ほとんど同じPostgreSQLクエリで1分の違いがありますか？

Question

私はstate_codeでレコードをフィルタリングする機能を持つRailsアプリケーションを持っています。私は検索用語として「CA」を渡すとすぐに結果が得られることに気付きました。もし私が 'AZ'に合格すれば、それは1分以上かかるでしょう。

なぜそういうことはありませんか？以下は

クエリはpsqlのからの説明です： 高速1：

EXPLAIN ANALYZE SELECT 
    accounts.id 
FROM "accounts" 
LEFT OUTER JOIN "addresses" 
    ON "addresses"."addressable_id" = "accounts"."id" 
    AND "addresses"."address_type" = 'mailing' 
    AND "addresses"."addressable_type" = 'Account' 
WHERE "accounts"."organization_id" = 16 
AND (addresses.state_code IN ('CA')) 
ORDER BY accounts.name DESC; 
                     QUERY PLAN 
--------------------------------------------------------------------------------------------------------------------------------------------------------- 
Sort (cost=4941.94..4941.94 rows=1 width=18) (actual time=74.810..74.969 rows=821 loops=1) 
    Sort Key: accounts.name 
    Sort Method: quicksort Memory: 75kB 
    -> Hash Join (cost=4.46..4941.93 rows=1 width=18) (actual time=70.044..73.148 rows=821 loops=1) 
     Hash Cond: (addresses.addressable_id = accounts.id) 
     -> Seq Scan on addresses (cost=0.00..4911.93 rows=6806 width=4) (actual time=0.027..65.547 rows=15244 loops=1) 
       Filter: (((address_type)::text = 'mailing'::text) AND ((addressable_type)::text = 'Account'::text) AND ((state_code)::text = 'CA'::text)) 
       Rows Removed by Filter: 129688 
     -> Hash (cost=4.45..4.45 rows=1 width=18) (actual time=2.037..2.037 rows=1775 loops=1) 
       Buckets: 1024 Batches: 1 Memory Usage: 87kB 
       -> Index Scan using organization_id_index on accounts (cost=0.29..4.45 rows=1 width=18) (actual time=0.018..1.318 rows=1775 loops=1) 
        Index Cond: (organization_id = 16) 
Planning time: 0.565 ms 
Execution time: 75.224 ms 
(14 rows) 

遅い1：

EXPLAIN ANALYZE SELECT 
    accounts.id 
FROM "accounts" 
LEFT OUTER JOIN "addresses" 
    ON "addresses"."addressable_id" = "accounts"."id" 
    AND "addresses"."address_type" = 'mailing' 
    AND "addresses"."addressable_type" = 'Account' 
WHERE "accounts"."organization_id" = 16 
AND (addresses.state_code IN ('NV')) 
ORDER BY accounts.name DESC; 
                     QUERY PLAN 
--------------------------------------------------------------------------------------------------------------------------------------------------------- 
Sort (cost=4917.27..4917.27 rows=1 width=18) (actual time=97091.270..97091.277 rows=25 loops=1) 
    Sort Key: accounts.name 
    Sort Method: quicksort Memory: 26kB 
    -> Nested Loop (cost=0.29..4917.26 rows=1 width=18) (actual time=844.250..97091.083 rows=25 loops=1) 
     Join Filter: (accounts.id = addresses.addressable_id) 
     Rows Removed by Join Filter: 915875 
     -> Index Scan using organization_id_index on accounts (cost=0.29..4.45 rows=1 width=18) (actual time=0.017..10.315 rows=1775 loops=1) 
       Index Cond: (organization_id = 16) 
     -> Seq Scan on addresses (cost=0.00..4911.93 rows=70 width=4) (actual time=0.110..54.521 rows=516 loops=1775) 
       Filter: (((address_type)::text = 'mailing'::text) AND ((addressable_type)::text = 'Account'::text) AND ((state_code)::text = 'NV'::text)) 
       Rows Removed by Filter: 144416 
Planning time: 0.308 ms 
Execution time: 97091.325 ms 
(13 rows) 

スローつの結果はさらに混乱している、高速の1が821行で、25行です。

Answer 1

psqlコマンドラインのVACUUM ANALYZEコマンドを使用して解決しました。