相关疑难解决方法(0)

原始查询如下

SELECT "TIME", "TRADEPRICE"
  FROM "YEAR" where "DATE"='2010-03-01' 
  and "SECURITY"='STW.AX' 
  AND "TIME" < '10:16:00' 
  AND "TYPE" = 'TRADE'
  ORDER BY "TIME" ASC LIMIT 3

我已经建立了三个指数如下

Columns "DATE" DESC NULLS LAST
Columns "SECURITY" DESC NULLS LAST
Columns "TIME" DESC NULLS LAST

我没有索引TYPE,因为它只接受两个可能值中的一个

解释分析产生以下内容

"Limit  (cost=50291.28..50291.28 rows=3 width=16) (actual time=1794484.566..1794484.567 rows=3 loops=1)"
"  ->  Sort  (cost=50291.28..50291.29 rows=4 width=16) (actual time=1794484.562..1794484.563 rows=3 loops=1)"
"        Sort Key: "TIME""
"        Sort Method:  top-N heapsort  Memory: 25kB"
"        ->  Bitmap Heap Scan on "YEAR"  (cost=48569.54..50291.24 rows=4 …