Added support for X/Open XA prepare, recover, commit and rollback.

innobase/include/trx0roll.h:
  Changed prototype of the function trx_rollback_or_clean_all_without_sess
  because this function is executed in a background thread.
innobase/include/trx0trx.h:
  Added support for X/Open XA prepare, recover and search by X/Open XA XID.
innobase/include/trx0undo.h:
  Added support for X/Open XA prepare and recover. We need to store X/Open XA XID
  to the undo log header for recovery.
innobase/log/log0recv.c:
  Create a thread to run trx_rollback_or_clean_all_without_sess function
  to rollback the uncommitted transactions which have no user session.
innobase/row/row0ins.c:
  Remove unnecessary variables.
innobase/trx/trx0roll.c:
  Changed so that trx_rollback_or_clean_all_without_sess is executed
  in a background thread. We should also leave all prepared transactions
  active to wait for commit or abort from MySQL.
innobase/trx/trx0sys.c:
  Only those rows which belong to the active transaction in crash recovery
  are undone.
innobase/trx/trx0trx.c:
  Added support for X/Open XA prepare and recover. We need to store X/Open XA
  XID to trx structure and left prepared transactions to wait for a
  commit or abort from MySQL. This requires also that we add TRX_PREPARED
  state to the transaction and TRX_UNDO_PREPARED state for undo logs.
innobase/trx/trx0undo.c:
  Added support for X/Open XA prepare and recover. We need to store X/Open XA
  XID to undo log header for recovery of distributed transactions.
sql/ha_innodb.h:
  Added prototypes for X/Open XA prepare, recover, commit and rollback.
sql/handler.h:
  Added definition for X/Open XA XID structure.

13 files changed, 1029 insertions, 48 deletions

diff --git a/innobase/include/trx0roll.h b/innobase/include/trx0roll.h
index 6004551f456..893e5af6c01 100644
--- a/innobase/include/trx0roll.h
+++ b/innobase/include/trx0roll.h
@@ -104,11 +104,12 @@ trx_rollback(
 /***********************************************************************
 Rollback or clean up transactions which have no user session. If the
 transaction already was committed, then we clean up a possible insert
-undo log. If the transaction was not yet committed, then we roll it back. */
+undo log. If the transaction was not yet committed, then we roll it back. 
+Note: this is done in a background thread */
 
-void
-trx_rollback_or_clean_all_without_sess(void);
-/*========================================*/
+void *
+trx_rollback_or_clean_all_without_sess(void *);
+/*============================================*/
 /********************************************************************
 Finishes a transaction rollback. */
 
diff --git a/innobase/include/trx0trx.h b/innobase/include/trx0trx.h
index 602291f946a..8a16fa82057 100644
--- a/innobase/include/trx0trx.h
+++ b/innobase/include/trx0trx.h
@@ -16,6 +16,7 @@ Created 3/26/1996 Heikki Tuuri
 #include "que0types.h"
 #include "mem0mem.h"
 #include "read0types.h"
+#include "xa.h"
 
 extern ulint	trx_n_mysql_transactions;
 
@@ -156,6 +157,36 @@ trx_commit_for_mysql(
 /*=================*/
 			/* out: 0 or error number */
 	trx_t*	trx);	/* in: trx handle */
+
+/**************************************************************************
+Does the transaction prepare for MySQL. */
+
+ulint
+trx_prepare_for_mysql(
+/*=================*/
+			/* out: 0 or error number */
+	trx_t*	trx);	/* in: trx handle */
+
+/**************************************************************************
+This function is used to find number of prepared transactions and
+their transaction objects for a recovery. */
+
+int
+trx_recover_for_mysql(
+/*=================*/
+				/* out: number of prepared transactions */
+	XID*    xid_list, 	/* in/out: prepared transactions */
+	uint	len);		/* in: number of slots in xid_list */
+
+/***********************************************************************
+This function is used to commit one X/Open XA distributed transaction
+which is in the prepared state */
+trx_t *
+trx_get_trx_by_xid(
+/*===============*/
+			/* out: trx or NULL */
+	XID*	xid);	/*  in: X/Open XA Transaction Idenfication */
+
 /**************************************************************************
 If required, flushes the log to disk if we called trx_commit_for_mysql()
 with trx->flush_log_later == TRUE. */
@@ -339,6 +370,9 @@ struct trx_struct{
 					if we can use the insert buffer for
 					them, we set this FALSE */
 	dulint		id;		/* transaction id */
+	XID		xid;		/* X/Open XA transaction 
+					identification to identify a 
+					transaction branch */
 	dulint		no;		/* transaction serialization number ==
 					max trx id when the transaction is 
 					moved to COMMITTED_IN_MEMORY state */
@@ -353,8 +387,10 @@ struct trx_struct{
 	dulint		table_id;	/* table id if the preceding field is
 					TRUE */
 	/*------------------------------*/
-        void*           mysql_thd;      /* MySQL thread handle corresponding
-                                        to this trx, or NULL */
+	int		active_trans;	/* whether a transaction in MySQL
+					is active */
+	void*           mysql_thd;      /* MySQL thread handle corresponding
+					to this trx, or NULL */
 	char**		mysql_query_str;/* pointer to the field in mysqld_thd
 					which contains the pointer to the
 					current SQL query string */
@@ -543,6 +579,7 @@ struct trx_struct{
 #define	TRX_NOT_STARTED		1
 #define	TRX_ACTIVE		2
 #define	TRX_COMMITTED_IN_MEMORY	3
+#define	TRX_PREPARED		4	/* Support for 2PC/XA */
 
 /* Transaction execution states when trx state is TRX_ACTIVE */
 #define TRX_QUE_RUNNING		1	/* transaction is running */
diff --git a/innobase/include/trx0undo.h b/innobase/include/trx0undo.h
index 20002076cc3..5aecada05d8 100644
--- a/innobase/include/trx0undo.h
+++ b/innobase/include/trx0undo.h
@@ -14,6 +14,7 @@ Created 3/26/1996 Heikki Tuuri
 #include "mtr0mtr.h"
 #include "trx0sys.h"
 #include "page0types.h"
+#include "xa.h"
 
 /***************************************************************************
 Builds a roll pointer dulint. */
@@ -36,7 +37,7 @@ trx_undo_decode_roll_ptr(
 	ibool*	is_insert,	/* out: TRUE if insert undo log */
 	ulint*	rseg_id,	/* out: rollback segment id */
 	ulint*	page_no,	/* out: page number */
-	ulint*	offset);		/* out: offset of the undo entry within page */
+	ulint*	offset);	/* out: offset of the undo entry within page */
 /***************************************************************************
 Returns TRUE if the roll pointer is of the insert type. */
 UNIV_INLINE
@@ -239,6 +240,18 @@ trx_undo_set_state_at_finish(
 	trx_t*		trx,	/* in: transaction */
 	trx_undo_t*	undo,	/* in: undo log memory copy */
 	mtr_t*		mtr);	/* in: mtr */
+/**********************************************************************
+Sets the state of the undo log segment at a transaction prepare. */
+
+page_t*
+trx_undo_set_state_at_prepare(
+/*==========================*/
+				/* out: undo log segment header page,
+				x-latched */
+	trx_t*		trx,	/* in: transaction */
+	trx_undo_t*	undo,	/* in: undo log memory copy */
+	mtr_t*		mtr);	/* in: mtr */
+
 /**************************************************************************
 Adds the update undo log header as the first in the history list, and
 frees the memory object, or puts it to the list of cached update undo log
@@ -294,7 +307,23 @@ trx_undo_parse_discard_latest(
 	byte*	end_ptr,/* in: buffer end */
 	page_t*	page,	/* in: page or NULL */
 	mtr_t*	mtr);	/* in: mtr or NULL */
+/************************************************************************
+Write X/Open XA Transaction Identification (XID) to undo log header */
 
