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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">Database file sizes</h1>
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<div><p>When designing files on the <span class="keyword">iSeries™</span> server,
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you should keep in mind the sizes for database files.</p>
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<div class="section"><p>The following table lists the maximum values for database files:</p>
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</div>
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<table cellpadding="4" cellspacing="0" border="1" class="tableborder"><tr><td>
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<table cellpadding="4" cellspacing="0" summary="" width="100%" border="0"><thead align="left"><tr><th align="left" valign="bottom" width="50%" id="d0e62">Description</th>
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<th align="left" valign="bottom" width="50%" id="d0e64">Maximum value</th>
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</tr>
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</thead>
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<tbody><tr><td align="left" valign="top" width="50%" headers="d0e62 ">Number of bytes in a record</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">32 766 bytes</td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Number of fields in a record format</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">8 000 fields</td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Number of key fields in a file</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">120 fields</td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Size of key for physical and logical files</td>
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<td align="left" valign="top" width="50%" headers="d0e64 "><span><img src="./delta.gif" alt="Start of change" />32 768 characters<sup>1</sup><img src="./deltaend.gif" alt="End of change" /></span></td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Size of key for ORDER BY (SQL) and KEYFLD
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(OPNQRYF)</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">10 000 bytes</td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Number of records contained in a file member</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">4 294 967 294 records<sup>2</sup></td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Number of bytes in a file member</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">1 869 162 846 624 bytes<sup>3</sup></td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Number of bytes in an access path</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">1 099 511 627 776 bytes<sup>3
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5</sup></td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Number of keyed logical files built over
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a physical file member</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">3686 files</td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Number of physical file members in a logical
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file member</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">32 members</td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Number of members that can be joined</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">256 members</td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Size of a character or DBCS field</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">32 766 bytes<sup>4</sup></td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Size of a zoned decimal or packed decimal
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field</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">63 digits</td>
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</tr>
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<tr><td valign="top" width="50%" headers="d0e62 ">Maximum number of distinct database files that can be
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in use at one time</td>
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<td valign="top" width="50%" headers="d0e64 ">~500 000</td>
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</tr>
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<tr><td valign="top" width="50%" headers="d0e62 ">Maximum number of members in a physical or logical file</td>
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<td valign="top" width="50%" headers="d0e64 ">32 767</td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Maximum number of constraints per physical
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file</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">300 constraints</td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Maximum number of triggers per physical file</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">300 triggers</td>
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</tr>
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<tr><td align="left" valign="top" width="50%" headers="d0e62 ">Maximum number of recursive insert and update
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trigger calls</td>
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<td align="left" valign="top" width="50%" headers="d0e64 ">200</td>
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</tr>
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<tr><td colspan="2" align="left" valign="top" headers="d0e62 d0e64 "><p><img src="./delta.gif" alt="Start of change" /><sup>1</sup> When a first-changed-first-out (FCFO) access path
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is specified for the file, the maximum value for the size of the key for physical
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and logical files is 32 763 for ACCPTHSIZ(*MAX1TB) and 1995 characters
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for ACCPTHSIZ(*MAX4GB).<img src="./deltaend.gif" alt="End of change" /></p>
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<p><img src="./delta.gif" alt="Start of change" /><sup>2</sup> For files with keyed
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sequence access paths, the maximum number of records in a member varies and
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can be estimated using the following formulas.<img src="./deltaend.gif" alt="End of change" /></p>
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<div class="p"><img src="./delta.gif" alt="Start of change" />When ACCPTHSIZ(*MAX4GB)
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is specified, use the following formula:<p><u>2,867,200,000 </u><br />
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10 + (.8 x key length)</p>
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<img src="./deltaend.gif" alt="End of change" /></div>
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<div class="p"><img src="./delta.gif" alt="Start of change" />When ACCPTHSIZ(*MAX1TB)
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is specified, use the following formula:<p><u>725,680,000,000 </u><br />
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12 + (.8 x key length)</p>
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<img src="./deltaend.gif" alt="End of change" /></div>
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<p><img src="./delta.gif" alt="Start of change" />These are estimated values.
