DECREASE command: Difference between revisions
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<p>The DECREASE command allows the file manager to conserve file space by deallocating a certain portion of a <var class="product">Model 204</var> file. Unused pages in Table B (except for hash key files) and Table D can be reassigned to free space. The sizes of Tables A and C cannot be changed without recreating the file and reloading all of the data.</p> | <p>The DECREASE command allows the file manager to conserve file space by deallocating a certain portion of a <var class="product">Model 204</var> file. Unused pages in Table B (except for hash key files) and Table D can be reassigned to free space. The sizes of Tables A and C cannot be changed without recreating the file and reloading all of the data.</p> | ||
<p>The DECREASE command can be issued only in file context, that is, the current default must be a file, not a group.</p> | <p>The DECREASE command can be issued only in file context, that is, the current default must be a file, not a group.</p> | ||
<p>Increasing and decreasing file sizes, the various tables that make up a file, and the relevant table parameters are discussed in detail in | <p>Increasing and decreasing file sizes, the various tables that make up a file, and the relevant table parameters are discussed in detail in File Management topics such as [[Creating a File (File Management)]].</p> | ||
<p>When it processes a DECREASE command, <var class="product">Model 204</var> ends any update unit in progress and begins a non-backoutable update unit | <p>When it processes a DECREASE command, <var class="product">Model 204</var> ends any update unit in progress and begins a [[File_Integrity_and_Recovery#Model_204_update_units|non-backoutable update unit]]. </p> | ||
<p>To use the DECREASE command you must have update authority to the selected file. If the file is open for read-only access, the DECREASE command is rejected with the following message: </p> | <p>To use the DECREASE command you must have update authority to the selected file. If the file is open for read-only access, the DECREASE command is rejected with the following message: </p> | ||
<p class="code">M204.1036: UPDATES NOT PERMITTED. | <p class="code">M204.1036: UPDATES NOT PERMITTED. | ||
Revision as of 22:08, 19 July 2013
Summary
- Privileges
- File manager
- Function
- Decreases the size of a Model 204 file by deallocating a portion of the file space
Syntax
DECREASE {TABLEB | TABLED | TABLEE | TABLEX} n
Where: n is the number of pages in the specified file table to be reassigned to free space. You can free only pages that are not currently in use. The legal value for n depends upon the settings of the file parameters, as follows:
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If TABLEB is specified, n must be in the range 1 through (BSIZE - BHIGHPG - 1).
If a Table B base record, which has one and only one extension record elsewhere in the file, resides on a Table B page with sufficient free space, then the data compactor will recombine the fields in the extension record with the base record and delete the extension. The compactor will continue to recombine multiple extension records into fewer extensions, but will not attempt to recombine those with the base record.
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If TABLED is specified, n must be in the range 1 through the value of DSIZE less the value of DHIGHPG. (See "Usage notes" below.)
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If TABLEE is specified, n must be in the range 1 through (ESIZE - EHIGHPG -1). Additionally, you cannot decrease the size of Table E below 20 pages; thus (ESIZE - n) must be greater than or equal to 20.
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If TABLEX is specified, n must be in the range 1 through (XSIZE - XHIGHPG -1).
Example
DECREASE TABLED 14
Usage notes
The DECREASE command allows the file manager to conserve file space by deallocating a certain portion of a Model 204 file. Unused pages in Table B (except for hash key files) and Table D can be reassigned to free space. The sizes of Tables A and C cannot be changed without recreating the file and reloading all of the data.
The DECREASE command can be issued only in file context, that is, the current default must be a file, not a group.
Increasing and decreasing file sizes, the various tables that make up a file, and the relevant table parameters are discussed in detail in File Management topics such as Creating a File (File Management).
When it processes a DECREASE command, Model 204 ends any update unit in progress and begins a non-backoutable update unit.
To use the DECREASE command you must have update authority to the selected file. If the file is open for read-only access, the DECREASE command is rejected with the following message:
M204.1036: UPDATES NOT PERMITTED.