+void
+trx_undo_write_xid(
+/*===============*/
+	trx_ulogf_t*	log_hdr,/* in: undo log header */
+	XID*		xid);	/* in: X/Open XA Transaction Identification */
+
+/************************************************************************
+Read X/Open XA Transaction Identification (XID) from undo log header */
+
+void
+trx_undo_read_xid(
+/*==============*/
+	trx_ulogf_t*	log_hdr,/* in: undo log header */
+	XID*		xid);	/* out: X/Open XA Transaction Identification */
 
 /* Types of an undo log segment */
 #define	TRX_UNDO_INSERT		1	/* contains undo entries for inserts */
@@ -310,6 +339,8 @@ trx_undo_parse_discard_latest(
 #define	TRX_UNDO_TO_PURGE	4	/* update undo segment will not be
 					reused: it can be freed in purge when
 					all undo data in it is removed */
+#define	TRX_UNDO_PREPARED	5	/* contains an undo log of an 
+					prepared transaction */
 
 /* Transaction undo log memory object; this is protected by the undo_mutex
 in the corresponding transaction object */
@@ -332,6 +363,8 @@ struct trx_undo_struct{
 					field */
 	dulint		trx_id;		/* id of the trx assigned to the undo
 					log */
+	XID             xid;		/* X/Open XA transaction 
+					identification */
 	ibool		dict_operation;	/* TRUE if a dict operation trx */
 	dulint		table_id;	/* if a dict operation, then the table
 					id */
@@ -452,7 +485,18 @@ page of an update undo log segment. */
 #define TRX_UNDO_HISTORY_NODE	34	/* If the log is put to the history
 					list, the file list node is here */
 /*-------------------------------------------------------------*/
-#define TRX_UNDO_LOG_HDR_SIZE	(34 + FLST_NODE_SIZE)
+/* X/Open XA Transaction Identification (XID)                  */
+
+#define	TRX_UNDO_XA_FORMAT	(34 + FLST_NODE_SIZE)
+#define	TRX_UNDO_XA_TRID_LEN	(TRX_UNDO_XA_FORMAT + 4)
+#define	TRX_UNDO_XA_BQUAL_LEN	(TRX_UNDO_XA_TRID_LEN + 4)
+#define	TRX_UNDO_XA_XID		(TRX_UNDO_XA_BQUAL_LEN + 4)
+#define	TRX_UNDO_XA_LEN		(TRX_UNDO_XA_XID + XIDDATASIZE)
+#define	TRX_UNDO_XA_EXISTS	256
+
+/*-------------------------------------------------------------*/
+#define	TRX_UNDO_LOG_HDR_SIZE	(TRX_UNDO_XA_LEN)
+/*-------------------------------------------------------------*/
 
 #ifndef UNIV_NONINL
 #include "trx0undo.ic"
diff --git a/innobase/include/xa.h b/innobase/include/xa.h
new file mode 100644
index 00000000000..c1ecd3cc1e7
--- /dev/null
+++ b/innobase/include/xa.h
@@ -0,0 +1,182 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 1998-2002
+ *	Sleepycat Software.  All rights reserved.
+ *
+ * $Id: xa.h,v 11.5 2002/01/11 15:52:30 bostic Exp $
+ */
+/*
+ * Start of xa.h header
+ *
+ * Define a symbol to prevent multiple inclusions of this header file
+ */
+#ifndef	XA_H
+#define	XA_H
+
+/*
+ * Transaction branch identification: XID and NULLXID:
+ */
+#ifndef XIDDATASIZE
+
+#define	XIDDATASIZE	128		/* size in bytes */
+#define	MAXGTRIDSIZE	 64		/* maximum size in bytes of gtrid */
+#define	MAXBQUALSIZE	 64		/* maximum size in bytes of bqual */
+
+struct xid_t {
+	long formatID;			/* format identifier */
+	long gtrid_length;		/* value from 1 through 64 */
+	long bqual_length;		/* value from 1 through 64 */
+	char data[XIDDATASIZE];
+};
+typedef	struct xid_t XID;
+#endif
+/*
+ * A value of -1 in formatID means that the XID is null.
+ */
+
+/*
+ * Declarations of routines by which RMs call TMs:
+ */
+extern int ax_reg __P((int, XID *, long));
+extern int ax_unreg __P((int, long));
+
+/*
+ * XA Switch Data Structure
+ */
+#define	RMNAMESZ	32		/* length of resource manager name, */
+					/* including the null terminator */
+#define	MAXINFOSIZE	256		/* maximum size in bytes of xa_info */
+					/* strings, including the null
+					terminator */
+struct xa_switch_t {
+	char name[RMNAMESZ];		/* name of resource manager */
+	long flags;			/* resource manager specific options */
+	long version;			/* must be 0 */
+	int (*xa_open_entry)		/* xa_open function pointer */
+	    __P((char *, int, long));
+	int (*xa_close_entry)		/* xa_close function pointer */
+	    __P((char *, int, long));
+	int (*xa_start_entry)		/* xa_start function pointer */
+	    __P((XID *, int, long));
+	int (*xa_end_entry)		/* xa_end function pointer */
+	    __P((XID *, int, long));
+	int (*xa_rollback_entry)	/* xa_rollback function pointer */
+	    __P((XID *, int, long));
+	int (*xa_prepare_entry)		/* xa_prepare function pointer */
+	    __P((XID *, int, long));
+	int (*xa_commit_entry)		/* xa_commit function pointer */
+	    __P((XID *, int, long));
+	int (*xa_recover_entry)		/* xa_recover function pointer */
+	    __P((XID *, long, int, long));
+	int (*xa_forget_entry)		/* xa_forget function pointer */
+	    __P((XID *, int, long));
+	int (*xa_complete_entry)	/* xa_complete function pointer */
+	    __P((int *, int *, int, long));
+};
+
+/*
+ * Flag definitions for the RM switch
+ */
+#define	TMNOFLAGS	0x00000000L	/* no resource manager features
+					selected */
+#define	TMREGISTER	0x00000001L	/* resource manager dynamically
+					registers */
+#define	TMNOMIGRATE	0x00000002L	/* resource manager does not support
+					association migration */
+#define	TMUSEASYNC	0x00000004L	/* resource manager supports
+					asynchronous operations */
+/*
+ * Flag definitions for xa_ and ax_ routines
+ */
+/* use TMNOFLAGGS, defined above, when not specifying other flags */
+#define	TMASYNC		0x80000000L	/* perform routine asynchronously */
+#define	TMONEPHASE	0x40000000L	/* caller is using one-phase commit
+					optimisation */
+#define	TMFAIL		0x20000000L	/* dissociates caller and marks
+					transaction branch rollback-only */
+#define	TMNOWAIT	0x10000000L	/* return if blocking condition
+					exists */
+#define	TMRESUME	0x08000000L	/* caller is resuming association with
+					suspended transaction branch */
+#define	TMSUCCESS	0x04000000L	/* dissociate caller from transaction
+					branch */
+#define	TMSUSPEND	0x02000000L	/* caller is suspending, not ending,
+					association */
+#define	TMSTARTRSCAN	0x01000000L	/* start a recovery scan */
+#define	TMENDRSCAN	0x00800000L	/* end a recovery scan */
+#define	TMMULTIPLE	0x00400000L	/* wait for any asynchronous
+					operation */
+#define	TMJOIN		0x00200000L	/* caller is joining existing
+					transaction branch */
+#define	TMMIGRATE	0x00100000L	/* caller intends to perform
+					migration */
+
+/*
+ * ax_() return codes (transaction manager reports to resource manager)
+ */
+#define	TM_JOIN		2		/* caller is joining existing
+					transaction branch */
+#define	TM_RESUME	1		/* caller is resuming association with
+					suspended transaction branch */
+#define	TM_OK		0		/* normal execution */
+#define	TMER_TMERR	-1		/* an error occurred in the transaction
+					manager */
+#define	TMER_INVAL	-2		/* invalid arguments were given */
+#define	TMER_PROTO	-3		/* routine invoked in an improper
+					context */
+
+/*
+ * xa_() return codes (resource manager reports to transaction manager)
+ */
+#define	XA_RBBASE	100		/* The inclusive lower bound of the
+					rollback codes */
+#define	XA_RBROLLBACK	XA_RBBASE	/* The rollback was caused by an
+					unspecified reason */
+#define	XA_RBCOMMFAIL	XA_RBBASE+1	/* The rollback was caused by a
+					communication failure */
+#define	XA_RBDEADLOCK	XA_RBBASE+2	/* A deadlock was detected */
+#define	XA_RBINTEGRITY	XA_RBBASE+3	/* A condition that violates the
+					integrity of the resources was
+					detected */
+#define	XA_RBOTHER	XA_RBBASE+4	/* The resource manager rolled back the
+					transaction branch for a reason not
+					on this list */
+#define	XA_RBPROTO	XA_RBBASE+5	/* A protocol error occurred in the
+					resource manager */
+#define	XA_RBTIMEOUT	XA_RBBASE+6	/* A transaction branch took too long */
+#define	XA_RBTRANSIENT	XA_RBBASE+7	/* May retry the transaction branch */
+#define	XA_RBEND	XA_RBTRANSIENT	/* The inclusive upper bound of the
+					rollback codes */
+#define	XA_NOMIGRATE	9		/* resumption must occur where
+					suspension occurred */
+#define	XA_HEURHAZ	8		/* the transaction branch may have
+					been heuristically completed */
+#define	XA_HEURCOM	7		/* the transaction branch has been
+					heuristically committed */
+#define	XA_HEURRB	6		/* the transaction branch has been
+					heuristically rolled back */
+#define	XA_HEURMIX	5		/* the transaction branch has been
+					heuristically committed and rolled
+					back */
+#define	XA_RETRY	4		/* routine returned with no effect and
+					may be re-issued */
+#define	XA_RDONLY	3		/* the transaction branch was read-only
+					and has been committed */
+#define	XA_OK		0		/* normal execution */
+#define	XAER_ASYNC	-2		/* asynchronous operation already
+					outstanding */
+#define	XAER_RMERR	-3		/* a resource manager error occurred in
+					 the transaction branch */
+#define	XAER_NOTA	-4		/* the XID is not valid */
+#define	XAER_INVAL	-5		/* invalid arguments were given */
+#define	XAER_PROTO	-6		/* routine invoked in an improper
+					context */
+#define	XAER_RMFAIL	-7		/* resource manager unavailable */
+#define	XAER_DUPID	-8		/* the XID already exists */
+#define	XAER_OUTSIDE	-9		/* resource manager doing work outside
+					transaction */
+#endif /* ifndef XA_H */
+/*
+ * End of xa.h header
+ */
diff --git a/innobase/log/log0recv.c b/innobase/log/log0recv.c
index 10f921bb1f0..28b9dec8aa0 100644
--- a/innobase/log/log0recv.c
+++ b/innobase/log/log0recv.c
@@ -2851,11 +2851,13 @@ void
 recv_recovery_from_checkpoint_finish(void)
 /*======================================*/
 {
+	int 		i;
+	os_thread_id_t	recovery_thread_id;
+
 	/* Rollback the uncommitted transactions which have no user session */
 
