how to print barcode in c# net BUILDING YOUR OWN STORAGE ENGINE in Font

Encoder QR Code 2d barcode in Font BUILDING YOUR OWN STORAGE ENGINE

CHAPTER 7 BUILDING YOUR OWN STORAGE ENGINE
Drawing QR In None
Using Barcode maker for Font Control to generate, create Denso QR Bar Code image in Font applications.
www.OnBarcode.com
EAN-13 Supplement 5 Generation In None
Using Barcode generator for Font Control to generate, create EAN 13 image in Font applications.
www.OnBarcode.com
/* Start the transaction and create a savepoint then register the transaction. */ if (txn->stmt == NULL && !(error= txn->tx_begin())) { txn->stmt= txn->new_savepoint(); trans_register_ha(thd, FALSE, &my_handler_hton); } DBUG_RETURN(error); } Starting a transaction from external_lock() is a bit more complicated. MySQL calls the external_lock() method for every table in use at the start of a transaction. Thus, you have some more work to do to detect the transaction and process it accordingly. This can be seen in the check of the trx->active_trans flag. The start transaction operation is also implied when the external_lock() method is called for the first table. Listing 7-59 shows an example implementation of the external_lock() method (some sections are omitted for brevity). See the ha_innodb.cc file for the complete code. Listing 7-59. Example external_lock() Method Implementation (from InnoDB) int ha_innobase::external_lock(THD* thd, int Lock_type) { row_prebuilt_t* prebuilt = (row_prebuilt_t*) innobase_prebuilt; trx_t* trx; DBUG_ENTER("ha_innobase::external_lock"); DBUG_PRINT("enter",("lock_type: %d", lock_type)); update_thd(thd); trx = prebuilt->trx; prebuilt->sql_stat_start = TRUE; prebuilt->hint_need_to_fetch_extra_cols = 0; prebuilt->read_just_key = 0; prebuilt->keep_other_fields_on_keyread = FALSE; if (lock_type == F_WRLCK) { /* If this is a SELECT, then it is in UPDATE TABLE ... or SELECT ... FOR UPDATE */ prebuilt->select_lock_type = LOCK_X; prebuilt->stored_select_lock_type = LOCK_X; }
Code 128A Encoder In None
Using Barcode generator for Font Control to generate, create Code128 image in Font applications.
www.OnBarcode.com
Print PDF417 In None
Using Barcode printer for Font Control to generate, create PDF-417 2d barcode image in Font applications.
www.OnBarcode.com
CHAPTER 7 BUILDING YOUR OWN STORAGE ENGINE
QR Printer In None
Using Barcode generator for Font Control to generate, create Quick Response Code image in Font applications.
www.OnBarcode.com
Barcode Generation In None
Using Barcode creator for Font Control to generate, create Barcode image in Font applications.
www.OnBarcode.com
if (lock_type != F_UNLCK) { /* MySQL is setting a new table lock */ trx->detailed_error[0] = '\0'; /* Set the MySQL flag to mark that there is an active transaction */ if (trx->active_trans == 0) { innobase_register_trx_and_stmt(thd); trx->active_trans = 1; } else if (trx->n_mysql_tables_in_use == 0) { innobase_register_stmt(thd); } trx->n_mysql_tables_in_use++; prebuilt->mysql_has_locked = TRUE; ... DBUG_RETURN(0); } /* MySQL is releasing a table lock */ trx->n_mysql_tables_in_use--; prebuilt->mysql_has_locked = FALSE; /* If the MySQL lock count drops to zero we know that the current SQL statement has ended */ if (trx->n_mysql_tables_in_use == 0) { ... DBUG_RETURN(0); } Now that you ve seen how to start transactions, let s see how they are stopped (also known as committed or rolled back). Committing a transaction just means writing the pending changes to disk, storing the appropriate keys, and cleaning up the transaction. MySQL AB provides a method in the handlerton (int (*commit)(THD *thd, bool all)) that can be implemented using the function description shown here. The parameters are the current thread and whether you want the entire set of commands committed. int (*commit)(THD *thd, bool all); Rolling back the transaction is more complicated. In this case, you have to undo everything that was done since the last start of the transaction. MySQL AB supports rollback using a
Print Barcode In None
Using Barcode printer for Font Control to generate, create Barcode image in Font applications.
