数据库序列的监控

需要监控数据库的序列，在达到最大值前，进行告警。特别是mysql，往往因为字段的定义和auto incremental的定义不同，导致各自的上限不同。

Oracle：

SELECT 
x.*,
CASE WHEN increment_by<0
 THEN round(last_number/min_value*100,4)
WHEN increment_by>0
  THEN round(last_number/max_value*100,4)
 ELSE 0
  END 
AS percent_usage
from DBA_SEQUENCES x  WHERE cycle_flag='N'
ORDER BY percent_usage DESC;

SQL Server:

SELECT 
max(
CASE WHEN increment_by<0
 THEN round(last_number/min_value*100,4)
WHEN increment_by>0
  THEN round(last_number/max_value*100,4)
 ELSE 0
  END 
) AS percent_usage
from DBA_SEQUENCES x  WHERE cycle_flag='N'
ORDER BY percent_usage DESC;

pg:

--(1)初始化部署：
--(1.1)数据库内部署表和函数（注，如果一个pg实例中有多个数据库需要监控，需要部署到多个库）：
drop table oracleblog_pg_sequence;
create table oracleblog_pg_sequence
(
 record_time timestamp with time zone,
 sequence_name TEXT   , 
 last_value    bigint , 
 start_value   bigint , 
 increment_by  bigint , 
 max_value     bigint , 
 min_value     bigint , 
 cache_value   bigint , 
 log_cnt       bigint , 
 is_cycled     boolean, 
 is_called     boolean,
 sequence_schema TEXT,
 table_name   text,
 column_name TEXT,
 data_type text,
 datatype_maxval bigint,
 datatype_minval bigint,
 cap_value   bigint 
);


DROP function oracleblog_get_seqval();
CREATE OR REPLACE FUNCTION oracleblog_get_seqval() RETURNS void AS $sequence_values$
DECLARE
   nsp_name TEXT;
   seq_name TEXT;
BEGIN
   EXECUTE 'truncate table oracleblog_pg_sequence';
   FOR nsp_name, seq_name IN
       SELECT nspname::text, relname::text
          FROM pg_class 
          JOIN pg_namespace
          ON pg_class.relnamespace = pg_namespace.oid WHERE relkind='S'
   LOOP
       EXECUTE 'INSERT into oracleblog_pg_sequence(sequence_name,last_value,start_value,increment_by,max_value,min_value,cache_value,log_cnt,is_cycled,is_called,sequence_schema) SELECT x.*,'
               || ''''
               || nsp_name
               || ''''
               ||' from '
               || nsp_name
               ||'.'
               ||seq_name
               ||' x';
   END LOOP;
   
update oracleblog_pg_sequence a
set 
table_name=(select table_name from INFORMATION_SCHEMA.COLUMNS b where SPLIT_PART(COLUMN_DEFAULT, '''', 2) = SEQUENCE_NAME and sequence_schema=table_schema),
column_name=(select column_name from INFORMATION_SCHEMA.COLUMNS b where SPLIT_PART(COLUMN_DEFAULT, '''', 2) = SEQUENCE_NAME and sequence_schema=table_schema),
data_type=(select data_type from INFORMATION_SCHEMA.COLUMNS b where SPLIT_PART(COLUMN_DEFAULT, '''', 2) = SEQUENCE_NAME and sequence_schema=table_schema),
datatype_maxval=(select
CASE lower(DATA_TYPE)
         when 'smallint'  then     32767
         when 'integer'   then     2147483647
         when 'serial'    then     2147483647
         when 'bigint'    then     9223372036854775807
         when 'bigserial' then     9223372036854775807
         else  null 
         end from INFORMATION_SCHEMA.COLUMNS b where SPLIT_PART(COLUMN_DEFAULT, '''', 2) = SEQUENCE_NAME and sequence_schema=table_schema),
datatype_minval=(select
CASE lower(DATA_TYPE)
         when 'smallint'   then      -32767
         when 'integer'    then      -2147483647
         when 'serial'     then      1
         when 'bigint'     then      -9223372036854775807
         when 'bigserial'  then      1
         else  null 
         end from INFORMATION_SCHEMA.COLUMNS b where SPLIT_PART(COLUMN_DEFAULT, '''', 2) = SEQUENCE_NAME and sequence_schema=table_schema); 
         
update oracleblog_pg_sequence 
set cap_value=(
case when INCREMENT_BY < 0 then 
          (case  when min_value>=datatype_minval then min_value
                 when min_value<=datatype_minval then datatype_minval
           end)      
     when INCREMENT_BY > 0 then 
          (case  when max_value>=datatype_maxval then datatype_maxval
                 when max_value<=datatype_maxval then max_value
           end)         
end),
record_time=now()
;
          
END;
$sequence_values$
LANGUAGE plpgsql;

