Обсуждение: Optimize query

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Optimize query

От
Yambu
Дата:
Hi

How would you optimize a query with greater than in where clause eg

select * from table1 where id > 1000 

and there is an index on id column

regards

Re: Optimize query

От
Raul Giucich
Дата:
Hi Yambu, the btree index type is optimized for this kind of operators (>, >=, <, <=, =).
For deep understanding on how to plan an query optimization I would recommend https://classroom.google.com/c/MTQ4MzczNDExMjM4 and https://use-the-index-luke.com.
Another tip is use in the select clause only the columns that are significant to answer the question you user is making executing this query.
Sorry for my foreign english.
Best regards.
Raúl.


El mar, 15 dic 2020 a las 11:18, Yambu (<hyambu@gmail.com>) escribió:
Hi

How would you optimize a query with greater than in where clause eg

select * from table1 where id > 1000 

and there is an index on id column

regards

Re: Optimize query

От
Ron
Дата:
On 12/15/20 8:17 AM, Yambu wrote:
Hi

How would you optimize a query with greater than in where clause eg

select * from table1 where id > 1000 

and there is an index on id column

The question as written is unanswerable.

- Why do you think it needs to be optimized?
- What is the table cardinality, and the query cardinality?
- What does EXPLAIN say?
- Have you run ANALYZE on table1?

Bottom line: Postgres might think that it is more efficient to scan the whole table.

--
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