Em 05-12-2017 16:15, Rodrigo Rosenfeld Rosas escreveu:
Em 05-12-2017 15:49, Alvaro Herrera escreveu:
Rodrigo Rosenfeld Rosas wrote:
Em 05-12-2017 15:25, Tom Lane escreveu:
Normally this is because you lack indexes on the referencing
columns, so
the query that scans the table to find the referencing rows is a
seqscan.
Actually though ... the weird thing about this is that I'd expect to
see a separate line in the EXPLAIN output for time spent in the FK
trigger. Where'd that go?
Yes, I was also hoping to get more insights through the EXPLAIN
output :)
It normally does. Can you show \d of the table containing the FK?
\d highlighted_text
Tabela "public.highlighted_text"
Coluna | Tipo | Collation | Nullable
| Default
--------------+-----------------------------+-----------+----------+----------------------------------------------
id | integer | | not null |
nextval('highlighted_text_id_seq'::regclass)
date_created | timestamp without time zone | | not null |
last_updated | timestamp without time zone | | not null |
reference_id | integer | | not null |
highlighting | text | | |
Índices:
"highlighted_text_pkey" PRIMARY KEY, btree (id)
"highlighted_text_reference_id_idx" btree (reference_id)
Restrições de chave estrangeira:
"fk_highlighted_text_reference" FOREIGN KEY (reference_id)
REFERENCES "references"(id) ON DELETE CASCADE
The highlighted_text_reference_id_idx was previously missing.
begin; explain analyze delete from "references" where id=966539;
rollback;
BEGIN
Tempo: 0,466 ms
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------
Delete on "references" (cost=0.43..8.45 rows=1 width=6) (actual
time=2.683..2.683 rows=0 loops=1)
-> Index Scan using references_pkey on "references"
(cost=0.43..8.45 rows=1 width=6) (actual time=2.609..2.612 rows=1
loops=1)
Index Cond: (id = 966539)
Planning time: 0.186 ms
Trigger for constraint fk_highlighted_text_reference: time=0.804 calls=1
Execution time: 3.551 ms
(6 registros)
Tempo: 4,791 ms
ROLLBACK
Tempo: 0,316 ms
drop index highlighted_text_reference_id_idx;
DROP INDEX
Tempo: 35,938 ms
begin; explain analyze delete from "references" where id=966539;
rollback;
BEGIN
Tempo: 0,494 ms
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------
Delete on "references" (cost=0.43..8.45 rows=1 width=6) (actual
time=0.112..0.112 rows=0 loops=1)
-> Index Scan using references_pkey on "references"
(cost=0.43..8.45 rows=1 width=6) (actual time=0.071..0.074 rows=1
loops=1)
Index Cond: (id = 966539)
Planning time: 0.181 ms
Trigger for constraint fk_highlighted_text_reference: time=2513.816
calls=1
Execution time: 2513.992 ms
(6 registros)
Time: 2514,801 ms (00:02,515)
ROLLBACK
Tempo: 0,291 ms
It displayed the spent on the trigger this time. How about deleting
the field values?
begin; explain analyze delete from field_values where
transaction_id=2479; rollback;
BEGIN
Tempo: 0,461 ms
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------------------------
Delete on field_values (cost=0.43..364.98 rows=453 width=6) (actual
time=4.732..4.732 rows=0 loops=1)
-> Index Scan using index_field_values_on_transaction_id on
field_values (cost=0.43..364.98 rows=453 width=6) (actual
time=0.137..0.949 rows=624 loops=1)
Index Cond: (transaction_id = 2479)
Planning time: 0.210 ms
Trigger for constraint field_value_booleans_field_value_id_fkey on
field_values: time=7.953 calls=624
Trigger for constraint field_value_currencies_field_value_id_fkey on
field_values: time=5.548 calls=624
Trigger for constraint field_value_jurisdictions_field_value_id_fkey
on field_values: time=6.376 calls=624
Trigger for constraint fk_field_value_date_range_field_value_id on
field_values: time=5.735 calls=624
Trigger for constraint fk_field_value_dates_field_value_id on
field_values: time=6.316 calls=624
Trigger for constraint fk_field_value_numerics_field_value_id on
field_values: time=6.368 calls=624
Trigger for constraint fk_field_value_options_field_value_id on
field_values: time=6.503 calls=624
Trigger for constraint fk_field_value_strings_field_value_id on
field_values: time=6.794 calls=624
Trigger for constraint fk_field_value_time_spans_field_value_id on
field_values: time=6.332 calls=624
Trigger for constraint fk_references_field_value_id on field_values:
time=7.382 calls=624
Trigger for constraint fk_highlighted_text_reference on references:
time=644994.047 calls=390
Execution time: 645065.326 ms
(16 registros)
Time: 645066,726 ms (10:45,067)
ROLLBACK
Tempo: 0,300 ms
Yeah, for some reason, now I got the relevant trigger hints :) Go
figure out why it didn't work the last time I tried before subscribing
to this list :)
Glad it's working now anyway :)
Just in case you're curious, creating the index took 6s and running the
same delete this time only took 75ms with the index in place :)