www.OnBarcode.com
Planet Generator In None
Using Barcode printer for Font Control to generate, create USPS Confirm Service Barcode image in Font applications.
www.OnBarcode.com
CHAPTER 7 BUILDING YOUR OWN STORAGE ENGINE
Printing Denso QR Bar Code In Objective-C
Using Barcode generator for iPad Control to generate, create Denso QR Bar Code image in iPad applications.
www.OnBarcode.com
QR Generator In Java
Using Barcode printer for Java Control to generate, create QR Code image in Java applications.
www.OnBarcode.com
callback in the handlerton (int (*rollback)(THD *thd, bool all)) that can be implemented using the function description shown here. The parameters are the current thread and whether the entire transaction should be rolled back. int (*rollback)(THD *thd, bool all); To implement transactions, the storage engine must provide some sort of buffer mechanism to hold the unsaved changes to the database. Some storage engines use heap-like structures; others use queues and similar internal memory structures. If you are going to implement transactions in your storage engine, you ll need to create an internal caching (also called versioning) mechanism. When a commit is issued, the data must be taken out of the buffer and written to disk. When a rollback occurs, the operations must be canceled and their changes reversed. Savepoints are another transaction mechanism available to you for managing data during transactions. Savepoints are areas in memory that allow you to save information. You can use them to save information during a transaction. For example, you may want to save information about an internal buffer you implement to store the dirty or uncommitted changes. The savepoint concept was created for just such a use. MySQL AB provides several savepoint operations that you can define in your handlerton. These appear in lines 13 through 15 in the handlerton structure shown in Listing 7-1. The method descriptions for the savepoint methods are shown here: uint savepoint_offset; int (*savepoint_set)(THD *thd, void *sv); int (*savepoint_rollback)(THD *thd, void *sv); int (*savepoint_release)(THD *thd, void *sv); The savepoint_offset value is the size of the memory area you want to save. The savepoint_set() method allows you to set a value to the parameter sv and save it as a savepoint. The savepoint_rollback() method is called when a rollback operation is triggered. In this case, the server returns the information saved in sv to the method. Similarly, savepoint_release() is called when the server responds to a release savepoint event and also returns the data via the sv that was set as a savepoint. For more information about savepoints, see the MySQL source code and online reference manual.
Barcode Maker In Visual C#.NET
Using Barcode generator for .NET Control to generate, create Barcode image in .NET applications.
www.OnBarcode.com
Encode GS1 - 12 In Java
Using Barcode creation for Java Control to generate, create Universal Product Code version A image in Java applications.
www.OnBarcode.com
Code 128 Code Set B Decoder In Visual Basic .NET
Using Barcode reader for .NET framework Control to read, scan read, scan image in Visual Studio .NET applications.
www.OnBarcode.com
UPC A Maker In Java
Using Barcode generator for Android Control to generate, create UPC Code image in Android applications.
www.OnBarcode.com
DataMatrix Maker In Objective-C
Using Barcode maker for iPad Control to generate, create Data Matrix 2d barcode image in iPad applications.
www.OnBarcode.com
Encoding Code-39 In Objective-C
Using Barcode generator for iPhone Control to generate, create Code 39 Extended image in iPhone applications.
www.OnBarcode.com
EAN 13 Creator In None
Using Barcode creator for Software Control to generate, create EAN-13 image in Software applications.
www.OnBarcode.com
QR Code Maker In None
Using Barcode generator for Excel Control to generate, create QR image in Office Excel applications.
www.OnBarcode.com
Code 39 Extended Creator In .NET Framework
Using Barcode creator for Reporting Service Control to generate, create Code 39 Full ASCII image in Reporting Service applications.
www.OnBarcode.com
PDF417 Reader In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
Copyright © OnBarcode.com . All rights reserved.