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Allow pg_stat_statements to track WAL usage statistics. 

This commit adds three new columns in pg_stat_statements output to
display WAL usage statistics added by commit df3b181499.

This commit doesn't bump the version of pg_stat_statements as the
same is done for this release in commit 17e0328224.

Author: Kirill Bychik and Julien Rouhaud
Reviewed-by: Julien Rouhaud, Fujii Masao, Dilip Kumar and Amit Kapila
Discussion: https://postgr.es/m/CAB-hujrP8ZfUkvL5OYETipQwA=e3n7oqHFU=4ZLxWS_Cza3kQQ@mail.gmail.com
This commit is contained in:
Amit Kapila 2020-04-05 07:34:04 +05:30
parent 70de4e950c
commit 6b466bf5f2
5 changed files with 145 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
contrib/pg_stat_statements/expected/pg_stat_statements.out
View File

@ -211,6 +211,45 @@ SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
UPDATE test SET b = $1 WHERE a > $2 | 1 | 3
(10 rows)
--
-- INSERT, UPDATE, DELETE on test table to validate WAL generation metrics
--
SELECT pg_stat_statements_reset();
pg_stat_statements_reset
--------------------------
(1 row)
-- utility "create table" should not be shown
CREATE TABLE pgss_test (a int, b char(20));
INSERT INTO pgss_test VALUES(generate_series(1, 10), 'aaa');
UPDATE pgss_test SET b = 'bbb' WHERE a > 7;
DELETE FROM pgss_test WHERE a > 9;
-- DROP test table
SET pg_stat_statements.track_utility = TRUE;
DROP TABLE pgss_test;
SET pg_stat_statements.track_utility = FALSE;
-- Check WAL is generated for the above statements
SELECT query, calls, rows,
wal_bytes > 0 as wal_bytes_generated,
wal_records > 0 as wal_records_generated,
wal_records = rows as wal_records_as_rows
FROM pg_stat_statements ORDER BY query COLLATE "C";
query | calls | rows | wal_bytes_generated | wal_records_generated | wal_records_as_rows
-----------------------------------------------------------+-------+------+---------------------+-----------------------+---------------------
DELETE FROM pgss_test WHERE a > $1 | 1 | 1 | t | t | t
DROP TABLE pgss_test | 1 | 0 | t | t | f
INSERT INTO pgss_test VALUES(generate_series($1, $2), $3) | 1 | 10 | t | t | t
SELECT pg_stat_statements_reset() | 1 | 1 | f | f | f
SELECT query, calls, rows, +| 0 | 0 | f | f | t
wal_bytes > $1 as wal_bytes_generated, +| | | | |
wal_records > $2 as wal_records_generated, +| | | | |
wal_records = rows as wal_records_as_rows +| | | | |
FROM pg_stat_statements ORDER BY query COLLATE "C" | | | | |
SET pg_stat_statements.track_utility = FALSE | 1 | 0 | f | f | t
UPDATE pgss_test SET b = $1 WHERE a > $2 | 1 | 3 | t | t | t
(7 rows)
--
-- pg_stat_statements.track = none
--

5
contrib/pg_stat_statements/pg_stat_statements--1.7--1.8.sql
View File

@ -41,7 +41,10 @@ CREATE FUNCTION pg_stat_statements(IN showtext boolean,
OUT temp_blks_read int8,
OUT temp_blks_written int8,
OUT blk_read_time float8,
OUT blk_write_time float8
OUT blk_write_time float8,
OUT wal_records int8,
OUT wal_num_fpw int8,
OUT wal_bytes numeric
)
RETURNS SETOF record
AS 'MODULE_PATHNAME', 'pg_stat_statements_1_8'

