Converge all SQL-level statistics timing values to float8 milliseconds.

This patch adjusts the core statistics views to match the decision already
taken for pg_stat_statements, that values representing elapsed time should
be represented as float8 and measured in milliseconds.  By using float8,
we are no longer tied to a specific maximum precision of timing data.
(Internally, it's still microseconds, but we could now change that without
needing changes at the SQL level.)

The columns affected are
pg_stat_bgwriter.checkpoint_write_time
pg_stat_bgwriter.checkpoint_sync_time
pg_stat_database.blk_read_time
pg_stat_database.blk_write_time
pg_stat_user_functions.total_time
pg_stat_user_functions.self_time
pg_stat_xact_user_functions.total_time
pg_stat_xact_user_functions.self_time

The first four of these are new in 9.2, so there is no compatibility issue
from changing them.  The others require a release note comment that they
are now double precision (and can show a fractional part) rather than
bigint as before; also their underlying statistics functions now match
the column definitions, instead of returning bigint microseconds.

1 files changed, 10 insertions, 11 deletions

diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 8549d17f280..3583bbe3014 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -233,7 +233,7 @@ typedef struct PgStat_MsgTabstat
 	int			m_nentries;
 	int			m_xact_commit;
 	int			m_xact_rollback;
-	PgStat_Counter	  m_block_read_time;
+	PgStat_Counter	  m_block_read_time;		/* times in microseconds */
 	PgStat_Counter	  m_block_write_time;
 	PgStat_TableEntry m_entry[PGSTAT_NUM_TABENTRIES];
 } PgStat_MsgTabstat;
@@ -366,7 +366,7 @@ typedef struct PgStat_MsgBgWriter
 	PgStat_Counter m_buf_written_backend;
 	PgStat_Counter m_buf_fsync_backend;
 	PgStat_Counter m_buf_alloc;
-	PgStat_Counter m_checkpoint_write_time;
+	PgStat_Counter m_checkpoint_write_time;		/* times in milliseconds */
 	PgStat_Counter m_checkpoint_sync_time;
 } PgStat_MsgBgWriter;
 
@@ -407,8 +407,8 @@ typedef struct PgStat_MsgTempFile
 typedef struct PgStat_FunctionCounts
 {
 	PgStat_Counter f_numcalls;
-	instr_time	f_time;
-	instr_time	f_time_self;
+	instr_time	f_total_time;
+	instr_time	f_self_time;
 } PgStat_FunctionCounts;
 
 /* ----------
@@ -429,8 +429,8 @@ typedef struct PgStat_FunctionEntry
 {
 	Oid			f_id;
 	PgStat_Counter f_numcalls;
-	PgStat_Counter f_time;		/* times in microseconds */
-	PgStat_Counter f_time_self;
+	PgStat_Counter f_total_time;		/* times in microseconds */
+	PgStat_Counter f_self_time;
 } PgStat_FunctionEntry;
 
 /* ----------
@@ -545,7 +545,6 @@ typedef struct PgStat_StatDBEntry
 
 	TimestampTz stat_reset_timestamp;
 
-
 	/*
 	 * tables and functions must be last in the struct, because we don't write
 	 * the pointers out to the stats file.
@@ -601,8 +600,8 @@ typedef struct PgStat_StatFuncEntry
 
 	PgStat_Counter f_numcalls;
 
-	PgStat_Counter f_time;		/* times in microseconds */
-	PgStat_Counter f_time_self;
+	PgStat_Counter f_total_time;		/* times in microseconds */
+	PgStat_Counter f_self_time;
 } PgStat_StatFuncEntry;
 
 
@@ -705,7 +704,7 @@ typedef struct PgStat_FunctionCallUsage
 	/* NULL means we are not tracking the current function call */
 	PgStat_FunctionCounts *fs;
 	/* Total time previously charged to function, as of function start */
-	instr_time	save_f_time;
+	instr_time	save_f_total_time;
 	/* Backend-wide total time as of function start */
 	instr_time	save_total;
 	/* system clock as of function start */
@@ -730,7 +729,7 @@ extern char *pgstat_stat_filename;
 extern PgStat_MsgBgWriter BgWriterStats;
 
 /*
- * Updated by pgstat_count_time_* macros.
+ * Updated by pgstat_count_buffer_*_time macros
  */
 extern PgStat_Counter pgStatBlockReadTime;
 extern PgStat_Counter pgStatBlockWriteTime;