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The actual maximum number of records can vary significantly.<img src="./deltaend.gif" alt="End of change" /></p>
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<p><sup>3</sup> Both
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the number of bytes in a file member and the number of bytes in an access
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path must be looked at when message CPF5272 is sent indicating that the maximum
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system object size has been reached.</p>
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<p><sup>4</sup> The maximum size of
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a variable-length character or DBCS field is 32 740 bytes. DBCS-graphic
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field lengths are expressed in terms of characters; therefore, the maximums
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are 16 383 characters (fixed length) and 16 370 characters (variable
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length).</p>
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<p><sup>5</sup> The maximum is 4 294 966 272 bytes
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if the access path is created with a maximum size of 4 gigabytes (GB), ACCPTHSIZ(*MAX4GB).</p>
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</td>
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</tr>
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</tbody>
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</table>
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</td></tr></table>
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<div class="section"><p>These are maximum values. There are situations where the actual
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limit you experience will be less than the stated maximum. For example, certain
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high-level languages can have more restrictive limits than those described
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above.</p>
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</div>
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<div class="section"><p>Keep in mind that performance can suffer as you approach some
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of these maximums. For example, the more logical files you have built over
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a physical file, the greater the chance that system performance can suffer
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(if you are frequently changing data in the physical file that causes a change
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in many logical file access paths).</p>
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</div>
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<div class="section"><p>Normally, an <span class="keyword">iSeries</span> database file can grow until
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it reaches the maximum size allowed on the system. The system normally will
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not allocate all the file space at once. Rather, the system will occasionally
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allocate additional space as the file grows larger. This method of automatic
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storage allocation provides the best combination of good performance and effective
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auxiliary storage space management.</p>
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</div>
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<div class="section"><p>If you want to control the size of the file, the storage allocation,
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and whether the file should be connected to auxiliary storage, you can use
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the SIZE, ALLOCATE, and CONTIG parameters on the Create Physical File (CRTPF)
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and the Create Source Physical File (CRTSRCPF) commands.</p>
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</div>
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<div class="section"><div class="p">You can use the following
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formulas to estimate the disk size of your physical and logical files. <ul><li>For a physical file (excluding the access path) that does not contain
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null-capable fields: <img src="./delta.gif" alt="Start of change" /><p>Disk size = (number of valid and deleted records + 1) x <br />
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(record length + 1) + 20480 x (number of members) + 8192</p><img src="./deltaend.gif" alt="End of change" />
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The
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size of the physical file depends on the SIZE and ALLOCATE parameters on the
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CRTPF and CRTSRCPF commands. If you specify ALLOCATE(*YES), the initial allocation
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and increment size on the SIZE keyword must be used instead of the number
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of records.</li>
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</ul>
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<ul><li>For a physical file (excluding the access path) that contains null-capable
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fields: <img src="./delta.gif" alt="Start of change" /><p>Disk size = (number of valid and deleted records + 1) x <br />
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(record length + 1) + 20480 x (number of members) + <br />
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8192 + ((number of fields in format ÷ 8) rounded up) x <br />
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(number of valid and deleted records + 1) </p><img src="./deltaend.gif" alt="End of change" />
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The
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size of the physical file depends on the SIZE and ALLOCATE parameters on the
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CRTPF and CRTSRCPF commands. If you specify ALLOCATE(*YES), the initial allocation
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and increment size on the SIZE keyword must be used instead of the number
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of records.</li>
