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  • Overview
  • Benefits of optimization
  • Optimization
  • General points
  • The views
  • The queries
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Stored procedures
Optimizing the remote access
Overview
The remote access allows you to consult a HFSQL database via Internet/Intranet or via STN (Switched Telephone Network).
This help page explains how to optimize the remote access (RPC on HFSQL).
On slow networks, the performance deteriorates as the number of exchanges increases between the different computers.
To improve the performance, some modifications must be performed in the programs and/or data. These modifications consist in reducing the number of exchanges between the different computers.
Example
A program performs a search on 50 000 records. When reading the 50 000 records with the HFSQL browse functions (HReadFirst, HReadNext, ...), 50 000 round-trips are required to bring the information back to the application.
On a slow network or over phone lines (RTC), this method for reading records is penalizing.
Note: From version 19, HFSQL is the new name of HyperFileSQL.
Benefits of optimization
Optimizing the remote access is essential in case of slow networks (LAN, RTC, ...). The optimization consists in reducing the number of exchanges. Therefore, the processes are faster and the access to data is improved.
Optimization

General points

To optimize the remote access (RPC) on HFSQL, we advise you to:
  • use the following functions to find or browse records:
  • call HCreateView, HExecuteView for using the views.
  • call HExecuteQuery for using the queries.
  • associate the controls displaying data (Table, List Box and Combo Box controls) with queries (instead data files).
  • if you are not using the memo items, call HSetMemo to disable the management of memos (hMemoNo constant).

The views

A HFSQL view corresponds to a "memory image" of a data file. It is handled like a standard data file.
When creating the view (HCreateView), you have the ability to specify the number of records to return whenever a browse function is called (<Page Size> parameter in HCreateView).
The number of round-trips between the remote computers is limited. Therefore, the views should be used when you are handling a single file.

The queries

A query is used to interrogate a database in order to view, insert, modify or delete data. The query structure defines the data used. See What is a query? for more details
The queries are used to select data coming from one or more data files. To optimize the queries, use HOptimize on the base files of query.
To take into account the modifications performed on the query result, use HExecuteQuery associated with the hModifyFile constant.
Minimum required version
  • Version 9
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