Making High-Efficiency Reports

This topic introduces the settings you can specify in Designer in order to make your reports more efficient, reliable, and fast at runtime.

You can use the following methods to improve the efficiency, reliability, and running speed of your reports.

Suppress all unused panels in a banded object, such as Group Header and Footer panels which are not adding values to a report.
To do this, select the panel, go to the Report Inspector, and then change the property Suppress to true. When you right-click in the panel and select Hide, Designer also sets Suppress to "true" automatically.
Set the precision (length) of DBFields or record level formulas to the size of the maximum value you need to display in a report. Making them larger than necessary wastes resources.
To do this:
1. Go to the Catalog Manager, select Show Properties on the toolbar to expand the Properties sheet.
2. Select the DBField or record level formula, then change the Precision property to an appropriate value.
Set the data buffer size to a larger value.
By default, the size of one data buffer is 2MB. When data exceeds the default size, Logi Report Engine writes it to disk, which slows down data processing. You can set the data buffer size by specifying two properties of a dataset or subreport in the Report Inspector: Max Page Number and Records per Page. For more information, see Data Buffer.
Adjust the result buffer size.
The result buffer is used to store the report result in pages. Its default size is 4, which indicates Logi Report Engine allocates four pages of the report result to the result buffer, and stores other pages on disk. If you have enough memory, to get better performance, you can increase the result buffer size to store more pages of the report result.
To adjust the result buffer size, in the Report Inspector, highlight the node which represents the page report tab or web report, and then change the value of the Result Buffer Size property to the number of pages you want to hold in memory.
Adjust the Excel buffer size for exporting to Excel.
The Excel buffer is used to store the report result in the Excel buffer sheets when you export page report tabs to Excel. Its default size is 1, meaning, Logi Report Engine allocates one sheet of the report result to the result buffer, and stores other sheets on disk. If you have enough memory, you can increase the Excel buffer size to store more sheets of the Excel output in memory by setting the Excel Buffer Size property of page report tabs in the Report Inspector.
Arrange the object coordinates for exporting to a columned file.
Normally, when you export a report to a columned file, such as Excel and CSV, Logi Report Engine calculates the coordinates of the report objects, which can require a great deal of processing time. You can predefine the coordinates of the report objects to save the extra position calculating time (you should set the Columned property to "true" for the report tab or web report in order for the customized coordinates to take effect).
When running a page report tab to the delimited format such as CSV on Server, the property Fast Pass can help you speed up the generation process. Setting Fast Pass to "true" enables you to specify the position of the object you want to display in the output, thus Logi Report Engine does not need to calculate the position for every object during the generation process. For more information, see Improving the Performance of Running a Page Report to Delimited Format on Server.
Set the Cache Section property.
You can set the Cache Section property for the detail panel in a banded object to true in the Report Inspector so as to cache the objects in the panel instead of creating them repeatedly, which is helpful in improving the performance.
The Cache Section property doesn't work if there is crosstab, text object, chart, and so on in the detail panel of the banded object, because these objects may contain child DBFields.
Set the Cache Value property (only for DBFields).
To get better performance, you can set the Cache Value property for DBFields to true in the Report Inspector, which caches the layout attributes (font size, font face, width, and so on) when you export the report to any format.
Set the Push Down Group Query property.
The Push Down Group Query property controls whether to push down group level summary computations in reports to the DBMS at runtime. By pushing down the computations, the DBMS' computation capability can be made use of, and thus the reports' running efficiency is improved.
Limit the size of the fetch data buffer.

If you create your reports on queries that use data from a relational database which supports the JDBC method Statement.setFetchSize(), you can request the database to retrieve a specified number of rows in each read instead of all rows by setting the property setFetchSize in the file JdbcDriversConfig.properties that is saved in the <designer_install_root>\bin directory. This can minimize memory usage and improve performance, and also avoid Java heap out of memory errors when executing large queries.

The following is an example of setting the setFetchSize property in JdbcDriversConfig.properties and detailed description of each property:

DriverName_D1 = MySQL-AB JDBC Driver Vendor_D1 = MySql.com Version_D1 = 3.0.8-stable ($Date: 2003/05/19 00:57:19 $, $Revision: 1.27.2.18 $) setFetchSize_D1 = 5000
- DriverName_[Name]
  Database driver name that should be used to establish a connection. You can use connection.getMetaData().getDriverName() to obtain the value.
- Vendor_[Name]
  The vendor of current JDBC driver. It is a string value.
- Version_[Name]
  The version of current JDBC driver. You can use connection.getMetaData().getDriverVersion() to obtain the value. The entire string must match exactly.
- setFetchSize_[Name]
  The number of rows retrieved in each buffer from the database. It is an Integer value that should be larger than 0 and less than or equal to getMaxRows(). The default value is different according to the driver in use. You can refer to your own database driver specification.
- _[Name]
  It is a user-defined name used to mark a group of driver settings different from the other groups.

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