hamsterdb Transaction Functions

Defines
#define	HAM_TXN_READ_ONLY   1
#define	HAM_TXN_TEMPORARY   2
Typedefs
typedef struct ham_txn_t	ham_txn_t
Functions
HAM_EXPORT ham_status_t	ham_txn_begin (ham_txn_t **txn, ham_env_t *env, const char *name, void *reserved, ham_u32_t flags)
HAM_EXPORT const char *	ham_txn_get_name (ham_txn_t *txn)
HAM_EXPORT ham_status_t	ham_txn_commit (ham_txn_t *txn, ham_u32_t flags)
HAM_EXPORT ham_status_t	ham_txn_abort (ham_txn_t *txn, ham_u32_t flags)

---

Define Documentation

#define HAM_TXN_READ_ONLY   1

Flag for ham_txn_begin

Definition at line 950 of file hamsterdb.h.

#define HAM_TXN_TEMPORARY   2

Definition at line 953 of file hamsterdb.h.

---

Typedef Documentation

typedef struct ham_txn_t ham_txn_t

Definition at line 915 of file hamsterdb.h.

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Function Documentation

HAM_EXPORT ham_status_t ham_txn_abort	(	ham_txn_t *	txn,
		ham_u32_t	flags
	)

Aborts a Transaction

This function aborts (= cancels) the sequence of Database operations.

Note that the function will fail with HAM_CURSOR_STILL_OPEN if a Cursor was attached to this Transaction (with ham_cursor_create or ham_cursor_clone), and the Cursor was not closed.

Parameters:

txn	Pointer to a Transaction structure
flags	Optional flags for aborting the Transaction, combined with bitwise OR. Unused, set to 0.

Returns:

HAM_SUCCESS upon success

HAM_IO_ERROR if writing to the Database file or logfile failed

HAM_CURSOR_STILL_OPEN if there are Cursors attached to this Transaction

Referenced by hamsterdb::txn::abort().

HAM_EXPORT ham_status_t ham_txn_begin	(	ham_txn_t **	txn,
		ham_env_t *	env,
		const char *	name,
		void *	reserved,
		ham_u32_t	flags
	)

Begins a new Transaction

A Transaction is an atomic sequence of Database operations. With ham_txn_begin such a new sequence is started. To write all operations of this sequence to the Database use ham_txn_commit. To abort and cancel this sequence use ham_txn_abort.

In order to use Transactions, the Environment has to be created or opened with the flag HAM_ENABLE_TRANSACTIONS.

You can create as many Transactions as you want (older versions of hamsterdb did not allow to create more than one Transaction in parallel).

Parameters:

txn	Pointer to a pointer of a Transaction structure
env	A valid Environment handle
name	An optional Transaction name
reserved	A reserved pointer; always set to NULL
flags	Optional flags for beginning the Transaction, combined with bitwise OR. Possible flags are: HAM_TXN_READ_ONLY This Transaction is read-only and will not modify the Database.

Returns:

HAM_SUCCESS upon success

HAM_OUT_OF_MEMORY if memory allocation failed

Referenced by hamsterdb::env::begin().

HAM_EXPORT ham_status_t ham_txn_commit	(	ham_txn_t *	txn,
		ham_u32_t	flags
	)

Commits a Transaction

This function applies the sequence of Database operations.

Note that the function will fail with HAM_CURSOR_STILL_OPEN if a Cursor was attached to this Transaction (with ham_cursor_create or ham_cursor_clone), and the Cursor was not closed.

Parameters:

txn	Pointer to a Transaction structure
flags	Optional flags for committing the Transaction, combined with bitwise OR. Unused, set to 0.

Returns:

HAM_SUCCESS upon success

HAM_IO_ERROR if writing to the file failed

HAM_CURSOR_STILL_OPEN if there are Cursors attached to this Transaction

Referenced by hamsterdb::txn::commit().

HAM_EXPORT const char* ham_txn_get_name

(

ham_txn_t *

txn

)

Retrieves the Transaction name

Returns:

NULL if the name was not assigned or if txn is invalid

Referenced by hamsterdb::txn::get_name().