_stat_statements_reset()                                            |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C" |     1 |   10
+ SET ROLE regress_stats_user1                                                 |     1 |    0
+ SET ROLE regress_stats_user2                                                 |     1 |    0
+(12 rows)
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1 AS "ONE"                                                               |     1 |    1
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     2 |   22
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(12 rows)
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(0,0,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+ pg_stat_statements_reset 
+--------------------------
+ 
+ 
+(2 rows)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT $1+$2 AS "TWO"                                                            |     1 |    1
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    2
+         FROM pg_stat_statements AS s WHERE s.query = $3                          |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     3 |   34
+ SET ROLE regress_stats_user1                                                     |     1 |    0
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(11 rows)
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                                      query                                       | calls | rows 
+----------------------------------------------------------------------------------+-------+------
+ CREATE ROLE regress_stats_user1                                                  |     1 |    0
+ CREATE ROLE regress_stats_user2                                                  |     1 |    0
+ RESET ROLE                                                                       |     2 |    0
+ SELECT pg_stat_statements_reset(                                                +|     1 |    1
+         (SELECT r.oid FROM pg_roles AS r WHERE r.rolname = $1),                 +|       | 
+         (SELECT d.oid FROM pg_database As d where datname = current_database()),+|       | 
+         (SELECT s.queryid FROM pg_stat_statements AS s                          +|       | 
+                                 WHERE s.query = $2 LIMIT $3))                    |       | 
+ SELECT pg_stat_statements_reset($1)                                              |     1 |    1
+ SELECT pg_stat_statements_reset($1,$2,s.queryid)                                +|     1 |    2
+         FROM pg_stat_statements AS s WHERE s.query = $3                          |       | 
+ SELECT pg_stat_statements_reset()                                                |     1 |    1
+ SELECT pg_stat_statements_reset(r.oid)                                          +|     1 |    1
+                 FROM pg_roles AS r WHERE r.rolname = $1                          |       | 
+ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C"     |     4 |   45
+ SET ROLE regress_stats_user2                                                     |     1 |    0
+(10 rows)
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset(0,0,0);
+ pg_stat_statements_reset 
+--------------------------
+ 
+(1 row)
+
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+                 query                  | calls | rows 
+----------------------------------------+-------+------
+ SELECT pg_stat_statements_reset(0,0,0) |     1 |    1
+(1 row)
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
 DROP EXTENSION pg_stat_statements;

contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql

+/* contrib/pg_stat_statements/pg_stat_statements--1.6--1.7.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.7'" to load this file. \quit
+
+/* First we have to remove them from the extension */
+ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements_reset();
+
+/* Then we can drop them */
+DROP FUNCTION pg_stat_statements_reset();
+
+/* Now redefine */
+CREATE FUNCTION pg_stat_statements_reset(IN userid Oid DEFAULT 0,
+	IN dbid Oid DEFAULT 0,
+	IN queryid bigint DEFAULT 0
+)
+RETURNS void
+AS 'MODULE_PATHNAME', 'pg_stat_statements_reset_1_7'
+LANGUAGE C STRICT PARALLEL SAFE;
+
+-- Don't want this to be available to non-superusers.
+REVOKE ALL ON FUNCTION pg_stat_statements_reset(Oid, Oid, bigint) FROM PUBLIC;

contrib/pg_stat_statements/pg_stat_statements.c

@@ -290,6 +290,7 @@ void		_PG_init(void);
 void		_PG_fini(void);
 
 PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
+PG_FUNCTION_INFO_V1(pg_stat_statements_reset_1_7);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
 PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
 PG_FUNCTION_INFO_V1(pg_stat_statements);
@@ -327,7 +328,7 @@ static char *qtext_fetch(Size query_offset, int query_len,
 			char *buffer, Size buffer_size);
 static bool need_gc_qtexts(void);
 static void gc_qtexts(void);
-static void entry_reset(void);
+static void entry_reset(Oid userid, Oid dbid, uint64 queryid);
 static void AppendJumble(pgssJumbleState *jstate,
 			 const unsigned char *item, Size size);
 static void JumbleQuery(pgssJumbleState *jstate, Query *query);
@@ -1148,8 +1149,17 @@ pgss_store(const char *query, uint64 queryId,
 	 * For utility statements, we just hash the query string to get an ID.
 	 */
 	if (queryId == UINT64CONST(0))
+	{
 		queryId = pgss_hash_string(query, query_len);
 