-	if (srv_force_recovery < SRV_FORCE_NO_TRX_UNDO) {
-		trx_rollback_or_clean_all_without_sess();
-	}
+	fprintf(stderr,
+		"InnoDB: Starting to apply log records to the database...\n");
 
 	/* Apply the hashed log records to the respective file pages */
 	
@@ -2888,9 +2890,15 @@ recv_recovery_from_checkpoint_finish(void)
 	/* Free the resources of the recovery system */
 
 	recv_recovery_on = FALSE;
+
 #ifndef UNIV_LOG_DEBUG
 	recv_sys_free();
 #endif
+
+	if (srv_force_recovery < SRV_FORCE_NO_TRX_UNDO) {
+		os_thread_create(trx_rollback_or_clean_all_without_sess,
+				(void *)&i, &recovery_thread_id);
+	}
 }
 
 /**********************************************************
diff --git a/innobase/row/row0ins.c b/innobase/row/row0ins.c
index c45818ddd26..6d1482b6720 100644
--- a/innobase/row/row0ins.c
+++ b/innobase/row/row0ins.c
@@ -1509,7 +1509,6 @@ row_ins_scan_sec_index_for_duplicate(
 	ibool		moved;
 	mtr_t		mtr;
 	trx_t*		trx;
-	const char*	ptr;
 	
 	n_unique = dict_index_get_n_unique(index);
 
@@ -1630,7 +1629,6 @@ row_ins_duplicate_error_in_clust(
 	page_t*	page;
 	ulint	n_unique;
 	trx_t*	trx	= thr_get_trx(thr);
-	const char*	ptr;
 
 	UT_NOT_USED(mtr);
 	
diff --git a/innobase/trx/trx0roll.c b/innobase/trx/trx0roll.c
index eb7c7f43f03..db5e16c7778 100644
--- a/innobase/trx/trx0roll.c
+++ b/innobase/trx/trx0roll.c
@@ -331,10 +331,11 @@ trx_savept_take(
 /***********************************************************************
 Rollback or clean up transactions which have no user session. If the
 transaction already was committed, then we clean up a possible insert
-undo log. If the transaction was not yet committed, then we roll it back. */
+undo log. If the transaction was not yet committed, then we roll it back. 
+Note: this is done in a background thread */
 
-void
-trx_rollback_or_clean_all_without_sess(void)
+void *
+trx_rollback_or_clean_all_without_sess(void *i)
 /*========================================*/
 {
 	mem_heap_t*	heap;
@@ -362,7 +363,7 @@ trx_rollback_or_clean_all_without_sess(void)
 		fprintf(stderr,
 		"InnoDB: Starting rollback of uncommitted transactions\n");
 	} else {		
-		return;
+		os_thread_exit(i);
 	}
 loop:
 	heap = mem_heap_create(512);
@@ -371,9 +372,15 @@ loop:
 
 	trx = UT_LIST_GET_FIRST(trx_sys->trx_list);
 
-	while (trx && (trx->sess || (trx->conc_state == TRX_NOT_STARTED))) {
+	while (trx) {
 
-		trx = UT_LIST_GET_NEXT(trx_list, trx);
+		if ((trx->sess || (trx->conc_state == TRX_NOT_STARTED))) {
+			trx = UT_LIST_GET_NEXT(trx_list, trx);
+		} else if (trx->conc_state == TRX_PREPARED) {
+			trx->sess = trx_dummy_sess;
+		} else {
+			break;
+		}
 	}
 	
 	mutex_exit(&kernel_mutex);
@@ -384,10 +391,11 @@ loop:
 
  		mem_heap_free(heap);
 		
