On Thu, 7 Dec 2006, Thomas Pundt wrote:
Hi,
On Wednesday 06 December 2006 16:44, Richard Ray wrote:
| select count(*) from documents where doc_num = '106973821' and (select
| bit_or(group_access) from mda_groups where group_name in (select groname
| from pg_user,pg_group where usename = 'bbob' and usesysid = any(grolist)
| and (groname ~ '.*owner$' or groname = 'admin'))) & access >
| '0'::bit(100);
|
| returns very fast
|
| If I create function
|
| create or replace function check_for_update_permission(text,text) returns
| boolean as '
| declare
| doc_number alias for $1;
| user alias for $2;
| doc_count integer;
| begin
...
| end;
| ' language 'plpgsql';
|
|
| and run "select check_for_update_permission('106973821','bbob');"
| it returns the correct info but takes several minutes
| Would someone please enlighten me.
| Can you do something like explain analyze on a function
Just a guess: is the column "doc_num" really of type text? Maybe using "text"
in the function lets the planner choose a sequential scan?
Actually "doc_num" is char(9)
I changed text to char(9) and got same slow results
I'd try putting a "raise notice '%', explain analyze ..." statement into the
function and check the log file.
It appears that the function is not using the index
The table documents has a index on doc_num and doc_num is a unique value
dcc=# explain analyze select doc_num from documents where doc_num =
'106973821';
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------
Index Scan using documents_pkey on documents (cost=0.00..5.48 rows=1
width=13) (actual time=37.475..37.481 rows=1 loops=1)
Index Cond: (doc_num = '106973821'::bpchar)
Total runtime: 37.535 ms
(3 rows)
dcc=#
But this same statement in a function takes several minutes;
My SQL knowledge is pitiful so would you explain how to use
"explain analyze" in the function
I get errors when I try to load the file with
raise notice ''%'',explain analyze select doc_num from documents where
doc_num = doc_number;
dcc=# \i
/src/check_for_update_permission
psql:/src/check_for_update_permission:52:
ERROR: syntax error at or near "analyze" at character 16
QUERY: SELECT explain analyze select doc_num from documents where doc_num
= $1
CONTEXT: SQL statement in PL/PgSQL function "check_for_update_permission"
near line 18
psql:/src/check_for_update_permission:52:
LINE 1: SELECT explain analyze select doc_num from documents where d...
psql:/src/check_for_update_permission:52:
^
dcc=#
Ciao,
Thomas
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