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<li>For a logical file (excluding the access path): <img src="./delta.gif" alt="Start of change" /><p>Disk size = (12288) x (number of members) + 8192</p><img src="./deltaend.gif" alt="End of change" />
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</li>
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<li>For a keyed sequence access path the generalized equation for index size,
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per member, is: <p> <br />
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let a = (LimbPageUtilization - LogicalPageHeaderSize) *<br />
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(LogicalPageHeaderSize - LeafPageUtilization - 2 * NodeSize)<br />
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<br />
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let b = NumKeys * (TerminalTextPerKey + 2 * NodeSize) *<br />
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(LimbPageUtilization - LogicalPageHeaderSize + 2 * NodeSize)<br />
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+ CommonTextPerKey * [ LimbPageUtilization + LeafPageUtilization<br />
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- 2 * (LogicalPageHeaderSize - NodeSize) ]<br />
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- 2 * NodeSize * (LeafPageUtilization - LogicalPageHeaderSize<br />
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+ 2 * NodeSize)<br />
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<br />
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let c = CommonTextPerKey * [ 2 * NodeSize - CommonTextPerKey<br />
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- NumKeys * (TerminalTextPerKey + 2 * NodeSize) ]<br />
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<br />
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<br />
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then NumberLogicalPages = ceil( [ -b - sqrt(b ** 2 - 4 * a * c) ]<br />
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/ (2 * a))<br />
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<br />
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and TotalIndexSize = NumberLogicalPages * LogicalPageSize<br />
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</p>
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<div class="p">This equation is used for both three and four byte indexes by
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changing the set of constants in the equation as follows:
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<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" width="90%" frame="hsides" border="0" rules="none"><thead align="left"><tr><th align="left" valign="bottom" width="33.33333333333333%" class="firstcol" id="d0e268">Constant</th>
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<th align="left" valign="bottom" width="33.33333333333333%" id="d0e270">Three-byte index</th>
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<th align="left" valign="bottom" width="33.33333333333333%" id="d0e272">Four-byte index</th>
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</tr>
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</thead>
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<tbody><tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e276" headers="d0e268 ">NodeSize</th>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e276 d0e270 "><strong>3</strong></td>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e276 d0e272 "><strong>4</strong></td>
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</tr>
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<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e285" headers="d0e268 ">LogicalPageHeaderSize</th>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e285 d0e270 "><strong>16</strong></td>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e285 d0e272 "><strong>64</strong></td>
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</tr>
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<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e294" headers="d0e268 ">LimbPageUtilization</th>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e294 d0e270 "><strong>.75 * LogicalPageSize</strong></td>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e294 d0e272 "><strong>.75 * LogicalPageSize</strong></td>
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</tr>
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<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e303" headers="d0e268 ">LeafPageUtilization</th>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e303 d0e270 "><strong>.75 * LogicalPageSize</strong></td>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e303 d0e272 "><strong>.80 * LogicalPageSize</strong></td>
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</tr>
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</tbody>
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</table>
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</div>
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</div>
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<div class="p">The remaining constants, CommonTextPerKey and TerminalTextPerKey,
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are probably best estimated by using the following formulas: <p> <br />
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CommonTextPerKey = [ min(max(NumKeys - 256,0),256)<br />
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+ min(max(NumKeys - 256 * 256,0),256 * 256)<br />
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+ min(max(NumKeys - 256 * 256 * 256,0),<br />
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256 * 256 * 256)<br />
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+ min(max(NumKeys - 256 * 256 * 256 * 256,0),<br />
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256 * 256 * 256 * 256) ]<br />
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* (NodeSize + 1) / NumKeys<br />
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<br />
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TerminalTextPerKey = KeySizeInBytes - CommonTextPerKey<br />
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</p>
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</div>
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<p>This should reduce everything needed to calculate the index
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size to the type of index (that is, 3 or 4 byte), the total key size, and
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the number of keys. The estimate should be greater than the actual index size
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because the common text estimate is minimal.</p>
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<div class="p">Given this generalized
