performance - Mysql Slow Query group concat with subquery -


i have following query

select    `cs`.sku ,   group_concat(     if(         (           (             select                 count(id_catalog_category)                              `catalog_category`                              lft <= `ccg`.lft                 ,  rgt >= `ccg`.rgt           )=2        ),        `ccg`.name_en,        null     ) ) level_1_categories    catalog_simple `cs`  left join `catalog_config` `cc`    on `cs`.`fk_catalog_config` = `cc`.`id_catalog_config` left join `catalog_config_has_catalog_category` `cchcc`    on `cc`.`id_catalog_config` = `cchcc`.`fk_catalog_config` left join `catalog_category` `ccg`    on `cchcc`.`fk_catalog_category` = `ccg`.`id_catalog_category`  group `cc`.sku

explain extended give following results.

"id"    "select_type"   "table" "type"  "possible_keys" "key"   "key_len"   "ref"   "rows"  "filtered"  "extra" "1" "primary"   "cs"    "all"   null    null    null    null    "27384" "100.00"    "using temporary; using filesort" "1" "primary"   "cc"    "eq_ref"    "primary"   "primary"   "4" "pkfas.cs.fk_catalog_config"    "1" "100.00"    "" "1" "primary"   "cchcc" "ref"   "uk_id_catalog_config_has_catalog_category,fk_catalog_config"   "uk_id_catalog_config_has_catalog_category" "4" "pkfas.cc.id_catalog_config"    "2" "100.00"    "using index" "1" "primary"   "ccg"   "eq_ref"    "primary"   "primary"   "4" "pkfas.cchcc.fk_catalog_category"   "1" "100.00"    "" "2" "dependent subquery"    "catalog_category"  "all"   "lft,rgt"   null    null    null    "1739"  "100.00"    "using where"

this query takes around 100 seconds execute

sql slow has following results

query_time: 95.189445  lock_time: 0.000000 rows_sent: 8523  rows_examined: 242668622

please guide me way make fast. in advance

the performance of query can achieved removing dependent subquery (which executed each row) try this:

select    `cs`.sku ,   group_concat(     if(        tmp.za_count = 2,        `ccg`.name_en,        null     ) ) level_1_categories    catalog_simple `cs`  left join `catalog_config` `cc`    on `cs`.`fk_catalog_config` = `cc`.`id_catalog_config` left join `catalog_config_has_catalog_category` `cchcc`    on `cc`.`id_catalog_config` = `cchcc`.`fk_catalog_config` left join (     select       `ccg`.`id_catalog_category`,       sum(if(`ccg1`.`id_catalog_category` null,0,1)) za_count     `catalog_category` `ccg`        on `cchcc`.`fk_catalog_category` = `ccg`.`id_catalog_category`     left join `catalog_category` `ccg1`        on `ccg1`.lft <= `ccg`.lft        ,  `ccg1`.rgt >= `ccg`.rgt     group       `ccg`.`id_catalog_category` ) tmp     on tmp.id_catalog_category = `cchcc`.`fk_catalog_category` group `cc`.sku

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