-1
votes
4answers
78 views

Index on 'GROUP BY' with functions

I have a log table. It logs visitor data (time of visit, browser, window size ...). I want to create reports. I use a query like this (MySQL): SELECT COUNT(*) as raw_views ... FROM logs WHERE ...
6
votes
2answers
288 views

Improve performance of COUNT/GROUP-BY in large PostgresSQL table?

I am running PostgresSQL 9.2 and have a 12 column relation with about 6,700,000 rows. It contains nodes in a 3D space, each one referencing a user (who created it). To query which user has created how ...
0
votes
0answers
53 views

is it good to add index on column used in group by clause?

I have a query like- select x, sum(y) from xyz where z>=100 group by x order by sum(y) desc; will it be faster if I am going to add index on x?
2
votes
2answers
116 views

Optimize query or model, to get an population overview in time

I think I've got a very simple model and query, but I cannot find a way to make use of indexes to boost performance. I wonder if there is a trick in my model, or MySQL query, to speed up the ...
1
vote
2answers
472 views

Avoiding a sort on an already clustered index for group by

On a table T with two fields, pid and did, the following query results in a seq. scan followed by a sort on pid: select count(did), pid from T group by pid Here is the query plan: ...
3
votes
3answers
885 views

PostgreSQL 8.3: Slow GROUP BY on large table

I have a table with about 10 million records. I want to do a simple group by, but it's using a sequential scan and is slow... select run_id, count(*) from result group by run_id; I have an index ...
0
votes
1answer
515 views

Group By on column from joined table

its about the following query. EXPLAIN SELECT phrase, infinitiv FROM `dict_verbs_all` `t` INNER JOIN `dict_verbs_all_language` `verbsGerman_c` ON (`t`.`id`=`verbsGerman_c`.`verb_id`) INNER JOIN ...
3
votes
3answers
3k views

Slow query on large table with GROUP BY and ORDER BY

I have a table with 7.2 million tuples which looks like this: table public.methods column | type | attributes ...