+		/*
+		 * If we are unlucky enough to get a hash of zero(invalid), use queryID
+		 * as 2 instead, queryID 1 is already in use for normal statements.
+		 */
+		if (queryId == UINT64CONST(0))
+			queryId = UINT64CONST(2);
+	}
+
 	/* Set up key for hashtable search */
 	key.userid = GetUserId();
 	key.dbid = MyDatabaseId;
@@ -1293,16 +1303,32 @@ done:
 }
 
 /*
- * Reset all statement statistics.
+ * Reset statement statistics corresponding to userid, dbid, and queryid.
+ */
+Datum
+pg_stat_statements_reset_1_7(PG_FUNCTION_ARGS)
+{
+	Oid			userid;
+	Oid			dbid;
+	uint64		queryid;
+
+	userid = PG_GETARG_OID(0);
+	dbid = PG_GETARG_OID(1);
+	queryid = (uint64) PG_GETARG_INT64(2);
+
+	entry_reset(userid, dbid, queryid);
+
+	PG_RETURN_VOID();
+}
+
+/*
+ * Reset statement statistics.
  */
 Datum
 pg_stat_statements_reset(PG_FUNCTION_ARGS)
 {
-	if (!pgss || !pgss_hash)
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
-	entry_reset();
+	entry_reset(0, 0, 0);
+
 	PG_RETURN_VOID();
 }
 
@@ -2229,23 +2255,68 @@ gc_fail:
 }
 
 /*
- * Release all entries.
+ * Release entries corresponding to parameters passed.
  */
 static void
-entry_reset(void)
+entry_reset(Oid userid, Oid dbid, uint64 queryid)
 {
 	HASH_SEQ_STATUS hash_seq;
 	pgssEntry  *entry;
 	FILE	   *qfile;
+	long		num_entries;
+	long		num_remove = 0;
+	pgssHashKey key;
+
+	if (!pgss || !pgss_hash)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("pg_stat_statements must be loaded via shared_preload_libraries")));
 
 	LWLockAcquire(pgss->lock, LW_EXCLUSIVE);
+	num_entries = hash_get_num_entries(pgss_hash);
 
-	hash_seq_init(&hash_seq, pgss_hash);
-	while ((entry = hash_seq_search(&hash_seq)) != NULL)
+	if (userid != 0 && dbid != 0 && queryid != UINT64CONST(0))
+	{
+		/* If all the parameters are available, use the fast path. */
+		key.userid = userid;
+		key.dbid = dbid;
+		key.queryid = queryid;
+
+		/* Remove the key if exists */
+		entry = (pgssEntry *) hash_search(pgss_hash, &key, HASH_REMOVE, NULL);
+		if (entry)				/* found */
+			num_remove++;
+	}
+	else if (userid != 0 || dbid != 0 || queryid != UINT64CONST(0))
 	{
-		hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+		/* Remove entries corresponding to valid parameters. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			if ((!userid || entry->key.userid == userid) &&
+				(!dbid || entry->key.dbid == dbid) &&
+				(!queryid || entry->key.queryid == queryid))
+			{
+				hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+				num_remove++;
+			}
+		}
+	}
+	else
+	{
+		/* Remove all entries. */
+		hash_seq_init(&hash_seq, pgss_hash);
+		while ((entry = hash_seq_search(&hash_seq)) != NULL)
+		{
+			hash_search(pgss_hash, &entry->key, HASH_REMOVE, NULL);
+			num_remove++;
+		}
 	}
 
+	/* All entries are removed? */
+	if (num_entries != num_remove)
+		goto release_lock;
+
 	/*
 	 * Write new empty query file, perhaps even creating a new one to recover
 	 * if the file was missing.
@@ -2274,6 +2345,7 @@ done:
 	/* This counts as a query text garbage collection for our purposes */
 	record_gc_qtexts();
 
