41bfe82b7a
This optimises searching for users when using queries consisting out of
one or two characters such as "ab". We optimise such cases by searching
for `LOWER(name)` and `LOWER(username)` instead of using `ILIKE`. Using
`LOWER` produces a _much_ better performing query.
For example, when searching for all users matching the term "a" we'd
produce the following plan:
Limit (cost=637.69..637.74 rows=20 width=805) (actual time=41.983..41.995 rows=20 loops=1)
Buffers: shared hit=8330
-> Sort (cost=637.69..638.61 rows=368 width=805) (actual time=41.982..41.990 rows=20 loops=1)
Sort Key: (CASE WHEN ((name)::text = 'a'::text) THEN 0 WHEN ((username)::text = 'a'::text) THEN 1 WHEN ((email)::text = 'a'::text) THEN 2 ELSE 3 END), name
Sort Method: top-N heapsort Memory: 35kB
Buffers: shared hit=8330
-> Bitmap Heap Scan on users (cost=75.47..627.89 rows=368 width=805) (actual time=9.452..41.305 rows=277 loops=1)
Recheck Cond: (((name)::text ~~* 'a'::text) OR ((username)::text ~~* 'a'::text) OR ((email)::text = 'a'::text))
Rows Removed by Index Recheck: 7601
Heap Blocks: exact=7636
Buffers: shared hit=8327
-> BitmapOr (cost=75.47..75.47 rows=368 width=0) (actual time=8.290..8.290 rows=0 loops=1)
Buffers: shared hit=691
-> Bitmap Index Scan on index_users_on_name_trigram (cost=0.00..38.85 rows=180 width=0) (actual time=4.369..4.369 rows=4071 loops=1)
Index Cond: ((name)::text ~~* 'a'::text)
Buffers: shared hit=360
-> Bitmap Index Scan on index_users_on_username_trigram (cost=0.00..34.41 rows=188 width=0) (actual time=3.896..3.896 rows=4140 loops=1)
Index Cond: ((username)::text ~~* 'a'::text)
Buffers: shared hit=328
-> Bitmap Index Scan on users_email_key (cost=0.00..1.94 rows=1 width=0) (actual time=0.022..0.022 rows=0 loops=1)
Index Cond: ((email)::text = 'a'::text)
Buffers: shared hit=3
Planning time: 3.912 ms
Execution time: 42.171 ms
With the changes in this commit we now produce the following plan
instead:
Limit (cost=13257.48..13257.53 rows=20 width=805) (actual time=1.567..1.579 rows=20 loops=1)
Buffers: shared hit=287
-> Sort (cost=13257.48..13280.93 rows=9379 width=805) (actual time=1.567..1.572 rows=20 loops=1)
Sort Key: (CASE WHEN ((name)::text = 'a'::text) THEN 0 WHEN ((username)::text = 'a'::text) THEN 1 WHEN ((email)::text = 'a'::text) THEN 2 ELSE 3 END), name
Sort Method: top-N heapsort Memory: 35kB
Buffers: shared hit=287
-> Bitmap Heap Scan on users (cost=135.66..13007.91 rows=9379 width=805) (actual time=0.194..1.107 rows=277 loops=1)
Recheck Cond: ((lower((name)::text) = 'a'::text) OR (lower((username)::text) = 'a'::text) OR ((email)::text = 'a'::text))
Heap Blocks: exact=277
Buffers: shared hit=287
-> BitmapOr (cost=135.66..135.66 rows=9379 width=0) (actual time=0.152..0.152 rows=0 loops=1)
Buffers: shared hit=10
-> Bitmap Index Scan on yorick_test_users (cost=0.00..124.75 rows=9377 width=0) (actual time=0.101..0.101 rows=277 loops=1)
Index Cond: (lower((name)::text) = 'a'::text)
Buffers: shared hit=4
-> Bitmap Index Scan on index_on_users_lower_username (cost=0.00..1.94 rows=1 width=0) (actual time=0.035..0.035 rows=1 loops=1)
Index Cond: (lower((username)::text) = 'a'::text)
Buffers: shared hit=3
-> Bitmap Index Scan on users_email_key (cost=0.00..1.94 rows=1 width=0) (actual time=0.014..0.014 rows=0 loops=1)
Index Cond: ((email)::text = 'a'::text)
Buffers: shared hit=3
Planning time: 0.303 ms
Execution time: 1.687 ms
Here we can see the new query is 25 times faster compared to the old
query.
29 lines
845 B
Ruby
29 lines
845 B
Ruby
# See http://doc.gitlab.com/ce/development/migration_style_guide.html
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# for more information on how to write migrations for GitLab.
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class UsersNameLowerIndex < ActiveRecord::Migration
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include Gitlab::Database::MigrationHelpers
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# Set this constant to true if this migration requires downtime.
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DOWNTIME = false
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INDEX_NAME = 'index_on_users_name_lower'
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disable_ddl_transaction!
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def up
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return unless Gitlab::Database.postgresql?
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# On GitLab.com this produces an index with a size of roughly 60 MB.
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execute "CREATE INDEX CONCURRENTLY #{INDEX_NAME} ON users (LOWER(name))"
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end
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def down
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return unless Gitlab::Database.postgresql?
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if supports_drop_index_concurrently?
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execute "DROP INDEX CONCURRENTLY IF EXISTS #{INDEX_NAME}"
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else
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execute "DROP INDEX IF EXISTS #{INDEX_NAME}"
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end
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end
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end
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