55
contrib/pg_stat_statements/pg_stat_statements.c
View File

@ -188,6 +188,9 @@ typedef struct Counters
double blk_read_time; /* time spent reading, in msec */
double blk_write_time; /* time spent writing, in msec */
double usage; /* usage factor */
int64 wal_records; /* # of WAL records generated */
int64 wal_num_fpw; /* # of WAL full page image records generated */
uint64 wal_bytes; /* total amount of WAL bytes generated */
} Counters;
/*
@ -348,6 +351,7 @@ static void pgss_store(const char *query, uint64 queryId,
pgssStoreKind kind,
double total_time, uint64 rows,
const BufferUsage *bufusage,
const WalUsage *walusage,
pgssJumbleState *jstate);
static void pg_stat_statements_internal(FunctionCallInfo fcinfo,
pgssVersion api_version,
@ -891,6 +895,7 @@ pgss_post_parse_analyze(ParseState *pstate, Query *query)
0,
0,
NULL,
NULL,
&jstate);
}
@ -926,9 +931,17 @@ pgss_planner(Query *parse,
instr_time duration;
BufferUsage bufusage_start,
bufusage;
WalUsage walusage_start,
walusage;
/* We need to track buffer usage as the planner can access them. */
bufusage_start = pgBufferUsage;
/*
* Similarly the planner could write some WAL records in some cases
* (e.g. setting a hint bit with those being WAL-logged)
*/
walusage_start = pgWalUsage;
INSTR_TIME_SET_CURRENT(start);
plan_nested_level++;
@ -954,6 +967,10 @@ pgss_planner(Query *parse,
memset(&bufusage, 0, sizeof(BufferUsage));
BufferUsageAccumDiff(&bufusage, &pgBufferUsage, &bufusage_start);
/* calc differences of WAL counters. */
memset(&walusage, 0, sizeof(WalUsage));
WalUsageAccumDiff(&walusage, &pgWalUsage, &walusage_start);
pgss_store(query_string,
parse->queryId,
parse->stmt_location,
@ -962,6 +979,7 @@ pgss_planner(Query *parse,
INSTR_TIME_GET_MILLISEC(duration),
0,
&bufusage,
&walusage,
NULL);
}
else
@ -1079,6 +1097,7 @@ pgss_ExecutorEnd(QueryDesc *queryDesc)
queryDesc->totaltime->total * 1000.0, /* convert to msec */
queryDesc->estate->es_processed,
&queryDesc->totaltime->bufusage,
&queryDesc->totaltime->walusage,
NULL);
}
@ -1123,8 +1142,11 @@ pgss_ProcessUtility(PlannedStmt *pstmt, const char *queryString,
uint64 rows;
BufferUsage bufusage_start,
bufusage;
WalUsage walusage_start,
walusage;
bufusage_start = pgBufferUsage;
walusage_start = pgWalUsage;
INSTR_TIME_SET_CURRENT(start);
exec_nested_level++;
@ -1154,6 +1176,10 @@ pgss_ProcessUtility(PlannedStmt *pstmt, const char *queryString,
memset(&bufusage, 0, sizeof(BufferUsage));
BufferUsageAccumDiff(&bufusage, &pgBufferUsage, &bufusage_start);
/* calc differences of WAL counters. */
memset(&walusage, 0, sizeof(WalUsage));
WalUsageAccumDiff(&walusage, &pgWalUsage, &walusage_start);
pgss_store(queryString,
0, /* signal that it's a utility stmt */
pstmt->stmt_location,
@ -1162,6 +1188,7 @@ pgss_ProcessUtility(PlannedStmt *pstmt, const char *queryString,
INSTR_TIME_GET_MILLISEC(duration),
rows,
&bufusage,
&walusage,
NULL);
}
else
@ -1197,7 +1224,8 @@ pgss_hash_string(const char *str, int len)
*
* If jstate is not NULL then we're trying to create an entry for which
* we have no statistics as yet; we just want to record the normalized
* query string. total_time, rows, bufusage are ignored in this case.
* query string. total_time, rows, bufusage and walusage are ignored in this
* case.
*
* If kind is PGSS_PLAN or PGSS_EXEC, its value is used as the array position
* for the arrays in the Counters field.
@ -1208,6 +1236,7 @@ pgss_store(const char *query, uint64 queryId,
pgssStoreKind kind,
double total_time, uint64 rows,
const BufferUsage *bufusage,
const WalUsage *walusage,
pgssJumbleState *jstate)
{
pgssHashKey key;
@ -1402,6 +1431,9 @@ pgss_store(const char *query, uint64 queryId,
e->counters.blk_read_time += INSTR_TIME_GET_MILLISEC(bufusage->blk_read_time);
e->counters.blk_write_time += INSTR_TIME_GET_MILLISEC(bufusage->blk_write_time);
e->counters.usage += USAGE_EXEC(total_time);
e->counters.wal_records += walusage->wal_records;
e->counters.wal_num_fpw += walusage->wal_num_fpw;
e->counters.wal_bytes += walusage->wal_bytes;
SpinLockRelease(&e->mutex);
}
@ -1449,8 +1481,8 @@ pg_stat_statements_reset(PG_FUNCTION_ARGS)
#define PG_STAT_STATEMENTS_COLS_V1_1 18
#define PG_STAT_STATEMENTS_COLS_V1_2 19
#define PG_STAT_STATEMENTS_COLS_V1_3 23
#define PG_STAT_STATEMENTS_COLS_V1_8 29
#define PG_STAT_STATEMENTS_COLS 29 /* maximum of above */
#define PG_STAT_STATEMENTS_COLS_V1_8 32
#define PG_STAT_STATEMENTS_COLS 32 /* maximum of above */
/*
* Retrieve statement statistics.
@ -1786,6 +1818,23 @@ pg_stat_statements_internal(FunctionCallInfo fcinfo,
values[i++] = Float8GetDatumFast(tmp.blk_read_time);
values[i++] = Float8GetDatumFast(tmp.blk_write_time);
}
if (api_version >= PGSS_V1_8)
{
char buf[256];
Datum wal_bytes;
values[i++] = Int64GetDatumFast(tmp.wal_records);
values[i++] = Int64GetDatumFast(tmp.wal_num_fpw);
snprintf(buf, sizeof buf, UINT64_FORMAT, tmp.wal_bytes);
/* Convert to numeric. */
wal_bytes = DirectFunctionCall3(numeric_in,
CStringGetDatum(buf),
ObjectIdGetDatum(0),
Int32GetDatum(-1));
values[i++] = wal_bytes;
}
Assert(i == (api_version == PGSS_V1_0 ? PG_STAT_STATEMENTS_COLS_V1_0 :
api_version == PGSS_V1_1 ? PG_STAT_STATEMENTS_COLS_V1_1 :

