为什么'；其中col=int'；是否使此PostgreSQL查询变慢？

我正在做一个全文PostgreSQL搜索，我注意到只需将其中一个筛选条件上的运算符从“”更改为“=”，查询时间就会大幅增加，从24.7毫秒增加到3979毫秒。我在下面发布了解释分析输出。我操作的列是“region_id”，其数据类型是bigint

你知道为什么这会变得如此缓慢吗

谢谢

Limit  (cost=0.00..330941.18 rows=50 width=12) (actual time=0.752..24.278 rows=50 loops=1)
  ->  Index Scan Backward using date_idx on article  (cost=0.00..2574722.38 rows=389 width=12) (actual time=0.742..24.216 rows=50 loops=1)
        Index Cond: ((date >= '2009-10-25'::date) AND (date <= '2014-11-24'::date))
        Filter: ((region_id <> 15) AND (tsv @@ to_tsquery('((((((((((((((((((((asia) | (pacific)) | (china)) | (india)) | (indonesia)) | (pakistan)) | (bangladesh)) | (japan)) | (philippines)) | (vietnam)) | (thailand)) | (burma)) | (south & korea)) | (afghanistan)) | (nepal)) | (malaysia)) | (uzbekistan)) | (north & korea)) | (taiwan)) | (australia))'::text)) AND (((tsv @@ to_tsquery('(asia)'::text)) AND (body ~~* '%asia%'::text)) OR ((tsv @@ to_tsquery('(pacific)'::text)) AND (body ~~* '%pacific%'::text)) OR ((tsv @@ to_tsquery('(china)'::text)) AND (body ~~* '%china%'::text)) OR ((tsv @@ to_tsquery('(india)'::text)) AND (body ~~* '%india%'::text)) OR ((tsv @@ to_tsquery('(indonesia)'::text)) AND (body ~~* '%indonesia%'::text)) OR ((tsv @@ to_tsquery('(pakistan)'::text)) AND (body ~~* '%pakistan%'::text)) OR ((tsv @@ to_tsquery('(bangladesh)'::text)) AND (body ~~* '%bangladesh%'::text)) OR ((tsv @@ to_tsquery('(japan)'::text)) AND (body ~~* '%japan%'::text)) OR ((tsv @@ to_tsquery('(philippines)'::text)) AND (body ~~* '%philippines%'::text)) OR ((tsv @@ to_tsquery('(vietnam)'::text)) AND (body ~~* '%vietnam%'::text)) OR ((tsv @@ to_tsquery('(thailand)'::text)) AND (body ~~* '%thailand%'::text)) OR ((tsv @@ to_tsquery('(burma)'::text)) AND (body ~~* '%burma%'::text)) OR ((tsv @@ to_tsquery('(south & korea)'::text)) AND (body ~~* '%south korea%'::text)) OR ((tsv @@ to_tsquery('(afghanistan)'::text)) AND (body ~~* '%afghanistan%'::text)) OR ((tsv @@ to_tsquery('(nepal)'::text)) AND (body ~~* '%nepal%'::text)) OR ((tsv @@ to_tsquery('(malaysia)'::text)) AND (body ~~* '%malaysia%'::text)) OR ((tsv @@ to_tsquery('(uzbekistan)'::text)) AND (body ~~* '%uzbekistan%'::text)) OR ((tsv @@ to_tsquery('(north & korea)'::text)) AND (body ~~* '%north korea%'::text)) OR ((tsv @@ to_tsquery('(taiwan)'::text)) AND (body ~~* '%taiwan%'::text)) OR ((tsv @@ to_tsquery('(australia)'::text)) AND (body ~~* '%australia%'::text))))
Total runtime: 24.704 ms

