mirror of https://github.com/postgres/postgres
Add stats for min, max, mean, stddev times to pg_stat_statements.
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.
This commit is contained in:
Andrew Dunstan
parent
8816af65e4
commit
717f709532
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@ -4,8 +4,9 @@ MODULE_big = pg_stat_statements
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OBJS = pg_stat_statements.o $(WIN32RES)
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EXTENSION = pg_stat_statements
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DATA = pg_stat_statements--1.2.sql pg_stat_statements--1.1--1.2.sql \
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pg_stat_statements--1.0--1.1.sql pg_stat_statements--unpackaged--1.0.sql
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DATA = pg_stat_statements--1.3.sql pg_stat_statements--1.2--1.3.sql \
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pg_stat_statements--1.1--1.2.sql pg_stat_statements--1.0--1.1.sql \
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pg_stat_statements--unpackaged--1.0.sql
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PGFILEDESC = "pg_stat_statements - execution statistics of SQL statements"
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ifdef USE_PGXS
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@ -0,0 +1,47 @@
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/* contrib/pg_stat_statements/pg_stat_statements--1.2--1.3.sql */
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-- complain if script is sourced in psql, rather than via ALTER EXTENSION
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\echo Use "ALTER EXTENSION pg_stat_statements UPDATE TO '1.3'" to load this file. \quit
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/* First we have to remove them from the extension */
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ALTER EXTENSION pg_stat_statements DROP VIEW pg_stat_statements;
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ALTER EXTENSION pg_stat_statements DROP FUNCTION pg_stat_statements(boolean);
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/* Then we can drop them */
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DROP VIEW pg_stat_statements;
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DROP FUNCTION pg_stat_statements(boolean);
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/* Now redefine */
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CREATE FUNCTION pg_stat_statements(IN showtext boolean,
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OUT userid oid,
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OUT dbid oid,
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OUT queryid bigint,
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OUT query text,
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OUT calls int8,
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OUT total_time float8,
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OUT min_time float8,
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OUT max_time float8,
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OUT mean_time float8,
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OUT stddev_time float8,
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OUT rows int8,
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OUT shared_blks_hit int8,
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OUT shared_blks_read int8,
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OUT shared_blks_dirtied int8,
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OUT shared_blks_written int8,
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OUT local_blks_hit int8,
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OUT local_blks_read int8,
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OUT local_blks_dirtied int8,
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OUT local_blks_written int8,
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OUT temp_blks_read int8,
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OUT temp_blks_written int8,
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OUT blk_read_time float8,
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OUT blk_write_time float8
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)
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RETURNS SETOF record
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AS 'MODULE_PATHNAME', 'pg_stat_statements_1_3'
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LANGUAGE C STRICT VOLATILE;
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CREATE VIEW pg_stat_statements AS
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SELECT * FROM pg_stat_statements(true);
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GRANT SELECT ON pg_stat_statements TO PUBLIC;
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@ -1,4 +1,4 @@
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/* contrib/pg_stat_statements/pg_stat_statements--1.2.sql */
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/* contrib/pg_stat_statements/pg_stat_statements--1.3.sql */
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-- complain if script is sourced in psql, rather than via CREATE EXTENSION
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\echo Use "CREATE EXTENSION pg_stat_statements" to load this file. \quit
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@ -16,6 +16,10 @@ CREATE FUNCTION pg_stat_statements(IN showtext boolean,
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OUT query text,
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OUT calls int8,
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OUT total_time float8,
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OUT min_time float8,
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OUT max_time float8,
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OUT mean_time float8,
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OUT stddev_time float8,
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OUT rows int8,
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OUT shared_blks_hit int8,
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OUT shared_blks_read int8,
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@ -31,7 +35,7 @@ CREATE FUNCTION pg_stat_statements(IN showtext boolean,
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OUT blk_write_time float8
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)
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RETURNS SETOF record
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AS 'MODULE_PATHNAME', 'pg_stat_statements_1_2'
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AS 'MODULE_PATHNAME', 'pg_stat_statements_1_3'
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LANGUAGE C STRICT VOLATILE;
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-- Register a view on the function for ease of use.
