Question

我花了很多时间尝试优化我们的pgsql日志触发器，这开始成为一个问题。我做了很大的进步（通过插入3M行从18分钟到2.5分钟）但我想知道一些pgSql主人是否能够做得更好。

CREATE OR REPLACE FUNCTION table_log_trig()
  RETURNS trigger AS
$BODY$
    DECLARE
        col TEXT; -- Single column name to save
        newVal TEXT; -- New value for column
        oldVal TEXT; -- Old value for column
        colLimit TEXT[]; -- Columns that should be logged
    BEGIN
        IF TG_ARGV[0] IS NOT NULL THEN
        -- Trigger specifies columns to log
            SELECT array_agg(unnest)
            FROM unnest(string_to_array(TG_ARGV[0], ','))
            INTO colLimit;
        ELSE
        -- Trigger with no params. Log all columns
            SELECT array_agg(json_object_keys)
            FROM json_object_keys(row_to_json(NEW))
            WHERE json_object_keys NOT IN ('id', 'created_at', 'updated_at') -- Exceptions
            INTO colLimit;
        END IF;

        -- Loop over columns that should be saved in log
        FOREACH col IN ARRAY colLimit
        LOOP
            -- INSERT & UPDATE
            EXECUTE 'SELECT ($1).' || col || '::text' INTO newVal USING NEW;
            -- UPDATE
            IF TG_OP = 'UPDATE' THEN
                EXECUTE 'SELECT ($1).' || col || '::text' INTO oldVal USING OLD;
            END iF;
            -- Add only new or changed data
            IF
                newVal != oldVal OR
                (oldVal IS NULL AND newVal IS NOT NULL) OR
                (oldVal IS NOT NULL AND newVal IS NULL)
            THEN
                INSERT INTO tab_logs (record_id, field_name, old_value, new_value, created_at, created_by, action)
                VALUES (NEW.id, col, oldVal, newVal, NOW(), 999, 'O');
            END IF;
        END LOOP;

        RETURN NEW;
    END;
$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100;

Answer 1

row_to_json()返回列名和值;您也可以使用这些值，而不是稍后通过动态SQL提取它们。

我没有对此进行过彻底的测试，更不用说对它进行基准测试了，但这是它的要点：

CREATE OR REPLACE FUNCTION table_log_trig() RETURNS trigger AS
$$
DECLARE
  OldJson JSONB = NULL;
BEGIN
  IF TG_OP <> 'INSERT' THEN
    OldJson := to_jsonb(old);
  END IF;

  INSERT INTO tab_logs (record_id, field_name, old_value, new_value, created_at, created_by, action)
  SELECT new.id, key, OldValues.value, NewValues.value, now(), 999, 'O'
  FROM jsonb_each(to_jsonb(new)) NewValues
  LEFT JOIN jsonb_each(OldJson) OldValues USING (key)
  WHERE
    (
      (TG_ARGV[0] IS NULL AND key NOT IN ('id', 'created_at', 'updated_at')) OR
      (TG_ARGV[0] IS NOT NULL AND key = ANY(string_to_array(TG_ARGV[0], ',')))
    ) AND
    OldValues.value::text IS DISTINCT FROM NewValues.value::text;

  RETURN NULL;
END
$$
LANGUAGE plpgsql VOLATILE;

PostgreSQL日志触发器优化

1 个答案: