SELECT 
  p.product_id, 
  ifnull(
    count(dp.post_id), 
    0
  ) as discussion_amount_posts 
FROM 
  q_discussion 
  INNER JOIN q_products as p ON (
    q_discussion.object_id = p.product_id
  ) 
  INNER JOIN q_discussion_posts as dp ON (
    q_discussion.thread_id = dp.thread_id 
    AND q_discussion.object_type = 'P'
  ) 
WHERE 
  dp.status = 'A' 
  and p.product_id in (
    1848, 
    2004, 
    2006, 
    2007, 
    2008, 
    2009, 
    2010, 
    2011, 
    2012, 
    2013, 
    2014, 
    2015, 
    2016, 
    2017, 
    2018, 
    2019, 
    1856, 
    2079, 
    2081, 
    2082, 
    2083, 
    2084, 
    2085, 
    2086, 
    2087, 
    2088, 
    2089, 
    2090, 
    2020, 
    2091, 
    2093, 
    2094, 
    2095, 
    2096, 
    2097, 
    2098, 
    2099, 
    2100, 
    2101, 
    2102, 
    1868, 
    2105, 
    2106, 
    2107, 
    2108, 
    2109, 
    2110, 
    2111, 
    2112, 
    2113, 
    1878, 
    2115, 
    2116, 
    2117, 
    2118, 
    2119, 
    2120, 
    2121, 
    1886, 
    2122, 
    2123, 
    2124, 
    2125, 
    2126, 
    2127, 
    2128, 
    2129, 
    2130, 
    2131, 
    2132, 
    2133, 
    2134, 
    2135, 
    2136, 
    2137, 
    2138, 
    2139, 
    2140, 
    2141, 
    2142, 
    2143, 
    2144, 
    2145, 
    2146, 
    2147, 
    2148, 
    2149, 
    2150, 
    2151, 
    2152, 
    2153, 
    2154, 
    2155, 
    2156, 
    2157, 
    2158, 
    2159, 
    2160, 
    2161, 
    2162, 
    2164, 
    2165, 
    2166, 
    2032, 
    2241, 
    2243, 
    2244, 
    2245, 
    2246, 
    2247, 
    2248, 
    2249, 
    2250, 
    2058, 
    2263, 
    2264, 
    2265, 
    2266, 
    2042, 
    2267, 
    2268, 
    2269, 
    2270, 
    2271, 
    2272, 
    2273, 
    2274, 
    2275, 
    2277, 
    2278, 
    2279, 
    2280, 
    2281, 
    2282, 
    2403, 
    2509, 
    2510, 
    2511, 
    2512, 
    2399, 
    2514, 
    2515, 
    2516, 
    2394, 
    2518
  ) 
GROUP BY 
  p.product_id

Query time 0.00089

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.61"
    },
    "grouping_operation": {
      "using_temporary_table": true,
      "using_filesort": true,
      "cost_info": {
        "sort_cost": "0.29"
      },
      "nested_loop": [
        {
          "table": {
            "table_name": "dp",
            "access_type": "ALL",
            "possible_keys": [
              "thread_id",
              "thread_id_2"
            ],
            "rows_examined_per_scan": 57,
            "rows_produced_per_join": 5,
            "filtered": "10.00",
            "cost_info": {
              "read_cost": "13.01",
              "eval_cost": "1.14",
              "prefix_cost": "14.15",
              "data_read_per_join": "2K"
            },
            "used_columns": [
              "post_id",
              "thread_id",
              "status"
            ],
            "attached_condition": "(`portal`.`dp`.`status` = 'A')"
          }
        },
        {
          "table": {
            "table_name": "q_discussion",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY",
              "object_id"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "thread_id"
            ],
            "key_length": "3",
            "ref": [
              "portal.dp.thread_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 0,
            "filtered": "5.00",
            "cost_info": {
              "read_cost": "5.70",
              "eval_cost": "0.06",
              "prefix_cost": "20.99",
              "data_read_per_join": "4"
            },
            "used_columns": [
              "thread_id",
              "object_id",
              "object_type"
            ],
            "attached_condition": "((`portal`.`q_discussion`.`object_id` in (1848,2004,2006,2007,2008,2009,2010,2011,2012,2013,2014,2015,2016,2017,2018,2019,1856,2079,2081,2082,2083,2084,2085,2086,2087,2088,2089,2090,2020,2091,2093,2094,2095,2096,2097,2098,2099,2100,2101,2102,1868,2105,2106,2107,2108,2109,2110,2111,2112,2113,1878,2115,2116,2117,2118,2119,2120,2121,1886,2122,2123,2124,2125,2126,2127,2128,2129,2130,2131,2132,2133,2134,2135,2136,2137,2138,2139,2140,2141,2142,2143,2144,2145,2146,2147,2148,2149,2150,2151,2152,2153,2154,2155,2156,2157,2158,2159,2160,2161,2162,2164,2165,2166,2032,2241,2243,2244,2245,2246,2247,2248,2249,2250,2058,2263,2264,2265,2266,2042,2267,2268,2269,2270,2271,2272,2273,2274,2275,2277,2278,2279,2280,2281,2282,2403,2509,2510,2511,2512,2399,2514,2515,2516,2394,2518)) and (`portal`.`q_discussion`.`object_type` = 'P'))"
          }
        },
        {
          "table": {
            "table_name": "p",
            "access_type": "eq_ref",
            "possible_keys": [
              "PRIMARY"
            ],
            "key": "PRIMARY",
            "used_key_parts": [
              "product_id"
            ],
            "key_length": "3",
            "ref": [
              "portal.q_discussion.object_id"
            ],
            "rows_examined_per_scan": 1,
            "rows_produced_per_join": 0,
            "filtered": "100.00",
            "using_index": true,
            "cost_info": {
              "read_cost": "0.29",
              "eval_cost": "0.06",
              "prefix_cost": "21.33",
              "data_read_per_join": "1K"
            },
            "used_columns": [
              "product_id"
            ]
          }
        }
      ]
    }
  }
}