-		return;
+		os_thread_exit(i);
 	}
 
 	trx->sess = trx_dummy_sess;
+
 	
 	if (trx->conc_state == TRX_COMMITTED_IN_MEMORY) {	
 		fprintf(stderr, "InnoDB: Cleaning up trx with id %lu %lu\n",
@@ -486,6 +494,8 @@ loop:
 	mem_heap_free(heap);
 
 	goto loop;
+
+	os_thread_exit(i); /* not reached */
 }
 	
 /***********************************************************************
diff --git a/innobase/trx/trx0sys.c b/innobase/trx/trx0sys.c
index 54bd5be01a1..35e18064329 100644
--- a/innobase/trx/trx0sys.c
+++ b/innobase/trx/trx0sys.c
@@ -887,8 +887,12 @@ trx_sys_init_at_db_start(void)
 		trx = UT_LIST_GET_FIRST(trx_sys->trx_list);
 
 		for (;;) {
-			rows_to_undo +=
+
+			if ( trx->conc_state != TRX_PREPARED) {
+			    rows_to_undo +=
 				ut_conv_dulint_to_longlong(trx->undo_no);
+			}
+
 			trx = UT_LIST_GET_NEXT(trx_list, trx);
 
 			if (!trx) {
diff --git a/innobase/trx/trx0trx.c b/innobase/trx/trx0trx.c
index f7497ac4090..d7daecdb5b7 100644
--- a/innobase/trx/trx0trx.c
+++ b/innobase/trx/trx0trx.c
@@ -24,6 +24,7 @@ Created 3/26/1996 Heikki Tuuri
 #include "thr0loc.h"
 #include "btr0sea.h"
 #include "os0proc.h"
+#include "xa.h"
 
 /* Copy of the prototype for innobase_mysql_print_thd: this
 copy MUST be equal to the one in mysql/sql/ha_innodb.cc ! */
@@ -156,6 +157,10 @@ trx_create(
 	trx->read_view_heap = mem_heap_create(256);
 	trx->read_view = NULL;
 
+	/* Set X/Open XA transaction identification to NULL */
+	memset(&trx->xid,0,sizeof(trx->xid));
+	trx->xid.formatID = -1;
+
 	return(trx);
 }
 
@@ -408,13 +413,22 @@ trx_lists_init_at_db_start(void)
 			trx = trx_create(NULL); 
 
 			trx->id = undo->trx_id;
-
+			trx->xid = undo->xid;
 			trx->insert_undo = undo;
 			trx->rseg = rseg;
 
 			if (undo->state != TRX_UNDO_ACTIVE) {
 
-				trx->conc_state = TRX_COMMITTED_IN_MEMORY;
+				/* Prepared transactions are left in
+				the prepared state waiting for a
+				commit or abort decision from MySQL */
+
+				if (undo->state == TRX_UNDO_PREPARED) {
+					trx->conc_state = TRX_PREPARED;
+				} else {
+					trx->conc_state = 
+						TRX_COMMITTED_IN_MEMORY;
+				}
 
 				/* We give a dummy value for the trx no;
 				this should have no relevance since purge
@@ -457,10 +471,22 @@ trx_lists_init_at_db_start(void)
 				trx = trx_create(NULL); 
 
 				trx->id = undo->trx_id;
+				trx->xid = undo->xid;
 
 				if (undo->state != TRX_UNDO_ACTIVE) {
-					trx->conc_state =
-						TRX_COMMITTED_IN_MEMORY;
+
+					/* Prepared transactions are left in
+					the prepared state waiting for a
+					commit or abort decision from MySQL */
+
+					if (undo->state == TRX_UNDO_PREPARED) {
+						trx->conc_state =
+							TRX_PREPARED;
+					} else {
+						trx->conc_state =
+							TRX_COMMITTED_IN_MEMORY;
+					}
+
 					/* We give a dummy value for the trx
 					number */
 
@@ -726,7 +752,8 @@ trx_commit_off_kernel(
 		mutex_enter(&kernel_mutex);
 	}
 
-	ut_ad(trx->conc_state == TRX_ACTIVE);
+	ut_ad(trx->conc_state == TRX_ACTIVE || trx->conc_state == TRX_PREPARED);
+
 #ifdef UNIV_SYNC_DEBUG
 	ut_ad(mutex_own(&kernel_mutex));
 #endif /* UNIV_SYNC_DEBUG */
@@ -1667,3 +1694,238 @@ trx_print(
 		innobase_mysql_print_thd(f, trx->mysql_thd);
   	}  
 }
+
+/********************************************************************
+Prepares a transaction. */
+
+void
+trx_prepare_off_kernel(
+/*==================*/
+	trx_t*	trx)	/* in: transaction */
+{
+	page_t*		update_hdr_page;
+	dulint		lsn;
+	trx_rseg_t*	rseg;
+	trx_undo_t*	undo;
+	ibool		must_flush_log	= FALSE;
+	mtr_t		mtr;
+	
+#ifdef UNIV_SYNC_DEBUG
+	ut_ad(mutex_own(&kernel_mutex));
+#endif /* UNIV_SYNC_DEBUG */
+
+	rseg = trx->rseg;
+	
+	if (trx->insert_undo != NULL || trx->update_undo != NULL) {
+
+		mutex_exit(&kernel_mutex);
+
+		mtr_start(&mtr);
+		
+		must_flush_log = TRUE;
+
+		/* Change the undo log segment states from TRX_UNDO_ACTIVE
+		to some other state: these modifications to the file data
+		structure define the transaction as prepared in the file
+		based world, at the serialization point of the log sequence
+		number lsn obtained below. */
+
+		mutex_enter(&(rseg->mutex));
+			
+		if (trx->insert_undo != NULL) {
+			trx_undo_set_state_at_prepare(trx, trx->insert_undo,
+							   &mtr);
+		}
+
+		undo = trx->update_undo;
+
+		if (undo) {
+			mutex_enter(&kernel_mutex);
+			trx->no = trx_sys_get_new_trx_no();
+			
+			mutex_exit(&kernel_mutex);
+
+			/* It is not necessary to obtain trx->undo_mutex here
+			because only a single OS thread is allowed to do the
+			transaction prepare for this transaction. */
+					
+			update_hdr_page = trx_undo_set_state_at_prepare(trx,								undo, &mtr);
+		}
+
+		mutex_exit(&(rseg->mutex));
+
+		/*--------------*/
+		mtr_commit(&mtr);
+		/*--------------*/
+		lsn = mtr.end_lsn;
+
+		mutex_enter(&kernel_mutex);
+	}
+
+#ifdef UNIV_SYNC_DEBUG
+	ut_ad(mutex_own(&kernel_mutex));
+#endif /* UNIV_SYNC_DEBUG */
+
+	/*--------------------------------------*/
+	trx->conc_state = TRX_PREPARED;
+	/*--------------------------------------*/
+
+	if (trx->read_view) {
+		read_view_close(trx->read_view);
+
+		mem_heap_empty(trx->read_view_heap);
+		trx->read_view = NULL;
+	}
+
+	if (must_flush_log) {
+
+		mutex_exit(&kernel_mutex);
+	
+		if (trx->insert_undo != NULL) {
+
+			trx_undo_insert_cleanup(trx);
+		}
+
+		/* Write the log to the log files AND flush them to disk */
+
+		/*-------------------------------------*/
+
+		log_write_up_to(lsn, LOG_WAIT_ONE_GROUP, TRUE);
+
+		/*-------------------------------------*/
+	
+		mutex_enter(&kernel_mutex);
+	}
+}
+
+/**************************************************************************
+Does the transaction prepare for MySQL. */
+
+ulint
+trx_prepare_for_mysql(
+/*=================*/
+			/* out: 0 or error number */
+	trx_t*	trx)	/* in: trx handle */
+{
+	/* Because we do not do the prepare by sending an Innobase
+	sig to the transaction, we must here make sure that trx has been
+	started. */
+
+	ut_a(trx);
+
+	trx->op_info = "preparing";
+	
+	trx_start_if_not_started(trx);
+
+	mutex_enter(&kernel_mutex);
+
+	trx_prepare_off_kernel(trx);
+
+	mutex_exit(&kernel_mutex);
+
+	trx->op_info = "";
+	
+	return(0);
+}
+
+/**************************************************************************
+This function is used to find number of prepared transactions and
+their transaction objects for a recovery. */
+
+int
+trx_recover_for_mysql(
+/*==================*/
+				/* out: number of prepared transactions 
+				stored in xid_list */
+	XID*    xid_list, 	/* in/out: prepared transactions */
+	uint	len)		/* in: number of slots in xid_list */
+{
+	trx_t*	trx;
+	int	num_of_transactions = 0;
+
+	ut_ad(xid_list);
+	ut_ad(len);
+
+	fprintf(stderr,
+		"InnoDB: Starting recovery for XA transactions...\n");
+
+
+	/* We should set those transactions which are in
+	the prepared state to the xid_list */
+
+	mutex_enter(&kernel_mutex);
+
+	trx = UT_LIST_GET_FIRST(trx_sys->trx_list);
+
+	while (trx) {
+		if (trx->conc_state == TRX_PREPARED) {
+			xid_list[num_of_transactions] = trx->xid;
+			num_of_transactions++;
+		
+			if ( (uint)num_of_transactions == len ) {
+				break;
+			}
+		}
+
+		trx = UT_LIST_GET_NEXT(trx_list, trx);
+	}
+
+	mutex_exit(&kernel_mutex);
+
+	fprintf(stderr,
+		"InnoDB: %d transactions in prepare state after recovery\n",
+		num_of_transactions);
+
+	return (num_of_transactions);			
+}
+
+/***********************************************************************
+This function is used to find one X/Open XA distributed transaction
+which is in the prepared state */
+
+trx_t * 
+trx_get_trx_by_xid(
+/*===============*/
+			/* out: trx or NULL */
+	XID*	xid)	/*  in: X/Open XA Transaction Idenfication */
+{
+	trx_t*	trx;
+
+	if (xid == NULL) {
+		return (NULL);
+	}
+ 
+	mutex_enter(&kernel_mutex);
+
+	trx = UT_LIST_GET_FIRST(trx_sys->trx_list);
+
+	while (trx) {
+		/* Compare two X/Open XA transaction id's: their
+		length should be the same and binary comparison
+		of gtrid_lenght+bqual_length bytes should be
+		the same */
+
+		if (xid->gtrid_length == trx->xid.gtrid_length &&
+		    xid->bqual_length == trx->xid.bqual_length &&
+		    memcmp(xid, &trx->xid, 
+				xid->gtrid_length + 
+				xid->bqual_length) == 0) {
+			break;
+		}
+
+		trx = UT_LIST_GET_NEXT(trx_list, trx);
+	}
+
+	mutex_exit(&kernel_mutex);
+
+	if (trx) {
+		if (trx->conc_state != TRX_PREPARED) {
+			return(NULL);
+		}
+
+		return(trx);
+	} else {
+		return(NULL);
+	}
+}
+
diff --git a/innobase/trx/trx0undo.c b/innobase/trx/trx0undo.c
index c1edc223cbc..8c911b29d26 100644
--- a/innobase/trx/trx0undo.c
+++ b/innobase/trx/trx0undo.c
@@ -19,6 +19,7 @@ Created 3/26/1996 Heikki Tuuri
 #include "srv0srv.h"
 #include "trx0rec.h"
 #include "trx0purge.h"
+#include "xa.h"
 
