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  1. Oct 19, 2022
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  3. Oct 17, 2022
  4. Oct 10, 2022
  5. Sep 29, 2022
    • vlorentz's avatar
      postgresql: Remove merge join with origin_visit in origin_visit_get_latest · 657d31f6
      vlorentz authored
      I noticed that `origin_visit_get_latest` spends a lot of time doing index
      scans on `origin_visit_pkey`:
      
      ```
      swh=> explain analyze SELECT * FROM origin_visit ov INNER JOIN origin o ON o.id = ov.origin INNER JOIN origin_visit_status ovs USING (origin, visit) WHERE ov.origin = (SELECT id FROM origin o WHERE o.url = 'https://pypi.org/project/simpleado/') AND ovs.snapshot is not null AND ovs.status = 'full' ORDER BY ov.visit DESC, ovs.date DESC LIMIT 1;
                                                                                            QUERY PLAN
      --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
       Limit  (cost=10.14..29.33 rows=1 width=171) (actual time=1432.475..1432.479 rows=1 loops=1)
         InitPlan 1 (returns $0)
           ->  Index Scan using origin_url_idx on origin o_1  (cost=0.56..8.57 rows=1 width=8) (actual time=0.077..0.079 rows=1 loops=1)
                 Index Cond: (url = 'https://pypi.org/project/simpleado/'::text)
         ->  Merge Join  (cost=1.56..2208.37 rows=115 width=171) (actual time=1432.473..1432.476 rows=1 loops=1)
               Merge Cond: (ovs.visit = ov.visit)
               ->  Nested Loop  (cost=1.00..1615.69 rows=93 width=143) (actual time=298.705..298.707 rows=1 loops=1)
                     ->  Index Scan Backward using origin_visit_status_pkey on origin_visit_status ovs  (cost=0.57..1606.07 rows=93 width=85) (actual time=298.658..298.658 rows=1 loops=1)
                           Index Cond: (origin = $0)
                           Filter: ((snapshot IS NOT NULL) AND (status = 'full'::origin_visit_state))
                           Rows Removed by Filter: 198
                     ->  Materialize  (cost=0.43..8.46 rows=1 width=58) (actual time=0.042..0.043 rows=1 loops=1)
                           ->  Index Scan using origin_pkey on origin o  (cost=0.43..8.45 rows=1 width=58) (actual time=0.038..0.038 rows=1 loops=1)
                                 Index Cond: (id = $0)
               ->  Index Scan Backward using origin_visit_pkey on origin_visit ov  (cost=0.56..590.92 rows=150 width=28) (actual time=30.120..1133.650 rows=100 loops=1)
                     Index Cond: (origin = $0)
       Planning Time: 0.577 ms
       Execution Time: 1432.532 ms
      (18 lignes)
      ```
      
      As far as I understand, this is because we do not have a FK to tell the
      planner that every row in `origin_visit_status` does have a
      corresponding row in `origin_visit`, so it checks every row from
      `origin_visit_status` in this loop.
      
      Therefore, I rewrote the query to use a `LEFT JOIN`, so it will spare
      this check.
      
      First, here is the original query:
      
      ```
      swh=> explain SELECT * FROM origin_visit ov INNER JOIN origin_visit_status ovs USING (origin, visit) WHERE ov.origin = (SELECT id FROM origin o WHERE o.url = 'https://pypi.org/project/simpleado/') AND ovs.snapshot is not null AND ovs.status = 'full' ORDER BY ov.visit DESC, ovs.date DESC LIMIT 1;
                                                                  QUERY PLAN
      ----------------------------------------------------------------------------------------------------------------------------------
       Limit  (cost=9.71..28.82 rows=1 width=113)
         InitPlan 1 (returns $0)
           ->  Index Scan using origin_url_idx on origin o  (cost=0.56..8.57 rows=1 width=8)
                 Index Cond: (url = 'https://pypi.org/project/simpleado/'::text)
         ->  Merge Join  (cost=1.13..2198.75 rows=115 width=113)
               Merge Cond: (ovs.visit = ov.visit)
               ->  Index Scan Backward using origin_visit_status_pkey on origin_visit_status ovs  (cost=0.57..1606.07 rows=93 width=85)
                     Index Cond: (origin = $0)
                     Filter: ((snapshot IS NOT NULL) AND (status = 'full'::origin_visit_state))
               ->  Index Scan Backward using origin_visit_pkey on origin_visit ov  (cost=0.56..590.92 rows=150 width=28)
                     Index Cond: (origin = $0)
      (11 lignes)
      ```
      
