View source for Adding a date-time stamp field

<p>You can add a date-time stamp field to your files to keep track of when records in the file were last modified. The date-time stamp feature lets you put a date-time stamp (DTS) on each record that was updated in a transaction. You can then use the data in the <var class="term">date-time stamp</var> field in an end-user written application to find and process all the rows of data that were changed.</p>
<p>An application that processes these records can track the <var class="term">date-time stamp</var> field values that have been processed to date, or it may take another action, including updating the date-time stamp field.</p>
<p>To install and use this functionality, you must obtain the correct decrypt keys and install this release. After it is installed, the date-time stamp feature works only in files created in V6R1.0 or later.</p>
<p class="note"><b>Note:</b> There is no support in PQO/204 for the date/time stamp feature.</p>
==Overview of the date-time stamp feature==
<p>The date-time stamp (DTS) feature in <var class="product">Model&nbsp;204</var> can track when records are modified. The DTS feature is implemented on a file-by-file basis.</p>
<p>Except for DELETE RECORD(S) processing, all other updates are captured, including those made by BATCH204 and ONLINE jobs.</p>

<p>The default date-time stamp format uses the operating system timestamp value. If your site prefers a different field value or a different data format, consult your Rocket Model 204 installation guide to customize the date-time stamp field name and to activate the date-time stamp feature.</p>

<p>Also of note:</p>

* The DTS feature is implemented on a file-by-file basis.
* Precision and accuracy of the date-time stamp is to the millisecond when you use the date-time stamp as delivered. Rocket Software recommends that the date-time stamp field be defined as ORDERED CHARACTER to support ordered index FIND processing. (The length of this field is 17 bytes.)
* While it should not be updated directly, you can read and display the date-time stamp as you can any other field. User Language and IFAM may both be used to find and display date-time stamp field data 
* The date-time stamp field is updated at the beginning of commit processing when a new record is stored or an existing record is updated: changes, inserts, or deletes to fields or fieldgroups.
* You can exclude a user thread from date-time stamp field maintenance by resetting the DTS parameter to 0.
<p>.</p>

==Extracting date-time stamp field data==
<p>Since the date-time stamp field is a normal <var class="product">Model&nbsp;204</var> field, all methods of extraction may be used.</p>
===Date-time stamp field in User Language===
<p>The date-time stamp field may be:</p>
<ul>
<li>Read and printed either as a field name reference or through a $function.</li>
<li>Searched in normal FIND statements.</li>
<li>Assigned to %variables or other fields.</li>
<li>Printed as supported for all <var class="product">Model&nbsp;204</var> fields, including a PAI statement.</li>
</ul>
===Date-time stamp field and OPEN processing===
<p>If the specified date-time stamp field name is not defined in a date-time stamp file, an OPEN command is rejected. If the date-time stamp field name is DATE.TIMESTAMP, for example, the following messages are issued:</p>
<p class="code">> OPEN DTSFILE
<b></b>***  1  M204.1265: NO SUCH FIELD NAME. FIELD = DATE.TIMESTAMP
<b></b>***  M204.2730: DATE/TIME STAMP FILE, BUT DTSFN NOT DEFINED IN FILE
<b></b>***  M204.0608: FILE CLOSED: DTSFILE
<b></b>***  2  M204.0630: FILE OPEN COMMAND REJECTED
</p>
<p>If you do not set the DTSFN system parameter, files with FOPT=X'10' cannot be opened. An OPEN command will not be processed and the following message is issued:</p>
<p class="code">M204.2729: DATE/TIME STAMP FILE, BUT DTSFN UNSPECIFIED IN RUN
</p>
<p>If you have reset DTS to 0, you must open DTS enabled files with file manager privileges. Otherwise, the open is rejected.</p>
==Date-time stamp considerations==
===Backup and recovery===
<p>If any errors occur during processing, the transaction is backed out.</p>
<p>Backup and recovery activity synchronize the date-time stamp with the data changes made. Date-time stamp field updates are part of your updating transaction and follow the normal <var class="product">Model&nbsp;204</var> rules for BACKOUT, COMMIT, DUMP, RESTORE, ROLL BACK, and ROLL FORWARD.</p>
===File load utilities===
<p>FLOD and FASTLOAD do not update the date-time stamp values. However, you can manually update date-time stamp values as you might update another field name value pair.</p>
===Procedures with more than one request===
<p>If there are two requests in one procedure, for example, and neither COMMIT nor CLOSE is called between the two, then both requests are one transaction.</p>
<p>The following procedure has two requests. </p>
<p class="code">BEGIN
   STORE a record in a DTS file
END
BEGIN
   PAI the record
END
</p>
<p>DTS updates are not displayed by the PAI output, since the transaction does not complete until the end of the procedure.</p>
<p>If there is no COMMIT in the first request or if the file is not closed after the first request, then the date-time stamp field is not updated.</p>
<p>If the same User Language requests are executed as separate procedures, the date-time stamp field is updated. </p>
==<div id="Suspending date-time stamp updates">Suspending date-time stamp updates</div>==
<p>There are two ways to suspend date=time stamp updates:</p>

===Suspending updates for all files on one thread's updates ===
<p>A user with system manager privileges can exclude date-time stamp files from DTS processing, suspending DTS updates for that user's thread. The user's thread does no date-time stamp processing on any file.</p>
<p>To suspend DTS updates, reset the DTS parameter to 0. When DTS=0, the user can update any field, including the date-time stamp field, without automatically updating the date-time stamp field.</p>
<p>To reset the DTS parameter, the user must have system manager privileges. The user must also have file manager privileges for any DTS-enabled files opened, either before or after DTS is reset to 0.</p>
<p class="note"><b>Note:</b> Automatic date-time stamp field updates are still performed for updates made to the files by other user threads with DTS set to 1.</p>
===Suspending all updates for a file===
<p>To disable all date-time stamp processing for a specific file, turn off the FOPT parameter X'10' bit on the command line or using the File Management Subsystem facility. Turning off this bit disables date-time stamp updates made by all users of that file.</p>
<p>For more information on the DTS and FOPT parameters, see the Rocket <var class="product">Model&nbsp;204</var> Parameter and Command Reference.</p>
[[Category:File manager]]
[[Category:File management]]