 /* How should the old versions in the history list be managed?
    ----------------------------------------------------------
@@ -97,6 +98,7 @@ trx_undo_mem_create(
 				TRX_UNDO_UPDATE */
 	dulint		trx_id,	/* in: id of the trx for which the undo log
 				is created */	
+	XID*		xid,    /* in: X/Open XA transaction identification*/
 	ulint		page_no,/* in: undo log header page number */
 	ulint		offset);	/* in: undo log header byte offset on page */
 /*******************************************************************
@@ -109,6 +111,7 @@ trx_undo_insert_header_reuse(
 	page_t*	undo_page,	/* in: insert undo log segment header page,
 				x-latched */
 	dulint	trx_id,		/* in: transaction id */
+	XID*	xid,		/* in: X/Open XA transaction identification*/
 	mtr_t*	mtr);		/* in: mtr */
 /**************************************************************************
 If an update undo log can be discarded immediately, this function frees the
@@ -484,6 +487,7 @@ trx_undo_header_create(
 				TRX_UNDO_LOG_HDR_SIZE bytes free space
 				on it */
 	dulint	trx_id,		/* in: transaction id */
+	XID*	xid,		/* in: X/Open XA XID */
 	mtr_t*	mtr)		/* in: mtr */
 {
 	trx_upagef_t*	page_hdr;
@@ -530,11 +534,24 @@ trx_undo_header_create(
 	mach_write_to_8(log_hdr + TRX_UNDO_TRX_ID, trx_id);
 	mach_write_to_2(log_hdr + TRX_UNDO_LOG_START, new_free);
 
-	mach_write_to_2(log_hdr + TRX_UNDO_DICT_OPERATION, FALSE);
-	
+	/* If X/Open XID exits in the log header we store a
+	flag of it in upper byte of dict operation flag. */
+
+	if ( xid == NULL ||  xid->formatID == -1) {
+		mach_write_to_2(log_hdr + TRX_UNDO_DICT_OPERATION, FALSE);
+	} else {
+		mach_write_to_2(log_hdr + TRX_UNDO_DICT_OPERATION, 
+					TRX_UNDO_XA_EXISTS|FALSE);
+	}
+
 	mach_write_to_2(log_hdr + TRX_UNDO_NEXT_LOG, 0);
 	mach_write_to_2(log_hdr + TRX_UNDO_PREV_LOG, prev_log);
-	
+
+	/* Write X/Open XA transaction identification if exists */
+	if ( xid && xid->formatID != -1) {
+		trx_undo_write_xid(log_hdr, xid);
+	}
+
 	trx_undo_header_create_log(undo_page, trx_id, mtr);
 	
 	return(free);
@@ -569,6 +586,11 @@ trx_undo_parse_page_header(
 	mtr_t*	mtr)	/* in: mtr or NULL */
 {
 	dulint	trx_id;
+	XID	xid;
+
+	/* Set X/Open XA transaction identification to NULL */
+	memset(&xid, 0, sizeof(xid));
+	xid.formatID = -1;
 	
 	ptr = mach_dulint_parse_compressed(ptr, end_ptr, &trx_id);
 
@@ -579,10 +601,10 @@ trx_undo_parse_page_header(
 
 	if (page) {
 		if (type == MLOG_UNDO_HDR_CREATE) {
-			trx_undo_header_create(page, trx_id, mtr);
+			trx_undo_header_create(page, trx_id, &xid, mtr);
 		} else {
 			ut_ad(type == MLOG_UNDO_HDR_REUSE);
-			trx_undo_insert_header_reuse(page, trx_id, mtr);
+			trx_undo_insert_header_reuse(page, trx_id, &xid, mtr);
 		}
 	}
 
@@ -599,6 +621,7 @@ trx_undo_insert_header_reuse(
 	page_t*	undo_page,	/* in: insert undo log segment header page,
 				x-latched */
 	dulint	trx_id,		/* in: transaction id */
+	XID*	xid,		/* in: X/Open XA transaction identification */
 	mtr_t*	mtr)		/* in: mtr */
 {
 	trx_upagef_t*	page_hdr;
@@ -636,7 +659,17 @@ trx_undo_insert_header_reuse(
 	mach_write_to_8(log_hdr + TRX_UNDO_TRX_ID, trx_id);
 	mach_write_to_2(log_hdr + TRX_UNDO_LOG_START, new_free);
 