      Change columns to filter directly on the "materialized" fields in ovs
      instead of those on those in ov (no actual change yet):
      
      ```
      swh=> explain SELECT * FROM origin_visit ov INNER JOIN origin_visit_status ovs USING (origin, visit) WHERE ovs.origin = (SELECT id FROM origin o WHERE o.url = 'https://pypi.org/project/simpleado/') AND ovs.snapshot is not null AND ovs.status = 'full' ORDER BY ovs.visit DESC, ovs.date DESC LIMIT 1;
                                                                  QUERY PLAN
      ----------------------------------------------------------------------------------------------------------------------------------
       Limit  (cost=9.71..28.82 rows=1 width=113)
         InitPlan 1 (returns $0)
           ->  Index Scan using origin_url_idx on origin o  (cost=0.56..8.57 rows=1 width=8)
                 Index Cond: (url = 'https://pypi.org/project/simpleado/'::text)
         ->  Merge Join  (cost=1.13..2198.75 rows=115 width=113)
               Merge Cond: (ovs.visit = ov.visit)
               ->  Index Scan Backward using origin_visit_status_pkey on origin_visit_status ovs  (cost=0.57..1606.07 rows=93 width=85)
                     Index Cond: (origin = $0)
                     Filter: ((snapshot IS NOT NULL) AND (status = 'full'::origin_visit_state))
               ->  Index Scan Backward using origin_visit_pkey on origin_visit ov  (cost=0.56..590.92 rows=150 width=28)
                     Index Cond: (origin = $0)
      (11 lignes)
      ```
      
      Then, reorder tables (obviously no change either):
      
      ```
      swh=> explain SELECT * FROM origin_visit_status ovs INNER JOIN origin_visit ov USING (origin, visit) WHERE ovs.origin = (SELECT id FROM origin o WHERE o.url = 'https://pypi.org/project/simpleado/') AND ovs.snapshot is not null AND ovs.status = 'full' ORDER BY ovs.visit DESC, ovs.date DESC LIMIT 1;
                                                                  QUERY PLAN
      ----------------------------------------------------------------------------------------------------------------------------------
       Limit  (cost=9.71..28.82 rows=1 width=113)
         InitPlan 1 (returns $0)
           ->  Index Scan using origin_url_idx on origin o  (cost=0.56..8.57 rows=1 width=8)
                 Index Cond: (url = 'https://pypi.org/project/simpleado/'::text)
         ->  Merge Join  (cost=1.13..2198.75 rows=115 width=113)
               Merge Cond: (ovs.visit = ov.visit)
               ->  Index Scan Backward using origin_visit_status_pkey on origin_visit_status ovs  (cost=0.57..1606.07 rows=93 width=85)
                     Index Cond: (origin = $0)
                     Filter: ((snapshot IS NOT NULL) AND (status = 'full'::origin_visit_state))
               ->  Index Scan Backward using origin_visit_pkey on origin_visit ov  (cost=0.56..590.92 rows=150 width=28)
                     Index Cond: (origin = $0)
      (11 lignes)
      ```
      
      Finally, replace `INNER JOIN` with `LEFT JOIN`:
      
