From 717f709532642f5f7756785c9be17b7ffcec8ae8 Mon Sep 17 00:00:00 2001 From: Andrew Dunstan Date: Fri, 27 Mar 2015 15:43:22 -0400 Subject: [PATCH] Add stats for min, max, mean, stddev times to pg_stat_statements. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The new fields are min_time, max_time, mean_time and stddev_time. Based on an original patch from Mitsumasa KONDO, modified by me. Reviewed by Petr Jelínek. --- contrib/pg_stat_statements/Makefile | 5 +- .../pg_stat_statements--1.2--1.3.sql | 47 ++++++++++ ...s--1.2.sql => pg_stat_statements--1.3.sql} | 8 +- .../pg_stat_statements/pg_stat_statements.c | 87 ++++++++++++++++++- .../pg_stat_statements.control | 2 +- doc/src/sgml/pgstatstatements.sgml | 28 ++++++ 6 files changed, 170 insertions(+), 7 deletions(-) create mode 100644 contrib/pg_stat_statements/pg_stat_statements--1.2--1.3.sql rename contrib/pg_stat_statements/{pg_stat_statements--1.2.sql => pg_stat_statements--1.3.sql} (84%) diff --git a/contrib/pg_stat_statements/Makefile b/contrib/pg_stat_statements/Makefile index 270990964c..975a637897 100644 --- a/contrib/pg_stat_statements/Makefile +++ b/contrib/pg_stat_statements/Makefile @@ -4,8 +4,9 @@ MODULE_big = pg_stat_statements OBJS = pg_stat_statements.o $(WIN32RES) EXTENSION = pg_stat_statements -DATA = pg_stat_statements--1.2.sql pg_stat_statements--1.1--1.2.sql \ - pg_stat_statements--1.0--1.1.sql pg_stat_statements--unpackaged--1.0.sql +DATA = pg_stat_statements--1.3.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" ifdef USE_PGXS diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.2--1.3.sql b/contrib/pg_stat_statements/pg_stat_statements--1.2--1.3.sql new file mode 100644 index 0000000000..a56f151b99 --- /dev/null +++ b/contrib/pg_stat_statements/pg_stat_statements--1.2--1.3.sql @@ -0,0 +1,47 @@ +/* contrib/pg_stat_statements/pg_stat_statements--1.2--1.3.sql */ + +-- complain if script is sourced in psql, rather than via ALTER EXTENSION +\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.3'" to load this file. \quit + +/* First we have to remove them from the extension */ +ALTER EXTENSION pg_stat_statements DROP VIEW pg_stat_statements; +ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements(boolean); + +/* Then we can drop them */ +DROP VIEW pg_stat_statements; +DROP FUNCTION pg_stat_statements(boolean); + +/* Now redefine */ +CREATE FUNCTION pg_stat_statements(IN showtext boolean, + OUT userid oid, + OUT dbid oid, + OUT queryid bigint, + OUT query text, + OUT calls int8, + OUT total_time float8, + OUT min_time float8, + OUT max_time float8, + OUT mean_time float8, + OUT stddev_time float8, + OUT rows int8, + OUT shared_blks_hit int8, + OUT shared_blks_read int8, + OUT shared_blks_dirtied int8, + OUT shared_blks_written int8, + OUT local_blks_hit int8, + OUT local_blks_read int8, + OUT local_blks_dirtied int8, + OUT local_blks_written int8, + OUT temp_blks_read int8, + OUT temp_blks_written int8, + OUT blk_read_time float8, + OUT blk_write_time float8 +) +RETURNS SETOF record +AS 'MODULE_PATHNAME', 'pg_stat_statements_1_3' +LANGUAGE C STRICT VOLATILE; + +CREATE VIEW pg_stat_statements AS + SELECT * FROM pg_stat_statements(true); + +GRANT SELECT ON pg_stat_statements TO PUBLIC; diff --git a/contrib/pg_stat_statements/pg_stat_statements--1.2.sql b/contrib/pg_stat_statements/pg_stat_statements--1.3.sql similarity index 84% rename from contrib/pg_stat_statements/pg_stat_statements--1.2.sql rename to contrib/pg_stat_statements/pg_stat_statements--1.3.sql index 5bfa9a55d0..92ed0571e9 100644 --- a/contrib/pg_stat_statements/pg_stat_statements--1.2.sql +++ b/contrib/pg_stat_statements/pg_stat_statements--1.3.sql @@ -1,4 +1,4 @@ -/* contrib/pg_stat_statements/pg_stat_statements--1.2.sql */ +/* contrib/pg_stat_statements/pg_stat_statements--1.3.sql */ -- complain if script is sourced in psql, rather than via CREATE EXTENSION \echo Use "CREATE EXTENSION pg_stat_statements" to load this file. \quit @@ -16,6 +16,10 @@ CREATE FUNCTION pg_stat_statements(IN showtext boolean, OUT query text, OUT calls int8, OUT total_time float8, + OUT min_time float8, + OUT max_time float8, + OUT mean_time float8, + OUT stddev_time float8, OUT rows int8, OUT shared_blks_hit int8, OUT shared_blks_read int8, @@ -31,7 +35,7 @@ CREATE FUNCTION pg_stat_statements(IN showtext boolean, OUT blk_write_time float8 ) RETURNS SETOF record -AS 'MODULE_PATHNAME', 'pg_stat_statements_1_2' +AS 'MODULE_PATHNAME', 'pg_stat_statements_1_3' LANGUAGE C STRICT VOLATILE; -- Register a view on the function for ease of use. diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c index 95616b3691..ec0846d0a8 100644 --- a/contrib/pg_stat_statements/pg_stat_statements.c +++ b/contrib/pg_stat_statements/pg_stat_statements.c @@ -115,7 +115,8 @@ typedef enum pgssVersion { PGSS_V1_0 = 0, PGSS_V1_1, - PGSS_V1_2 + PGSS_V1_2, + PGSS_V1_3 } pgssVersion; /* @@ -136,6 +137,10 @@ typedef struct Counters { int64 calls; /* # of times executed */ double total_time; /* total execution time, in msec */ + double min_time; /* minimim execution time in msec */ + double max_time; /* maximum execution time in msec */ + double mean_time; /* mean execution time in msec */ + double sum_var_time; /* sum of variances in 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 */ @@ -274,6 +279,7 @@ void _PG_fini(void); PG_FUNCTION_INFO_V1(pg_stat_statements_reset); 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); static void pgss_shmem_startup(void); @@ -320,6 +326,7 @@ static char *generate_normalized_query(pgssJumbleState *jstate, const char *quer int *query_len_p, int encoding); static void fill_in_constant_lengths(pgssJumbleState *jstate, const char *query); static int comp_location(const void *a, const void *b); +static inline double sqrtd(const double x); /* @@ -1215,6 +1222,32 @@ pgss_store(const char *query, uint32 queryId, e->counters.calls += 1; e->counters.total_time += total_time; + if (e->counters.calls == 1) + { + e->counters.min_time = total_time; + e->counters.max_time = total_time; + e->counters.mean_time = total_time; + } + else + { + /* + * Welford's method for accurately computing variance. + * See + */ + double old_mean = e->counters.mean_time; + + e->counters.mean_time += + (total_time - old_mean) / e->counters.calls; + e->counters.sum_var_time += + (total_time - old_mean) * (total_time - e->counters.mean_time); + + /* calculate min and max time */ + if (e->counters.min_time > total_time) + e->counters.min_time = total_time; + if (e->counters.max_time < total_time) + e->counters.max_time = total_time; + + } e->counters.rows += rows; e->counters.shared_blks_hit += bufusage->shared_blks_hit; e->counters.shared_blks_read += bufusage->shared_blks_read; @@ -1259,7 +1292,8 @@ pg_stat_statements_reset(PG_FUNCTION_ARGS) #define PG_STAT_STATEMENTS_COLS_V1_0 14 #define PG_STAT_STATEMENTS_COLS_V1_1 18 #define PG_STAT_STATEMENTS_COLS_V1_2 19 -#define PG_STAT_STATEMENTS_COLS 19 /* maximum of above */ +#define PG_STAT_STATEMENTS_COLS_V1_3 23 +#define PG_STAT_STATEMENTS_COLS 23 /* maximum of above */ /* * Retrieve statement statistics. @@ -1271,6 +1305,16 @@ pg_stat_statements_reset(PG_FUNCTION_ARGS) * expected API version is identified by embedding it in the C name of the * function. Unfortunately we weren't bright enough to do that for 1.1. */ +Datum +pg_stat_statements_1_3(PG_FUNCTION_ARGS) +{ + bool showtext = PG_GETARG_BOOL(0); + + pg_stat_statements_internal(fcinfo, PGSS_V1_3, showtext); + + return (Datum) 0; +} + Datum pg_stat_statements_1_2(PG_FUNCTION_ARGS) { @@ -1360,6 +1404,10 @@ pg_stat_statements_internal(FunctionCallInfo fcinfo, if (api_version != PGSS_V1_2) elog(ERROR, "incorrect number of output arguments"); break; + case PG_STAT_STATEMENTS_COLS_V1_3: + if (api_version != PGSS_V1_3) + elog(ERROR, "incorrect number of output arguments"); + break; default: elog(ERROR, "incorrect number of output arguments"); } @@ -1519,6 +1567,23 @@ pg_stat_statements_internal(FunctionCallInfo fcinfo, values[i++] = Int64GetDatumFast(tmp.calls); values[i++] = Float8GetDatumFast(tmp.total_time); + if (api_version >= PGSS_V1_3) + { + values[i++] = Float8GetDatumFast(tmp.min_time); + values[i++] = Float8GetDatumFast(tmp.max_time); + values[i++] = Float8GetDatumFast(tmp.mean_time); + /* + * Note we are calculating the population variance here, not the + * sample variance, as we have data for the whole population, + * so Bessel's correction is not used, and we don't divide by + * tmp.calls - 1. + */ + if (tmp.calls > 1) + values[i++] = + Float8GetDatumFast(sqrtd(tmp.sum_var_time / tmp.calls)); + else + values[i++] = Float8GetDatumFast(0.0); + } values[i++] = Int64GetDatumFast(tmp.rows); values[i++] = Int64GetDatumFast(tmp.shared_blks_hit); values[i++] = Int64GetDatumFast(tmp.shared_blks_read); @@ -1541,6 +1606,7 @@ pg_stat_statements_internal(FunctionCallInfo fcinfo, Assert(i == (api_version == PGSS_V1_0 ? PG_STAT_STATEMENTS_COLS_V1_0 : api_version == PGSS_V1_1 ? PG_STAT_STATEMENTS_COLS_V1_1 : api_version == PGSS_V1_2 ? PG_STAT_STATEMENTS_COLS_V1_2 : + api_version == PGSS_V1_3 ? PG_STAT_STATEMENTS_COLS_V1_3 : -1 /* fail if you forget to update this assert */ )); tuplestore_putvalues(tupstore, tupdesc, values, nulls); @@ -2899,3 +2965,20 @@ comp_location(const void *a, const void *b) else return 0; } + +/* + * fast sqrt algorithm: reference from Fast inverse square root algorithms. + */ +static inline double +sqrtd(const double x) +{ + double x_half = 0.5 * x; + long long int tmp = 0x5FE6EB50C7B537AAl - ( *(long long int*)&x >> 1); + double x_result = * (double*)&tmp; + + x_result *= (1.5 - (x_half * x_result * x_result)); + /* If retry this calculation, it becomes higher precision at sqrt */ + x_result *= (1.5 - (x_half * x_result * x_result)); + + return x_result * x; +} diff --git a/contrib/pg_stat_statements/pg_stat_statements.control b/contrib/pg_stat_statements/pg_stat_statements.control index 6ecf2b6d1b..53df9789df 100644 --- a/contrib/pg_stat_statements/pg_stat_statements.control +++ b/contrib/pg_stat_statements/pg_stat_statements.control @@ -1,5 +1,5 @@ # pg_stat_statements extension comment = 'track execution statistics of all SQL statements executed' -default_version = '1.2' +default_version = '1.3' module_pathname = '$libdir/pg_stat_statements' relocatable = true diff --git a/doc/src/sgml/pgstatstatements.sgml b/doc/src/sgml/pgstatstatements.sgml index a58ecf7065..04b3f01ed5 100644 --- a/doc/src/sgml/pgstatstatements.sgml +++ b/doc/src/sgml/pgstatstatements.sgml @@ -86,6 +86,34 @@ Total time spent in the statement, in milliseconds + + min_time + double precision + + Minimum time spent in the statement, in milliseconds + + + + max_time + double precision + + Maximum time spent in the statement, in milliseconds + + + + mean_time + double precision + + Mean time spent in the statement, in milliseconds + + + + stddev_time + double precision + + Population standard deviation of time spent in the statement, in milliseconds + + rows bigint