-	mach_write_to_2(log_hdr + TRX_UNDO_DICT_OPERATION, FALSE);
+	/* If X/Open XID exits in the log header we store a
+	flag of it in upper byte of dict operation flag and
+	then write the xid. */
+
+	if ( xid && xid->formatID != -1) {
+		mach_write_to_2(log_hdr + TRX_UNDO_DICT_OPERATION, 
+					TRX_UNDO_XA_EXISTS|FALSE);
+		trx_undo_write_xid(log_hdr, xid);
+	} else {
+		mach_write_to_2(log_hdr + TRX_UNDO_DICT_OPERATION, FALSE);
+	}
 
 	trx_undo_insert_header_reuse_log(undo_page, trx_id, mtr);
 	
@@ -718,6 +751,52 @@ trx_undo_discard_latest_update_undo(
 }
 
 /************************************************************************
+Write X/Open XA Transaction Identification (XID) to undo log header */
+
+void
+trx_undo_write_xid(
+/*===============*/
+	trx_ulogf_t*	log_hdr,/* in: undo log header */
+	XID*		xid)	/* in: X/Open XA Transaction Identification */
+{
+	ulint i;
+
+	mach_write_to_4(log_hdr + TRX_UNDO_XA_FORMAT, xid->formatID);
+
+	mach_write_to_4(log_hdr + TRX_UNDO_XA_TRID_LEN, xid->gtrid_length);
+
+	mach_write_to_4(log_hdr + TRX_UNDO_XA_BQUAL_LEN, xid->bqual_length);
+
+	for(i=0; i < XIDDATASIZE; i++) {
+		mach_write_to_1(log_hdr + TRX_UNDO_XA_XID + i,
+					(ulint)(xid->data[i]));
+	}
+}
+
+/************************************************************************
+Read X/Open XA Transaction Identification (XID) from undo log header */
+
+void
+trx_undo_read_xid(
+/*==============*/
+	trx_ulogf_t*	log_hdr,/* in: undo log header */
+	XID*		xid)	/* out: X/Open XA Transaction Identification */
+{
+	ulint i;
+
+	xid->formatID = mach_read_from_4(log_hdr + TRX_UNDO_XA_FORMAT);
+	
+	xid->gtrid_length = mach_read_from_4(log_hdr + TRX_UNDO_XA_TRID_LEN);
+
+	xid->bqual_length = mach_read_from_4(log_hdr + TRX_UNDO_XA_BQUAL_LEN);
+
+	for(i=0; i < XIDDATASIZE; i++) {
+		xid->data[i] = (char)mach_read_from_1(log_hdr + 
+							TRX_UNDO_XA_XID +i);
+	}
+}
+
+/************************************************************************
 Tries to add a page to the undo log segment where the undo log is placed. */
 
 ulint
@@ -1123,6 +1202,8 @@ trx_undo_mem_create_at_db_start(
 	fil_addr_t	last_addr;
 	page_t*		last_page;
 	trx_undo_rec_t*	rec;
+	XID		xid;
+	ulint		dict_op;
 	
 	if (id >= TRX_RSEG_N_SLOTS) {
 		fprintf(stderr,
@@ -1145,15 +1226,29 @@ trx_undo_mem_create_at_db_start(
 	undo_header = undo_page + offset;
 
 	trx_id = mtr_read_dulint(undo_header + TRX_UNDO_TRX_ID, mtr);
+
+	dict_op = mtr_read_ulint(
+				undo_header + TRX_UNDO_DICT_OPERATION,
+							MLOG_2BYTES, mtr);
+
+	/* Read X/Open XA transaction identification if exists or
+	set it to NULL. */
+
+	memset(&xid, 0, sizeof(xid));
+	xid.formatID = -1;
+
+	if (dict_op & TRX_UNDO_XA_EXISTS) {
+		trx_undo_read_xid(undo_header, &xid);
+	} 
+
 	mutex_enter(&(rseg->mutex));
 
-	undo = trx_undo_mem_create(rseg, id, type, trx_id, page_no, offset);
+	undo = trx_undo_mem_create(rseg, id, type, trx_id, &xid, 
+						page_no, offset);
 	
 	mutex_exit(&(rseg->mutex));
 
-	undo->dict_operation = mtr_read_ulint(
-				undo_header + TRX_UNDO_DICT_OPERATION,
-							MLOG_2BYTES, mtr);
+	undo->dict_operation = (dict_op & 1);
 	undo->table_id = mtr_read_dulint(undo_header + TRX_UNDO_TABLE_ID, mtr);
 	undo->state = state;
 	undo->size = flst_get_len(seg_header + TRX_UNDO_PAGE_LIST, mtr);
@@ -1272,7 +1367,8 @@ trx_undo_mem_create(
 	ulint		type,	/* in: type of the log: TRX_UNDO_INSERT or
 				TRX_UNDO_UPDATE */
 	dulint		trx_id,	/* in: id of the trx for which the undo log
-				is created */	
+				is created */
+	XID*		xid,	/* in: X/Open transaction identification */
 	ulint		page_no,/* in: undo log header page number */
 	ulint		offset)	/* in: undo log header byte offset on page */
 {
@@ -1295,6 +1391,7 @@ trx_undo_mem_create(
 	undo->state = TRX_UNDO_ACTIVE;
 	undo->del_marks = FALSE;
 	undo->trx_id = trx_id;
+	undo->xid    = *xid;
 
 	undo->dict_operation = FALSE;
 
@@ -1322,6 +1419,7 @@ trx_undo_mem_init_for_reuse(
 	trx_undo_t*	undo,	/* in: undo log to init */
 	dulint		trx_id,	/* in: id of the trx for which the undo log
 				is created */
+	XID*		xid,	/* in: X/Open XA transaction identification*/
 	ulint		offset)	/* in: undo log header byte offset on page */
 {
 #ifdef UNIV_SYNC_DEBUG
@@ -1339,6 +1437,7 @@ trx_undo_mem_init_for_reuse(
 	undo->state = TRX_UNDO_ACTIVE;
 	undo->del_marks = FALSE;
 	undo->trx_id = trx_id;
+	undo->xid = *xid;
 
 	undo->dict_operation = FALSE;
 
@@ -1376,6 +1475,7 @@ trx_undo_create(
 				TRX_UNDO_UPDATE */
 	dulint		trx_id,	/* in: id of the trx for which the undo log
 				is created */ 
+	XID*		xid,	/* in: X/Open transaction identification*/
 	mtr_t*		mtr)	/* in: mtr */
 {
 	trx_rsegf_t*	rseg_header;
@@ -1410,9 +1510,10 @@ trx_undo_create(
 
 	page_no = buf_frame_get_page_no(undo_page);
 	
-	offset = trx_undo_header_create(undo_page, trx_id, mtr);	
+	offset = trx_undo_header_create(undo_page, trx_id, xid, mtr);	
 
-	undo = trx_undo_mem_create(rseg, id, type, trx_id, page_no, offset);
+	undo = trx_undo_mem_create(rseg, id, type, trx_id, xid ,
+							page_no, offset);
 	
 	return(undo);
 }
@@ -1432,6 +1533,7 @@ trx_undo_reuse_cached(
 				TRX_UNDO_UPDATE */
 	dulint		trx_id,	/* in: id of the trx for which the undo log
 				is used */	
+	XID*		xid,	/* in: X/Open XA transaction identification*/
 	mtr_t*		mtr)	/* in: mtr */
 {
 	trx_undo_t*	undo;
@@ -1475,16 +1577,17 @@ trx_undo_reuse_cached(
 	undo_page = trx_undo_page_get(undo->space, undo->hdr_page_no, mtr);
 
 	if (type == TRX_UNDO_INSERT) {
-		offset = trx_undo_insert_header_reuse(undo_page, trx_id, mtr);
+		offset = trx_undo_insert_header_reuse(undo_page, trx_id, 
+								xid, mtr);
 	} else {
 		ut_a(mach_read_from_2(undo_page + TRX_UNDO_PAGE_HDR
 					+ TRX_UNDO_PAGE_TYPE)
 						== TRX_UNDO_UPDATE);
 
