1DBD::File::Roadmap(3) User Contributed Perl DocumentationDBD::File::Roadmap(3)
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NAME

6       DBD::File::Roadmap - Planned Enhancements for DBD::File and pure Perl
7       DBD's
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9       Jens Rehsack - May 2010
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SYNOPSIS

12       This document gives a high level overview of the future of the
13       DBD::File DBI driver and groundwork for pure Perl DBI drivers.
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15       The planned enhancements cover features, testing, performance,
16       reliability, extensibility and more.
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CHANGES AND ENHANCEMENTS

19   Features
20       There are some features missing we would like to add, but there is no
21       time plan:
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23       LOCK TABLE
24           The newly implemented internal common table meta storage area would
25           allow us to implement LOCK TABLE support based on file system
26           "flock ()" support.
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28       Transaction support
29           While DBD::AnyData recommends explicitly committing by importing
30           and exporting tables, DBD::File might be enhanced in a future
31           version to allow transparent transactions using the temporary
32           tables of SQL::Statement as shadow (dirty) tables.
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34           Transaction support will heavily rely on lock table support.
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36       Data Dictionary Persistence
37           SQL::Statement provides dictionary information when a "CREATE TABLE
38           ..."  statement is executed. This dictionary is preserved for some
39           statement handle attribute fetches (as "NULLABLE" or "PRECISION").
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41           It is planned to extend DBD::File to support data dictionaries to
42           work on the tables in it. It is not planned to support one table in
43           different dictionaries, but you can have several dictionaries in
44           one directory.
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46       SQL Engine selecting on connect
47           Currently the SQL engine selected is chosen during the loading of
48           the module DBI::SQL::Nano. Ideally end users should be able to
49           select the engine used in "DBI->connect ()" with a special
50           DBD::File attribute.
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52       Other points of view to the planned features (and more features for the
53       SQL::Statement engine) are shown in SQL::Statement::Roadmap.
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55   Testing
56       DBD::File and the dependent DBD::DBM requires a lot more automated
57       tests covering API stability and compatibility with optional modules
58       like SQL::Statement.
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60   Performance
61       Several arguments for support of features like indexes on columns and
62       cursors are made for DBD::CSV (which is a DBD::File based driver, too).
63       Similar arguments could be made for DBD::DBM, DBD::AnyData, DBD::RAM or
64       DBD::PO etc.
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66       To improve the performance of the underlying SQL engines, a clean re-
67       implementation seems to be required. Currently both engines are
68       prematurely optimized and therefore it is not trivial to provide
69       further optimization without the risk of breaking existing features.
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71       Join the DBI developers IRC channel at <irc://irc.perl.org/dbi> to
72       participate or post to the DBI Developers Mailing List.
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74   Reliability
75       DBD::File currently lacks the following points:
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77       duplicate table names
78           It is currently possible to access a table quoted with a relative
79           path (a) and additionally using an absolute path (b). If (a) and
80           (b) are the same file that is not recognized (except for flock
81           protection handled by the Operating System) and two independent
82           tables are handled.
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84       invalid table names
85           The current implementation does not prevent someone choosing a
86           directory name as a physical file name for the table to open.
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88   Extensibility
89       I (Jens Rehsack) have some (partially for example only) DBD's in mind:
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91       DBD::Sys
92           Derive DBD::Sys from a common code base shared with DBD::File which
93           handles all the emulation DBI needs (as getinfo, SQL engine
94           handling, ...)
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96       DBD::Dir
97           Provide a DBD::File derived to work with fixed table definitions
98           through the file system to demonstrate how DBI / Pure Perl DBDs
99           could handle databases with hierarchical structures.
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101       DBD::Join
102           Provide a DBI driver which is able to manage multiple connections
103           to other Databases (as DBD::Multiplex), but allow them to point to
104           different data sources and allow joins between the tables of them:
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106             # Example
107             # Let table 'lsof' being a table in DBD::Sys giving a list of open files using lsof utility
108             # Let table 'dir' being a atable from DBD::Dir
109             $sth = $dbh->prepare( "select * from dir,lsof where path='/documents' and dir.entry = lsof.filename" )
110             $sth->execute(); # gives all open files in '/documents'
111             ...
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113             # Let table 'filesys' a DBD::Sys table of known file systems on current host
114             # Let table 'applications' a table of your Configuration Management Database
115             #  where current applications (relocatable, with mountpoints for filesystems)
116             #  are stored
117             $sth = dbh->prepare( "select * from applications,filesys where " .
118                                  "application.mountpoint = filesys.mountpoint and ".
119                                  "filesys.mounted is true" );
120             $sth->execute(); # gives all currently mounted applications on this host
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PRIORITIES

123       Our priorities are focused on current issues. Initially many new test
124       cases for DBD::File and DBD::DBM should be added to the DBI test suite.
125       After that some additional documentation on how to use the DBD::File
126       API will be provided.
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128       Any additional priorities will come later and can be modified by
129       (paying) users.
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RESOURCES AND CONTRIBUTIONS

132       See <http://dbi.perl.org/contributing> for how you can help.
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134       If your company has benefited from DBI, please consider if it could
135       make a donation to The Perl Foundation "DBI Development" fund at
136       <http://dbi.perl.org/donate> to secure future development.
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138       Alternatively, if your company would benefit from a specific new DBI
139       feature, please consider sponsoring it's development through the
140       options listed in the section "Commercial Support from the Author" on
141       <http://dbi.perl.org/support/>.
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143       Using such targeted financing allows you to contribute to DBI
144       development and rapidly get something specific and directly valuable to
145       you in return.
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147       My company also offers annual support contracts for the DBI, which
148       provide another way to support the DBI and get something specific in
149       return. Contact me for details.
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151       Thank you.
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155perl v5.26.3                      2013-04-04             DBD::File::Roadmap(3)
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