Question

我对Informix查询存在一些性能问题。如何分析这些查询以缩小问题的根源？

Answer 1

select  der.session_id,
der.blocking_session_id, 
der.wait_type, 
der.wait_time,
der.start_time, 
DATEDIFF(second,der.start_time,GETDATE())/60.0 AS executeTime_Minutes,
percent_complete,
der.status as requestStatus, 
des.login_name, 
cast(db_name(der.database_id) as varchar(30)) as databaseName,
 des.program_name,
 der.command as commandType,
der.percent_complete,
case des.transaction_isolation_level
 when 0 then 'Unspecified' when 1 then 'ReadUncomitted'
 when 2 then 'ReadCommitted' when 3 then 'Repeatable'
 when 4 then 'Serializable' when 5 then 'Snapshot'
 end as transaction_isolation_level,
char(13) + char(10) + Current Command + char(13) + char(10) + 
case when der.statement_end_offset = -1 then

- 请参阅objectText-- else SUBSTRING（execText.textder.statement_start_offset / 2，（der.statement_end_offset - der.statement_start_offset）/ 2） end + char（13）+ char（10）+'------ Full Object ------------'AS currentExecutingCommand， execText.text作为objectText 来自sys.dm_exec_sessions des - 返回有关SQL Server实例上每个用户和内部系统会话的信息，包括会话设置，安全性和累积CPU，内存和I / O使用情况作为der加入sys.dm_exec_requests - sys.dm_exec_requests DMV向我们显示当前正在运行的内容 on der.session_id = des.session_id
- 在SQL Server实例中，它对内存，CPU，磁盘和缓存的影响。 outer将sys.dm_exec_sql_text（der.sql_handle）作为execText应用其中--des.session_id＆lt;＆gt; @@ spid和 des.session_id＆gt; 40;

Answer 2

来自here： -

Informix为收集提供的最全面的工具详细的SQL查询计划和执行统计信息是SET EXPLAIN 效用。该实用程序将生成一个名为sqexplain.out的文件详细记录查询执行的每一步。另外它提供查询的估计成本并估计查询结果。通过检查SET EXPLAIN输出文件，您可以确定如果可以采取措施来提高查询的性能。该以下示例显示了相当复杂的set explain输出查询：

SELECT --+AVOID_FULL(omchn)+AVOID_FULL(daphn)
                omchn.omc_hn_uanc,
                nvl(daphn.gtt_version,"0000000000000000000"),
                nvl(idachn.egt4_version,"0000000000000000000"),
                nvl(ihlrhn.hlr_timestamp,"00000000000000"),
                vsgw_hn.hn_igw_uanc,
                nvl(vsgw_hn.hn_igw_version, "00000000000000")
           FROM omchn, daphn, idachn, ihlrhn, vsgw_hn
          WHERE daphn.dap_hn_inst  = omchn.omc_hn_inst
            AND idachn.idac_hn_inst = omchn.omc_hn_inst
            AND ihlrhn.hlr_hn_inst = omchn.omc_hn_inst
            AND vsgw_hn.vsgw_hn_inst = omchn.omc_hn_inst

DIRECTIVES FOLLOWED:
AVOID_FULL ( omchn )
AVOID_FULL ( daphn )
DIRECTIVES NOT FOLLOWED:

Estimated Cost: 8
Estimated # of Rows Returned: 1

  1) root.idachn: SEQUENTIAL SCAN

  2) root.daphn: INDEX PATH

    (1) Index Keys: dap_hn_inst   (Serial, fragments: ALL)
        Lower Index Filter: root.daphn.dap_hn_inst = root.idachn.idac_hn_inst
NESTED LOOP JOIN

  3) root.vsgw_hn: SEQUENTIAL SCAN
NESTED LOOP JOIN

  4) root.omchn: INDEX PATH

                Filters: root.vsgw_hn.vsgw_hn_inst = root.omchn.omc_hn_inst
            (1) Index Keys: omc_hn_inst   (Serial, fragments: ALL)
      Lower Index Filter: root.idachn.idac_hn_inst = oot.omchn.omc_hn_inst
NESTED LOOP JOIN

     5) root.ihlrhn: INDEX PATH

            (1) Index Keys: hlr_hn_inst   (Serial, fragments: ALL)
      Lower Index Filter: root.ihlrhn.hlr_hn_inst = root.omchn.omc_hn_inst
NESTED LOOP JOIN

如何在Informix上测量查询性能？

2 个答案: