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88 строки
6.3 KiB
Plaintext
88 строки
6.3 KiB
Plaintext
2024
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AzatYakupov - BTree Index in PG 0:00 of 1:09:10
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https://www.youtube.com/watch?v=hMoBH7drftk
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JPoint - Salnikov - PostgreSQL Indices ru 0:00 of 2:00:44
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https://www.youtube.com/watch?v=ju9F8OvnL4E
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https://squidex.jugru.team/api/assets/srm/5a15546d-af53-46d4-be84-63367a5aaaf3/jpoint2022.andrei-.salsnikov.pdf
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Percona - PostgreSQL Indexes demystified — Charly Batista 0:00 of 2:40:09
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https://www.youtube.com/watch?v=C3GGR4f8CLk
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2023
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JPoint - Sitnikov - B-Tree indices using Boot, PostgreSQL, JPA of 45:07
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https://www.youtube.com/watch?v=y-Wtyvme4gE
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! using indices improves search-perf, but degrades ins/upd perf
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! indices have types
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! 21:30 explain (analyze, costs off, buffers) -- buffers is aprox about num of disk ops
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! b-tree index has nodes with like 100 children
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! 26:00 index only scan
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! Heap Fetches: 4 (pg went into table because of visibility/autovac)
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! 28:00 index on random uuid - will have more r/w
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! because of randomizeness (pg optimized insert of sequential values)
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! !!! UUID v7 can generate sequential ones
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! select ... from users where state = 'PENDING' and name = ?
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! create index state_name_users on users(name) include(state) -- idx will not sort by state, just include it
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! create index of (col1, col2) -- index sorted on combination of state, name
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Tenzor - Backend School - PG Indices p2 of 1:21:33
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https://www.youtube.com/watch?v=WTELBpLUb2E
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! 4:00 - hash idx - https://www.postgresql.org/docs/current/hash-index.html
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! 6:00 - !! hash idx can be created only on one field (with = operator), we can use op with single eq-op
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! 7:00 - create index ... using hash(fild-name);
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! 10:00 - gist - generalized search tree -- https://www.postgresql.org/docs/current/gist.html
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! universal infrastructure (b-tree, r-tree, rd-tree)
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! 12:00 - gist support geom-operators (<<, &<, &>, >>, <@, ~=, &&, <<|, &<|, ~, @), point, box, circle, poly types
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! https://www.postgresql.org/docs/current/functions-geometry.html
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! 18:00 https://www.postgresql.org/docs/current/functions-net.html, inet-type
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! 25:00 - gist is good for ranges ... using gist(daterange(dtb, dte, '[]'));
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! ... where daterange(dtb, dte, '[]') @> '2023-01-01'::date; -- 8-times less hits than b-tree
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! 29:00 - gist-operators with btree behavior
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! https://www.postgresql.org/docs/current/btree-gist.html
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! 31:00 - pg-antipatterns for gist - https://habr.com/ru/companies/tensor/articles/679834/
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! 40:00 - https://www.postgresql.org/docs/16/gist-examples.html (? no from v17)
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! 51:00 - create index ...with (buffering=auto); -- https://www.postgresql.org/docs/16/gist-implementation.html (? no for 17)
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! 52:00 - spgist (gist optimized for space partitioning) -- https://www.postgresql.org/docs/current/spgist.html
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! only for the single field
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! 54:00 - gin (generalized inverted index) -- https://www.postgresql.org/docs/current/gin.html
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! https://www.postgresql.org/docs/16/gin-examples.html (? no from v17)
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! 1:02:00 - brin - store only min/max or bloom-mask -- https://www.postgresql.org/docs/current/brin.html
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! good for cases like append-only logs with timestamps
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! https://www.postgresql.org/docs/16/brin-intro.html (? no from v17)
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! 1:10:00 - bloom - store only min/max or bloom-mask -- https://www.postgresql.org/docs/current/bloom.html
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! logic is the same as for hash
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Tenzor - Backend School - PG Indices p1 of 1:10:44
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https://www.youtube.com/watch?v=sNCKlklvGO0
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! 11:00 - select relname, relpages from pg_class where relaname like 'idx_%'; -- for estimating idx size
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! 12:00 create index on <tbl>((field=val)) -- expr-base idx, but bad
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! 12:30 create index on <tbl>(field) where field=val; -- partial/conditional ind - better because size of it is smaller
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! 15:00 pg has 3 types of expr: immutable, stable, volatile -- https://www.postgresql.org/docs/current/xfunc-volatility.html
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! only immutable are for idx
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! 21:00 create index concurrently - for helping queries not to wait, but concurrent-idxes can't be rolled back from transactions
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! 24:00 - create unique index ... alter table ... add primary key using index ...
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! 25:00 - select * from pg_stat_progress_create_index; -- https://www.postgresql.org/docs/current/progress-reporting.html
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! 27:00 - Uber - from PG to MySQL and back - https://habr.com/ru/companies/slurm/articles/322624/
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! 28:00 - select * from pg_stat_user_indexes where idx_scan = 0; -- find not-used indexes
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! drop index concurrently;
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! 31:00 - index types - https://www.postgresql.org/docs/current/indexes-types.html
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! btree, hash, gist, spgist, gin, brin, xindex (https://www.postgresql.org/docs/current/xindex.html)
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! 33:00 btree - balanced tree, good for ordered types - https://www.postgresql.org/docs/current/btree.html
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! 36:00 btree uses prefix condition idx(a, b, c) - can be used for (a), (a, b)
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! 39:00 for conditions a <> .., a not in ... a <> any/all - index will be used very bad (search all the layer)
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! 44:00 for btree it is good to use field in cardinality grow order
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! 49:00 for btree array field using is bad
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! 51:00 ... null values - better to use conditional indexes - where a is not null or b is not null, where (a, b) is not null
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! 54:00 if we have 2 independent indexes for (a) and for (b), then select ... where a=1 and b=1;
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! will use use bitmap index scan, but with a lot of rows each
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! create idx on (a, b), create idx on (a) where v = 1; create idx on (?) where a=1 and b=1;
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! 58:00 suspicious Limit/Sort/Scan
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! better to put sorb-by field to index fields tail
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! 59:00 btree can be used for prefix like-search ... relname like 'pg\_class\_%'
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! 1:05:00 - create index on prefix(md5 text_pattern_ops) -- use uperator-class text_pattern_ops
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ListenIT - SQL Indices in 10 min of 10:40
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https://www.youtube.com/watch?v=LpEwssOYRKA
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2022
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Percona - A Deep Dive Into PostgreSQL Indexing - Ibrar Ahmad 0:00 of 46:10
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https://www.youtube.com/watch?v=7OvrBmxW_e8
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https://www.youtube.com/watch?v=yWrJC2k1C8A
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! by company of pg_stat_activity ext
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2017
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BartunovKorotkov - All truth about Indices 0:00 of 46:35
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https://www.youtube.com/watch?v=aaecM4wKdhY
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