-		offset = trx_undo_header_create(undo_page, trx_id, mtr);
+		offset = trx_undo_header_create(undo_page, trx_id, xid, mtr);
 	}
 	
-	trx_undo_mem_init_for_reuse(undo, trx_id, offset);
+	trx_undo_mem_init_for_reuse(undo, trx_id, xid, offset);
 
 	return(undo);
 }
@@ -1506,9 +1609,19 @@ trx_undo_mark_as_dict_operation(
 	
 	hdr_page = trx_undo_page_get(undo->space, undo->hdr_page_no, mtr);
 
-	mlog_write_ulint(hdr_page + undo->hdr_offset + TRX_UNDO_DICT_OPERATION,
-			trx->dict_operation, MLOG_2BYTES, mtr);
-	
+	/* Mark X/Open XA XID if it is not NULL to dict operation bit */
+
+	if ( trx->xid.formatID == -1) {
+		mlog_write_ulint(hdr_page + undo->hdr_offset + 
+				TRX_UNDO_DICT_OPERATION,
+				trx->dict_operation, MLOG_2BYTES, mtr);
+	} else {
+		mlog_write_ulint(hdr_page + undo->hdr_offset + 
+				TRX_UNDO_DICT_OPERATION,
+				trx->dict_operation | TRX_UNDO_XA_EXISTS, 
+				MLOG_2BYTES, mtr);
+	}
+
 	mlog_write_dulint(hdr_page + undo->hdr_offset + TRX_UNDO_TABLE_ID,
 			trx->table_id, mtr);	
 
@@ -1548,10 +1661,10 @@ trx_undo_assign_undo(
 #endif /* UNIV_SYNC_DEBUG */
 	mutex_enter(&(rseg->mutex));
 
-	undo = trx_undo_reuse_cached(rseg, type, trx->id, &mtr);
+	undo = trx_undo_reuse_cached(rseg, type, trx->id, &trx->xid, &mtr);
 
 	if (undo == NULL) {
-		undo = trx_undo_create(rseg, type, trx->id, &mtr);
+		undo = trx_undo_create(rseg, type, trx->id, &trx->xid, &mtr);
 
 		if (undo == NULL) {
 			/* Did not succeed */
@@ -1632,6 +1745,53 @@ trx_undo_set_state_at_finish(
 	return(undo_page);
 }
 
+/**********************************************************************
+Sets the state of the undo log segment at a transaction prepare. */
+
+page_t*
+trx_undo_set_state_at_prepare(
+/*==========================*/
+				/* out: undo log segment header page,
+				x-latched */
+	trx_t*		trx,	/* in: transaction */
+	trx_undo_t*	undo,	/* in: undo log memory copy */
+	mtr_t*		mtr)	/* in: mtr */
+{
+	trx_usegf_t*	seg_hdr;
+	trx_upagef_t*	page_hdr;
+	trx_ulogf_t*	undo_header;
+	page_t*		undo_page;
+	ulint		offset;
+	
+	ut_ad(trx && undo && mtr);
+
+	if (undo->id >= TRX_RSEG_N_SLOTS) {
+		fprintf(stderr, "InnoDB: Error: undo->id is %lu\n",
+			(ulong) undo->id);
+		mem_analyze_corruption((byte*)undo);
+		ut_error;
+	}
+
+	undo_page = trx_undo_page_get(undo->space, undo->hdr_page_no, mtr);
+
+	seg_hdr = undo_page + TRX_UNDO_SEG_HDR;
+	page_hdr = undo_page + TRX_UNDO_PAGE_HDR;
+
+	/*------------------------------*/
+	undo->state = TRX_UNDO_PREPARED;
+	undo->xid   = trx->xid;
+	/*------------------------------*/
+		   
+	mlog_write_ulint(seg_hdr + TRX_UNDO_STATE, undo->state, 
+			 MLOG_2BYTES, mtr);
+
+	offset = mach_read_from_2(seg_hdr + TRX_UNDO_LAST_LOG);
+        undo_header = undo_page + offset;
+
+	trx_undo_write_xid(undo_header, &undo->xid);	
+	return(undo_page);
+}
+
 /**************************************************************************
 Adds the update undo log header as the first in the history list, and
 frees the memory object, or puts it to the list of cached update undo log
diff --git a/sql/ha_innodb.cc b/sql/ha_innodb.cc
index 650cb86e253..e3fddd1a137 100644
--- a/sql/ha_innodb.cc
+++ b/sql/ha_innodb.cc
@@ -80,6 +80,7 @@ extern "C" {
 #include "../innobase/include/fsp0fsp.h"
 #include "../innobase/include/sync0sync.h"
 #include "../innobase/include/fil0fil.h"
+#include "../innobase/include/xa.h"
 }
 
 #define HA_INNOBASE_ROWS_IN_TABLE 10000 /* to get optimization right */
@@ -149,6 +150,15 @@ static mysql_byte* innobase_get_key(INNOBASE_SHARE *share,uint *length,
 static INNOBASE_SHARE *get_share(const char *table_name);
 static void free_share(INNOBASE_SHARE *share);
 
+/*********************************************************************
+Commits a transaction in an InnoDB database. */
+
+void
+innobase_commit_low(
+/*================*/
+	trx_t*	trx);	/* in: transaction handle */
+
+
 /* General functions */
 
 /**********************************************************************
@@ -1254,7 +1264,7 @@ innobase_commit(
 	if (trx_handle != (void*)&innodb_dummy_stmt_trx_handle
 	    || (!(thd->options & (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN)))) {
 	        
-		/* We were instructed to commit the whole transaction, or
+ 		/* We were instructed to commit the whole transaction, or
 		this is an SQL statement end and autocommit is on */
 
 		innobase_commit_low(trx);
@@ -1396,6 +1406,39 @@ innobase_rollback(
 }
 
 /*********************************************************************
+Rolls back a transaction */
+
+int
+innobase_rollback_trx(
+/*==================*/
+			/* out: 0 or error number */
+	trx_t*	trx)	/*  in: transaction */
+{
+	int	error = 0;
+
+	DBUG_ENTER("innobase_rollback_trx");
+	DBUG_PRINT("trans", ("aborting transaction"));
+
+	/* Release a possible FIFO ticket and search latch. Since we will
+	reserve the kernel mutex, we have to release the search system latch
+	first to obey the latching order. */
+
+	innobase_release_stat_resources(trx);
+
+        if (trx->auto_inc_lock) {
+		/* If we had reserved the auto-inc lock for some table (if
+		we come here to roll back the latest SQL statement) we
+		release it now before a possibly lengthy rollback */
+		
+		row_unlock_table_autoinc_for_mysql(trx);
+	}
+
+	error = trx_rollback_for_mysql(trx);
+
+	DBUG_RETURN(convert_error_code_to_mysql(error, NULL));
+}
+
+/*********************************************************************
 Rolls back a transaction to a savepoint. */
 
