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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2014-10-15 18:50:13 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2014-10-15 18:50:13 -0400 |
| commit | 90063a7612e2730f7757c2a80ba384bbe7e35c4b (patch) | |
| tree | 2e106aa9065c7f8f5e9e1937252118a19c64da9d /doc/src | |
| parent | 076d29a1eed5fe51fb2b25b98fcde9dd7c506902 (diff) | |
| download | postgresql-90063a7612e2730f7757c2a80ba384bbe7e35c4b.tar.gz postgresql-90063a7612e2730f7757c2a80ba384bbe7e35c4b.zip | |
Print planning time only in EXPLAIN ANALYZE, not plain EXPLAIN.
We've gotten enough push-back on that change to make it clear that it
wasn't an especially good idea to do it like that. Revert plain EXPLAIN
to its previous behavior, but keep the extra output in EXPLAIN ANALYZE.
Per discussion.
Internally, I set this up as a separate flag ExplainState.summary that
controls printing of planning time and execution time. For now it's
just copied from the ANALYZE option, but we could consider exposing it
to users.
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/perform.sgml | 25 | ||||
| -rw-r--r-- | doc/src/sgml/ref/explain.sgml | 19 |
2 files changed, 13 insertions, 31 deletions
diff --git a/doc/src/sgml/perform.sgml b/doc/src/sgml/perform.sgml index 94c11adaa49..5a087fbe6a0 100644 --- a/doc/src/sgml/perform.sgml +++ b/doc/src/sgml/perform.sgml @@ -89,7 +89,6 @@ EXPLAIN SELECT * FROM tenk1; QUERY PLAN ------------------------------------------------------------- Seq Scan on tenk1 (cost=0.00..458.00 rows=10000 width=244) - Planning time: 0.113 ms </screen> </para> @@ -163,12 +162,6 @@ EXPLAIN SELECT * FROM tenk1; </para> <para> - The <literal>Planning time</literal> shown is the time it took to generate - the query plan from the parsed query and optimize it. It does not include - rewriting and parsing. - </para> - - <para> Returning to our example: <screen> @@ -177,7 +170,6 @@ EXPLAIN SELECT * FROM tenk1; QUERY PLAN ------------------------------------------------------------- Seq Scan on tenk1 (cost=0.00..458.00 rows=10000 width=244) - Planning time: 0.113 ms </screen> </para> @@ -206,7 +198,6 @@ EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 7000; ------------------------------------------------------------ Seq Scan on tenk1 (cost=0.00..483.00 rows=7001 width=244) Filter: (unique1 < 7000) - Planning time: 0.104 ms </screen> Notice that the <command>EXPLAIN</> output shows the <literal>WHERE</> @@ -243,7 +234,6 @@ EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100; Recheck Cond: (unique1 < 100) -> Bitmap Index Scan on tenk1_unique1 (cost=0.00..5.04 rows=101 width=0) Index Cond: (unique1 < 100) - Planning time: 0.093 ms </screen> Here the planner has decided to use a two-step plan: the child plan @@ -272,7 +262,6 @@ EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100 AND stringu1 = 'xxx'; Filter: (stringu1 = 'xxx'::name) -> Bitmap Index Scan on tenk1_unique1 (cost=0.00..5.04 rows=101 width=0) Index Cond: (unique1 < 100) - Planning time: 0.089 ms </screen> The added condition <literal>stringu1 = 'xxx'</literal> reduces the @@ -294,7 +283,6 @@ EXPLAIN SELECT * FROM tenk1 WHERE unique1 = 42; ----------------------------------------------------------------------------- Index Scan using tenk1_unique1 on tenk1 (cost=0.29..8.30 rows=1 width=244) Index Cond: (unique1 = 42) - Planning time: 0.076 ms </screen> In this type of plan the table rows are fetched in index order, which @@ -323,7 +311,6 @@ EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100 AND unique2 > 9000; Index Cond: (unique1 < 100) -> Bitmap Index Scan on tenk1_unique2 (cost=0.00..19.78 rows=999 width=0) Index Cond: (unique2 > 9000) - Planning time: 0.094 ms </screen> But this requires visiting both indexes, so it's not necessarily a win @@ -344,7 +331,6 @@ EXPLAIN SELECT * FROM tenk1 WHERE unique1 < 100 AND unique2 > 9000 LIMIT 2 -> Index Scan using tenk1_unique2 on tenk1 (cost=0.29..71.27 rows=10 width=244) Index Cond: (unique2 > 