Adjust timing units in pg_stat_statements.

Display total time and I/O timings in milliseconds, for consistency with
the units used for timings in the core statistics views.  The columns
remain of float8 type, so that sub-msec precision is available.  (At some
point we will probably want to convert the core views to use float8 type
for the same reason, but this patch does not touch that issue.)

This is a release-note-requiring change in the meaning of the total_time
column.  The I/O timing columns are new as of 9.2, so there is no
compatibility impact from redefining them.

Do some minor copy-editing in the documentation, too.

contrib/pg_stat_statements/pg_stat_statements.c

@@ -101,7 +101,7 @@ typedef struct pgssHashKey
 typedef struct Counters
 {
 	int64		calls;			/* # of times executed */
-	double		total_time;		/* total execution time in seconds */
+	double		total_time;		/* total execution time, in msec */
 	int64		rows;			/* total # of retrieved or affected rows */
 	int64		shared_blks_hit;	/* # of shared buffer hits */
 	int64		shared_blks_read;		/* # of shared disk blocks read */
@@ -113,8 +113,8 @@ typedef struct Counters
 	int64		local_blks_written;		/* # of local disk blocks written */
 	int64		temp_blks_read; /* # of temp blocks read */
 	int64		temp_blks_written;		/* # of temp blocks written */
-	double		time_read;		/* time spent reading in seconds */
-	double		time_write;		/* time spent writing in seconds */
+	double		time_read;		/* time spent reading, in msec */
+	double		time_write;		/* time spent writing, in msec */
 	double		usage;			/* usage factor */
 } Counters;
 
@@ -752,7 +752,7 @@ pgss_ExecutorEnd(QueryDesc *queryDesc)
 
 		pgss_store(queryDesc->sourceText,
 				   queryId,
-				   queryDesc->totaltime->total,
+				   queryDesc->totaltime->total * 1000.0, /* convert to msec */
 				   queryDesc->estate->es_processed,
 				   &queryDesc->totaltime->bufusage,
 				   NULL);
@@ -856,7 +856,7 @@ pgss_ProcessUtility(Node *parsetree, const char *queryString,
 
 		pgss_store(queryString,
 				   queryId,
-				   INSTR_TIME_GET_DOUBLE(duration),
+				   INSTR_TIME_GET_MILLISEC(duration),
 				   rows,
 				   &bufusage,
 				   NULL);
@@ -1021,9 +1021,9 @@ pgss_store(const char *query, uint32 queryId,
 		e->counters.local_blks_written += bufusage->local_blks_written;
 		e->counters.temp_blks_read += bufusage->temp_blks_read;
 		e->counters.temp_blks_written += bufusage->temp_blks_written;
-		e->counters.time_read += INSTR_TIME_GET_DOUBLE(bufusage->time_read);
-		e->counters.time_write += INSTR_TIME_GET_DOUBLE(bufusage->time_write);
-		e->counters.usage += USAGE_EXEC(duration);
+		e->counters.time_read += INSTR_TIME_GET_MILLISEC(bufusage->time_read);
+		e->counters.time_write += INSTR_TIME_GET_MILLISEC(bufusage->time_write);
+		e->counters.usage += USAGE_EXEC(total_time);
 
 		SpinLockRelease(&e->mutex);
 	}

doc/src/sgml/pgstatstatements.sgml

@@ -75,7 +75,7 @@
       <entry><structfield>total_time</structfield></entry>
       <entry><type>double precision</type></entry>
       <entry></entry>
-      <entry>Total time spent in the statement, in seconds</entry>
+      <entry>Total time spent in the statement, in milliseconds</entry>
      </row>
 
      <row>
@@ -89,14 +89,14 @@
       <entry><structfield>shared_blks_hit</structfield></entry>
       <entry><type>bigint</type></entry>
       <entry></entry>
-      <entry>Total number of shared blocks hits by the statement</entry>
+      <entry>Total number of shared block cache hits by the statement</entry>
      </row>
 
      <row>
       <entry><structfield>shared_blks_read</structfield></entry>
       <entry><type>bigint</type></entry>
       <entry></entry>
-      <entry>Total number of shared blocks reads by the statement</entry>
+      <entry>Total number of shared blocks read by the statement</entry>
      </row>
 