限制（成本=0.00..330941.18行=50宽=12）（实际时间=0.752..24.278行=50圈=1）
->使用文章上的日期\u idx向后扫描索引（成本=0.00..2574722.38行=389宽度=12）（实际时间=0.742..24.216行=50圈=1）
索引条件：（（日期>='2009-10-25'：：日期）和（日期排序（成本=275163.14..275163.18行=16宽度=12）（实际时间=3978.508..3978.522行=50圈=1）
排序键：日期
排序方法：top-N堆口内存：27kB
->文章上的位图堆扫描（成本=44418.98..275162.82行=16宽度=12）（实际时间=425.783..3970.721行=6808循环=1）
重新检查条件：（（区域id=15）和（日期>='2009-10-25'：：日期）和（日期位图和（成本=44418.98..44418.98行=80194宽度=0）（实际时间=424.591..424.591行=0循环=1）
->文章“区域”idx上的位图索引扫描（成本=0.00..2626.27行=129281宽度=0）（实际时间=31.828..31.828行=130290循环=1）
索引条件：（区域id=15）
->日期时位图索引扫描（成本=0.00..41792.45行=1991585宽度=0）（实际时间=387.058..387.058行=2012923循环=1）
索引条件：（（日期>='2009-10-25'：：日期）和（日期='20091025'）和（日期排序（成本=411239.49..411239.53行=16宽度=1205）（实际时间=3804.224..3804.234行=50圈=1）
排序键：日期
排序方法：top-N堆口内存：117kB
->在文章上使用文章\区域\ idx进行索引扫描（成本=0.00..411239.17行=16宽度=1205）（实际时间=0.555..3790.489行=6808循环=1）
索引条件：（区域id=15）
筛选器：（（日期>='2009-10-25'：：日期）和（日期清楚，因为它会更改优化路径以使用索引。这不是最优的。SQL优化器有时会出错。如何使其使用与“”相同的路径？请在查询之前尝试设置
enable\u bitmapscan=off
。谢谢，但这似乎没有多大帮助。我添加了上面的解释输出。这是发现
案例高估了匹配记录的数量，而
=
案例低估了匹配记录的数量。您是否有有效的区域id统计信息？请尝试运行
分析文章（区域id）
（可能会增加区域id的统计信息目标）
Limit  (cost=275163.14..275163.18 rows=16 width=12) (actual time=3978.517..3978.550 rows=50 loops=1)
  ->  Sort  (cost=275163.14..275163.18 rows=16 width=12) (actual time=3978.508..3978.522 rows=50 loops=1)
        Sort Key: date
        Sort Method: top-N heapsort  Memory: 27kB
        ->  Bitmap Heap Scan on article  (cost=44418.98..275162.82 rows=16 width=12) (actual time=425.783..3970.721 rows=6808 loops=1)
              Recheck Cond: ((region_id = 15) AND (date >= '2009-10-25'::date) AND (date <= '2014-11-24'::date))
              Filter: ((tsv @@ to_tsquery('((((((((((((((((((((asia) | (pacific)) | (china)) | (india)) | (indonesia)) | (pakistan)) | (bangladesh)) | (japan)) | (philippines)) | (vietnam)) | (thailand)) | (burma)) | (south & korea)) | (afghanistan)) | (nepal)) | (malaysia)) | (uzbekistan)) | (north & korea)) | (taiwan)) | (australia))'::text)) AND (((tsv @@ to_tsquery('(asia)'::text)) AND (body ~~* '%asia%'::text)) OR ((tsv @@ to_tsquery('(pacific)'::text)) AND (body ~~* '%pacific%'::text)) OR ((tsv @@ to_tsquery('(china)'::text)) AND (body ~~* '%china%'::text)) OR ((tsv @@ to_tsquery('(india)'::text)) AND (body ~~* '%india%'::text)) OR ((tsv @@ to_tsquery('(indonesia)'::text)) AND (body ~~* '%indonesia%'::text)) OR ((tsv @@ to_tsquery('(pakistan)'::text)) AND (body ~~* '%pakistan%'::text)) OR ((tsv @@ to_tsquery('(bangladesh)'::text)) AND (body ~~* '%bangladesh%'::text)) OR ((tsv @@ to_tsquery('(japan)'::text)) AND (body ~~* '%japan%'::text)) OR ((tsv @@ to_tsquery('(philippines)'::text)) AND (body ~~* '%philippines%'::text)) OR ((tsv @@ to_tsquery('(vietnam)'::text)) AND (body ~~* '%vietnam%'::text)) OR ((tsv @@ to_tsquery('(thailand)'::text)) AND (body ~~* '%thailand%'::text)) OR ((tsv @@ to_tsquery('(burma)'::text)) AND (body ~~* '%burma%'::text)) OR ((tsv @@ to_tsquery('(south & korea)'::text)) AND (body ~~* '%south korea%'::text)) OR ((tsv @@ to_tsquery('(afghanistan)'::text)) AND (body ~~* '%afghanistan%'::text)) OR ((tsv @@ to_tsquery('(nepal)'::text)) AND (body ~~* '%nepal%'::text)) OR ((tsv @@ to_tsquery('(malaysia)'::text)) AND (body ~~* '%malaysia%'::text)) OR ((tsv @@ to_tsquery('(uzbekistan)'::text)) AND (body ~~* '%uzbekistan%'::text)) OR ((tsv @@ to_tsquery('(north & korea)'::text)) AND (body ~~* '%north korea%'::text)) OR ((tsv @@ to_tsquery('(taiwan)'::text)) AND (body ~~* '%taiwan%'::text)) OR ((tsv @@ to_tsquery('(australia)'::text)) AND (body ~~* '%australia%'::text))))
              ->  BitmapAnd  (cost=44418.98..44418.98 rows=80194 width=0) (actual time=424.591..424.591 rows=0 loops=1)
                    ->  Bitmap Index Scan on article_region_idx  (cost=0.00..2626.27 rows=129281 width=0) (actual time=31.828..31.828 rows=130290 loops=1)
                          Index Cond: (region_id = 15)
                    ->  Bitmap Index Scan on date_idx  (cost=0.00..41792.45 rows=1991585 width=0) (actual time=387.058..387.058 rows=2012923 loops=1)
                          Index Cond: ((date >= '2009-10-25'::date) AND (date <= '2014-11-24'::date))
Total runtime: 3979.345 ms

