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Product Environment 9-45
Two-Phase Commit and Logical Log Records
TABLOCKS
The TABLOCKS logical log record can be written by either a coordinator or a
participant OnLine database server. It is associated with either a BEGPREP or
a PREPARE record and contains a list of the locked tblspaces (by tblspace
number) held by the transaction. (Within the IBM Informix STAR
environment, transactions, not database server processes, are shown as the
owners of locks.)
The output from tblog contains three fields: type; number of locks, expressed
as an integer; and locked tblspace number, expressed as a hexadecimal. (If
you convert the hexadecimal value to an integer, the result is the value stored
as partnum in the systables system catalog table.) The output appears as
follows:
TABLOCKS number_of_locks hex_tblspace_number
HEURTX
The HEURTX logical log record is written by a participant OnLine database
server to record a heuristic decision to roll back the transaction. It should be
associated with a standard ROLLBACK record indicating that the transaction
was rolled back.
The output from tblog contains two fields: type and a heuristic flag,
expressed as a hexadecimal. The value of the flag is always one. The output
appears as follows:
HEURTX 0x01
ENDTRANS
The ENDTRANS logical log record is written by both the coordinator and
participant OnLine database servers to record the end of the transaction.
ENDTRANS instructs OnLine to remove the transaction entry from its shared-
memory transaction table and close the transaction.
In the coordinator logical log, each BEGPREP that results in a committed
transaction is paired with an ENDTRANS record. If the coordinator’s final
decision is to roll back the transaction, no ENDTRANS record is written.
In the participant logical log, each ENDTRANS record is paired with a corre-
sponding HEURTX record.