Differences Betweeen PDAC and Embarcadero Components
The following table summarizes the functional differences between Pervasive and Embarcadero components.:
TPvTable
All alias management functions perform ”named database” management.
Inherits from TPvDataSet rather than TDBDataSet;
Properties TableLevel, UpdateObject, UnlockTable, OpenIndexFile, CloseIndexFile have been dropped, TableType is ignored.
The Database Name property can be provided at both design time and runtime as a DSN, a Pervasive Named Database, or as a fully-qualified path to the database.
TPvDatabase
Property DriverName, Locale, and TTraceFlags have been dropped;
Handle's type is changed to DRM_DBID
IsSQLBased always returns False;
TransIsolation has only two possible values, 'tiDirtyRead' and 'tiReadCommitted' (the default).
EPvDBEngineError (see Class EPvDBEngineError)
Replaces EDBEngineError
TPvDBError (see Class TPvDBError
Replaces TDBError
TPvSQLSession
All alias management functions perform DSN management.
The type of Property 'Handle' has been changed to SQLHENV.
Method 'AddStandardAlias' adds an Engine DSN with default settings.
Property 'UpdateDsnType: TDsnTypes' has been added. 'TDsnTypes = (dsnSystem, dsnUser)'. 'UpdateDsnType' means:
In case of 'DeleteAlias' function - which DSN user is going to delete: System or User DSN?
In case of 'AddAlias' and 'GetAliasParameters' functions - hints which DSN type is preferred.
TPvSQLDatabase
The type of Property 'Handle' has been changed to SQLHDBC.
Property 'IsSQLBased' is always true.
Properties 'Tables' and 'StoredProcs' have type 'TSqlTablesInfoCollection' and 'TSqlStoredProcInfoCollection' correspondingly.
TPvQuery
Inherited from TQuery
The type of Property 'Handle' has been changed to SQLHSTMT.
The type of Property 'DBHandle' has been changed to SQLHDBC.
Property 'StmtHandle' has been dropped.
Property 'Text' always returns text from property 'SQL'.
Method 'CheckOpen' has been dropped.
All index and key related properties and methods (like 'GetIndexInfo') have been dropped.
If 'LoadBlobOnOpen' property is true, then all BLOBs will be cached in memory on query open. If 'LoadBlobOnOpen' is false, then BLOBs will be read as required.
TransIsolation Property Differences
The TransIsolation property behavior of the Pervasive Direct Access Components is different from that of their Embarcadero equivalents.
Transaction isolation level determines how a transaction interacts with other simultaneous transactions when they work with the same tables, and how much a transaction sees of operations performed by other transactions.
Use the property TPvDatabase.TransIsolation to specify the transaction isolation level for the database.
Pervasive Direct Access Components only support the tiReadCommitted mode. This means that other users cannot see the changes made to a file until the transaction ends. This is the only setting supported by the Pervasive PSQL database engine.