我有两个表格scheduling_flownode和xact_message,它们之间的关系很弱。我正在尝试执行以下查询:
set search_path='ad_96d5be';
explain analyze
SELECT f.id, f.target_object_id
FROM "scheduling_flownode" f,
"xact_message" m
where f.target_object_id = m.id
and f.root_node=True
AND f.state=1
and m.state=4
and m.templatelanguage_id IN (17, 18, 19, 20, 21, 22, 23, 24);
执行时,我得到了以下查询计划
Gather (cost=252701.26..1711972.04 rows=374109 width=8) (actual time=17737.908..164181.063 rows=441130 loops=1)
Workers Planned: 2
Workers Launched: 2
Buffers: shared hit=35705 read=1346425, temp read=18190 written=18148
-> Hash Join (cost=251701.26..1673561.14 rows=155879 width=8) (actual time=18805.587..163991.468 rows=147043 loops=3)
Hash Cond: (f.target_object_id = m.id)
Buffers: shared hit=35705 read=1346425, temp read=18190 written=18148
-> Parallel Bitmap Heap Scan on scheduling_flownode f (cost=124367.21..1523127.76 rows=2061083 width=8) (actual time=963.910..155466.840 rows=1642157 loops=3)
Recheck Cond: (state = 1)
Rows Removed by Index Recheck: 44
Filter: root_node
Rows Removed by Filter: 12406874
Heap Blocks: exact=10570 lossy=427078
Buffers: shared read=1328631
-> Bitmap Index Scan on "root-node-and-state" (cost=0.00..123130.57 rows=4946600 width=0) (actual time=955.044..955.045 rows=4926472 loops=1)
Index Cond: ((root_node = true) AND (state = 1))
Buffers: shared read=13464
-> Hash (cost=120677.64..120677.64 rows=405712 width=4) (actual time=7124.131..7124.131 rows=441128 loops=3)
Buckets: 131072 Batches: 8 Memory Usage: 2966kB
Buffers: shared hit=35591 read=17793, temp written=3384
-> Bitmap Heap Scan on xact_message m (cost=7893.56..120677.64 rows=405712 width=4) (actual time=61.307..6925.456 rows=441128 loops=3)
Recheck Cond: (state = 4)
Filter: (templatelanguage_id = ANY ('{17,18,19,20,21,22,23,24}'::integer[]))
Rows Removed by Filter: 4
Heap Blocks: exact=16585
Buffers: shared hit=35591 read=17793
-> Bitmap Index Scan on "state-index" (cost=0.00..7792.13 rows=421826 width=0) (actual time=58.781..58.781 rows=441132 loops=3)
Index Cond: (state = 4)
Buffers: shared hit=2420 read=1209
Planning time: 1.382 ms
Execution time: 164289.481 ms
(31 rows)
scheduling_flownode 表有超过 4 亿条记录,xact_message 表大约有 500 万行。我在使用 postgres 10 ,我认为这么大的负载应该可以轻松处理,如果可以,请问我在查询方面有什么问题吗?
analyze scheduling_flownode;
会改变什么吗? - user330315