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Indexes and trigger changes to improve performance #5111

Merged
merged 4 commits into from
Sep 17, 2024
Merged

Indexes and trigger changes to improve performance #5111

merged 4 commits into from
Sep 17, 2024
+161 −5

Commits on Sep 17, 2024

  1. perf(db): Add indexes on foreign key to improve delete performance 

    This adds indexes for a few categories:

1. Foreign keys on the session table. These are set to `null` when the
   referenced row is deleted. These indexes will help to more
   efficiently set these `null` values in the case where a target is
   deleted, or and auth token is deleted.
2. Foreign keys from other tables to the session table. These are either
   set to `null` or cascade deleted when a session is deleted. These
   indexes help with these update/deletes when a session is deleted.
3. A multi-column index on session_state. This helps with the query that
   is used to delete all terminated sessions that have been terminated
   for over an hour.
    @tmessi
    tmessi committed Sep 17, 2024
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  2. perf(db): Reorder index columns for primary keys 

    When processing a controller API request, system uses a query to fetch
the grants for the requesting user. This query requires pulling together
information from several tables, and is currently performing many
sequential scans to do so. For a number of the tables involved, there
are indexes from multi-column primary keys, however, due to the order of
the columns in the index, the postgres planner would need to do a full
scan of the index, which can be less efficient than a sequential scan,
so instead it will perform a sequential scan of the table.

This recreates the primary keys while swapping the order of the columns
in the primary key definition, and thus the order in the index. By doing
so, the planner will not need to perform a full index scan, and will be
more likely to use the index when executing the grants query.
    @tmessi
    tmessi committed Sep 17, 2024
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  3. perf(db): Use statement trigger for marking deleted sessions 

    When sessions are deleted, a trigger is used to insert records into the
session_deleted table. This table is utilized by the sessions list
endpoint when using a refresh token to inform a client of the sessions
that have been deleted since the last request. We delete sessions in
bulk via a controller job to delete sessions that have been terminated
over an hour ago, which results in the trigger running a large number of
separate insert statements while processing the delete statement.

This changes the trigger to run once for the delete statement, instead
of for each row, resulting in a single bulk insert statement to the
session_deleted table.

This new trigger function also avoids the use of `on conflict`. When
testing this function, while the single statement was still faster than
running multiple inserts, the `on conflict` still added significant
overhead, even when there were no conflicts. It should be safe to
perform the insert without the `on conflict`, since the same ID should
never be deleted more than once if it is successfully deleted.
    @tmessi
    tmessi committed Sep 17, 2024
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  4. refact(db): Replace get_deleted_tables function with a view 

    This function was returning the set of deletion tables. A view seems
better suited for this task since it would allow for applying additional
filters of the result set. This was particularly necessary to easily
make changes to some sqltests due to switching the delete trigger for
the session table.
    @tmessi
    tmessi committed Sep 17, 2024
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