PostgreSql version 8.2.4
Memory = 8 Gig
CPUs 1 dual core Zeon running at 3.0
I have a problem with an update query taking over 10 hours in order to run. I rebooted my server. I ran the SQL command “analyze”. Could you please help me with any suggestions? I have included the two tables involved in the update below as well as the indexes I am using.
The table result_entry contains 17,767,240 rows and the table question_number contains 40,787. Each row from the result_entry table will match to one and only one row in the table question_number using the fk_question_id field. Each row from the question_number table matches to an average of 436 rows on the result_entry table.
CREATE TABLE question_number
(
fk_form_id integer not null,
fk_question_id integer not null,
question_number integer not null,
sequence_id integer not null
);
ALTER TABLE ONLY question_number ADD CONSTRAINT question_number_pkey PRIMARY KEY (fk_question_id);
CREATE INDEX question_number_index1 ON question_number USING btree (question_number);
CREATE TABLE result_entry (
fk_result_submission_id integer NOT NULL,
fk_question_id integer NOT NULL,
fk_option_order_id integer NOT NULL,
value character varying,
order_id integer NOT NULL,
question_number integer
);
CREATE INDEX result_entery_index1 ON result_entry USING btree (fk_question_id);
update result_entry set question_number=question_number.question_number
from question_number where result_entry.fk_question_id=question_number.fk_question_id;
explain update result_entry set question_number=question_number.question_number
from question_number where result_entry.fk_question_id=question_number.fk_question_id;
QUERY PLAN
---------------------------------------------------------------------------------
Hash Join (cost=1437.71..1046983.94 rows=17333178 width=32)
Hash Cond: (result_entry.fk_question_id = question_number.fk_question_id)
-> Seq Scan on result_entry (cost=0.00..612216.78 rows=17333178 width=28)
-> Hash (cost=927.87..927.87 rows=40787 width=8)
-> Seq Scan on question_number (cost=0.00..927.87 rows=40787 width=8)
(5 rows)
Postgresql.conf settings:
shared_buffers = 1GB
work_mem = 10MB
max_fsm_pages = 204800
random_page_cost = 1.0
effective_cache_size = 8GB
Thanks for any help!
Lance Campbell
Project Manager/Software Architect
Web Services at Public Affairs
University of Illinois
217.333.0382
http://webservices.uiuc.edu
