从视图查询时执行速度慢

Question

我在3个表格select *，gis_wcdma_cells，wcdma_cells上的视图中执行wcdma_cells_statistic：

CREATE OR REPLACE VIEW gisview_wcdma_cell_statistic AS 
 SELECT gis_wcdma_cells.wcdma_cell_id,
    gis_wcdma_cells.geometry,
    wcdma_cells."Cellname",
    wcdma_cells."Longitude",
    wcdma_cells."Latitude",
    wcdma_cells."Orientation",
    wcdma_cell_statistic.avg_ecio,
    wcdma_cell_statistic.avg_rssi,
    wcdma_cell_statistic.message_count,
    wcdma_cell_statistic.measurement_count
 FROM gis_wcdma_cells,
    wcdma_cells
 LEFT JOIN wcdma_cell_statistic ON wcdma_cells.id = wcdma_cell_statistic.cell_id
 WHERE gis_wcdma_cells.wcdma_cell_id = wcdma_cells.id;

但是，虽然我在视图中为3个表创建了索引，但我觉得它很慢：

• 在wcdma_cells.id
中创建的哈希索引
• wcdma_cell_statistic.cell_id
• gis_wcdma_cells.wcdma_cell_id

我发现select * from view比从视图中选择特定列要慢得多。虽然select *的SQL解释看起来更快（我的意思是select *情况下的成本要低得多。）。你能帮忙解释一下原因吗？如果有任何建议可以让查询更快？

SQL解释＆＃34;选择*＆＃34;从视图

Nested Loop Left Join  (cost=0.00..11501.93 rows=41036 width=479) (actual time=0.034..326.680 rows=41036 loops=1)
  Buffers: shared hit=238761
  ->  Nested Loop  (cost=0.00..9017.44 rows=41036 width=467) (actual time=0.026..183.752 rows=41036 loops=1)
        Buffers: shared hit=125390
        ->  Seq Scan on gis_wcdma_cells  (cost=0.00..2690.36 rows=41036 width=396) (actual time=0.007..13.359 rows=41036 loops=1)
              Buffers: shared hit=2280
        ->  Index Scan using wcdma_cells_id_idx on wcdma_cells  (cost=0.00..0.14 rows=1 width=71) (actual time=0.002..0.003 rows=1 loops=41036)
              Index Cond: (id = gis_wcdma_cells.wcdma_cell_id)
              Rows Removed by Index Recheck: 0
              Buffers: shared hit=123110
  ->  Index Scan using wcdma_cell_statistic_cell_id_idx on wcdma_cell_statistic  (cost=0.00..0.05 rows=1 width=20) (actual time=0.002..0.002 rows=1 loops=41036)
        Index Cond: (wcdma_cells.id = cell_id)
        Rows Removed by Index Recheck: 0
        Buffers: shared hit=113371
Total runtime: 334.551 ms

从我的视图中选择特定列的SQL解释

Nested Loop Left Join  (cost=2340.31..9007.59 rows=41036 width=58) (actual time=46.498..263.589 rows=41036 loops=1)
  Buffers: shared hit=116667, temp read=400 written=394
  ->  Hash Join  (cost=2340.31..6523.10 rows=41036 width=58) (actual time=46.471..119.983 rows=41036 loops=1)
        Hash Cond: (gis_wcdma_cells.wcdma_cell_id = wcdma_cells.id)
        Buffers: shared hit=3296, temp read=400 written=394
        ->  Seq Scan on gis_wcdma_cells  (cost=0.00..2690.36 rows=41036 width=4) (actual time=0.007..14.688 rows=41036 loops=1)
              Buffers: shared hit=2280
        ->  Hash  (cost=1426.36..1426.36 rows=41036 width=54) (actual time=46.358..46.358 rows=41036 loops=1)
              Buckets: 2048  Batches: 4  Memory Usage: 927kB
              Buffers: shared hit=1016, temp written=299
              ->  Seq Scan on wcdma_cells  (cost=0.00..1426.36 rows=41036 width=54) (actual time=0.004..24.612 rows=41036 loops=1)
                    Buffers: shared hit=1016
  ->  Index Scan using wcdma_cell_statistic_cell_id_idx on wcdma_cell_statistic  (cost=0.00..0.05 rows=1 width=8) (actual time=0.002..0.002 rows=1 loops=41036)
        Index Cond: (wcdma_cells.id = cell_id)
        Rows Removed by Index Recheck: 0
        Buffers: shared hit=113371
Total runtime: 271.146 ms

我在Navicat或PgAdmin工具中运行SQL查询。查询执行时间为： 15秒用于选择特定列，几分钟用于select *。