SELECT article_id

from article

 WHERE        
   ( tsv @@ to_tsquery('((((((((((((((((((((asia) | (pacific)) | (china)) | (india)) | (indonesia)) | (pakistan)) | (bangladesh)) | (japan)) | (philippines)) | (vietnam)) | (thailand)) | (burma)) | (south & korea)) | (afghanistan)) | (nepal)) | (malaysia)) | (uzbekistan)) | (north & korea)) | (taiwan)) | (australia))') )

  and ((((((((((((((((((((tsv @@ to_tsquery('(asia)') and body ilike '%asia%') or (tsv @@ to_tsquery('(pacific)') and body ilike '%pacific%')) or (tsv @@ to_tsquery('(china)') and body ilike '%china%')) or (tsv @@ to_tsquery('(india)') and body ilike '%india%')) or (tsv @@ to_tsquery('(indonesia)') and body ilike '%indonesia%')) or (tsv @@ to_tsquery('(pakistan)') and body ilike '%pakistan%')) or (tsv @@ to_tsquery('(bangladesh)') and body ilike '%bangladesh%')) or (tsv @@ to_tsquery('(japan)') and body ilike '%japan%')) or (tsv @@ to_tsquery('(philippines)') and body ilike '%philippines%')) or (tsv @@ to_tsquery('(vietnam)') and body ilike '%vietnam%')) or (tsv @@ to_tsquery('(thailand)') and body ilike '%thailand%')) or (tsv @@ to_tsquery('(burma)') and body ilike '%burma%')) or (tsv @@ to_tsquery('(south & korea)') and body ilike '%south korea%')) or (tsv @@ to_tsquery('(afghanistan)') and body ilike '%afghanistan%')) or (tsv @@ to_tsquery('(nepal)') and body ilike '%nepal%')) or (tsv @@ to_tsquery('(malaysia)') and body ilike '%malaysia%')) or (tsv @@ to_tsquery('(uzbekistan)') and body ilike '%uzbekistan%')) or (tsv @@ to_tsquery('(north & korea)') and body ilike '%north korea%')) or (tsv @@ to_tsquery('(taiwan)') and body ilike '%taiwan%')) or (tsv @@ to_tsquery('(australia)') and body ilike '%australia%'))

