En esta página se describe cómo monitorizar el rendimiento de tu base de datos AlloyDB Omni mediante secuencias de comandos de observabilidad de PostgreSQL.
Ver el estado de los procesos conectados y los eventos de espera
Puedes determinar los procesos conectados a tu instancia de AlloyDB Omni, así como los back-ends que están esperando actividad, consultando la vista pg_stat_activity.
SELECT
pid,
datname,
age(backend_xid) AS age_in_xids,
now() - xact_start AS xact_age,
now() - query_start AS query_age,
state,
wait_event_type,
wait_event,
query_id,
query
FROM
pg_stat_activity
WHERE
state != 'idle'
AND pid <> pg_backend_pid()
ORDER BY
4 DESC
LIMIT 10;
Ver las tablas más grandes
Para determinar el tamaño de las tablas más grandes, consulta la vista pg_stat_user_tables.
SELECT
oid,
oid::regclass table_name,
pg_size_pretty(pg_relation_size(oid)),
relpages,
s.seq_scan,
s.idx_scan
FROM
pg_class,
pg_stat_user_tables s
WHERE
s.relid = oid
AND oid > 16383
AND relpages > 100
AND relkind = 'r'
ORDER BY
relpages DESC
LIMIT 20;
Ver las comprobaciones secuenciales principales
Para ver las principales exploraciones secuenciales, consulta la vista pg_stat_user_tables.
SELECT
relid,
relname,
seq_scan,
pg_size_pretty(pg_relation_size(relid))
FROM
pg_stat_user_tables
ORDER BY
seq_scan DESC
LIMIT 15;
Ver las principales comprobaciones de índices
Puede ver las principales lecturas de índice consultando la vista pg_stat_user_tables.
SELECT
relid,
relid::regclass table_name,
idx_scan,
pg_size_pretty(pg_relation_size(relid))
FROM
pg_stat_user_tables
WHERE
idx_scan > 10
ORDER BY
idx_scan DESC
LIMIT 15;
Ver las transacciones de mayor duración
Para ver las transacciones de mayor duración, consulta la vista pg_stat_activity y comprueba la antigüedad de la transacción.
SELECT
pid,
age(backend_xid) AS age_in_xids,
now() - xact_start AS xact_age,
now() - query_start AS query_age,
state,
query
FROM
pg_stat_activity
WHERE
state != 'idle'
ORDER BY
2 DESC
LIMIT 10;
Comprobar el progreso del aspirador
Puedes comprobar el progreso de las operaciones de vacío consultando la vista pg_stat_progress_vacuum y uniéndola con la vista pg_stat_activity mediante IDs de proceso.
SELECT
p.pid,
now() - a.xact_start AS duration,
coalesce(wait_event_type ||'.'|| wait_event, 'f') AS waiting,
CASE
WHEN a.query ~*'^autovacuum.*to prevent wraparound' THEN 'wraparound'
WHEN a.query ~*'^vacuum' THEN 'user'
ELSE
'regular'
END AS mode,
p.datname AS database,
p.relid::regclass AS table,
p.phase,
pg_size_pretty(p.heap_blks_total * current_setting('block_size')::int) AS table_size,
pg_size_pretty(pg_total_relation_size(relid)) AS total_size,
pg_size_pretty(p.heap_blks_scanned * current_setting('block_size')::int) AS scanned,
pg_size_pretty(p.heap_blks_vacuumed * current_setting('block_size')::int) AS vacuumed,
round(100.0 * p.heap_blks_scanned / p.heap_blks_total, 1) AS scanned_pct,
round(100.0 * p.heap_blks_vacuumed / p.heap_blks_total, 1) AS vacuumed_pct,
p.index_vacuum_count,
round(100.0 * p.num_dead_tuples / p.max_dead_tuples,1) AS dead_pct
FROM pg_stat_progress_vacuum p
JOIN pg_stat_activity a using (pid)
ORDER BY now() - a.xact_start DESC;
Ver consultas asíncronas
Para ver las consultas que se están ejecutando de forma asíncrona, puede consultar la vista
pg_stat_activity y filtrar las consultas que no sean el proceso principal.
SELECT
query,
leader_pid,
array_agg(pid) FILTER (WHERE leader_pid != pid) AS members
FROM
pg_stat_activity
WHERE
leader_pid IS NOT NULL
GROUP BY
query,
leader_pid;
Ver el SQL de bloqueo
Para ver la actividad que se ha bloqueado, consulta la vista pg_locks y
únala a la vista pg_stat_activity.
SELECT blocked_locks.pid AS blocked_pid,
blocked_activity.usename AS blocked_user,
blocking_locks.pid AS blocking_pid,
blocking_activity.usename AS blocking_user,
blocked_activity.query AS blocked_statement,
blocked_activity.wait_event AS blocked_wait_event,
blocking_activity.wait_event AS blocking_wait_event,
blocking_activity.query AS current_statement_in_blocking_process
FROM pg_catalog.pg_locks blocked_locks
JOIN pg_catalog.pg_stat_activity blocked_activity ON blocked_activity.pid = blocked_locks.pid
JOIN pg_catalog.pg_locks blocking_locks
ON blocking_locks.locktype = blocked_locks.locktype
AND blocking_locks.database IS NOT DISTINCT FROM blocked_locks.database
AND blocking_locks.relation IS NOT DISTINCT FROM blocked_locks.relation
AND blocking_locks.page IS NOT DISTINCT FROM blocked_locks.page
AND blocking_locks.tuple IS NOT DISTINCT FROM blocked_locks.tuple
AND blocking_locks.virtualxid IS NOT DISTINCT FROM blocked_locks.virtualxid
AND blocking_locks.transactionid IS NOT DISTINCT FROM blocked_locks.transactionid
AND blocking_locks.classid IS NOT DISTINCT FROM blocked_locks.classid
AND blocking_locks.objid IS NOT DISTINCT FROM blocked_locks.objid
AND blocking_locks.objsubid IS NOT DISTINCT FROM blocked_locks.objsubid
AND blocking_locks.pid != blocked_locks.pid
JOIN pg_catalog.pg_stat_activity blocking_activity ON blocking_activity.pid = blocking_locks.pid
WHERE NOT blocked_locks.granted;
Determinar la eficacia del tamaño de work_mem y temp_buffers
Para determinar si los elementos work_mem y temp_buffers tienen el tamaño adecuado para tus necesidades, puedes consultar la vista pg_stat_database y comprobar el archivo postgres.log.
Con pg_stat_database, ejecuta la siguiente consulta y, si hay algún aumento en temp_files o temp_bytes entre ejecuciones, es probable que sea necesario ajustar work_mem o temp_buffers.
SELECT
datname,
temp_files,
temp_bytes
FROM
pg_stat_database;
Después de ejecutarlo, comprueba el archivo postgres.log para ver si se han usado archivos temporales:
LOG: [fd.c:1772] temporary file: path "base/pgsql_tmp/pgsql_tmp4640.1", size 139264
El objetivo es minimizar la creación de archivos temporales, no evitarla por completo. Esto se debe a que la configuración de work_mem y temp_buffers
supone un equilibrio entre la memoria disponible en el host y el número de conexiones
que requieren la memoria. Para definir estos parámetros correctamente, es necesario conocer cada carga de trabajo.