PostgreSQL："deadlock detected" 错误的可能原因

Question

我们目前在以下触发器上遇到死锁，该触发器同时被多个线程调用（不知道如何给出确切的线程数）。

任何提示，无论是发现锁定原因，还是解决问题，都将不胜感激。-

这是在 RHEL 6.4 上的 Enterprise DB 9.2.1.3 (PostgreSQL) 上运行

当前代码：

CREATE OR replace FUNCTION reports.update_cobertura
  () returns TRIGGER
AS
  $body$declare has_signal BOOLEAN;
  ip inet;
  id_proveedor INTEGER;
  mejora       BOOLEAN;
  thislat      NUMERIC;
  thislng      NUMERIC;
BEGIN
  has_signal := NEW.tipo='R';
  SELECT avl_instantaneo.ip
  INTO   ip
  FROM   avl_instantaneo
  WHERE  imei=NEW.imei
  AND    avl_instantaneo.ip<>'';

  IF ip IS NOT NULL THEN
    SELECT reports.proveedor_red.id_proveedor
    INTO   id_proveedor
    FROM   reports.proveedor_red
    WHERE  ip<<= red;

    IF id_proveedor IS NOT NULL THEN
      FOR decimales IN 0..4
      LOOP
        BEGIN
          thislat := round(NEW.latitud:: NUMERIC,decimales);
          thislng := round(NEW.longitud::NUMERIC,decimales);
          IF has_signal THEN
            INSERT INTO reports.cobertura
                        (
                                    lat,
                                    lng,
                                    ONLINE,
                                    id_provider,
                                    zoom
                        )
                        VALUES
                        (
                                    thislat,
                                    thislng,
                                    1,
                                    id_proveedor,
                                    decimales
                        );

          ELSE
            INSERT INTO reports.cobertura
                        (
                                    lat,
                                    lng,
                                    OFFLINE,
                                    id_provider,
                                    zoom
                        )
                        VALUES
                        (
                                    thislat,
                                    thislng,
                                    1,
                                    id_proveedor,
                                    decimales
                        );

          END IF;
        EXCEPTION
        WHEN integrity_constraint_violation THEN
          BEGIN
            thislat := round(NEW.latitud:: NUMERIC,decimales);
            thislng := round(NEW.longitud::NUMERIC,decimales);
            IF has_signal THEN
              UPDATE reports.cobertura
              SET    ONLINE=ONLINE+1
              WHERE  id_provider=id_proveedor
              AND    lat=thislat
              AND    lng=thislng
              AND    zoom=decimales;

            ELSE
              UPDATE reports.cobertura
              SET    OFFLINE=OFFLINE+1
              WHERE  id_provider=id_proveedor
              AND    lat=thislat
              AND    lng=thislng
              AND    zoom=decimales;

            END IF;
          EXCEPTION
          WHEN OTHERS THEN
            RAISE warning 'unknown exception on update: % / %',SQLERRM, SQLSTATE;
          END;
        WHEN restrict_violation THEN
          RAISE warning 'restrict_violation: % / %',SQLERRM, SQLSTATE;
        WHEN unique_violation THEN
          RAISE warning 'unique_violation: % / %',SQLERRM, SQLSTATE;
        WHEN check_violation THEN
          RAISE warning 'check_violation: % / %',SQLERRM, SQLSTATE;
        WHEN exclusion_violation THEN
          RAISE warning 'exclusion_violation: % / %',SQLERRM, SQLSTATE;
        WHEN deadlock_detected THEN
          RAISE warning 'deadlock_detected: % / %',SQLERRM, SQLSTATE;
          --raise;
        WHEN OTHERS THEN
          RAISE warning 'unknown exception: % / %',SQLERRM, SQLSTATE;
        END;
      END LOOP;
    END IF;
  END IF;
  RETURN NEW;
END;
$body$ LANGUAGE plpgsql volatile cost 100;

引用table:

CREATE TABLE reports.cobertura
         (
                      lat DOUBLE PRECISION NOT NULL,
                      lng DOUBLE PRECISION NOT NULL,
                      id_provider INTEGER NOT NULL,
                      zoom        INTEGER NOT NULL,
                      online      BIGINT DEFAULT 0,
                      OFFLINE     BIGINT DEFAULT 0,
                      CONSTRAINT cobertura_pkey PRIMARY KEY (lat, lng, id_provider),
                      CONSTRAINT cobertura_id_provider_fkey FOREIGN KEY (id_provider) REFERENCES reports.proveedor_movil (id_proveedor) match simple ON
         UPDATE no action
         ON
         DELETE no action
         )
         WITH
         (
                oids=FALSE
         );

  -- Index: reports.cobertura_update
  -- DROP INDEX reports.cobertura_update;CREATE INDEX cobertura_update
  ON reports.cobertura
  using        btree
               (
                            lat,
                            lng,
                            id_provider,
                            zoom
               );

Answer 1

您可能会发现此查询对于识别死锁事务很有用：

with locks as (
select
  pg_stat_activity.datname, application_name,
  substr(pg_class.relname, 1, 32) relname, page, tuple,
  pg_locks.transactionid as txid, 
  pg_locks.virtualtransaction as vtxid,
  locktype, pg_locks.mode, pg_locks.granted, pg_stat_activity.usename,
  substr(pg_stat_activity.query, 1, 255), pg_stat_activity.query_start,
  age(now(), pg_stat_activity.query_start) as "age",
  pg_stat_activity.pid -- , pg_locks.*
from pg_stat_activity, pg_locks
left outer join pg_class on (pg_locks.relation=pg_class.oid)  
where
  pg_locks.pid=pg_stat_activity.pid
  and pg_stat_activity.pid != pg_backend_pid()
  and (not granted OR pg_locks.mode like '%Exclusive%')
order by query_start
)
select * from locks a where not granted
or exists (select * from locks b where not b.granted
  and COALESCE(a.relname, '')=COALESCE(b.relname, '')
  and COALESCE(a.page, 0)=COALESCE(b.page, 0)
  and COALESCE(a.tuple, 0)=COALESCE(b.tuple, 0)
  and COALESCE(a.txid, '0'::xid)=COALESCE(b.txid, '0'::xid)
  -- and COALESCE(a.vtxid, '')=COALESCE(b.vtxid, '')
);

PostgreSQL："deadlock detected" 错误的可能原因

PostgreSQL: Possible causes for "deadlock detected" error

postgresql

triggers

deadlock

database-deadlocks

postgresql-9.2