      ```
      swh=> explain SELECT * FROM origin_visit_status ovs LEFT JOIN origin_visit ov USING (origin, visit) WHERE ovs.origin = (SELECT id FROM origin o WHERE o.url = 'https://pypi.org/project/simpleado/') AND ovs.snapshot is not null AND ovs.status = 'full' ORDER BY ovs.visit DESC, ovs.date DESC LIMIT 1;
                                                                  QUERY PLAN
      ----------------------------------------------------------------------------------------------------------------------------------
       Limit  (cost=9.71..35.47 rows=1 width=113)
         InitPlan 1 (returns $0)
           ->  Index Scan using origin_url_idx on origin o  (cost=0.56..8.57 rows=1 width=8)
                 Index Cond: (url = 'https://pypi.org/project/simpleado/'::text)
         ->  Nested Loop Left Join  (cost=1.13..2396.79 rows=93 width=113)
               ->  Index Scan Backward using origin_visit_status_pkey on origin_visit_status ovs  (cost=0.57..1606.07 rows=93 width=85)
                     Index Cond: (origin = $0)
                     Filter: ((snapshot IS NOT NULL) AND (status = 'full'::origin_visit_state))
               ->  Index Scan using origin_visit_pkey on origin_visit ov  (cost=0.56..8.59 rows=1 width=28)
                     Index Cond: ((origin = ovs.origin) AND (origin = $0) AND (visit = ovs.visit))
      (10 lignes)
      ```
      
      This would also work with a subquery just to get the value of `ov.date`
      and removing the actual join to `ov` entirely, but it was more annoying
      to implement because the function reuses `self.origin_visit_select_cols`
      as column list.
      
      All these EXPLAIN queries were run on staging.
      v1.7.0
      657d31f6
    • vlorentz's avatar
      conftest: Replace multiprocessing hack when pytest-cov >= 4 is installed · 44616afe
      vlorentz authored
      The hack crashes on >= 4 because 'pytest_cov.embed.multiprocessing_start'
      is not in the hook list anymore.
      
      https://pytest-cov.readthedocs.io/en/latest/changelog.html
      44616afe
  6. Sep 28, 2022
  7. Sep 27, 2022
  8. Sep 13, 2022
  9. Aug 31, 2022
  10. Aug 30, 2022
  11. Aug 29, 2022
  12. Aug 22, 2022
    • vlorentz's avatar
      origin_visit_add: Fix crash when adding multiple visits to the same origin simultaneously · b5836bab
      vlorentz authored
      This works by adding a RW lock on the row of the latest visit,
      which should block other transactions until the insertion
      is committed; so other transactions will generate a different
      (larger) visit id
      
      This commit also slightly rewrites how the max visit id is
      computed, as we need to actually select a row to lock it,
      instead of using the `max()` aggregate function.
      b5836bab
  13. Aug 16, 2022
  14. Aug 09, 2022
  15. Aug 08, 2022
  16. Aug 05, 2022
  17. Aug 04, 2022
    • vlorentz's avatar
      Stop logging and sending postgresql timeouts to Sentry · fc890595
      vlorentz authored
      They are very noisy, and clients are expected to retry a few times
      before re-raising the exception on their side.
      fc890595
    • vlorentz's avatar
      Stop using `USE <keyspace>` with prepared statements · 1e7ede18
      vlorentz authored
      This caused the following warning:
      
      ```
      WARNING  cassandra.protocol:libevreactor.py:361 Server warning: `USE <keyspace>` with prepared statements is considered to be an anti-pattern due to ambiguity in non-qualified table names. Please consider removing instances of `Session#setKeyspace(<keyspace>)`, `Session#execute("USE <keyspace>")` and `cluster.newSession(<keyspace>)` from your code, and always use fully qualified table names (e.g. <keyspace>.<table>).
      ```
      
      This also prepends 'test' to the name of keyspaces used in tests, so
      they are guaranteed to start with an letter (starting with digits cause
      syntax errors in most statements).
      1e7ede18
    • vlorentz's avatar
      0aff4618
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