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Posted to commits@empire-db.apache.org by "Rainer Döbele (JIRA)" <em...@incubator.apache.org> on 2016/02/25 12:52:18 UTC
[jira] [Assigned] (EMPIREDB-213) DBReader performance improvement
with field caching
[ https://issues.apache.org/jira/browse/EMPIREDB-213?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Rainer Döbele reassigned EMPIREDB-213:
--------------------------------------
Assignee: Rainer Döbele
> DBReader performance improvement with field caching
> ---------------------------------------------------
>
> Key: EMPIREDB-213
> URL: https://issues.apache.org/jira/browse/EMPIREDB-213
> Project: Empire-DB
> Issue Type: Improvement
> Reporter: Ivan Nemeth
> Assignee: Rainer Döbele
>
> DBReader can be much faster for resultsets with many columns if the getFieldIndex(ColumnExpr c) method uses some kind of caching. The following code is 10 times faster for a resultset with 20000 rows and 70 columns.
> public class MyDBReader extends DBReader {
> private static final long serialVersionUID = 1L;
>
> private Map<ColumnExpr, Integer> fieldIndices = new HashMap<ColumnExpr, Integer>();
> @Override
> public int getFieldIndex(ColumnExpr column) {
> Integer i = fieldIndices.get(column);
> if (i == null){
> i = super.getFieldIndex(column);
> fieldIndices.put(column, i);
> }
> return i;
> }
>
> }
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