23
contrib/pg_stat_statements/sql/pg_stat_statements.sql
View File

@ -101,6 +101,29 @@ SELECT * FROM test WHERE a IN (1, 2, 3, 4, 5);
SELECT query, calls, rows FROM pg_stat_statements ORDER BY query COLLATE "C";
--
-- INSERT, UPDATE, DELETE on test table to validate WAL generation metrics
--
SELECT pg_stat_statements_reset();
-- utility "create table" should not be shown
CREATE TABLE pgss_test (a int, b char(20));
INSERT INTO pgss_test VALUES(generate_series(1, 10), 'aaa');
UPDATE pgss_test SET b = 'bbb' WHERE a > 7;
DELETE FROM pgss_test WHERE a > 9;
-- DROP test table
SET pg_stat_statements.track_utility = TRUE;
DROP TABLE pgss_test;
SET pg_stat_statements.track_utility = FALSE;
-- Check WAL is generated for the above statements
SELECT query, calls, rows,
wal_bytes > 0 as wal_bytes_generated,
wal_records > 0 as wal_records_generated,
wal_records = rows as wal_records_as_rows
FROM pg_stat_statements ORDER BY query COLLATE "C";
--
-- pg_stat_statements.track = none
--

27
doc/src/sgml/pgstatstatements.sgml
View File

@ -264,6 +264,33 @@
</entry>
</row>
<row>
<entry><structfield>wal_bytes</structfield></entry>
<entry><type>numeric</type></entry>
<entry></entry>
<entry>
Total amount of WAL bytes generated by the statement
</entry>
</row>
<row>
<entry><structfield>wal_records</structfield></entry>
<entry><type>bigint</type></entry>
<entry></entry>
<entry>
Total count of WAL records generated by the statement
</entry>
</row>
<row>
<entry><structfield>wal_num_fpw</structfield></entry>
<entry><type>bigint</type></entry>
<entry></entry>
<entry>
Total count of WAL full page writes generated by the statement
</entry>
</row>
</tbody>
</tgroup>
</table>