+release_lock:
 	LWLockRelease(pgss->lock);
 }
 

contrib/pg_stat_statements/pg_stat_statements.control

 # pg_stat_statements extension
 comment = 'track execution statistics of all SQL statements executed'
-default_version = '1.6'
+default_version = '1.7'
 module_pathname = '$libdir/pg_stat_statements'
 relocatable = true

contrib/pg_stat_statements/sql/pg_stat_statements.sql

@@ -195,4 +195,68 @@ DROP FUNCTION PLUS_TWO(INTEGER);
 
 SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
 
+--
+-- Track user activity and reset them
+--
+SELECT pg_stat_statements_reset();
+CREATE ROLE regress_stats_user1;
+CREATE ROLE regress_stats_user2;
+
+SET ROLE regress_stats_user1;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SET ROLE regress_stats_user2;
+
+SELECT 1 AS "ONE";
+SELECT 1+1 AS "TWO";
+
+RESET ROLE;
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- Don't reset anything if any of the parameter is NULL
+--
+SELECT pg_stat_statements_reset(NULL);
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1+$2 AS "TWO"') executed by regress_stats_user2
+-- in the current_database
+--
+SELECT pg_stat_statements_reset(
+	(SELECT r.oid FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user2'),
+	(SELECT d.oid FROM pg_database As d where datname = current_database()),
+	(SELECT s.queryid FROM pg_stat_statements AS s
+				WHERE s.query = 'SELECT $1+$2 AS "TWO"' LIMIT 1));
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query ('SELECT $1 AS "ONE"') executed by two users
+--
+SELECT pg_stat_statements_reset(0,0,s.queryid)
+	FROM pg_stat_statements AS s WHERE s.query = 'SELECT $1 AS "ONE"';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- remove query of a user (regress_stats_user1)
+--
+SELECT pg_stat_statements_reset(r.oid)
+		FROM pg_roles AS r WHERE r.rolname = 'regress_stats_user1';
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- reset all
+--
+SELECT pg_stat_statements_reset(0,0,0);
+SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
+
+--
+-- cleanup
+--
+DROP ROLE regress_stats_user1;
+DROP ROLE regress_stats_user2;
+
 DROP EXTENSION pg_stat_statements;

doc/src/sgml/pgstatstatements.sgml

@@ -336,7 +336,7 @@
   <variablelist>
    <varlistentry>
     <term>
-     <function>pg_stat_statements_reset() returns void</function>
+     <function>pg_stat_statements_reset(userid Oid, dbid Oid, queryid bigint) returns void</function>
      <indexterm>
       <primary>pg_stat_statements_reset</primary>
      </indexterm>
@@ -344,9 +344,16 @@
 