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@ -115,7 +115,8 @@ typedef enum pgssVersion
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{
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PGSS_V1_0 = 0,
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PGSS_V1_1,
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PGSS_V1_2
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PGSS_V1_2,
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PGSS_V1_3
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} pgssVersion;
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/*
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@ -136,6 +137,10 @@ typedef struct Counters
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{
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int64 calls; /* # of times executed */
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double total_time; /* total execution time, in msec */
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double min_time; /* minimim execution time in msec */
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double max_time; /* maximum execution time in msec */
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double mean_time; /* mean execution time in msec */
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double sum_var_time; /* sum of variances in execution time in msec */
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int64 rows; /* total # of retrieved or affected rows */
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int64 shared_blks_hit; /* # of shared buffer hits */
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int64 shared_blks_read; /* # of shared disk blocks read */
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@ -274,6 +279,7 @@ void _PG_fini(void);
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PG_FUNCTION_INFO_V1(pg_stat_statements_reset);
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PG_FUNCTION_INFO_V1(pg_stat_statements_1_2);
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PG_FUNCTION_INFO_V1(pg_stat_statements_1_3);
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PG_FUNCTION_INFO_V1(pg_stat_statements);
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static void pgss_shmem_startup(void);
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@ -320,6 +326,7 @@ static char *generate_normalized_query(pgssJumbleState *jstate, const char *quer
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int *query_len_p, int encoding);
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static void fill_in_constant_lengths(pgssJumbleState *jstate, const char *query);
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static int comp_location(const void *a, const void *b);
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static inline double sqrtd(const double x);
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/*
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@ -1215,6 +1222,32 @@ pgss_store(const char *query, uint32 queryId,
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e->counters.calls += 1;
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e->counters.total_time += total_time;
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if (e->counters.calls == 1)
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{
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e->counters.min_time = total_time;
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e->counters.max_time = total_time;
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e->counters.mean_time = total_time;
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}
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else
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{
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/*
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* Welford's method for accurately computing variance.
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* See <http://www.johndcook.com/blog/standard_deviation/>
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*/
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double old_mean = e->counters.mean_time;
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e->counters.mean_time +=
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(total_time - old_mean) / e->counters.calls;
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e->counters.sum_var_time +=
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(total_time - old_mean) * (total_time - e->counters.mean_time);
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/* calculate min and max time */
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if (e->counters.min_time > total_time)
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e->counters.min_time = total_time;
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if (e->counters.max_time < total_time)
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e->counters.max_time = total_time;
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}
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e->counters.rows += rows;
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e->counters.shared_blks_hit += bufusage->shared_blks_hit;
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e->counters.shared_blks_read += bufusage->shared_blks_read;
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@ -1259,7 +1292,8 @@ pg_stat_statements_reset(PG_FUNCTION_ARGS)
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#define PG_STAT_STATEMENTS_COLS_V1_0 14
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#define PG_STAT_STATEMENTS_COLS_V1_1 18
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#define PG_STAT_STATEMENTS_COLS_V1_2 19
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#define PG_STAT_STATEMENTS_COLS 19 /* maximum of above */
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#define PG_STAT_STATEMENTS_COLS_V1_3 23
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#define PG_STAT_STATEMENTS_COLS 23 /* maximum of above */
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/*
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* Retrieve statement statistics.
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@ -1271,6 +1305,16 @@ pg_stat_statements_reset(PG_FUNCTION_ARGS)
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* expected API version is identified by embedding it in the C name of the
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* function. Unfortunately we weren't bright enough to do that for 1.1.
