Release 10.1A: OpenEdge Development:
Debugging and Troubleshooting

Generating Query Info

The following 4GL constructs generate Query Info logging:

FOR [EACH|FIRST|LAST] statements:

FOR EACH Customer

Static PRESELECT statement on REPEAT or DO blocks:

REPEAT PRESELECT FOR EACH customer, EACH order OF CUSTOMER

Statically Opened Queries:

OPEN QUERY q FOR EACH CUSTOMER

Dynamically Opened Queries

It is possible to dynamically open both dynamic and static queries:

For a dynamic query object:

DEFINE VARIABLE qh AS HANDLE. CREATE QUERY qh. : qh:QUERY-PREPARE("FOR EACH customer"). qh:QUERY-OPEN().

For a static query object:

DEFINE QUERY q FOR CUSTOMER. DEFINE VARIABLE qh AS HANDLE NO-UNDO. qh = q:HANDLE. qh:QUERY-PREPARE("FOR EACH customer"). qh:QUERY-OPEN().

Query Info logging logs information separately for each instance of the same query. For example, if a program containing a query calls itself recursively, information is logged for each instance of the query.

Distinguishing between query objects

You typically generate 4GL query objects as follows:

You define static queries,. For example:

DEFINE QUERY q1 FOR Customer.

You create dynamic queries. For example:

DEFINE VARIABLE my-query-handle AS HANDLE. CREATE QUERY my-query-handle.

It also is possible for you to dynamically open a static query; that is, you can define the query statically, but then get a handle to the query, and prepare and open the query as you would a dynamic query. Since Query Info logging reacts to how a query is prepared and opened, not to how it is defined or created, it is necessary to distinguish between static and dynamic queries, and queries that are statically or dynamically opened.

For example, Query Info logging logs query preparation statistics for dynamically opened queries, as it happens at run time and can affect the performance of an application. For statically opened queries, the preparation happens at compile time, so there is no impact at run time.

There are some places in Query Info logging that do relate specifically to dynamic and static queries. For example, dynamic queries typically do not have a name, while static queries always have a name. This means that a dynamically opened query might or might not have a name. Thus, Query Info logging will log the name only when it is available.

Both database and temp-table queries are logged.

Unsupported queries

OpenEdge provides no Query Info logging for SQL statements within the 4GL, or for free-standing FIND statements. For example:

REPEAT:   FIND NEXT Customer. END.

Query Info logging does not log query information for any OpenEdge ADE applications, that is, any programs that begin with an underscore (_). Similarly, Query Info logging does not log query information for WebSpeed support programs, such as any programs in the web/objects, webutil, webedit, and webtools directories.