如何在PostgreSQL GIN索引中优化查询不起作用

问题描述 投票：1回答：1

我使用（PostgreSQL）11.8。而且，我尝试通过某些专栏提供全文搜索的机会。为此，我创建了具有多个字段并合并的GIN索引。在我的数据库产品在表产品中增长到344747行之后，我遇到了查询执行缓慢的问题。 

create index ndsprc_swedish_custom_index on products
using GIN(to_tsvector('pg_catalog.swedish',coalesce(name,'')||' '||coalesce(description,'')||' '||coalesce(sku,'')||' '||coalesce(price,0)||' '||coalesce(category,'')||' '||coalesce(brand,'')))

我进行查询分析后，没有找到我的GIN索引。应该在说明部分，如何检查该指标是否有效？在Navicat中，索引看起来像是损坏的或无效的，但也许我错了

enter image description here

我期望这样的事情：Index Cond：以及有关我的索引使用方式的一些信息

我可能不正确地创建了该索引或类似的内容。这是我的查询示例。并且在更改索引中的列数之后

to_tsvector('pg_catalog.swedish',products_alias.name||products_alias.price)

执行时间下降到2.546s，但看起来我的查询未使用索引

我的查询：

EXPLAIN ANALYZE
SELECT                                                     
products_alias.id,
products_alias.sku,
products_alias.name AS "name",
products_alias.description,
products_alias.category,
products_alias.price,
products_alias.shipping, 
products_alias.currency,
products_alias.instock,
products_alias.product_url AS "productUrl",
products_alias.image_url AS "imageUrl",
products_alias.tracking_url AS "trackingUrl",
products_alias.brand,
products_alias.shop,
products_alias.original_price AS "originalPrice",
products_alias.ean,
products_alias.manufacturer_article_number AS "manufacturerArticleNumber",
products_alias.extras,
products_alias.created_at AS "createdAt",
products_alias.brand_relation_id AS "brandRelationId",
products_alias.shop_relation_id AS "shopRelationId",
array_agg(DISTINCT cpt.category_id) AS categoryIds,
COUNT(DISTINCT uip.id) as "numberOfEntries",
ts_rank_cd(to_tsvector('pg_catalog.swedish',coalesce(name,'')||' '||coalesce(description,'')||' '||coalesce(sku,'')||' '||coalesce(price,0)||' '||coalesce(category,'')||' '||coalesce(brand,'')||' '||coalesce(shop,'')), query_search) AS rank                            


FROM products products_alias                         

JOIN to_tsquery('pg_catalog.swedish', 'Evy&bodystocking&ns:*|23.70:*|ebbe:*|BABYKLÄDER:*') query_search                

ON to_tsvector('pg_catalog.swedish',coalesce(name,'')||' '||coalesce(description,'')||' '||coalesce(sku,'')||' '||coalesce(price,0)||' '||coalesce(category,'')||' '||coalesce(brand,'')||' '||coalesce(shop,'')) @@ query_search                        

LEFT JOIN product_category cp on cp.product_id = products_alias.id                
LEFT JOIN product_category cpt on cpt.product_id = products_alias.id
LEFT JOIN user_ip_product uip on uip.products_id = products_alias.id         

WHERE products_alias.id NOT IN (720253)                                            
GROUP BY products_alias.id, query_search.query_search ORDER BY rank DESC
LIMIT 50

以及我所拥有的最重要的部分-计划时间：7.567毫秒，执行时间：12162.804毫秒。是否使用LIMIT 50计划时间：1.359毫秒，执行时间：12210.245毫秒。