AND region_id = 15
 AND  ( date >= '20091025' )  AND ( date <= '20141124' )
  ORDER BY date DESC
 LIMIT 50 OFFSET 0;

Limit  (cost=411239.49..411239.53 rows=16 width=1205) (actual time=3804.234..3804.263 rows=50 loops=1)
  ->  Sort  (cost=411239.49..411239.53 rows=16 width=1205) (actual time=3804.224..3804.234 rows=50 loops=1)
        Sort Key: date
        Sort Method: top-N heapsort  Memory: 117kB
        ->  Index Scan using article_region_idx on article  (cost=0.00..411239.17 rows=16 width=1205) (actual time=0.555..3790.489 rows=6808 loops=1)
              Index Cond: (region_id = 15)
              Filter: ((date >= '2009-10-25'::date) AND (date <= '2014-11-24'::date) AND (tsv @@ to_tsquery('((((((((((((((((((((asia) | (pacific)) | (china)) | (india)) | (indonesia)) | (pakistan)) | (bangladesh)) | (japan)) | (philippines)) | (vietnam)) | (thailand)) | (burma)) | (south & korea)) | (afghanistan)) | (nepal)) | (malaysia)) | (uzbekistan)) | (north & korea)) | (taiwan)) | (australia))'::text)) AND (((tsv @@ to_tsquery('(asia)'::text)) AND (body ~~* '%asia%'::text)) OR ((tsv @@ to_tsquery('(pacific)'::text)) AND (body ~~* '%pacific%'::text)) OR ((tsv @@ to_tsquery('(china)'::text)) AND (body ~~* '%china%'::text)) OR ((tsv @@ to_tsquery('(india)'::text)) AND (body ~~* '%india%'::text)) OR ((tsv @@ to_tsquery('(indonesia)'::text)) AND (body ~~* '%indonesia%'::text)) OR ((tsv @@ to_tsquery('(pakistan)'::text)) AND (body ~~* '%pakistan%'::text)) OR ((tsv @@ to_tsquery('(bangladesh)'::text)) AND (body ~~* '%bangladesh%'::text)) OR ((tsv @@ to_tsquery('(japan)'::text)) AND (body ~~* '%japan%'::text)) OR ((tsv @@ to_tsquery('(philippines)'::text)) AND (body ~~* '%philippines%'::text)) OR ((tsv @@ to_tsquery('(vietnam)'::text)) AND (body ~~* '%vietnam%'::text)) OR ((tsv @@ to_tsquery('(thailand)'::text)) AND (body ~~* '%thailand%'::text)) OR ((tsv @@ to_tsquery('(burma)'::text)) AND (body ~~* '%burma%'::text)) OR ((tsv @@ to_tsquery('(south & korea)'::text)) AND (body ~~* '%south korea%'::text)) OR ((tsv @@ to_tsquery('(afghanistan)'::text)) AND (body ~~* '%afghanistan%'::text)) OR ((tsv @@ to_tsquery('(nepal)'::text)) AND (body ~~* '%nepal%'::text)) OR ((tsv @@ to_tsquery('(malaysia)'::text)) AND (body ~~* '%malaysia%'::text)) OR ((tsv @@ to_tsquery('(uzbekistan)'::text)) AND (body ~~* '%uzbekistan%'::text)) OR ((tsv @@ to_tsquery('(north & korea)'::text)) AND (body ~~* '%north korea%'::text)) OR ((tsv @@ to_tsquery('(taiwan)'::text)) AND (body ~~* '%taiwan%'::text)) OR ((tsv @@ to_tsquery('(australia)'::text)) AND (body ~~* '%australia%'::text))))
Total runtime: 3804.746 ms