Question

问题在视图和表执行时间之间是不同的。

为什么两个查询之间有这么多差异？

使用“ LIMIT”子句，查询2查询的速度越来越快，但现在却非常慢。（例如Select * From ... limit 1000）

注意：我在VIEW中使用的功能不会做任何艰苦的工作。语言plpgsql。

查询1：执行时间= 106.726 ms；

   EXPLAIN ANALYZE SELECT * FROM dbo.ST_Foto    where     StationId='Sample Guid'  
        and  Tarih <='2018-09-12'   -- Table

查询1解释分析；

  "Seq Scan on st_foto  (cost=0.00..4559.68 rows=103878 width=215) (actual time=0.036..81.046 rows=103938 loops=1)"
"  Filter: ((tarih <= '2018-09-12 00:00:00'::timestamp without time zone) AND (stationid = 'ac5a2189-f931-47c0-9845-d0ff8eac7cb7'::uuid))"
"  Rows Removed by Filter: 20174"
"Planning time: 0.359 ms"
"Execution time: 106.726 ms"

查询2执行时间= 30562.223 ms;

  EXPLAIN ANALYZE SELECT * FROM dbo.VWST_Foto    where     StationId='Sample Guid'  
            and  Tarih <='2018-09-12'   -- VIEW

查询2解释分析；

"Seq Scan on st_foto  (cost=0.00..161415.46 rows=103878 width=439) (actual time=1.364..30510.830 rows=103938 loops=1)"
"  Filter: ((tarih <= '2018-09-12 00:00:00'::timestamp without time zone) AND (stationid = 'ac5a2189-f931-47c0-9845-d0ff8eac7cb7'::uuid))"
"  Rows Removed by Filter: 20174"
"Planning time: 0.517 ms"
"Execution time: 30562.223 ms"

查看：

  CREATE    VIEW dbo.vwst_foto AS
     SELECT id,
    created,
    changed,
    createdby,
    changedby,
    intid,
    hardwareid,
    stationid,
    zoom,
    tarih,
    tarihgmt2,
    gunesradyasyon,
    bitkiboyu,
    contrast,
    yesilorani,
    preset,
    rgb,
    fft,
    foto,
    dbo.fn_hardwarefullname(hardwareid) AS hardware_title,
    dbo.fn_stationfullname(stationid) AS station_title,
    dbo.fn_userfullname(createdby) AS createdby_title,
    dbo.fn_userfullname(changedby) AS changedby_title,
    ''::text AS fotograflink,
  /* the basic func */  dbo.fn_enumkeytodescription('ST_Foto'::character varying, 'Zoom'::character varying, zoom::character varying) AS zoom_title,
  /* the basic func */    dbo.fn_enumkeytodescription('ST_Foto'::character varying, 'Preset'::character varying, preset::character varying) AS preset_title
   FROM dbo.st_foto;

我的服务器的RAM为32 GB。

此外

解释（分析，缓冲）

分析：

查看：（查询2）

"Seq Scan on st_foto  (cost=0.00..161415.46 rows=103878 width=439) (actual time=0.552..30695.394 rows=103938 loops=1)"
"  Filter: ((tarih <= '2018-09-12 00:00:00'::timestamp without time zone) AND (stationid = 'ac5a2189-f931-47c0-9845-d0ff8eac7cb7'::uuid))"
"  Rows Removed by Filter: 20174"
"  Buffers: shared hit=1297179"
"Planning time: 0.489 ms"
"Execution time: 30749.816 ms"

对于表格：（查询1）

"Seq Scan on st_foto  (cost=0.00..4559.68 rows=103878 width=215) (actual time=0.035..80.967 rows=103938 loops=1)"
"  Filter: ((tarih <= '2018-09-12 00:00:00'::timestamp without time zone) AND (stationid = 'ac5a2189-f931-47c0-9845-d0ff8eac7cb7'::uuid))"
"  Rows Removed by Filter: 20174"
"  Buffers: shared hit=2698"
"Planning time: 0.352 ms"
"Execution time: 107.618 ms"

Postgresql的select视图使用where子句太慢

0 个答案: