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=head1 pgestraier - search Hyper Estraier indexes from PostgreSQL |
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This package is essentially PostgreSQL C function which calls Hyper Estraier |
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API and returns results in user defined format. |
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=head1 Why is it written? |
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Aside from providing single API to query your RDBMS and full text index |
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(using any language that has PostgreSQL client libraries), real power is |
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hidden in ability to join results from full text index and structured data |
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in RDBMS. |
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For simple real-life example which address problem |
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I<where like '%foo%' is slow> |
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see L<Tutorial>. |
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=head1 How to install |
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Installation should be simple. However, you will have to have following |
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software already installed before you try this function: |
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=over |
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=item * |
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PostgreSQL (tested with versions 7.4 and 8.0) with development libraries |
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=item * |
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Hyper Estraier (tested with various versions, recommended 1.2.4 of newer) |
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=back |
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To run tests you will also need: |
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=over |
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=item * |
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working perl installation |
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=item * |
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perl modules C<DBI>, C<DBD::Pg>, C<Test::More> and optionally C<Search::Estraier> |
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=item * |
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C<trivia.list.gz> from Internet Movie Database in C<data/> directory |
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=item * |
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PostgreSQL database C<test> with permissions for current user |
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=item * |
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Hyper Estraier C<estmaster> running with permissions for C<admin> user |
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to create C<trivia> node. |
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=back |
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If you have all that, you should be able to type |
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make |
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and see sample results. You will be asked your password once (via sudo) to |
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install C<pgest.so> shared library in system-wide location so that PostgreSQL |
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could access it. |
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=head2 Create sample index using Hyper Estraier perl bindings |
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Perl bindings for Hyper Estraier are available at CPAN: |
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L<http://search.cpan.org/~dpavlin/Search-Estraier/> |
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After installing C<Search::Estraier> you can create index using following commands: |
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cd data |
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make index |
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cd .. |
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To run tests (which require that you have estcmd in your $PATH) issue |
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make test |
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See also included file C<test.sql> for more examples of usage. |
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=head1 Usage of pgest from SQL |
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C<pgest> PostgreSQL function tries to mimic usage of normal database tables (with support for attribute filtering, limit and offset) in following way: |
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SELECT |
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-- columns to return (defined later) |
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id,title,size |
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FROM pgest( |
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-- node URI, login, password and depth of search |
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'http://localhost:1978/node/trivia', 'admin', 'admin', 42, |
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-- query |
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'blade runner', |
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-- additional attributes, use NULL or '' to disable |
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-- multiple attributes conditions can be separated by {{!}} |
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'@title ISTRINC blade', |
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-- order results by |
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'@title STRA', |
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-- limit, use NULL or 0 to disable |
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null, |
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-- offset, use NULL or 0 to disable |
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null, |
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-- attributes to return as columns |
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ARRAY['@id','@title','@size'] |
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) AS ( |
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-- specify names and types of returned attributes |
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id text, title text, size text |
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); |
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You should note that Hyper Estraier uses UTF-8 encoding, while your |
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PostgreSQL installation might use different encoding. To fix that, use |
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C<convert> function in PostgreSQL to convert encodings. |
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=head2 Using index via C<estmaster> server process |
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This is default and recommended way to use C<pgest> functionality. In this |
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case, C<pgest> will use node API and access index through C<estmaster> |
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process which should be running on (local or remote) machine. |
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This will remove database opening overhead, at a cost of (small) additional network |
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traffic. However, you can have Hyper Estraier C<estmaster> process running on |
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different machine or update index while doing searches, so benefits of this |
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approach are obvious. |
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=head2 Accessing database directly |
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B<Please note that direct access to database is depreciated.> As such, it's |
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not stated in example, and it's kept just for backward compatibility, but it |
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will probably be removed in future versions of C<pgest>. |
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If you want to access database directly (without running C<estmaster> process), you |
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have to replace node URI, login, password and depth with full path to database file. |
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Have in mind that C<postgres> user under which PostgreSQL is running must |
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have read permission on Hyper Estraier database files. |
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This will work a bit faster on really small indexes. However, when your |
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index grows bigger, you might consider using node API to remove overhead of |
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database opening on each query. |
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=head1 Who wrote this? |
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Hyper Estraier is written by Mikio Hirabayashi. |
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PostgreSQL is written by hackers calling themselves PostgreSQL Global |
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Development Group. |
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This small C function is written by L<Dobrica Pavlinusic|http://www.rot13.org/~dpavlin/>, dpavlin@rot13.org. |