GBASE 8S:SQLTRACE的用法

1. 打开SQL TRACE

database sysadmin;

execute function task (“set sql tracing on”,100000, “4k”, “low”,“niosdb”)

2. 查看TRACE缓冲中执行最慢的20个SQL;

a>按最大执行时间排序

select first 20 sql_maxtime,sql_executions,sql_estcost,sql_statement from sysmaster:syssqltrace order by 1 desc

3. 按平均执行时间排序

select first 20 sql_avgtime,sql_executions,sql_estcost,sql_statement from sysmaster:syssqltrace order by 1 desc

4. 查看包括’not in’语句的SQL

select first 20 sql_avgtime,sql_executions,sql_estcost,sql_statement from sysmaster:syssqltrace where sql_statement like ‘%not in%’ order by 1 desc

类似的，也可以查看包括not exist、in、exist等的语句。

5. 优化结束后，关闭SQL TRACE

execute function sysadmin:task(“SET SQL TRACING OFF”);