In order to reduce the overall computation time of the batch of queries, multiple query optimization in the SQL-on-Hadoop system groups multiple map reduce jobs converted from the query into a single job, , Avoiding redundant calculations by sharing opportunities for map functions and map output....
While many efforts have been paid for query processing of data streams in distributed environment, no previous study focused on multiple-query optimization. To address this problem, we propose EsperDist, a distributed query engine for multiple-query optimization over data stream. EsperDist can ...
Multiple query optimization (MQO) in the cloud has become a promising research direction due to the popularity of cloud computing, which runs massive data analysis queries (jobs) routinely. These CPU/IO intensive analysis queries are complex and time-consuming but share common components. It is ch...
Research,activity on query,evaluation,and,optimization,has,been centered,around,processing,one,query,at,a time. Query,processing systems.,in general. attempt,to minimize,the cost,of processing,a set of queries,by minimizing,the,processing,cost of each,query,separately. A separate,plan is generated...
Updating statistical information and building covering indexes alone do not effectively reduce query time (as expected), so are there any other optimization methods? When the output row count is small, such as querying 0-100 rows or 0-1000 rows, the time difference between offset fetch ...
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类型:New feature→Cleanup/optimization Accepting following the forum conversation. comment:9byGiannis Terzopoulos,8个月 ago 属主:从nobody改变为Giannis Terzopoulos 状态:new→assigned comment:10byGiannis Terzopoulos,7个月 ago Has patch:设置 PR ...
'Sort' in exuction plan is showing more than 90 % cost, what to do? 'TRY_CONVERT' is not a recognized built-in function name 'VARCHAR' is not a recognized built-in function name. 'WHEN MATCHED' cannot appear more than once in a 'UPDATE' cl...
Explanation The reason for this is optimization I would like to implement in my application, where data filtering would be performed using subquery if only one SQL query would be produced. In case of generating multiple SQL queries, I would first execute query that filters data (and return only...
This also gives OctoSQL more room for optimization, as it can push the Join predicate down to the right-side input, possibly reading only a small subset of the whole right-side input. This is very useful when the left-side input is very small, i.e., a CSV file with a few rows, ...