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
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                        |           | |
    "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;
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
Tempo: 0,316 ms

drop index highlighted_text_reference_id_idx;
Tempo: 35,938 ms

begin; explain analyze delete from "references" where id=966539; rollback;
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)
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;
Tempo: 0,461 ms
---------------------------------------------------------------------------------------------------------------------------------------------------------------  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)
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 :)

Reply via email to