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diff --git a/bdb/docs/ref/am_conf/renumber.html b/bdb/docs/ref/am_conf/renumber.html deleted file mode 100644 index 7c3594dff66..00000000000 --- a/bdb/docs/ref/am_conf/renumber.html +++ /dev/null @@ -1,80 +0,0 @@ -<!--$Id: renumber.so,v 10.23 2000/12/18 21:05:14 bostic Exp $--> -<!--Copyright 1997, 1998, 1999, 2000 by Sleepycat Software, Inc.--> -<!--All rights reserved.--> -<html> -<head> -<title>Berkeley DB Reference Guide: Logically renumbering records</title> -<meta name="description" content="Berkeley DB: An embedded database programmatic toolkit."> -<meta name="keywords" content="embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++"> -</head> -<body bgcolor=white> - <a name="2"><!--meow--></a> -<table><tr valign=top> -<td><h3><dl><dt>Berkeley DB Reference Guide:<dd>Access Methods</dl></h3></td> -<td width="1%"><a href="../../ref/am_conf/re_source.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../../ref/toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../../ref/am/ops.html"><img src="../../images/next.gif" alt="Next"></a> -</td></tr></table> -<p> -<h1 align=center>Logically renumbering records</h1> -<p>Records stored in the Queue and Recno access methods are accessed by -logical record number. In all cases in Btree databases, and optionally -in Recno databases (see the <a href="../../api_c/db_set_flags.html">DB->set_flags</a> function and the -<a href="../../api_c/db_set_flags.html#DB_RENUMBER">DB_RENUMBER</a> flag for more information), record numbers are -mutable. This means that the record numbers may change as records are -added to and deleted from the database. The deletion of record number -4 causes any records numbered 5 and higher to be renumbered downward by -1; the addition of a new record after record number 4 causes any -records numbered 5 and higher to be renumbered upward by 1. In all -cases in Queue databases, and by default in Recno databases, record -numbers are not mutable, and the addition or deletion of records to the -database will not cause already-existing record numbers to change. For -this reason, new records cannot be inserted between already-existing -records in databases with immutable record numbers. -<p>Cursors pointing into a Btree database or a Recno database with mutable -record numbers maintain a reference to a specific record, rather than -a record number, that is, the record they reference does not change as -other records are added or deleted. For example, if a database contains -three records with the record numbers 1, 2, and 3, and the data items -"A", "B", and "C", respectively, the deletion of record number 2 ("B") -will cause the record "C" to be renumbered downward to record number 2. -A cursor positioned at record number 3 ("C") will be adjusted and -continue to point to "C" after the deletion. Similarly, a cursor -previously referencing the now deleted record number 2 will be -positioned between the new record numbers 1 and 2, and an insertion -using that cursor will appear between those records. In this manner -records can be added and deleted to a database without disrupting the -sequential traversal of the database by a cursor. -<p>Only cursors created using a single DB handle can adjust each -other's position in this way, however. If multiple DB handles -have a renumbering Recno database open simultaneously (as when multiple -processes share a single database environment), a record referred to by -one cursor could change underfoot if a cursor created using another -DB handle inserts or deletes records into the database. For -this reason, applications using Recno databases with mutable record -numbers will usually make all accesses to the database using a single -DB handle and cursors created from that handle, or will -otherwise single-thread access to the database, e.g., by using the -Berkeley DB Concurrent Data Store product. -<p>In any Queue or Recno databases, creating new records will cause the -creation of multiple records if the record number being created is more -than one greater than the largest record currently in the database. For -example, creating record number 28, when record 25 was previously the -last record in the database, will implicitly create records 26 and 27 -as well as 28. All first, last, next and previous cursor operations -will automatically skip over these implicitly created records. So, if -record number 5 is the only record the application has created, -implicitly creating records 1 through 4, the <a href="../../api_c/dbc_get.html">DBcursor->c_get</a> interface -with the <a href="../../api_c/dbc_get.html#DB_FIRST">DB_FIRST</a> flag will return record number 5, not record -number 1. Attempts to explicitly retrieve implicitly created records -by their record number will result in a special error return, -<a href="../../ref/program/errorret.html#DB_KEYEMPTY">DB_KEYEMPTY</a>. -<p>In any Berkeley DB database, attempting to retrieve a deleted record, using -a cursor positioned on the record, results in a special error return, -<a href="../../ref/program/errorret.html#DB_KEYEMPTY">DB_KEYEMPTY</a>. In addition, when using Queue databases or Recno -databases with immutable record numbers, attempting to retrieve a deleted -record by its record number will also result in the <a href="../../ref/program/errorret.html#DB_KEYEMPTY">DB_KEYEMPTY</a> -return. -<table><tr><td><br></td><td width="1%"><a href="../../ref/am_conf/re_source.html"><img src="../../images/prev.gif" alt="Prev"></a><a href="../../ref/toc.html"><img src="../../images/ref.gif" alt="Ref"></a><a href="../../ref/am/ops.html"><img src="../../images/next.gif" alt="Next"></a> -</td></tr></table> -<p><font size=1><a href="http://www.sleepycat.com">Copyright Sleepycat Software</a></font> -</body> -</html> |