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ManagedEsent Sample

A managed version of the ESENT sample application on the Windows SDK blog. This program creates a database with one table, inserts a record and then retrieves the data from the record.

using namespace System;
using namespace System::Text;
using namespace Microsoft::Isam::Esent::Interop;

int main(array<System::String ^> ^args)
{
    JET_INSTANCE instance;
    JET_SESID sesid;
    JET_DBID dbid;
    JET_TABLEID tableid;

    JET_COLUMNDEF ^columndef = gcnew JET_COLUMNDEF();
    JET_COLUMNID columnid;

    // Initialize ESENT. Setting JET_param::CircularLog to 1 means ESENT will automatically
    // delete unneeded logfiles. JetInit will inspect the logfiles to see if the last
    // shutdown was clean. If it wasn't (e.g. the application crashed) recovery will be
    // run automatically bringing the database to a consistent state.
    Api::JetCreateInstance(instance, "instance");
    Api::JetSetSystemParameter(instance, JET_SESID::Nil, JET_param::CircularLog, 1, nullptr);
    Api::JetInit(instance);
    Api::JetBeginSession(instance, sesid, nullptr, nullptr);

    // Create the database. To open an existing database use the JetAttachDatabase and 
    // JetOpenDatabase APIs.
    Api::JetCreateDatabase(sesid, "edbtest.db", nullptr, dbid, CreateDatabaseGrbit::OverwriteExisting); 

    // Create the table. Meta-data operations are transacted and can be performed concurrently.
    // For example, one session can add a column to a table while another session is reading
    // or updating records in the same table.
    // This table has no indexes defined, so it will use the default sequential index. Indexes
    // can be defined with the JetCreateIndex Api.
    Api::JetBeginTransaction(sesid);
    Api::JetCreateTable(sesid, dbid, "table", 0, 100, tableid);
    columndef->coltyp = JET_coltyp::LongText;
    columndef->cp = JET_CP::ASCII;
    Api::JetAddColumn(sesid, tableid, "column1", columndef, nullptr, 0, columnid);
    Api::JetCommitTransaction(sesid, CommitTransactionGrbit::LazyFlush);

    // Insert a record. This table only has one column but a table can have slightly over 64,000
    // columns defined. Unless a column is declared as fixed or variable it won't take any space
    // in the record unless set. An individual record can have several hundred columns set at one
    // time, the exact number depends on the database page size and the contents of the columns.
    Api::JetBeginTransaction(sesid);
    Api::JetPrepareUpdate(sesid, tableid, JET_prep::Insert);
    String ^message = "Hello world";
    Api::SetColumn(sesid, tableid, columnid, message, Encoding::ASCII);
    Api::JetUpdate(sesid, tableid);
    Api::JetCommitTransaction(sesid, CommitTransactionGrbit::None);    // Use JetRollback() to abort the transaction

    // Retrieve a column from the record. Here we move to the first record with JetMove. By using
    // JetMoveNext it is possible to iterate through all records in a table. Use JetMakeKey and
    // JetSeek to move to a particular record.
    Api::JetMove(sesid, tableid, JET_Move::First, MoveGrbit::None);
    String ^buffer = Api::RetrieveColumnAsString(sesid, tableid, columnid, Encoding::ASCII);
    Console::WriteLine("{0}", buffer);

    // Terminate ESENT. This performs a clean shutdown.
    Api::JetCloseTable(sesid, tableid);
    Api::JetEndSession(sesid, EndSessionGrbit::None);
    Api::JetTerm(instance);
    return 0;
}

Last edited Mar 23, 2010 at 7:46 AM by laurionb, version 3

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