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https://issues.apache.org/jira/browse/MARMOTTA-175?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13617321#comment-13617321
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Sebastian Schaffert commented on MARMOTTA-175:
----------------------------------------------
Here is some PostgreSQL EXPLAIN data on GeoNames:
NOT IN:
Delete on triples (cost=64.25..142972548824713.22 rows=1 width=6) (actual
time=12511.678..12511.678 rows=0 loops=1)
-> Seq Scan on triples (cost=64.25..142972548824713.22 rows=1 width=6)
(actual time=12511.673..12511.673 rows=0 loops=1)
Filter: (deleted AND (NOT (hashed SubPlan 1)) AND (NOT (hashed SubPlan
3)) AND (NOT (SubPlan 2)))
SubPlan 1
-> Seq Scan on reasoner_just_supp_triples (cost=0.00..27.70
rows=1770 width=8) (never executed)
SubPlan 3
-> Seq Scan on versions_removed (cost=0.00..27.70 rows=1770
width=8) (never executed)
SubPlan 2
-> Materialize (cost=0.00..2594340.45 rows=105336830 width=8)
(never executed)
-> Seq Scan on versions_added (cost=0.00..1656184.30
rows=105336830 width=8) (never executed)
Total runtime: 12511.745 ms
NOT EXISTS:
Delete on triples (cost=0.00..5242181.49 rows=1 width=24) (actual
time=12465.628..12465.628 rows=0 loops=1)
-> Nested Loop Anti Join (cost=0.00..5242181.49 rows=1 width=24) (actual
time=12465.627..12465.627 rows=0 loops=1)
Join Filter: (versions_removed.triple_id = triples.id)
-> Nested Loop Anti Join (cost=0.00..5242118.39 rows=1 width=26)
(actual time=12465.626..12465.626 rows=0 loops=1)
-> Nested Loop Anti Join (cost=0.00..5242073.50 rows=1
width=20) (actual time=12465.626..12465.626 rows=0 loops=1)
Join Filter: (versions_added.triple_id = triples.id)
-> Seq Scan on triples (cost=0.00..2269178.82 rows=1
width=14) (actual time=12465.625..12465.625 rows=0 loops=1)
Filter: deleted
-> Seq Scan on versions_added (cost=0.00..1656184.30
rows=105336830 width=14) (never executed)
-> Index Scan using idx_just_supp_triples_triple on
reasoner_just_supp_triples (cost=0.00..40.41 rows=9 width=14) (never executed)
Index Cond: (triple_id = triples.id)
-> Materialize (cost=0.00..36.55 rows=1770 width=14) (never executed)
-> Seq Scan on versions_removed (cost=0.00..27.70 rows=1770
width=14) (never executed)
Total runtime: 12465.708 ms
(14 rows)
LEFT JOIN:
does not work on PostgreSQL (no LEFT JOIN in a DELETE)
> Garbage collection on triple tables
> -----------------------------------
>
> Key: MARMOTTA-175
> URL: https://issues.apache.org/jira/browse/MARMOTTA-175
> Project: Marmotta
> Issue Type: Bug
> Components: Triple Store
> Affects Versions: 3.1-incubating
> Environment: Centos 6.4 64b - JDK 1.6.0_38 - MySql 5.1.67 - Tomcat
> 7.0.37
> Reporter: Raffaele Palmieri
> Assignee: Sebastian Schaffert
> Priority: Minor
> Labels: garbage, mysql, triplestore
>
> During garbage collection of triple tables in log there is the following line:
> SQL error while executing garbage collection on triples table: You have an
> error in your SQL syntax; check the manual that corresponds to your MySQL
> server version for the right syntax to use near 'UNION (SELECT triple_id FROM
> reasoner_just_supp_triples WHERE triple_id = triple' at line 1
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