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CALL RTR_PREPARE_TX
The CALL RTR_PREPARE_TX can only be used in the context of nested
transactions (rtr_start_tx was called with the parameter join_txid not equal
to NOJOIN_TXID). If this call returns RTR_STS_OK, then the first (prepare)
phase of the RTR 2PC protocol has been initiated.
The message type associated with this command is
rtr_mt_prepared
. Similar to
the message types
rtr_mt_accepted
and
rtr_mt_rejected
, the
rtr_mt_prepared
message type returns data of type
rtr_status_data_t
in the user buffer. In
this case, the status field of rtr_status_data_t is always RTR_STS_OK, and the
reason field contains the same reason mask that would be returned in the rtr_
mt_accepted message type for the same TX were the TX to be accepted.
Only when the rtr_mt_prepared message is delivered, can the operator be sure
that all participants of the nested TX are ready to commit. Alternatively, calling
rtr_prepare_tx can result in the message rtr_mt_rejected being delivered if one of
the participating servers votes to reject the nested TX.
The rtr_mt_prepared message is only delivered to the console if the rtr_prepare_
tx is called.
A call to rtr_prepare_tx must be followed at some point by a call to rtr_accept_tx
(or rtr_reject_tx), which in this context implements the commit phase of the 2PC.
(Generally, rtr_prepare_tx and rtr_accept_tx will be called by the foreign TM
directly, not by the operator).
Qualifiers
/CHANNEL_NAME=channel_name
/CHANNEL_NAME=RTR$DEFAULT_CHANNEL
Specifies the channel for which the operation is to be performed.
The command server uses a combination of the channel_name and the window
from which the call was issued to uniquely identify which channel to use.
channel_name
is not case sensitive.
The default channel name is RTR$DEFAULT_CHANNEL.
/DATA[=data]
/DATA=0
The data parameter can be used to pass an ASCII string to RTR that will be
saved in the local journal. This string is not sent to the routers or backends, and
is used only during recovery, when it is passed back to the client application.
RTR does not interpret or modify this data in any way. The maximum size of the
data parameter is defined as
RTR_MAX_BLOB_LEN
and is set to 2048 bytes.
/NODE[=node-list]
/NODE=default-node-list (D)
Specifies that the command is executed on all nodes specified in
node-list
.If
node-list
is omitted then the command is executed only on the node where the
command was issued.
/OUTPUT[=file-spec]
/OUTPUT=stdout (D)
Specifies that the resulting information is written to the file
file-spec
.If
/OUTPUT
or
file-spec
is omitted then the standard or default output is used.
RTR Command Line Interface 6–23