Click above to get retro games delivered to your door ever month!

   CA-Clipper with TPS Error Conditions
------------------------------------------------------------------------------

   A few CA-Clipper commands and functions are illegal and will generate
   errors if used during a transaction. These commands and functions, if
   allowed during a transaction, would prevent the transaction from
   functioning properly. To prevent using these commands and functions
   in a transaction, the Advantage TPS returns an error if they are
   encountered. Each illegal operation is described below:

   Explicit Unlocks

   Explicit record and file unlocks are illegal during a transaction.
   Illegal unlocking commands and functions include:  UNLOCK, dbUnlock(),
   dbUnlockAll(), dbRUnlock() and AX_UnLock(). If these unlock commands
   or functions are used during a transaction, a 6102, "Unlock is illegal
   during a transaction", error is generated. Unlocks are illegal during
   a transaction because corresponding updates to those records/files
   cannot be made during the commit of a transaction if they are not locked.

   File Closes

   During a transaction, tables and their indexes cannot be
   explicitly and/or implicitly closed. Illegal close commands include:
   CLOSE and CLOSE INDEXES as well as related functions like dbCloseArea(),
   dbClearIndex(), AX_ClearOrder(), etc. If these close commands or
   functions are used, a 6102, "Close is illegal during a transaction",
   error is generated. This is because corresponding updates to those
   files cannot be made during the commit phase if they are no longer open.

   Note:  Due to CA-Clipper's handling of the closing of a table,
   a CLOSE command will not only generate a 6102 error, but will actually
   close the table and its indexes and then commence a rollback of
   the current transaction.

   PACK and ZAP

   Packing or zapping a file during a transaction is illegal. If the
   commands PACK or ZAP are used during a transaction, a 6102, "Pack/Zap
   is illegal during a transaction", error is generated. PACK and ZAP are
   illegal during a transaction because Advantage TPS cannot "unpack" or
   "unzap" a file in the event of a transaction rollback.

   Reindex

   Reindexing an index file during a transaction is illegal. If the command
   REINDEX or the function dbReindex() is used during a transaction, a
   6102, "Reindex is illegal during a transaction", error is generated.
   A reindex is illegal during a transaction because Advantage TPS may have
   multiple index keys referencing a single record during a transaction for
   data visibility purposes. A reindex of the index would disable this
   ability.

   Delete a CDX Index Tag

   Deleting a tag from a compound index is illegal during a transaction.
   Illegal commands and functions that delete CDX tags include:  DELETE
   TAG, ordDestroy(), and AX_KillTag(). If these commands or functions are
   used during a transaction, a 6102, "Delete Tag is illegal during a
   transaction", error is generated. Deleting a CDX tag is illegal during
   a transaction because Advantage TPS cannot "undelete" a tag in the
   event of a transaction rollback.

   Application termination during a transaction

   If an application terminates, whether normally or abnormally, an active
   transaction will be rolled back.

   Database file encryption/decryption

   Either encrypting or decrypting an entire table during a
   transaction is illegal. If the functions AX_DBFEncrypt() or
   AX_DBFDecrypt() are used during a transaction, the function will fail,
   and AX_Error() will return a 6102, "Function illegal during a transaction",
   error.  AX_DBFEncrypt() and AX_DBFDecrypt() are illegal during a
   transaction because Advantage TPS cannot "unencrypt" or "undecrypt" a
   file in the event of a transaction rollback.

   Non-standard memo writes

   Writing BLOB data or weakly-typed VariField data to a memo file during a
   transaction is illegal.  If the function AX_File2BLOB() is used during a
   transaction, the function will fail, and AX_Error() will return a 6102,
   "Function illegal during a transaction", error. If a write to a
   weakly-typed VariField is performed during a transaction, a 6102,
   "VariField write is illegal during a transaction," error is generated.
   Non-standard writes to memo fields are illegal during a transaction
   because support for rolling back these non-standard memo writes has not
   been incorporated into Advantage TPS.