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[Markus Korn <thekorn@xxxxxx>]

It is not *very* slow, it just seems to be at bit slower than it should be.
>From reading the query plan the reason seems to be that two temp b-trees are created, which is *slow*

sele  order          from  deta
----  -------------  ----  ----
1     0              0     SCAN TABLE event USING INDEX event_subj_id (~125000 rows)
0     0              1     SCAN SUBQUERY 1 (~100 rows)
0     1              0     SEARCH TABLE event USING INDEX event_subj_id (subj_id=?) (~2 rows)
0     0              0     USE TEMP B-TREE FOR GROUP BY
0     0              0     USE TEMP B-TREE FOR ORDER BY

It seems like all other queries are also using this temp b-trees (at least the ones I tried)
Right now I don't see a way to optimize it.

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https://bugs.launchpad.net/bugs/844877

Title:
  Query execution slow

Status in Zeitgeist Framework:
  New

Bug description:
  Synapse is using various not-so-complex find_events queries to display
  recent activities, and it seems that especially a query for "All"
  category is taking much longer than any other query (~750ms with a DB
  with 200k events).

  Here's the output from zg with the debug_sql extension:

  [DEBUG - root] # parameters: {'event_templates': [Event([dbus.Array([dbus.String(u''), '1315492708863', dbus.String(u''), dbus.String(u''), dbus.String(u''), ''], signature=dbus.Signature('s')), [Subject([dbus.String(u''), dbus.String(u''), dbus.String(u''), dbus.String(u''), dbus.String(u''), dbus.String(u''), dbus.String(u''), dbus.String(u'')]), Subject([dbus.String(u''), dbus.String(u'!http://www.semanticdesktop.org/ontologies/2007/03/22/nfo#Folder'), dbus.String(u''), dbus.String(u''), dbus.String(u''), dbus.String(u''), dbus.String(u''), dbus.String(u'')]), Subject([dbus.String(u''), dbus.String(u'!http://www.semanticdesktop.org/ontologies/2007/03/22/nfo#Software'), dbus.String(u''), dbus.String(u''), dbus.String(u''), dbus.String(u''), dbus.String(u''), dbus.String(u'')])], dbus.Array([], signature=dbus.Signature('y'))])],
   'max_events': dbus.UInt32(96L),
   'order': dbus.UInt32(2L),
   'return_mode': 1,
   'self': <_zeitgeist.engine.main.ZeitgeistEngine instance at 0x1b66248>,
   'sender': ':1.3604',
   'storage_state': dbus.UInt32(2L),
   'time_range': [1300977508860, 9223372036854775807]}

  [DEBUG - root] # database size: {'actor': 129,
   'event': 192746,
   'interpretation': 68,
   'manifestation': 27,
   'mimetype': 353,
   'uri': 60265}
  [DEBUG - root] # BEGIN SQL QUERY #
  no pretty sql: SELECT id FROM event_view
  				NATURAL JOIN (
  					SELECT subj_id,
  						max(timestamp) AS timestamp
  						
  					FROM event_view  WHERE (+timestamp >= ? AND ((NOT (subj_interpretation = ?) AND NOT (subj_interpretation = ? OR subj_interpretation = ? OR subj_interpretation = ?))))
  					GROUP BY subj_id)
  				GROUP BY subj_id
  				ORDER BY  timestamp DESC
  				 LIMIT 96 : [1300977508860, 45, 46, 47, 43]
  took 0.712120s
  # END SQL QUERY
  [DEBUG - zeitgeist.engine] Found 96 events IDs in 0.723284s

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