En esta página, se describe cómo supervisar el rendimiento de tu base de datos de AlloyDB Omni con secuencias de comandos de observabilidad de PostgreSQL.
Consulta el estado de los procesos conectados y los eventos de espera
Puedes determinar el estado de los procesos conectados a tu instancia de AlloyDB Omni, así como cualquier backend que esté esperando actividad, si consultas 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;
Cómo ver las tablas más grandes
Para determinar el tamaño de tus 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;
Consulta los análisis secuenciales principales
Para ver los análisis secuenciales principales, 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;
Consulta los análisis de índices principales
Para ver los análisis de índice principales, consulta 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;
Consulta las transacciones más largas en ejecución
Para ver las transacciones más largas en ejecución, consulta la vista pg_stat_activity y verifica la antigüedad de cada 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;
Cómo verificar el progreso de la limpieza
Para verificar el progreso de las operaciones de limpieza, consulta la vista pg_stat_progress_vacuum y únete a la vista pg_stat_activity con los 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;
Cómo ver consultas asíncronas
Para ver las consultas que se ejecutan de forma asíncrona, puedes consultar la vista pg_stat_activity y filtrar las consultas que no son el proceso líder.
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;
Consulta el SQL de bloqueo de bloqueo
Para ver la actividad bloqueada, consulta la vista pg_locks y combínala con 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;
Determina la eficacia del tamaño de work_mem y temp_buffers
Para determinar si tus work_mem y temp_buffers tienen el tamaño correcto para tus necesidades, puedes consultar la vista pg_stat_database y verificar el archivo postgres.log.
Con pg_stat_database, ejecuta la siguiente consulta y, si hay un aumento en temp_files o temp_bytes entre las ejecuciones, es probable que sea necesario realizar ajustes en work_mem o temp_buffers.
SELECT
datname,
temp_files,
temp_bytes
FROM
pg_stat_database;
Después de ejecutarlo, verifica el archivo postgres.log para ver si se usaron 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 evitar que se produzcan por completo. Esto se debe a que configurar work_mem y temp_buffers es un equilibrio entre la memoria disponible en el host y la cantidad de conexiones que requieren la memoria. Para configurar estos parámetros correctamente, es necesario comprender cada carga de trabajo individual.