NAME

Genezzo::Dict.pm - The Genezzo data dictionary

SYNOPSIS

use Genezzo::Dict;

# create a new dictionary

my $dictobj = Genezzo::Dict->new(
                 gnz_home => $gnz_home, 
                 init_db => $init);

# see if a table exists

if ($dictobj->DictTableExists (
                  tname => $tablename,
                  silent_exists => 0,
                  silent_notexists => 1 )))...

# create a new table

$dictobj->DictTableCreate (
                  tname => $tablename,
                  tabdef => \%coldatatype,
                  tablespace => "SYSTEM");

# drop a table

$dictobj->DictTableDrop (tname => $tablename);

# save the state of the dictionary to disk

$dictobj->DictSave();

my $colhash = 
    $dictobj->DictTableGetCols (tname => $tablename);

$dictobj->RowInsert (tname => $tablename, 
                     rowval => \@rowarr );

$dictobj->RowDelete (tname => $tablename, 
                     rid => $rid);

$dictobj->RowUpdate (tname => $tablename, 
                     rid => $rid,
                     rowval => \@rowarr);

# return the table as a tied hash

my $tablehash = 
    $dictobj->DictTableGetTable (tname => $tablename) ;

DESCRIPTION

The dictionary is a complete description of the Genezzo system, recording information on table structure and physical layout. It provides an interface to create, destroy, query, and manipulate tables.

Dictionary concepts

Core Tables

The dictionary itself is just a set of tables stored in the system tablespace. Genezzo only uses six core tables to describe its basic dictionary. NOTE: Modifying any dictionary tables will framboozle your nimwits. You have been warned.

_tspace -- the list of tablespaces for this Genezzo instance.

_tsfiles -- the list of files which compose each tablespace

_tab1 -- the list of tables and their associated tablespaces

_col1 -- the list of columns for each table

allfileused -- the list of files actually used by each table

FUNCTIONS

I want to reduce the interface to a simple tied hash, something like:

my $errormsg;

%args = (errormsg => \$errormsg );

my $dicthash = DictGetDictHash(%args);

Checking for the existance of a table would be something like:

my $tablename = "kitchentable";

if (exists($dicthash->{tableinfo}->{$tablename}))
{
   # do stuff...
}
else
{
   # errormsg was reference in tie of dicthash, 
   # contains last error status
   print $errormsg;
}

EXPORT

TODO

pref1 - distinguish fixed/mutable parameters

cons1 - distinguish user constraint names from system-defined names

IDXTAB indexed tables don't give a constraint error, or primary key error. They don't have constraints because they are themselves indexes. Need to give better error message.

Fix t/Cons1 constraint error

DictTableAllTab: need index on allfileused for delete

DictTableAllTab: update tsfiles for usefile

need some combo _get_table/corecolnum/getcol - create a custom iterator that returns specified cols

non-unique index support using bt2 use_keycount. Need to separate notion of SQL uniqueness from btree concept of unique, since a non-unique SQL index is a unique btree with the rid as least-significant key col (vs rid as value col).

need drop table/drop index linkage, delete constraints for table, etc

constraints: can fix check constraint in update case -- don't need to check insert if check columns aren't modified.

constraints: need not null/foreign key constraints

constraints: need to limit one primary key per table, prevent creation of duplicate indexes on same ordered key columns

expose drop index, drop constraint. tie drop index/drop table?

check usage of HCount for max tid, max fileidx, max consid. This won't work if have deletions

DictTableUseFile: update space management to use this function correctly

DictDefineCoreTabs, tsfiles: need to save file headersize as a tsfile column.

deal with dict->{headersize} attribute in some rational way. Currently set via tablespace->TSAddFile...

AUTHOR

Jeffrey I. Cohen, jcohen@genezzo.com

SEE ALSO

perl(1).

Copyright (c) 2003, 2004, 2005, 2006 Jeffrey I Cohen. All rights reserved.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

Address bug reports and comments to: jcohen@genezzo.com

For more information, please visit the Genezzo homepage at http://www.genezzo.com