Add query plan generation/visualisation to postgres note

20220104155310-postgres.org

@@ -1,6 +1,6 @@
 :PROPERTIES:
 :ID:       171ce2f7-4028-47b0-b4e0-5a4a6ccb74ac
-:mtime:    20220527114623
+:mtime:    20221229103915
 :ctime:    20220104155310
 :END:
 #+title: Postgres
@@ -12,7 +12,11 @@
  * Fonctionne sur Solaris, SunOS, Mac OS X, HP-UX, AIX, Linux, IRIX, Digital Unix, BSD, NetBSD, FreeBSD, OpenBSD, SCO unix, NeXTSTEP, UnixWare et toutes sortes d'Unix. Depuis la version 8.0, PostgreSQL fonctionne également nativement sur Windows.
 
 * Interfaces utilisateur
-** [[id:0455921f-3ac0-437e-ba76-1afb3f6f85ea][Psql]]
+** CLI
+ * [[id:0455921f-3ac0-437e-ba76-1afb3f6f85ea][Psql]]
+** Graphique
+ * [[https://arctype.com/][ArcType]]
+ * [[https://github.com/dbeaver/dbeaver][DBeaver]]
 
 * Howto
 ** Pour lister les utilisateurs
@@ -33,5 +37,55 @@ sudo -u postgres dropdb <database>
 \password <user>
 #+END_SRC
 
+* Profiling de requêtes (query plan)
+** Depuis [[id:0455921f-3ac0-437e-ba76-1afb3f6f85ea][Psql]]
+#+BEGIN_SRC sql
+EXPLAIN (ANALYZE, COSTS, VERBOSE, BUFFERS) SELECT _stops.kind, _stops.id, _stops.name, _stops.town_name, _stops.postal_region, _stops.xepsg2154, _stops.yepsg2154, _stops.version, _stops.created_ts, _stops.changed_ts, stops.id AS id_1, stops.latitude, stops.longitude, stops.transport_mode, stops.accessibility, stops.visual_signs_available, stops.audible_signs_available, stops.record_id, stops.record_ts, stop_areas.id AS id_2, stop_areas.type
+FROM _stops LEFT OUTER JOIN stops ON _stops.id = stops.id LEFT OUTER JOIN stop_areas ON _stops.id = stop_areas.id
+WHERE _stops.name ILIKE '%Chaville rive droite%'
+#+END_SRC
+
+#+BEGIN_SRC
+ Nested Loop Left Join  (cost=148.62..250.06 rows=5 width=194) (actual time=1.213..1.346 rows=12 loops=1)
+   Output: _stops.kind, _stops.id, _stops.name, _stops.town_name, _stops.postal_region, _stops.xepsg2154, _stops.yepsg2154, _stops.version, _stops.created_ts, _stops.changed_ts, stops.id, stops.latitude, stops.longitude, stops.transport_mode, stops.accessibility, stops.visual_signs_available, stops.audible_signs_available, stops.record_id, stops.record_ts, stop_areas.id, stop_areas.type
+   Inner Unique: true
+   Buffers: shared hit=123
+   ->  Nested Loop Left Join  (cost=148.33..208.53 rows=5 width=182) (actual time=1.196..1.296 rows=12 loops=1)
+         Output: _stops.kind, _stops.id, _stops.name, _stops.town_name, _stops.postal_region, _stops.xepsg2154, _stops.yepsg2154, _stops.version, _stops.created_ts, _stops.changed_ts, stops.id, stops.latitude, stops.longitude, stops.transport_mode, stops.accessibility, stops.visual_signs_available, stops.audible_signs_available, stops.record_id, stops.record_ts
+         Inner Unique: true
+         Buffers: shared hit=97
+         ->  Bitmap Heap Scan on public._stops  (cost=148.04..166.99 rows=5 width=93) (actual time=1.172..1.219 rows=12 loops=1)
+               Output: _stops.kind, _stops.id, _stops.name, _stops.town_name, _stops.postal_region, _stops.xepsg2154, _stops.yepsg2154, _stops.version, _stops.created_ts, _stops.changed_ts
+               Recheck Cond: ((_stops.name)::text ~~* '%Chaville rive droite%'::text)
+               Heap Blocks: exact=11
+               Buffers: shared hit=63
+               ->  Bitmap Index Scan on name_idx_gin  (cost=0.00..148.04 rows=5 width=0) (actual time=1.155..1.155 rows=12 loops=1)
+                     Index Cond: ((_stops.name)::text ~~* '%Chaville rive droite%'::text)
+                     Buffers: shared hit=52
+         ->  Index Scan using stops_pkey on public.stops  (cost=0.29..8.31 rows=1 width=89) (actual time=0.005..0.005 rows=1 loops=12)
+               Output: stops.id, stops.latitude, stops.longitude, stops.transport_mode, stops.accessibility, stops.visual_signs_available, stops.audible_signs_available, stops.record_id, stops.record_ts
+               Index Cond: (stops.id = _stops.id)
+               Buffers: shared hit=34
+   ->  Index Scan using stop_areas_pkey on public.stop_areas  (cost=0.29..8.30 rows=1 width=12) (actual time=0.003..0.003 rows=0 loops=12)
+         Output: stop_areas.id, stop_areas.type
+         Index Cond: (stop_areas.id = _stops.id)
+         Buffers: shared hit=26
+ Planning:
+   Buffers: shared hit=22
+ Planning Time: 1.015 ms
+ Execution Time: 1.521 ms
+(28 rows)
+
+Time: 3.503 ms
+#+END_SRC
+
+** Visualisation de Query plan
+Différents sites permettent de visualiser graphiquement les query plans:
+ * Gratuits:
+   * [[https://explain.dalibo.com/][PEV2 - Dalibo]]
+ * Payants:
+   * [[https://app.pgmustard.com/login][PgMustard]]
+
 * Références
  * [[https://stackoverflow.com/questions/45395538/postgres-md5-password-plain-password][Postgres: MD5 Password / Plain password - Github]]
+ * [[https://www.postgresql.org/docs/current/sql-explain.html][Sql-explain - PostgreSQL]]