9000) Filter: (unique1 < 100) - Planning time: 0.087 ms </screen> </para> @@ -378,7 +364,6 @@ WHERE t1.unique1 < 10 AND t1.unique2 = t2.unique2; Index Cond: (unique1 < 10) -> Index Scan using tenk2_unique2 on tenk2 t2 (cost=0.29..7.91 rows=1 width=244) Index Cond: (unique2 = t1.unique2) - Planning time: 0.117 ms </screen> </para> @@ -430,7 +415,6 @@ WHERE t1.unique1 < 10 AND t2.unique2 < 10 AND t1.hundred < t2.hundred; -> Materialize (cost=0.29..8.51 rows=10 width=244) -> Index Scan using tenk2_unique2 on tenk2 t2 (cost=0.29..8.46 rows=10 width=244) Index Cond: (unique2 < 10) - Planning time: 0.119 ms </screen> The condition <literal>t1.hundred < t2.hundred</literal> can't be @@ -478,7 +462,6 @@ WHERE t1.unique1 < 100 AND t1.unique2 = t2.unique2; Recheck Cond: (unique1 < 100) -> Bitmap Index Scan on tenk1_unique1 (cost=0.00..5.04 rows=101 width=0) Index Cond: (unique1 < 100) - Planning time: 0.182 ms </screen> </para> @@ -509,7 +492,6 @@ WHERE t1.unique1 < 100 AND t1.unique2 = t2.unique2; -> Sort (cost=197.83..200.33 rows=1000 width=244) Sort Key: t2.unique2 -> Seq Scan on onek t2 (cost=0.00..148.00 rows=1000 width=244) - Planning time: 0.195 ms </screen> </para> @@ -546,7 +528,6 @@ WHERE t1.unique1 < 100 AND t1.unique2 = t2.unique2; -> Index Scan using tenk1_unique2 on tenk1 t1 (cost=0.29..656.28 rows=101 width=244) Filter: (unique1 < 100) -> Index Scan using onek_unique2 on onek t2 (cost=0.28..224.79 rows=1000 width=244) - Planning time: 0.176 ms </screen> which shows that the planner thinks that sorting <literal>onek</> by @@ -781,6 +762,12 @@ ROLLBACK; </para> <para> + The <literal>Planning time</literal> shown by <command>EXPLAIN + ANALYZE</command> is the time it took to generate the query plan from the + parsed query and optimize it. It does not include parsing or rewriting. + </para> + + <para> The <literal>Execution time</literal> shown by <command>EXPLAIN ANALYZE</command> includes executor start-up and shut-down time, as well as the time to run any triggers that are fired, but it does not include diff --git a/doc/src/sgml/ref/explain.sgml b/doc/src/sgml/ref/explain.sgml index 72776a0fdef..f14a58dfc63 100644 --- a/doc/src/sgml/ref/explain.sgml +++ b/doc/src/sgml/ref/explain.sgml @@ -145,8 +145,8 @@ ROLLBACK; <para> Include information on the estimated startup and total cost of each plan node, as well as the estimated number of rows and the estimated - width of each row. Also, include the time spent planning the query, - if available. This parameter defaults to <literal>TRUE</literal>. + width of each row. + This parameter defaults to <literal>TRUE</literal>. </para> </listitem> </varlistentry> @@ -291,8 +291,7 @@ EXPLAIN SELECT * FROM foo; QUERY PLAN --------------------------------------------------------- Seq Scan on foo (cost=0.00..155.00 rows=10000 width=4) - Planning time: 0.114 ms -(2 rows) +(1 row) </programlisting> </para> @@ -312,8 +311,7 @@ EXPLAIN (FORMAT JSON) SELECT * FROM foo; "Total Cost": 155.00, + "Plan Rows": 10000, + "Plan Width": 4 + - }. + - "Planning Time": 0.114 + + } + } + ] (1 row) @@ -332,8 +330,7 @@ EXPLAIN SELECT * FROM foo WHERE i = 4; -------------------------------------------------------------- Index Scan using fi on foo (cost=0.00..5.98 rows=1 width=4) Index Cond: (i = 4) - Planning time: 0.073 ms -(3 rows) +(2 rows) </programlisting> </para> @@ -353,8 +350,7 @@ EXPLAIN (FORMAT YAML) SELECT * FROM foo WHERE i='4'; Total Cost: 5.98 + Plan Rows: 1 + Plan Width: 4 + - Index Cond: "(i = 4)" + - Planning Time: 0.073 + Index Cond: "(i = 4)" (1 row) </programlisting> @@ -386,7 +382,6 @@ EXPLAIN SELECT sum(i) FROM foo WHERE i < 10; Aggregate (cost=23.93..23.93 rows=1 width=4) -> Index Scan using fi on foo (cost=0.00..23.92 rows=6 width=4) Index Cond: (i < 10) - Planning time: 0.088 ms (3 rows) </programlisting> </para> @@ -410,7 +405,7 @@ EXPLAIN ANALYZE EXECUTE query(100, 200); Index Cond: ((id > $1) AND (id < $2)) Planning time: 0.197 ms Execution time: 0.225 ms -(5 rows) +(6 rows) </programlisting> </para> |