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DB_Database.html  view on Meta::CPAN

    $table->append_record_hash('jimmy', "age" => 25,
                                        &quot;msg&quot; =&gt; 'Nothing is easy!');</PRE>
<P>
<H2><A NAME="using index">Using Index</A></H2>
<P>Index file is stored in DB_File BTREE. Once created, all index files will be automatically 
opened when open the database file, and updated automatically when writing the database file.</P>
<DL>
<DT><STRONG><A NAME="item_create_index">create_index</A></STRONG><BR>
<DD>
Create index file for one field. Default permits of the index file is 0640. 'name' is the index 
tag name, 'key' is the formula for indexing. For example:
<PRE>
  'key' =&gt; 'Age'            # index by the age, from young to old
  'key' =&gt; '-Age'           # index by the age, from old to young
  'key' =&gt; '-Age(3)+Name'   # index by the age(up to 999),then name; from old to young,then from A to Z
  'key' =&gt; '-Age(3)+-Name'  # index by the age(up to 999),then name; from old to young,then from Z to A</PRE>
<P>'Age(3)' is similar to 'substr(Age,0,3)', only the length of the last field name appeared in 
the 'key' can be ommited. '+-' CAN'T be subsituded by '-'.</P>
<PRE>
  # Index File name will be dbexample_indexA 
  print $table-&gt;create_index( 'name'   =&gt; 'indexA' ,

lib/DB_File/DB_Database.pm  view on Meta::CPAN

=head2 Using Index

=over 4

Index file is stored in DB_File BTREE. Once created, all index files will be automatically 
opened when open the database file, and updated automatically when writing the database file.

=item create_index 

Create index file for one field. Default permits of the index file is 0640. 'name' is the index 
tag name, 'key' is the formula for indexing. For example:

  'key' => 'Age'            # index by the age, from young to old
  'key' => '-Age'           # index by the age, from old to young
  'key' => '-Age(3)+Name'   # index by the age(up to 999),then name; from old to young,then from A to Z
  'key' => '-Age(3)+-Name'  # index by the age(up to 999),then name; from old to young,then from Z to A

'Age(3)' is similar to 'substr(Age,0,3)', only the length of the last field name appeared in 
the 'key' can be ommited. '+-' CAN'T be subsituded by '-'.

  # Index File name will be dbexample_indexA