    Limit  (cost=95625.56..95625.69 rows=50 width=963) (actual time=12159.833..12159.841 rows=50 loops=1)
  ->  Sort  (cost=95625.56..95642.29 rows=6690 width=963) (actual time=12159.831..12159.834 rows=50 loops=1)
        Sort Key: (ts_rank_cd(to_tsvector('swedish'::regconfig, (((((((((((((COALESCE(products_alias.name, ''::character varying))::text || ' '::text) || COALESCE(products_alias.description, ''::text)) || ' '::text) || (COALESCE(products_alias.sku, ''::character varying))::text) || ' '::text) || (COALESCE(products_alias.price, '0'::numeric))::text) || ' '::text) || (COALESCE(products_alias.category, ''::character varying))::text) || ' '::text) || (COALESCE(products_alias.brand, ''::character varying))::text) || ' '::text) || (COALESCE(products_alias.shop, ''::character varying))::text)), query_search.query_search)) DESC
        Sort Method: top-N heapsort  Memory: 136kB
        ->  GroupAggregate  (cost=93312.70..95403.33 rows=6690 width=963) (actual time=10897.686..12149.352 rows=4336 loops=1)
              Group Key: products_alias.id, query_search.query_search
              ->  Sort  (cost=93312.70..93329.43 rows=6690 width=927) (actual time=10897.262..10908.173 rows=11762 loops=1)
                    Sort Key: products_alias.id, query_search.query_search
                    Sort Method: external merge  Disk: 11480kB
                    ->  Gather  (cost=88226.64..90164.63 rows=6690 width=927) (actual time=10830.873..10847.395 rows=11762 loops=1)
                          Workers Planned: 2
                          Workers Launched: 2
                          ->  Nested Loop Left Join  (cost=87226.64..88495.63 rows=2788 width=927) (actual time=10824.718..10840.108 rows=3921 loops=3)
                                ->  Nested Loop Left Join  (cost=87226.22..87656.05 rows=1417 width=923) (actual time=10824.687..10833.446 rows=2076 loops=3)
                                      ->  Merge Left Join  (cost=87225.79..87229.45 rows=720 width=923) (actual time=10824.649..10826.193 rows=1446 loops=3)
                                            Merge Cond: (products_alias.id = uip.products_id)
                                            ->  Sort  (cost=87117.93..87119.73 rows=720 width=919) (actual time=10824.610..10824.846 rows=1445 loops=3)
                                                  Sort Key: products_alias.id
                                                  Sort Method: quicksort  Memory: 2110kB
                                                  Worker 0:  Sort Method: quicksort  Memory: 2114kB
                                                  Worker 1:  Sort Method: quicksort  Memory: 2184kB
                                                  ->  Nested Loop  (cost=0.00..87083.76 rows=720 width=919) (actual time=8.350..10817.477 rows=1445 loops=3)
                                                        Join Filter: (to_tsvector('swedish'::regconfig, (((((((((((((COALESCE(products_alias.name, ''::character varying))::text || ' '::text) || COALESCE(products_alias.description, ''::text)) || ' '::text) || (COALESCE(products_alias.sku, ''::character varying))::text) || ' '::text) || (COALESCE(products_alias.price, '0'::numeric))::text) || ' '::text) || (COALESCE(products_alias.category, ''::character varying))::text) || ' '::text) || (COALESCE(products_alias.brand, ''::character varying))::text) || ' '::text) || (COALESCE(products_alias.shop, ''::character varying))::text)) @@ query_search.query_search)
                                                        Rows Removed by Join Filter: 113743
                                                        ->  Parallel Seq Scan on products products_alias  (cost=0.00..42767.48 rows=144118 width=887) (actual time=0.104..250.790 rows=115188 loops=3)
                                                              Filter: (id <> 720253)
                                                              Rows Removed by Filter: 0
                                                        ->  Function Scan on query_search  (cost=0.00..0.01 rows=1 width=32) (actual time=0.000..0.000 rows=1 loops=345564)
                                            ->  Sort  (cost=100.64..104.26 rows=1450 width=8) (actual time=0.033..0.037 rows=16 loops=3)
                                                  Sort Key: uip.products_id
                                                  Sort Method: quicksort  Memory: 25kB
                                                  Worker 0:  Sort Method: quicksort  Memory: 25kB
                                                  Worker 1:  Sort Method: quicksort  Memory: 25kB
                                                  ->  Seq Scan on user_ip_product uip  (cost=0.00..24.50 rows=1450 width=8) (actual time=0.022..0.025 rows=16 loops=3)
                                      ->  Index Only Scan using idx_cdfc73564584665a on product_category cp  (cost=0.42..0.56 rows=3 width=4) (actual time=0.004..0.004 rows=1 loops=4338)
                                            Index Cond: (product_id = products_alias.id)
                                            Heap Fetches: 6192
                                ->  Index Scan using idx_cdfc73564584665a on product_category cpt  (cost=0.42..0.56 rows=3 width=8) (actual time=0.002..0.002 rows=2 loops=6228)
                                      Index Cond: (product_id = products_alias.id)
Planning Time: 7.567 ms
Execution Time: 12162.804 ms

我的主要疑问是如何优化查询以及如何正确使用GIN索引，因为看起来我的索引无法正常工作？ ：（

postgresql
1个回答
0
投票

而不是将其写为怪异的联接，而是将其写为简单的WHERE条件：

FROM products products_alias
LEFT JOIN ...
WHERE to_tsvector('pg_catalog.swedish', ...)
      @@ to_tsquery('pg_catalog.swedish', 'Evy&bodystocking&ns:*|23.70:*|ebbe:*|BABYKLÄDER:*')

旁注：更容易编写

concat(col1, col2, ...)

than

coalesce(col1, '') || coalesce(col2, '') || ...
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