82 lines
6.7 KiB
HTML
82 lines
6.7 KiB
HTML
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="Lock records" />
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<meta name="abstract" content="DB2 Universal Database for iSeries has built-in integrity for records. For example, if PGMA reads a record for update operation, it locks that record. Another program cannot read the same record for update operation until PGMA releases the record, but another program can read the record just for inquiry." />
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<meta name="DC.subject" content="record, lock, integrity, ensuring database integrity, record lock, checking, displaying, WAITRCD (Wait Record) parameter, Wait Record (WAITRCD) parameter, parameter, WAITRCD (Wait Record), Display Record Locks (DSPRCDLCK) command, DSPRCDLCK (Display Record Locks) command, command, CL, DSPRCDLCK (Display Record Locks), Display Record Locks (DSPRCDLCK), Check Record Locks (CHKRCDLCK) command, CHKRCDLCK (Check Record Locks) command, CHKRCDLCK (Check Record Locks), Check Record Locks (CHKRCDLCK), record lock" />
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<title>Lock records</title>
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</head>
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<body id="rbafoconcrec"><a name="rbafoconcrec"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Lock records</h1>
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<div><p>DB2
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Universal Database™ for iSeries™ has built-in integrity for records. For example,
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if PGMA reads a record for update operation, it locks that record. Another
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program cannot read the same record for update operation until PGMA releases
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the record, but another program can read the record just for inquiry.</p>
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<p> In this way, the system ensures the integrity of the database. However,
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you can set your own wait time for a locked record to be released using the
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WAITRCD parameter.</p>
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<p>The system determines the lock condition based on the type of file processing
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specified in your program and the operation requested. For example, if your
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open options include update or delete, each record read is locked so that
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any number of users can read the record at the same time, but only one user
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can update the record.</p>
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<p>The system normally waits a specific number of seconds for a locked record
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to be released before it sends your program a message that it cannot get the
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record you are requesting. The default record wait time is 60 seconds; however,
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you can set your own wait time through the WAITRCD parameter on the create
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and change file commands and the override database file command. If your program
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is notified that the record it wants is locked by another operation, you can
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have your program take the appropriate action (for example, you can send a
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message to the operator that the requested record is currently unavailable).</p>
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<p>If the record lock is being implicitly acquired as a result of a referential
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integrity CASCADE DELETE, SET NULL, or SET DEFAULT delete rule, the lock wait
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time is limited to 30 seconds.</p>
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<div class="p">The system automatically releases a lock when the locked record is updated
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or deleted. However, you can release record locks without updating the record.
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For information about how to release a record lock, see your high-level language
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topic collection. <div class="note"><span class="notetitle">Note:</span> Using commitment control changes the record locking
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rules.</div>
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</div>
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<p>You can display locked records using either the Display Record Locks (DSPRCDLCK)
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command or iSeries Navigator.</p>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rbafoconcc.htm" title="By definition, all database files can be used by many users at the same time. However, some operations can lock the file, member, or data records in a member to prevent them from being shared across jobs.">Lock shared data</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="../rzakj/rzakjcommitkickoff.htm">Commitment control</a></div>
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<div><a href="rbafodsprcdlck.htm" title="You can also use the Display Record Locks (DSPRCDLCK) command to display the current lock status (wait or held) of records for a physical file member.">Display locked records using the Display Record Locks (DSPRCDLCK) command</a></div>
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</div>
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<div class="reltasks"><strong>Related tasks</strong><br />
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<div><a href="rbafodsplckrowon.htm" title="Use this procedure to display locked rows using iSeries Navigator.">Display locked rows using iSeries Navigator</a></div>
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</div>
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</body>
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