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Posted by Mikhail Kovalev on 12/05/07 13:56
On 5 Des, 14:11, "C. (http://symcbean.blogspot.com/)"
<colin.mckin...@gmail.com> wrote:
> On 5 Dec, 11:13, Mikhail Kovalev <mikhail_kova...@mail.ru> wrote:
>
> > Hi.
>
> > I work with recursive array trees of 10-20 levels in PHP. So far I
> > have been using serialize() to store the arrays, generating files 5+
> > MB large, which take 10-15 seconds to unserialize and about tenfold of
> > RAM! I've been adviced to use MySQL (relational db's), but are there
> > any other options beside that and var_export/include? Something that
> > works in a similar way as MySQL when adding a new element without
> > loading the whole database itself...
>
> > Thanks!
>
> Any relational DB can model a hierarchical data structure - at the
> simplest level:
>
> node_id unique identifier, not null
> parent_node null
> payload whatever
>
> But getting the threaded structure is a bit tricky -
>
> SELECT parent.node_id as Parent_node_id, parent.payload as
> parent_payload,
> child.node_id as child_node_id, child.payload as child_payload
> FROM mytable parent, mytable child
> WHERE child.parent_node=parent.node_id
> AND parent.node_id=$start_here
>
> .. i.e. by explicitly declaring aliases for each level in the tree you
> can get the sub-nodes, but when you don't know how deep the tree is,
> its not possible to return the whole structure in a single query using
> standard SQL. Oracle allows you to compose queries returning
> representations of hierarchical data (have a google for 'connect by' &
> 'start with') but thats rather non-standard.
I don't know how deep the tree is, but I don't need to return the
whole structure in a single query. Alas, I don't know the nature of
MySQL
At this moment everything I do with my structure happens by calling
addresses
See my reply to The Natural Philosopher.
Here's an example with one node at top level and it's childs:
112 (10)
225 (3)
930 (1)
11 (5)
$array[112][COUNT] = 10;
$array[112][NEXT][225][COUNT] = 3;
$array[112][NEXT][225][NEXT][930][COUNT] = 1;
$array[112][NEXT][225][NEXT][930][NEXT] = array();
$array[112][NEXT][11][COUNT] = 5;
$array[112][NEXT][11][NEXT] = array();
An address is an array, f ex array(112, 225, 930)
I then use the following mechanism:
// retrieves a node with its two values as an array(COUNT, NEXT)
// NEXT contain further childs, but i dont use them
// array_1 is the whole structure, and array_2 is the address
function function_7($array_1, $array_2) { return eval('return
$array_1'.function_8($array_2).';'); }
// array(112, 225, 930) becomes "[112][NEXT][225][NEXT][930]"
function function_8($array_1) { return implode('[NEXT]',
array_map('function_9', $array_1)); }
function function_9($integer_1) { return '['.$integer_1.']'; }
// saves a value array_3 to an address array_2 in structure array_1
function function_10($array_1, $array_2, $array_3)
{
eval('$array_1'.function_8($array_2).' = $array_3;');
return $array_1;
}
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