来自实体核心的 SQL 比原始 SQL 长 40 倍

Question

这是实体框架生成的SQL（查询洞察https://i.imgur.com/spanWyN.png ）

SELECT
  t."Id" AS "Id1",
  t."PositionId" AS "PositionId1",
  t."OddsDecimal" AS "OddsDecimal1",
  t0."Id" AS "Id2",
  t0."PositionId" AS "PositionId2",
  t0."OddsDecimal" AS "OddsDecimal2"
FROM (
  SELECT
    f."Id",
    f."EventKey",
    f."BetCategory",
    f."CustomLine",
    f."CustomParticipant",
    f."PositionId",
    f."OddsDecimal",
    f."BetPosition"
  FROM
    "FanduelPositions" AS f
  WHERE
    f."LastUpdated" > (now() + INTERVAL $1)
  UNION ALL
  SELECT
    d."Id",
    d."EventKey",
    d."BetCategory",
    d."CustomLine",
    d."CustomParticipant",
    d."PositionId",
    d."OddsDecimal",
    d."BetPosition"
  FROM
    "DraftkingsPositions" AS d
  WHERE
    d."LastUpdated" > (now() + INTERVAL $2) ) AS t
INNER JOIN (
  SELECT
    f0."Id",
    f0."EventKey",
    f0."BetCategory",
    f0."CustomLine",
    f0."CustomParticipant",
    f0."PositionId",
    f0."OddsDecimal",
    f0."BetPosition"
  FROM
    "FanduelPositions" AS f0
  WHERE
    f0."LastUpdated" > (now() + INTERVAL $3)
  UNION ALL
  SELECT
    d0."Id",
    d0."EventKey",
    d0."BetCategory",
    d0."CustomLine",
    d0."CustomParticipant",
    d0."PositionId",
    d0."OddsDecimal",
    d0."BetPosition"
  FROM
    "DraftkingsPositions" AS d0
  WHERE
    d0."LastUpdated" > (now() + INTERVAL $4) ) AS t0
ON
  (((t."EventKey" = t0."EventKey")
      AND (t."CustomParticipant" = t0."CustomParticipant"))
    AND (t."BetCategory" = t0."BetCategory"))
  AND (t."CustomLine" = t0."CustomLine")
WHERE
  (t."BetPosition" <> t0."BetPosition")
  AND ((($5 / t."OddsDecimal") + ($6 / t0."OddsDecimal")) < $7)

这是我正在执行的原始 SQL（查询洞察https://i.imgur.com/o2Z0Sl6.png ）

WITH
  tt AS (
  SELECT
    "Id",
    "EventKey",
    "BetCategory",
    "BetPosition",
    "OddsDecimal",
    "PositionId",
    "CustomLine",
    "CustomParticipant"
  FROM
    public."FanduelPositions" fd
  WHERE
    "LastUpdated" > CURRENT_TIMESTAMP - INTERVAL $1 second
  UNION ALL
  SELECT
    "Id",
    "EventKey",
    "BetCategory",
    "BetPosition",
    "OddsDecimal",
    "PositionId",
    "CustomLine",
    "CustomParticipant"
  FROM
    public."DraftkingsPositions" dk
  WHERE
    "LastUpdated" > CURRENT_TIMESTAMP - INTERVAL $2 second )
SELECT
  t1."PositionId",
  t1."OddsDecimal",
  t2."PositionId",
  t2."OddsDecimal"
FROM
  tt t1
JOIN
  tt t2
ON
  t1."EventKey" = t2."EventKey"
  AND t1."BetCategory" = t2."BetCategory"
  AND t1."CustomParticipant" = t2."CustomParticipant"
  AND t1."CustomLine" = t2."CustomLine"
  AND t1."BetPosition" <> t2."BetPosition"
  AND $3 / t1."OddsDecimal" + $4 / t2."OddsDecimal" < $5

原始 SQL 需要约 200 毫秒，而实体框架生成的 SQL 需要 15 秒以上。

这是我的实体框架代码 -

var fd = dbContext.FanduelPositions.Where(x => x.LastUpdated > DateTime.UtcNow.AddSeconds(-15)).Select(x => new { x.Id, x.EventKey, x.BetCategory, x.CustomLine, x.CustomParticipant, x.PositionId, x.OddsDecimal, x.BetPosition });
var dk = dbContext.DraftkingsPositions.Where(x => x.LastUpdated > DateTime.UtcNow.AddSeconds(-15)).Select(x => new { x.Id, x.EventKey, x.BetCategory, x.CustomLine, x.CustomParticipant, x.PositionId, x.OddsDecimal, x.BetPosition });
var baseTable = fd.Concat(dk);

var positions = (from x in baseTable
                             join y in baseTable
                             on new { x.EventKey, x.CustomParticipant, x.BetCategory, x.CustomLine } equals new { y.EventKey, y.CustomParticipant, y.BetCategory, y.CustomLine } 
                             where
                                x.BetPosition != y.BetPosition && (1 / x.OddsDecimal + 1 / y.OddsDecimal) < .985
                             select new
                             {
                                 Id1 = x.Id,
                                 PositionId1 = x.PositionId,
                                 OddsDecimal1 = x.OddsDecimal,
                                 Id2 = y.Id,
                                 PositionId2 = y.PositionId,
                                 OddsDecimal2 = y.OddsDecimal
                             });

是否可以以某种方式将 where 子句移至 on 子句？ 是否可以强制实体框架使用 with 语句？ 它导致每个表的 2 个全表扫描。 我不确定这两件事如何导致查询时间增加 40 倍（甚至独立于.net 执行实体框架 SQL），但我已将这两个查询的查询见解添加为一些可能的信息，我不确定如何消化这些信息。

Answer 1

看看跟随是否更快

var groups = baseTable.GroupBy(x => new { y.EventKey, y.CustomParticipant, y.BetCategory, y.CustomLine });
var positions = groups.SelectMany(x => x.SelectMany(y => x.Where(z => (y.BetPosition != z=BetPosition) &&  (1 / y.OddsDecimal + 1 / z.OddsDecimal) < .985).Select(z => new
                             {
                                 Id1 = y.Id,
                                 PositionId1 = y.PositionId,
                                 OddsDecimal1 = y.OddsDecimal,
                                 Id2 = z.Id,
                                 PositionId2 = z.PositionId,
                                 OddsDecimal2 = z.OddsDecimal
                             }));