      <row>
@@ -110,21 +110,21 @@
       <entry><structfield>shared_blks_written</structfield></entry>
       <entry><type>bigint</type></entry>
       <entry></entry>
-      <entry>Total number of shared blocks writes by the statement</entry>
+      <entry>Total number of shared blocks written by the statement</entry>
      </row>
 
      <row>
       <entry><structfield>local_blks_hit</structfield></entry>
       <entry><type>bigint</type></entry>
       <entry></entry>
-      <entry>Total number of local blocks hits by the statement</entry>
+      <entry>Total number of local block cache hits by the statement</entry>
      </row>
 
      <row>
       <entry><structfield>local_blks_read</structfield></entry>
       <entry><type>bigint</type></entry>
       <entry></entry>
-      <entry>Total number of local blocks reads by the statement</entry>
+      <entry>Total number of local blocks read by the statement</entry>
      </row>
 
      <row>
@@ -138,21 +138,21 @@
       <entry><structfield>local_blks_written</structfield></entry>
       <entry><type>bigint</type></entry>
       <entry></entry>
-      <entry>Total number of local blocks writes by the statement</entry>
+      <entry>Total number of local blocks written by the statement</entry>
      </row>
 
      <row>
       <entry><structfield>temp_blks_read</structfield></entry>
       <entry><type>bigint</type></entry>
       <entry></entry>
-      <entry>Total number of temp blocks reads by the statement</entry>
+      <entry>Total number of temp blocks read by the statement</entry>
      </row>
 
      <row>
       <entry><structfield>temp_blks_written</structfield></entry>
       <entry><type>bigint</type></entry>
       <entry></entry>
-      <entry>Total number of temp blocks writes by the statement</entry>
+      <entry>Total number of temp blocks written by the statement</entry>
      </row>
 
      <row>
@@ -160,7 +160,7 @@
       <entry><type>double precision</type></entry>
       <entry></entry>
       <entry>
-        Total time the statement spent reading blocks, in seconds
+        Total time the statement spent reading blocks, in milliseconds
         (if <xref linkend="guc-track-iotiming"> is enabled, otherwise zero)
       </entry>
      </row>
@@ -170,7 +170,7 @@
       <entry><type>double precision</type></entry>
       <entry></entry>
       <entry>
-        Total time the statement spent writing blocks, in seconds
+        Total time the statement spent writing blocks, in milliseconds
         (if <xref linkend="guc-track-iotiming"> is enabled, otherwise zero)
       </entry>
      </row>
@@ -285,7 +285,7 @@
       Specify <literal>top</> to track top-level statements (those issued
       directly by clients), <literal>all</> to also track nested statements
       (such as statements invoked within functions), or <literal>none</> to
-      disable.
+      disable statement statistics collection.
       The default value is <literal>top</>.
       Only superusers can change this setting.
      </para>
@@ -366,31 +366,31 @@ bench=# SELECT query, calls, total_time, rows, 100.0 * shared_blks_hit /
 -[ RECORD 1 ]---------------------------------------------------------------------
 query       | UPDATE pgbench_branches SET bbalance = bbalance + ? WHERE bid = ?;
 calls       | 3000
-total_time  | 9.60900100000002
+total_time  | 9609.00100000002
 rows        | 2836
 hit_percent | 99.9778970000200936
 -[ RECORD 2 ]---------------------------------------------------------------------
 query       | UPDATE pgbench_tellers SET tbalance = tbalance + ? WHERE tid = ?;
 calls       | 3000
-total_time  | 8.015156
+total_time  | 8015.156
 rows        | 2990
 hit_percent | 99.9731126579631345
 -[ RECORD 3 ]---------------------------------------------------------------------
 query       | copy pgbench_accounts from stdin
 calls       | 1
-total_time  | 0.310624
+total_time  | 310.624
 rows        | 100000
 hit_percent | 0.30395136778115501520
 -[ RECORD 4 ]---------------------------------------------------------------------
 query       | UPDATE pgbench_accounts SET abalance = abalance + ? WHERE aid = ?;
 calls       | 3000
-total_time  | 0.271741999999997
+total_time  | 271.741999999997
 rows        | 3000
 hit_percent | 93.7968855088209426
 -[ RECORD 5 ]---------------------------------------------------------------------
 query       | alter table pgbench_accounts add primary key (aid)
 calls       | 1
-total_time  | 0.08142
+total_time  | 81.42
 rows        | 0
 hit_percent | 34.4947735191637631
 </screen>