[英]Proper full text index Rails/PostgreSQL/pg_search
I am testing performance for PostgreSQL full text search (using pg_search gem) and solr (sunspot_solr gem). 我正在测试PostgreSQL全文搜索(使用pg_search gem)和solr(sunspot_solr gem)的性能。
For 4 million records I am getting 13456 ms for Tsearch and 800 ms with SOLR (that is SOLR query + DB retrival). 对于400万条记录,我获得了13456毫秒的Tsearch和800毫秒的SOLR (即SOLR查询+ DB回溯)。 It is obvious that I need index but I am not sure how to create one for full text search. 很明显,我需要索引,但我不知道如何创建一个全文搜索。 I investigated and found that for full text search I should use GIN index. 我调查并发现,对于全文搜索,我应该使用GIN索引。
execute "CREATE INDEX products_gin_title ON products USING GIN(to_tsvector('english', title))"
But I am searching via two more columns and I need multi-value index and I am not sure how to implement it? 但我正在搜索另外两列,我需要多值索引,我不知道如何实现它? I am not very familiar with DB part. 我对DB部分不是很熟悉。 My search code looks like: 我的搜索代码如下:
@results = Product.search_title(params[:search_term]).where("platform_id=? AND product_type=?", params[:platform_id], params[:type_id]).limit(10).all
How do I create proper query for this type of situations? 如何为此类情况创建正确的查询?
Here is SQL output from rails for search term car . 这是来自rails的搜索词车的 SQL输出。
Product Load (12494.0ms)
SELECT
"products".*,
( ts_rank((to_tsvector('simple', coalesce("products"."title"::text, ''))), (to_ tsquery('simple', ''' ' || 'car' || ' ''')), 2) ) AS pg_search_rank
FROM "products"
WHERE (((to_tsvector('simple', coalesce("products"."tit le"::text, ''))) @@ (to_tsquery('simple', ''' ' || 'car' || ' '''))))
AND (platform_id='26' AND product_type='2')
ORDER BY pg_search_rank DESC, "products"."id" ASC
LIMIT 10
EDIT: 编辑:
I am using PostgreSQL 8.4.11, EXPLAIN ANALYZE
output is following. 我正在使用PostgreSQL 8.4.11, EXPLAIN ANALYZE
输出如下。
Limit (cost=108126.34..108126.36 rows=10 width=3824) (actual time=12228.736..12228.738 rows=10 loops=1)
-> Sort (cost=108126.34..108163.84 rows=14999 width=3824) (actual time=12228.733..12228.734 rows=10 loops=1)
Sort Key: (ts_rank(to_tsvector('simple'::regconfig, COALESCE((title)::text, ''::text)), '''car'''::tsquery, 2)), id
Sort Method: top-N heapsort Memory: 18kB
-> Seq Scan on products (cost=0.00..107802.22 rows=14999 width=3824) (actual time=7.532..12224.585 rows=977 loops=1)
Filter: ((platform_id = 26) AND (product_type = 2) AND (to_tsvector('simple'::regconfig, COALESCE((title)::text, ''::text)) @@ '''car'''::tsquery))
Total runtime: 12228.813 ms
This expression: 这个表达式:
to_tsvector('simple', (COALESCE(title::TEXT), ''))
is not sargable against your index. 不能对你的索引进行抨击。
You should declare the index on the exactly that expression which is used in the query: 您应该在查询中使用的表达式上声明索引:
CREATE INDEX products_gin_title
ON products
USING GIN(to_tsvector('simple', COALESCE(title::TEXT,'')))
(or make ruby generate the expression which is used in the index). (或使ruby生成索引中使用的表达式)。
If you want multiple columns to be indexed, just concatenate them: 如果要将多列编入索引,只需将它们连接起来:
CREATE INDEX products_gin_title
ON products
USING GIN(to_tsvector('simple', title || ' ' || product_type || ' ' || platform_id))
but again, Ruby should be filtering on exactly same expression for the index to be of use. 但同样,Ruby应该过滤完全相同的表达式,以便使用索引。
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