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*/
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Datum
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pg_stat_statements_1_3(PG_FUNCTION_ARGS)
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{
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bool showtext = PG_GETARG_BOOL(0);
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pg_stat_statements_internal(fcinfo, PGSS_V1_3, showtext);
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return (Datum) 0;
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}
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Datum
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pg_stat_statements_1_2(PG_FUNCTION_ARGS)
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{
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@ -1360,6 +1404,10 @@ pg_stat_statements_internal(FunctionCallInfo fcinfo,
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if (api_version != PGSS_V1_2)
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elog(ERROR, "incorrect number of output arguments");
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break;
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case PG_STAT_STATEMENTS_COLS_V1_3:
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if (api_version != PGSS_V1_3)
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elog(ERROR, "incorrect number of output arguments");
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break;
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default:
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elog(ERROR, "incorrect number of output arguments");
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}
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@ -1519,6 +1567,23 @@ pg_stat_statements_internal(FunctionCallInfo fcinfo,
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values[i++] = Int64GetDatumFast(tmp.calls);
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values[i++] = Float8GetDatumFast(tmp.total_time);
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if (api_version >= PGSS_V1_3)
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{
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values[i++] = Float8GetDatumFast(tmp.min_time);
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values[i++] = Float8GetDatumFast(tmp.max_time);
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values[i++] = Float8GetDatumFast(tmp.mean_time);
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/*
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* Note we are calculating the population variance here, not the
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* sample variance, as we have data for the whole population,
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* so Bessel's correction is not used, and we don't divide by
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* tmp.calls - 1.
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*/
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if (tmp.calls > 1)
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values[i++] =
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Float8GetDatumFast(sqrtd(tmp.sum_var_time / tmp.calls));
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else
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values[i++] = Float8GetDatumFast(0.0);
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}
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values[i++] = Int64GetDatumFast(tmp.rows);
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values[i++] = Int64GetDatumFast(tmp.shared_blks_hit);
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values[i++] = Int64GetDatumFast(tmp.shared_blks_read);
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@ -1541,6 +1606,7 @@ pg_stat_statements_internal(FunctionCallInfo fcinfo,
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Assert(i == (api_version == PGSS_V1_0 ? PG_STAT_STATEMENTS_COLS_V1_0 :
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api_version == PGSS_V1_1 ? PG_STAT_STATEMENTS_COLS_V1_1 :
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api_version == PGSS_V1_2 ? PG_STAT_STATEMENTS_COLS_V1_2 :
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api_version == PGSS_V1_3 ? PG_STAT_STATEMENTS_COLS_V1_3 :
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-1 /* fail if you forget to update this assert */ ));
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tuplestore_putvalues(tupstore, tupdesc, values, nulls);
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@ -2899,3 +2965,20 @@ comp_location(const void *a, const void *b)
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else
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return 0;
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}
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/*
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* fast sqrt algorithm: reference from Fast inverse square root algorithms.
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*/
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static inline double
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sqrtd(const double x)
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{
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double x_half = 0.5 * x;
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long long int tmp = 0x5FE6EB50C7B537AAl - ( *(long long int*)&x >> 1);
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double x_result = * (double*)&tmp;
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x_result *= (1.5 - (x_half * x_result * x_result));
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/* If retry this calculation, it becomes higher precision at sqrt */
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x_result *= (1.5 - (x_half * x_result * x_result));
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return x_result * x;
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}
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@ -1,5 +1,5 @@
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# pg_stat_statements extension
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comment = 'track execution statistics of all SQL statements executed'
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default_version = '1.2'
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default_version = '1.3'
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module_pathname = '$libdir/pg_stat_statements'
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relocatable = true
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@ -86,6 +86,34 @@
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<entry>Total time spent in the statement, in milliseconds</entry>
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</row>
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<row>
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<entry><structfield>min_time</structfield></entry>
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<entry><type>double precision</type></entry>
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<entry></entry>
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<entry>Minimum time spent in the statement, in milliseconds</entry>
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</row>
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<row>
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<entry><structfield>max_time</structfield></entry>
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<entry><type>double precision</type></entry>
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<entry></entry>
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<entry>Maximum time spent in the statement, in milliseconds</entry>
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</row>
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<row>
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<entry><structfield>mean_time</structfield></entry>
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<entry><type>double precision</type></entry>
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<entry></entry>
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<entry>Mean time spent in the statement, in milliseconds</entry>
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</row>
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<row>
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<entry><structfield>stddev_time</structfield></entry>
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<entry><type>double precision</type></entry>
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<entry></entry>
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<entry>Population standard deviation of time spent in the statement, in milliseconds</entry>
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</row>
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<row>
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<entry><structfield>rows</structfield></entry>
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<entry><type>bigint</type></entry>
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