--(1.2)在没有安装pgAgent的环境下，用crontab实现定时刷新（注，如果一个pg实例中有多个数据库需要监控，需要部署多个crontab，每个crontab的-d参数后跟不同的库）：
cat /data001/PRD/postgres/9.6.2/home/postgres/crontab_script/fresh_oracleblog_pg_sequence.sh
#!/bin/bash
/data/PRD/postgres/base/9.6.2/bin/psql -d dbinfo -c "select oracleblog_get_seqval()"
chmod +x /data001/PRD/postgres/9.6.2/home/postgres/crontab_script/fresh_oracleblog_pg_sequence.sh

crontab -l
01 * * * *  /bin/bash /data001/PRD/postgres/9.6.2/home/postgres/crontab_script/fresh_oracleblog_pg_sequence.sh


--(2)给zabbix用户授权：
grant select on oracleblog_pg_sequence to zabbix;

--(3)查询结果：
--(3.1)用于监控语句：
select 
max(round((1-(cap_value-last_value)::numeric/(cap_value-start_value)::numeric)*100,4)) as max_usage_percent
from oracleblog_pg_sequence where is_cycled='f';


--(3.2)平时运维检查：
select 
SEQUENCE_NAME,
last_value,
start_value,
increment_by,
cap_value,
round((1-(cap_value-last_value)::numeric/(cap_value-start_value)::numeric)*100,4) as usage_percent
from oracleblog_pg_sequence where  is_cycled='f' order by usage_percent desc;

MySQL:

CREATE DEFINER=`root`@`localhost` PROCEDURE `proc_awr_getauto_increment_status`()
BEGIN
    TRUNCATE TABLE myawr.auto_increment_status;
    INSERT INTO myawr.auto_increment_status (clock, table_schema, table_name,auto_increment_increment,auto_increment_offset,auto_increment_max,auto_increment_used)
    SELECT now() AS clock, b.table_schema, b.table_name
        ,(select VARIABLE_VALUE from performance_schema.global_variables where VARIABLE_NAME = 'auto_increment_increment') as auto_increment_increment
        ,(select VARIABLE_VALUE from performance_schema.global_variables where VARIABLE_NAME = 'auto_increment_offset') as auto_increment_offset
        , CASE 
            WHEN COLUMN_TYPE LIKE 'bigint%' THEN 9223372036854775808
            WHEN COLUMN_TYPE LIKE 'int(%)' THEN 2147483647
            WHEN COLUMN_TYPE LIKE 'int(%) unsigned' THEN 4294967295
            WHEN COLUMN_TYPE LIKE 'MEDIUMINT(%)' THEN 8388607
            WHEN COLUMN_TYPE LIKE 'MEDIUMINT(%) unsigned' THEN 16777215
            WHEN COLUMN_TYPE LIKE 'SMALLINT(%)' THEN 32767
            WHEN COLUMN_TYPE LIKE 'SMALLINT(%) unsigned' THEN 65535
            WHEN COLUMN_TYPE LIKE 'TINYINT(%)' THEN 127
            WHEN COLUMN_TYPE LIKE 'TINYINT(%) unsigned' THEN 255
            ELSE 'other'
        END AS auto_increment_max
        , CASE 
            WHEN COLUMN_TYPE LIKE 'bigint%' THEN format(b.auto_increment / 9223372036854775808 * 100, 0)
            WHEN COLUMN_TYPE LIKE 'int(%)' THEN format(b.auto_increment / 2147483647 * 100, 0)
            WHEN COLUMN_TYPE LIKE 'int(%) unsigned' THEN format(b.auto_increment / 4294967295 * 100, 0)
            WHEN COLUMN_TYPE LIKE 'MEDIUMINT(%)' THEN format(b.auto_increment / 8388607 * 100, 0)
            WHEN COLUMN_TYPE LIKE 'MEDIUMINT(%) unsigned' THEN format(b.auto_increment / 16777215 * 100, 0)
            WHEN COLUMN_TYPE LIKE 'SMALLINT(%)' THEN format(b.auto_increment / 32767 * 100, 0)
            WHEN COLUMN_TYPE LIKE 'SMALLINT(%) unsigned' THEN format(b.auto_increment / 65535 * 100, 0)
            WHEN COLUMN_TYPE LIKE 'TINYINT(%)' THEN format(b.auto_increment / 127 * 100, 0)
            WHEN COLUMN_TYPE LIKE 'TINYINT(%) unsigned' THEN format(b.auto_increment / 255 * 100, 0)
            ELSE '100'
        END AS auto_increment_used
    FROM information_schema.columns a
        JOIN information_schema.tables b
        ON a.table_name = b.table_name
            AND a.table_schema = b.table_schema
    WHERE EXTRA = 'auto_increment'
    ORDER BY auto_increment_used + 0 DESC
    LIMIT 10;

CREATE DEFINER=`root`@`localhost` EVENT `event_awr_getauto_increment_status` ON SCHEDULE EVERY 1 HOUR STARTS '2019-04-17 11:45:34' ON COMPLETION PRESERVE ENABLE DO call myawr.proc_awr_getauto_increment_status()