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equation for index size, the LogicalPageSize is as follows:
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<div class="tablenoborder"><a name="rbafoappmax__rbafologpgsz"><!-- --></a><table cellpadding="4" cellspacing="0" summary="" id="rbafoappmax__rbafologpgsz" width="90%" frame="hsides" border="0" rules="none"><caption>Table 1. LogicalPageSize
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values</caption><thead align="left"><tr><th align="left" valign="bottom" width="33.33333333333333%" class="firstcol" id="d0e328">Key Length</th>
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<th align="left" valign="bottom" width="33.33333333333333%" id="d0e330">*MAX4GB (3-byte) LogicalPageSize</th>
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<th align="left" valign="bottom" width="33.33333333333333%" id="d0e332">*MAX1TB (4-byte) LogicalPageSize</th>
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</tr>
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</thead>
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<tbody><tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e336" headers="d0e328 ">1 - 500</th>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e336 d0e330 "><strong>4096 bytes</strong></td>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e336 d0e332 "><strong>8192 bytes</strong></td>
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</tr>
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<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e345" headers="d0e328 ">501 - 1000</th>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e345 d0e330 "><strong>8192 bytes</strong></td>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e345 d0e332 "><strong>16 384 bytes</strong></td>
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</tr>
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<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e354" headers="d0e328 ">1001 - 2000</th>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e354 d0e330 "><strong>16 384 bytes</strong></td>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e354 d0e332 "><strong>32 768 bytes</strong></td>
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</tr>
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<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e363" headers="d0e328 "><img src="./delta.gif" alt="Start of change" />2001 - 10 000<img src="./deltaend.gif" alt="End of change" /></th>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e363 d0e330 "><img src="./delta.gif" alt="Start of change" /><strong>N/A</strong><img src="./deltaend.gif" alt="End of change" /></td>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e363 d0e332 "><img src="./delta.gif" alt="Start of change" /><strong>65 536 bytes</strong><img src="./deltaend.gif" alt="End of change" /></td>
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</tr>
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<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e372" headers="d0e328 "><img src="./delta.gif" alt="Start of change" />10 001 - 18 000<img src="./deltaend.gif" alt="End of change" /></th>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e372 d0e330 "><img src="./delta.gif" alt="Start of change" /><strong>N/A</strong><img src="./deltaend.gif" alt="End of change" /></td>
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<td align="left" valign="top" width="33.33333333333333%" headers="d0e372 d0e332 "><img src="./delta.gif" alt="Start of change" /><strong>131 072 bytes</strong><img src="./deltaend.gif" alt="End of change" /></td>
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</tr>
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<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e381" headers="d0e328 "><img src="./delta.gif" alt="Start of change" />18 001 - 26 000<img src="./deltaend.gif" alt="End of change" /></th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e381 d0e330 "><img src="./delta.gif" alt="Start of change" /><strong>N/A</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e381 d0e332 "><img src="./delta.gif" alt="Start of change" /><strong>262 144 bytes</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
</tr>
|
||
<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e390" headers="d0e328 "><img src="./delta.gif" alt="Start of change" />26 001 - 32 768<img src="./deltaend.gif" alt="End of change" /></th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e390 d0e330 "><img src="./delta.gif" alt="Start of change" /><strong>N/A</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e390 d0e332 "><img src="./delta.gif" alt="Start of change" /><strong>524 288 bytes</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
</tr>
|
||
</tbody>
|
||
</table>
|
||
</div>
|
||
</div>
|
||
<div class="p">The LogicalPageSizes in <a href="#rbafoappmax__rbafologpgsz">Table 1</a> generate
|
||
the following LimbPageUtilizations:
|
||
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" width="90%" frame="hsides" border="0" rules="none"><thead align="left"><tr><th align="left" valign="bottom" width="33.33333333333333%" class="firstcol" id="d0e410">Key Length</th>
|
||
<th align="left" valign="bottom" width="33.33333333333333%" id="d0e412">*MAX4GB (3-byte) LimbPageUtilization</th>
|
||
<th align="left" valign="bottom" width="33.33333333333333%" id="d0e414">*MAX1TB (4-byte) LimbPageUtilization</th>
|
||
</tr>
|
||
</thead>
|
||
<tbody><tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e418" headers="d0e410 ">1 - 500</th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e418 d0e412 "><strong>3072 bytes</strong></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e418 d0e414 "><strong>6144 bytes</strong></td>
|
||
</tr>
|
||
<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e427" headers="d0e410 ">501 - 1000</th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e427 d0e412 "><strong>6144 bytes</strong></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e427 d0e414 "><strong>12 288 bytes</strong></td>
|
||
</tr>
|
||
<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e436" headers="d0e410 ">1001 - 2000</th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e436 d0e412 "><strong>12 288 bytes</strong></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e436 d0e414 "><strong>24 576 bytes</strong></td>
|
||
</tr>
|
||
<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e445" headers="d0e410 "><img src="./delta.gif" alt="Start of change" />2001 - 10 000<img src="./deltaend.gif" alt="End of change" /></th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e445 d0e412 "><img src="./delta.gif" alt="Start of change" /><strong>N/A</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e445 d0e414 "><img src="./delta.gif" alt="Start of change" /><strong>49 152 bytes</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
</tr>
|
||
<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e454" headers="d0e410 "><img src="./delta.gif" alt="Start of change" />10 001 - 18 000<img src="./deltaend.gif" alt="End of change" /></th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e454 d0e412 "><img src="./delta.gif" alt="Start of change" /><strong>N/A</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e454 d0e414 "><img src="./delta.gif" alt="Start of change" /><strong>98 304 bytes</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
</tr>
|
||
<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e463" headers="d0e410 "><img src="./delta.gif" alt="Start of change" />18 001 - 26 000<img src="./deltaend.gif" alt="End of change" /></th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e463 d0e412 "><img src="./delta.gif" alt="Start of change" /><strong>N/A</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e463 d0e414 "><img src="./delta.gif" alt="Start of change" /><strong>196 608 bytes</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
</tr>
|
||
<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e472" headers="d0e410 "><img src="./delta.gif" alt="Start of change" />26 001 - 32 768<img src="./deltaend.gif" alt="End of change" /></th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e472 d0e412 "><img src="./delta.gif" alt="Start of change" /><strong>N/A</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e472 d0e414 "><img src="./delta.gif" alt="Start of change" /><strong>393 216 bytes</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
</tr>
|
||
</tbody>
|
||
</table>
|
||
</div>
|
||
</div>
|
||
<div class="p">The LogicalPageSizes in <a href="#rbafoappmax__rbafologpgsz">Table 1</a> generate
|
||
the following LeafPageUtilizations:
|
||
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" width="90%" frame="hsides" border="0" rules="none"><thead align="left"><tr><th align="left" valign="bottom" width="33.33333333333333%" class="firstcol" id="d0e493">Key Length</th>
|
||
<th align="left" valign="bottom" width="33.33333333333333%" id="d0e495">*MAX4GB (3-byte) LeafPageUtilization</th>
|
||
<th align="left" valign="bottom" width="33.33333333333333%" id="d0e497">*MAX1TB (4-byte) LeafPageUtilization</th>
|
||
</tr>
|
||
</thead>
|
||
<tbody><tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e501" headers="d0e493 ">1 - 500</th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e501 d0e495 "><strong>3072 bytes</strong></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e501 d0e497 "><strong>6554 bytes</strong></td>
|
||
</tr>
|
||
<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e510" headers="d0e493 ">501 - 1000</th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e510 d0e495 "><strong>6144 bytes</strong></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e510 d0e497 "><strong>13 107 bytes</strong></td>
|
||
</tr>
|
||
<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e519" headers="d0e493 ">1001 - 2000</th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e519 d0e495 "><strong>12 288 bytes</strong></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e519 d0e497 "><strong>26 214 bytes</strong></td>
|
||
</tr>
|
||
<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e528" headers="d0e493 "><img src="./delta.gif" alt="Start of change" />2001 - 10 000<img src="./deltaend.gif" alt="End of change" /></th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e528 d0e495 "><img src="./delta.gif" alt="Start of change" /><strong>N/A</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e528 d0e497 "><img src="./delta.gif" alt="Start of change" /><strong>52 428 bytes</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
</tr>
|
||
<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e537" headers="d0e493 "><img src="./delta.gif" alt="Start of change" />10 001 - 18 000<img src="./deltaend.gif" alt="End of change" /></th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e537 d0e495 "><img src="./delta.gif" alt="Start of change" /><strong>N/A</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e537 d0e497 "><img src="./delta.gif" alt="Start of change" /><strong>104 857 bytes</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
</tr>
|
||
<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e546" headers="d0e493 "><img src="./delta.gif" alt="Start of change" />18 001 - 26 000<img src="./deltaend.gif" alt="End of change" /></th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e546 d0e495 "><img src="./delta.gif" alt="Start of change" /><strong>N/A</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e546 d0e497 "><img src="./delta.gif" alt="Start of change" /><strong>209 715 bytes</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
</tr>
|
||
<tr><th align="left" valign="top" width="33.33333333333333%" class="firstcol" id="d0e555" headers="d0e493 "><img src="./delta.gif" alt="Start of change" />26 001 - 32 768<img src="./deltaend.gif" alt="End of change" /></th>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e555 d0e495 "><img src="./delta.gif" alt="Start of change" /><strong>N/A</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
<td align="left" valign="top" width="33.33333333333333%" headers="d0e555 d0e497 "><img src="./delta.gif" alt="Start of change" /><strong>419 430 bytes</strong><img src="./deltaend.gif" alt="End of change" /></td>
|
||
</tr>
|
||
</tbody>
|
||
</table>
|
||
</div>
|
||
</div>
|
||
<div class="p">Then to simplify the generalized equation for index size,
|
||
let: <p> <br />
|
||
CommonTextPerKey = 0<br />
|
||
<br />
|
||
which would cause:<br />
|
||
<br />
|
||
TerminalTextPerKey = KeySizeInBytes<br />
|
||
<br />
|
||
b = NumKeys * (KeySizeInBytes + 2 * NodeSize) *<br />
|
||
(LimbPageUtilization - LogicalPageHeaderSize + 2 * NodeSize)<br />
|
||
- 2 * NodeSize * (LeafPageUtilization - LogicalPageHeaderSize<br />
|
||
+ 2 * NodeSize)<br />
|
||
<br />
|
||
c = 0<br />
|
||
<br />
|
||
NumberLogicalPages = ceil( [ -b - sqrt(b ** 2 ) ]<br />
|
||
/ (2 * a))<br />
|
||
= ceil[ (-2 * b) / (2 * a) ]<br />
|
||
= ceil[ -b/a ]<br />
|
||
</p>
|
||
</div>
|
||
</li>
|
||
</ul>
|
||
</div>
|
||
</div>
|
||
</div>
|
||
<div>
|
||
<ul class="ullinks">
|
||
<li class="ulchildlink"><strong><a href="rbafoappmaxex1.htm">Examples: Database file sizes</a></strong><br />
|
||
</li>
|
||
</ul>
|
||
|
||
<div class="familylinks">
|
||
<div class="parentlink"><strong>Parent topic:</strong> <a href="rbafodbfcon.htm" title="These topics provide some of the basic database concepts for setting up or working with IBM i5/OS database files.">Database file concepts</a></div>
|
||
</div>
|
||
</div>
|
||
</body>
|
||
</html> |