On 5/25/17 2:26 PM, Dinesh Chandra 12108 wrote:
Hi Tomas,
Please find the below input for slow query.
(a) something about the hardware it's running on
RAM-->64 GB, CPU->40core
(b) amounts of data in the tables / databases
Database size :32GB
-----------------
Tables size
-----------------
Workflow.project : 8194 byte
workflow.tool_performance :175 MB
workflow.evidence_to_do :580 MB
(c) EXPLAIN or even better EXPLAIN ANALYZE of the query
"GroupAggregate (cost=16583736169.63..18157894828.18 rows=5920110 width=69)"
" -> Sort (cost=16583736169.63..16714893857.43 rows=52463075120 width=69)"
" Sort Key: tool_performance.project_id, project.project_name,
tool_performance.step_id, (date_trunc('day'::text, tool_performance.insert_time)),
tool_performance.user_id"
" -> Nested Loop (cost=2.42..787115179.07 rows=52463075120 width=69)"
" -> Seq Scan on evidence_to_do (cost=0.00..119443.95 rows=558296
width=0)"
" Filter: (status_id = ANY
('{15100,15150,15200,15300,15400,15500}'::bigint[]))"
" -> Materialize (cost=2.42..49843.24 rows=93970 width=69)"
" -> Hash Join (cost=2.42..49373.39 rows=93970 width=69)"
" Hash Cond: (tool_performance.project_id =
project.project_id)"
" -> Seq Scan on tool_performance (cost=0.00..48078.88
rows=93970 width=39)"
" Filter: ((insert_time > '2017-05-01
00:00:00+05:30'::timestamp with time zone) AND (insert_time < '2017-05-02
00:00:00+05:30'::timestamp with time zone))"
" -> Hash (cost=1.63..1.63 rows=63 width=38)"
" -> Seq Scan on project (cost=0.00..1.63 rows=63
width=38)"
Are you sure this is the same query? The query you posted includes there
two join conditions:
evidence_to_do.project_id = tool_performance.project_id
evidence_to_do.project_id = project.project_id
But the plan only seems to enforce the equality between 'project' and
'tool_performance'. So when joining the evidence_to_do, it performs a
cartesian product, producing ~52B rows (estimated). That can't be fast.
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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