 int
@@ -5666,4 +5709,158 @@ innobase_query_is_replace(void)
 }
 }
 
+/***********************************************************************
+This function is used to prepare X/Open XA distributed transaction   */
+
+int innobase_xa_prepare(
+/*====================*/
+			/* out: 0 or error number */
+	THD*	thd,	/* in: handle to the MySQL thread of the user
+			whose XA transaction should be prepared */
+	bool	all)	/* in: TRUE - commit transaction
+			FALSE - the current SQL statement ended */
+{
+	int error = 0;
+        trx_t* trx;
+
+        trx = check_trx_exists(thd);
+
+	/* TODO: Get X/Open XA Transaction Identification from MySQL*/
+	memset(&trx->xid, 0, sizeof(trx->xid));
+	trx->xid.formatID = -1;
+
+	/* Release a possible FIFO ticket and search latch. Since we will
+	reserve the kernel mutex, we have to release the search system latch
+	first to obey the latching order. */
+
+	innobase_release_stat_resources(trx);
+
+	if (trx->active_trans == 0 && trx->conc_state != TRX_NOT_STARTED) {
+
+		fprintf(stderr,
+"InnoDB: Error: thd->transaction.all.innodb_active_trans == 0\n"
+"InnoDB: but trx->conc_state != TRX_NOT_STARTED\n");
+	}
+
+	if (all || (!(thd->options & (OPTION_NOT_AUTOCOMMIT | OPTION_BEGIN)))) {
+	        
+ 		/* We were instructed to prepare the whole transaction, or
+		this is an SQL statement end and autocommit is on */
+
+		error = trx_prepare_for_mysql(trx);
+	} else {
+	        /* We just mark the SQL statement ended and do not do a
+		transaction prepare */
+
+		if (trx->auto_inc_lock) {
+			/* If we had reserved the auto-inc lock for some
+			table in this SQL statement we release it now */
+		  	
+			row_unlock_table_autoinc_for_mysql(trx);
+		}
+		/* Store the current undo_no of the transaction so that we
+		know where to roll back if we have to roll back the next
+		SQL statement */
+
+		trx_mark_sql_stat_end(trx);
+	}
+
+	/* Tell the InnoDB server that there might be work for utility
+	threads: */
+
+	srv_active_wake_master_thread();
+
+        return error;
+}
+
+/***********************************************************************
+This function is used to recover X/Open XA distributed transactions   */
+
+int innobase_xa_recover(
+				/* out: number of prepared transactions 
+				stored in xid_list */
+	XID*    xid_list, 	/* in/out: prepared transactions */
+	uint	len)		/* in: number of slots in xid_list */
+/*====================*/
+{
+	if (len == 0 || xid_list == NULL) {
+		return 0;
+	}
+
+	return (trx_recover_for_mysql(xid_list, len));
+}
+
+/***********************************************************************
+This function is used to commit one X/Open XA distributed transaction
+which is in the prepared state */
+
+int innobase_commit_by_xid(
+/*=======================*/
+			/* out: 0 or error number */
+	XID*	xid)	/*  in: X/Open XA Transaction Identification */
+{
+	trx_t*	trx;
+
+	trx = trx_get_trx_by_xid(xid);
+
+	if (trx) {
+		innobase_commit_low(trx);
+		
+		return(XA_OK);
+	} else {
+		return(XAER_NOTA);
+	}
+}
+
+/***********************************************************************
+This function is used to rollback one X/Open XA distributed transaction
+which is in the prepared state */
+
+int innobase_rollback_by_xid(
+			/* out: 0 or error number */
+	XID	*xid)	/* in : X/Open XA Transaction Idenfification */
+{
+	trx_t*	trx;
+
+	trx = trx_get_trx_by_xid(xid);
+
+	if (trx) {
+		return(innobase_rollback_trx(trx));
+	} else {
+		return(XAER_NOTA);
+	}
+}
+
+/***********************************************************************
+This function is used to test commit/rollback of XA transactions */
+
+int innobase_xa_end(
+/*================*/
+	THD*	thd)	/* in: MySQL thread handle of the user for whom
+			transactions should be recovered */
+{
+        DBUG_ENTER("innobase_xa_end");
+
+	XID trx_list[100];
+	int trx_num, trx_num_max = 100;
+	int i;
+	XID xid;
+
+	while(trx_num = innobase_xa_recover(trx_list, trx_num_max)) {
+
+		for(i=0;i < trx_num; i++) {
+			xid = trx_list[i];
+
+			if ( i % 2) {
+				innobase_commit_by_xid(&xid);
+			} else {
+				innobase_rollback_by_xid(&xid);
+			}
+		}
+	}
+
+	free(trx_list);
+
+	DBUG_RETURN(0);
+}
 #endif /* HAVE_INNOBASE_DB */
diff --git a/sql/ha_innodb.h b/sql/ha_innodb.h
index 5ec5c207456..a62c754707c 100644
--- a/sql/ha_innodb.h
+++ b/sql/ha_innodb.h
@@ -243,3 +243,46 @@ void innobase_release_temporary_latches(void* innobase_tid);
 void innobase_store_binlog_offset_and_flush_log(char *binlog_name,longlong offset);
 
 int innobase_start_trx_and_assign_read_view(THD* thd);
+
+/***********************************************************************
+This function is used to prepare X/Open XA distributed transaction   */
+
+int innobase_xa_prepare(
+/*====================*/
+			/* out: 0 or error number */
+	THD*	thd,	/* in: handle to the MySQL thread of the user
+			whose XA transaction should be prepared */
+	bool	all);	/* in: TRUE - commit transaction
+			FALSE - the current SQL statement ended */
+
+/***********************************************************************
+This function is used to recover X/Open XA distributed transactions   */
+
+int innobase_xa_recover(
+/*====================*/
+				/* out: number of prepared transactions 
+				stored in xid_list */
+	XID*    xid_list, 	/* in/out: prepared transactions */
+	uint	len);		/* in: number of slots in xid_list */
+
+/***********************************************************************
+This function is used to commit one X/Open XA distributed transaction
+which is in the prepared state */
+
+int innobase_commit_by_xid(
+/*=======================*/
+			/* out: 0 or error number */
+	XID*	xid);	/* in : X/Open XA Transaction Identification */
+
+/***********************************************************************
+This function is used to rollback one X/Open XA distributed transaction
+which is in the prepared state */
+
+int innobase_rollback_by_xid(
+			/* out: 0 or error number */
+	XID	*xid);	/* in : X/Open XA Transaction Idenfification */
+
+
+int innobase_xa_end(THD *thd);
+
+
diff --git a/sql/handler.h b/sql/handler.h
index 31c6e2f902b..5dd47aea809 100644
--- a/sql/handler.h
+++ b/sql/handler.h
@@ -193,6 +193,41 @@ typedef struct st_thd_trans {
   void *ndb_tid;
 } THD_TRANS;
 
+#ifndef XIDDATASIZE  /* no xa.h included */
+
+/* XXX - may be we should disable xa completely in this case ? */
+#define XIDDATASIZE 128
+#define MAXGTRIDSIZE 64
+#define MAXBQUALSIZE 64
+
+struct xid_t {
+  long formatID;
+  long gtrid_length;
+  long bqual_length;
+  char data[XIDDATASIZE];
+};
+
+typedef struct xid_t XID;
+
+
+#endif
+
+typedef struct
+{
+   byte slot;
+   uint savepoint_offset;
+   int  (*close_connection)(THD *thd);
+   int  (*savepoint_set)(THD *thd, void *sv);
+   int  (*savepoint_rollback)(THD *thd, void *sv);
+   int  (*savepoint_release)(THD *thd, void *sv);
+   int  (*commit)(THD *thd, bool all);
+   int  (*rollback)(THD *thd, bool all);
+   int  (*prepare)(THD *thd, bool all);
+   int  (*recover)(XID *xid_list, uint len);
+   int  (*commit_by_xid)(XID *xid);
+   int  (*rollback_by_xid)(XID *xid);
+} handlerton;
+
 enum enum_tx_isolation { ISO_READ_UNCOMMITTED, ISO_READ_COMMITTED,
 			 ISO_REPEATABLE_READ, ISO_SERIALIZABLE};