BDE 3.0 Schema cache (ENABLE SCHEMA CACHE)

IDAPI 3.0 has the capability to Cache table schema locally for 
tables residing on a SQL server.  This greatly increases the time 
to open tables. Example:  ORDERS on Oracle took 3 seconds 
to open without cache, perhaps 1/2 second with cache.

How it works:

Oracle will be used as the example, but this applies equally to all 
servers.

In BDE Config, Oracle Driver, there are 2 parameters to set,
ENABLE SCHEMA CACHE:  TRUE
SCHEMA CACHE DIR: <some local directory>

If you open ORDERS on the Oracle server, the BDE will look to see 
if it has an associated schema file entry in SCACHE.INI (located 
in the local cache directory).  If it doesn't it will go ahead 
and read the schema from the server and open the table.  The 
associated schema file can be created at two different events,

1) When you disconnect from the server.
2) If the number of tables opened after you opened ORDERS 
exceeds the SCHEMA CACHE SIZE parameter (8 is the default).

The file SCACHE.INI will also be updated to associate the table 
name with the schema file.  The schema files have a .SCF extension 
and are not in a text.db or dbf format.

If the associated .SCF file is deleted or the line in SCACHE.INI that 
associates the table to the schema file is deleted, the BDE acts 
like there is no schema file and follows the same scenario as given 
above.

If SCACHE.INI has a table associated with the wrong .SCF file, the 
table specified in the .SCF file is what will be opened.

The .SCF files averaged about 4K in size for relatively simple 
tables; ORDERS was 7K.


3.21.96
CJ

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ID:CS1030