SQL 查询优化在执行中花费大量时间

Question

We have two tables one is properties and another one is property meta when we are getting data from one table "properties" , query only take less then one second in execution but when we are use join to get the data using bellow query from both tables its taking more then 5 second to fetch the data although we have only 12000 record in the tables , i think there is an issue in the sql query any help or suggestion will be appreciated.

SELECT 
        u.id, 
        u.property_title, 
        u.description, 
        u.city, 
        u.area,
        u.address, 
        u.slug, 
        u.latitude, 
        u.longitude, 
        u.sync_time, 
        u.add_date, 
        u.is_featured, 
        u.pre_construction, 
        u.move_in_date,
        u.property_status, 
        u.sale_price, 
        u.mls_number, 
        u.bedrooms, 
        u.bathrooms, 
        u.kitchens, 
        u.sub_area, 
        u.property_type, 
        u.main_image, 
        u.area_size as land_area, 
        pm7.meta_value as company_name, 
        pm8.meta_value as virtual_tour, 
        u.year_built, 
        u.garages 
    FROM 
        tbl_properties u 
            LEFT JOIN tbl_property_meta pm7 
                ON u.id = pm7.property_id 
            LEFT JOIN tbl_property_meta pm8 
                ON u.id = pm8.property_id 
    WHERE 
            u.status = 1 
        AND (pm7.meta_key = 'company_name') 
        AND (pm8.meta_key = 'virtual_tour') 
        AND (
                (
                        (   u.city = 'Delta' 
                        OR  u.post_code LIKE '%Delta%' 
                        OR  u.sub_area LIKE '%Delta%' 
                        OR  u.state LIKE '%Delta%') 
                    AND country = 'Canada'
                ) 
            OR  (
                        (   u.city = 'Metro Vancouver Regional District' 
                        OR  u.post_code LIKE '%Metro Vancouver Regional District%'
                        OR  u.sub_area LIKE '%Metro Vancouver Regional District%' 
                        OR  u.state LIKE '%Metro Vancouver Regional District%' )
                    AND country = 'Canada'
                )
            ) 
        AND 
            u.pre_construction ='0' 
    GROUP BY 
        u.id 
    ORDER BY 
        u.is_featured DESC, 
        u.add_date DESC

Answer 1

Try adding this compound index:

ALTER TABLE tbl_property_meta ADD INDEX id_key (property_id, meta_key);

If it doesn't help make things faster, try this one.

ALTER TABLE tbl_property_meta ADD INDEX key_id (meta_key, property_id);

And, you should know that column LIKE '%somevalue' (with a leading % ) is a notorious performance antipattern, resistant to optimization via indexes. (There's a way to create indexes for that shape of filter in PostgreSQL, but not in MariaDB / MySQL.)

Answer 2

Add another column with the meta stuff; throw city, post_code, sub_area, and state and probably some other things into it. Then build a FULLTEXT index on that column. Then use MATCH(..) AGAINST("Delta Metro Vancouver Regional District") in the WHERE clause _instead of the LEFT JOINs (which are actually INNER JOINs ) and the really messy part of the WHERE clause.

Also, the GROUP BY is probably unnecessary, thereby eliminating extra sort on the intermediate set of rows.