Fast/Reload differences with FLOD/FILELOAD - Revision history

JAL: /* FLOD and FILELOAD command processing */ link repair

2017-05-09T17:42:25Z

FLOD and FILELOAD command processing: link repair

← Older revision		Revision as of 17:42, 9 May 2017
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	==FLOD and FILELOAD command processing==		==FLOD and FILELOAD command processing==
	If the <var class="product">Fast/Reload FLOD Compiler</var> is authorized, the <var>FLOD</var> and <var>FILELOAD</var> commands work exactly like the usual <var>[[FLOD command\|FLOD]]</var> and <var>[[FILELOAD command\|FILELOAD]]</var> commands, except that they invoke the <var class="product">Fast/Reload FLOD Compiler</var> rather than the standard		If the <var class="product">[[Fast/Reload\|Fast/Reload FLOD Compiler]]</var> is authorized, the <var>FLOD</var> and <var>FILELOAD</var> commands work exactly like the usual <var>[[FLOD command\|FLOD]]</var> and <var>[[FILELOAD command\|FILELOAD]]</var> commands, except that they invoke the <var class="product">Fast/Reload FLOD Compiler</var> rather than the standard
	<var class="product">Model 204</var> command processing.		<var class="product">Model 204</var> command processing.

JAL: /* FLOD and FILELOAD command processing */ typo

2017-05-09T16:03:24Z

FLOD and FILELOAD command processing: typo

← Older revision		Revision as of 16:03, 9 May 2017
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	==FLOD and FILELOAD command processing==		==FLOD and FILELOAD command processing==
	If the <var class="product">~~Fast/Reload\|~~Fast/Reload FLOD Compiler</var> is authorized, the <var>FLOD</var> and <var>FILELOAD</var> commands work exactly like the usual <var>[[FLOD command\|FLOD]]</var> and <var>[[FILELOAD command\|FILELOAD]]</var> commands, except that they invoke the <var class="product">Fast/Reload FLOD Compiler</var> rather than the standard		If the <var class="product">Fast/Reload FLOD Compiler</var> is authorized, the <var>FLOD</var> and <var>FILELOAD</var> commands work exactly like the usual <var>[[FLOD command\|FLOD]]</var> and <var>[[FILELOAD command\|FILELOAD]]</var> commands, except that they invoke the <var class="product">Fast/Reload FLOD Compiler</var> rather than the standard
	<var class="product">Model 204</var> command processing.		<var class="product">Model 204</var> command processing.

JAL: add FLOD and FILELOAD command processing

2017-05-08T20:33:41Z

add FLOD and FILELOAD command processing

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 </ol>
 See the <var>BAVAIL</var> statement description for a complete discussion and some examples.
 ==See also==

Admin: 1 revision: from Stage

2016-02-19T01:41:13Z

1 revision: from Stage

← Older revision	Revision as of 01:41, 19 February 2016
(No difference)

JAL: add category

2016-02-19T01:29:47Z

add category

New page

In general, every effort was made to maintain compatibility between
<var class="product">Fast/Reload</var> and standard <var class="product">Model 204</var> <var>FLOD</var> and <var>FILELOAD</var>.
In some specific instances, however, it was determined that compatibility was undesirable.
These instances are described in this page.

==Extension records in hash key files==
When <var class="product">Model 204</var> determines that an extension record must be started while
loading data into a hash key file, it starts the extension record on a random page.
<var class="product">Fast/Reload</var>, when operating using full track I/O,
on the other hand, tries to start the extension record on the next page.
This is because the full track feature requires that pages be written in ascending order.
This has a side benefit that when retrieving the extension
record, head movement and caching characteristics are likely to be improved.

If you want <var class="product">Fast/Reload</var> to use the standard <var class="product">Model 204</var> extension
record allocation, specify the <var>DKONLY</var> option in the <var>FLOD</var> program. 

==Adding data to non-empty unordered files==
When loading data into unordered files that have had reusable space created
because of record or field deletions, <var class="product">Model 204</var> ordinarily tries to
put data in the reusable areas before appending data after the last record
in the file.
<var class="product">Fast/Reload</var> attempts to add
data after the last record in the file.
This ensures that records are
allocated in ascending order allowing full track I/O to be used for the
loaded Table B pages.

If you want <var class="product">Fast/Reload</var> to use the standard <var class="product">Model 204</var> record allocation for unordered files,
specify the <var>DKONLY</var> option in the <var>FLOD</var> program. 

==Ordered Index layout when field codes change==
Data in the Ordered Index is maintained in field code order.
A field code is an internal, numeric (between 0 and 4095) representation of a field name.
It is possible that a field code might change between a <var>UAI</var> and <var>LAI</var>. Since <var>UAI</var> simply loads the data in the order in which it was unloaded, this can produce
a slightly different layout of the non-leaf nodes in the Ordered Index.
The effect on <var>FLOD</var>/<var>FILELOAD</var> or Online performance is likely to be unmeasurable.


To minimize the chances of field code changes: 
<ul>
<li>Explicitly define fields in the same order they were defined in the original database file. </li>

<li>Use the same value of <var>[[ATRPG parameter|ATRPG]]</var> in the new database file as used in the old. </li>
</ul>

==Ordered Index layout if mixing generated and unloaded index data==
If the old database file had Ordered Index data unloaded via <code>UAI OINDEX</code> or
<code>UAI INVISIBLE</code>, and new Ordered Index fields are defined in the new database file,
the layout of non-leaf nodes is slightly different than if the Ordered Index data had all been regenerated and resorted via <var>FLOD</var>.
This is because the Ordered
Index data is loaded in a new step in the <var>FLOD</var> process called the "FLOD" step, before the <var>Z</var> step.

Thus the Ordered Index data is loaded in a different order
than if all the data had been sorted and the loaded in the <var>Z</var> step.
The effect on <var>FLOD</var>/<var>FILELOAD</var> or Online performance is likely to be unmeasurable. 

==Table B space allocation==
As stated in the [[Fast/Reload statements#bav|BAVail statement description]], setting <var>OPTION</var> <var>BAVAIL</var> to a non-negative number
causes a change in the way space is reserved on Table B pages.
<ol>
<li><var class="product">Fast/Reload</var> guarantees (if full track I/O is in use) that <var>BAVAIL</var> bytes are unused on
each Table B page.</li>

<li>If full track I/O is in use, and the file is not <var>SORTED</var> (<var>[[FILEORG parameter|FILEORG]]</var> X'01'),
<var class="product">Fast/Reload</var> allows records to be started with less than <code>BRESERVE + BAVAIL</code> bytes
available on the page, as long as the entire record fits on the page.</li>
</ol>
See the <var>BAVAIL</var> statement description for a complete discussion and some examples.

==See also==
{{Template:Fast/Reload topic list}}

[[Category:Fast/Reload]]