     <listitem>
      <para>
-      <function>pg_stat_statements_reset</function> discards all statistics
-      gathered so far by <filename>pg_stat_statements</filename>.
-      By default, this function can only be executed by superusers.
+      <function>pg_stat_statements_reset</function> discards statistics
+      gathered so far by <filename>pg_stat_statements</filename> corresponding
+      to the specified <structfield>userid</structfield>, <structfield>dbid</structfield>
+      and <structfield>queryid</structfield>.  If any of the parameters are not
+      specified, the default value <literal>0</literal>(invalid) is used for
+      each of them and the statistics that match with other parameters will be
+      reset.  If no parameter is specified or all the specified parameters are
+      <literal>0</literal>(invalid), it will discard all statistics.  By
+      default, this function can only be executed by superusers.  Access may be
+      granted to others using <command>GRANT</command>.
      </para>
     </listitem>
    </varlistentry>
@@ -494,36 +501,87 @@ bench=# \x
 bench=# SELECT query, calls, total_time, rows, 100.0 * shared_blks_hit /
                nullif(shared_blks_hit + shared_blks_read, 0) AS hit_percent
           FROM pg_stat_statements ORDER BY total_time DESC LIMIT 5;
--[ RECORD 1 ]---------------------------------------------------------------------
-query       | UPDATE pgbench_branches SET bbalance = bbalance + $1 WHERE bid = $2;
+-[ RECORD 1 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_branches SET bbalance = bbalance + $1 WHERE bid = $2
 calls       | 3000
-total_time  | 9609.00100000002
-rows        | 2836
-hit_percent | 99.9778970000200936
--[ RECORD 2 ]---------------------------------------------------------------------
-query       | UPDATE pgbench_tellers SET tbalance = tbalance + $1 WHERE tid = $2;
+total_time  | 25565.855387
+rows        | 3000
+hit_percent | 100.0000000000000000
+-[ RECORD 2 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_tellers SET tbalance = tbalance + $1 WHERE tid = $2
 calls       | 3000
-total_time  | 8015.156
-rows        | 2990
-hit_percent | 99.9731126579631345
--[ RECORD 3 ]---------------------------------------------------------------------
+total_time  | 20756.669379
+rows        | 3000
+hit_percent | 100.0000000000000000
+-[ RECORD 3 ]--------------------------------------------------------------------
 query       | copy pgbench_accounts from stdin
 calls       | 1
-total_time  | 310.624
+total_time  | 291.865911
 rows        | 100000
-hit_percent | 0.30395136778115501520
--[ RECORD 4 ]---------------------------------------------------------------------
-query       | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2;
+hit_percent | 100.0000000000000000
+-[ RECORD 4 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2
 calls       | 3000
-total_time  | 271.741999999997
+total_time  | 271.232977
 rows        | 3000
-hit_percent | 93.7968855088209426
--[ RECORD 5 ]---------------------------------------------------------------------
+hit_percent | 98.5723926698852723
+-[ RECORD 5 ]--------------------------------------------------------------------
 query       | alter table pgbench_accounts add primary key (aid)
 calls       | 1
-total_time  | 81.42
+total_time  | 160.588563
 rows        | 0
-hit_percent | 34.4947735191637631
+hit_percent | 100.0000000000000000
+
+
+bench=# SELECT pg_stat_statements_reset(0,0,s.queryid) FROM pg_stat_statements AS s
+            WHERE s.query = 'UPDATE pgbench_branches SET bbalance = bbalance + $1 WHERE bid = $2';
+
+bench=# SELECT query, calls, total_time, rows, 100.0 * shared_blks_hit /
+               nullif(shared_blks_hit + shared_blks_read, 0) AS hit_percent
+          FROM pg_stat_statements ORDER BY total_time DESC LIMIT 5;
+-[ RECORD 1 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_tellers SET tbalance = tbalance + $1 WHERE tid = $2
+calls       | 3000
+total_time  | 20756.669379
+rows        | 3000
+hit_percent | 100.0000000000000000
+-[ RECORD 2 ]--------------------------------------------------------------------
+query       | copy pgbench_accounts from stdin
+calls       | 1
+total_time  | 291.865911
+rows        | 100000
+hit_percent | 100.0000000000000000
+-[ RECORD 3 ]--------------------------------------------------------------------
+query       | UPDATE pgbench_accounts SET abalance = abalance + $1 WHERE aid = $2
+calls       | 3000
+total_time  | 271.232977
+rows        | 3000
+hit_percent | 98.5723926698852723
+-[ RECORD 4 ]--------------------------------------------------------------------
+query       | alter table pgbench_accounts add primary key (aid)
+calls       | 1
+total_time  | 160.588563
+rows        | 0
+hit_percent | 100.0000000000000000
+-[ RECORD 5 ]--------------------------------------------------------------------
+query       | vacuum analyze pgbench_accounts
+calls       | 1
+total_time  | 136.448116
+rows        | 0
+hit_percent | 99.9201915403032721
+
+bench=# SELECT pg_stat_statements_reset(0,0,0);
+
+bench=# SELECT query, calls, total_time, rows, 100.0 * shared_blks_hit /
+               nullif(shared_blks_hit + shared_blks_read, 0) AS hit_percent
+          FROM pg_stat_statements ORDER BY total_time DESC LIMIT 5;
+-[ RECORD 1 ]---------------------------------------
+query       | SELECT pg_stat_statements_reset(0,0,0)
+calls       | 1
+total_time  | 0.189497
+rows        | 1
+hit_percent | 
+
 </screen>
  </sect2>