I have a system running FreeBSD 11.1-STABLE, PostgreSQL 9.6.8,Java OpenJDK
1.8.0_131, jdbc 9.3-1104-jdbc41 which is exhibiting very bizarre behavior. A
query is executing against a couple of tables that have 1 and 0 records in
them. ds3.job_entry has 0 rows, ds3.blob has 1 row. If I execute the query
manually via command line, it executes fine. There are no other active
queries, no locks. The system is idle, in our Dev Test group, so I can leave
it this way for a bit of time. The general software setup is in production and
I’ve seen nothing like this before. Even a system with 300M ds3.blob entries
executes this query fine.
Jun 7 17:24:21 blackpearl postgres[10670]: [7737-1]
db=tapesystem,user=Administrator,app=[unknown],client=127.0.0.1 LOG: duration:
2903612.206 ms execute fetch from S_2037436/C_2037437: SELECT * FROM ds3.blob
WHERE EXISTS (SELECT * FROM ds3.job_entry WHERE blob_id = ds3.blob.id AND
(job_id = $1))
tapesystem=# explain analyze SELECT * FROM ds3.blob WHERE EXISTS (SELECT * FROM
ds3.job_entry WHERE blob_id = ds3.blob.id AND (job_id =
'b51357cd-e07a-4c87-a50b-999c347a5c71'));
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------
Nested Loop (cost=0.84..6.89 rows=1 width=77) (actual time=0.044..0.044
rows=0 loops=1)
-> Index Scan using job_entry_job_id_idx on job_entry (cost=0.42..2.44
rows=1 width=16) (actual time=0.042..0.042 rows=0 loops=1)
Index Cond: (job_id = 'b51357cd-e07a-4c87-a50b-999c347a5c71'::uuid)
-> Index Scan using blob_pkey on blob (cost=0.42..4.44 rows=1 width=77)
(never executed)
Index Cond: (id = job_entry.blob_id)
Planning time: 0.388 ms
Execution time: 0.118 ms
pid client_port runtime query_start datname state query usename
10670 11211 0 years 0 mons 0 days 0 hours 43 mins 28.852273 secs
2018-06-07 17:24:22.026384 tapesystem active SELECT * FROM ds3.blob
WHERE EXISTS (SELECT * FROM ds3.job_entry WHERE blob_id = ds3.blob.id AND
(job_id = $1)) Administrator
From the system with 300M ds3.blob entries, which works fine (along with every
other system in house):
QUERY PLAN
Nested Loop (cost=0.57..738052.90 rows=164379 width=75) (actual
time=1.001..1947.029 rows=50000 loops=1)
-> Seq Scan on job_entry (cost=0.00..10039.50 rows=164379 width=16) (actual
time=0.871..56.442 rows=50000 loops=1)
Filter: (job_id = 'ef27d2fa-2727-424e-8f44-da9e33a5ca05'::uuid)
Rows Removed by Filter: 60001
-> Index Scan using blob_pkey on blob (cost=0.57..4.42 rows=1 width=75)
(actual time=0.037..0.037 rows=1 loops=50000)
Index Cond: (id = job_entry.blob_id)
Planning time: 6.330 ms
Execution time: 1951.564 ms
Please keep my CC of my work e-mail present.
Best,
Robert
