Limit Query Buffer Size

Limit the size of the Query Buffer.

Background

The query mechanism fetches records one by one from the RDBMS into a query buffer on the client computer, and from there they are displayed on the screen. The number of records the memory buffer can contain is determined by the Buffer Height property, which defaults to 25 records. The size of the buffer has an influence on the client internal memory required for queries, on the speed at which the query results are first retrieved, and on the speed of scrolling through a list of queried records.

In idle time all query results are retrieved from database and stored in temporary files on the client computer. These files contain a copy of buffered records plus other queried records that could not be buffered because of the Buffer Height limit. These files are destroyed when the info box is cleared or the window is closed.

When to use

Limiting Buffer Height may improve performance if records in the table are especially large, for instance, when there are LONG columns or Large Objects (BLOB, CLOB). For LONG columns, 32K of buffer space is allocated per record. You can limit Buffer Height in cases where scrolling speed is not essential.