[TYPO3-dev] DB query iterator; worth a try?

[Jigal van Hemert]

Ries van Twisk wrote:
> On Apr 22, 2010, at 4:23 PM, Jigal van Hemert wrote:
>> I don't think the dataset is loaded in PHP allocated memory. It's more
>> likely that the database client receives the entire dataset or a large
>> part of it. That will be handled by the database client.
>> Anyway, these are details that we don't have to worry about :-)
> 
> Actually, in this case you should. Because it can be a difference 
> between a very slow
> iteration (using a cursors fetching each record using DB communications) 
> or a fast iterator.

I think that I know what you mean! One would need to worry about the 
method of retrieving data if the implementation of the iterator would 
use a completely different method than we normally would use.

> While looking at the source and it shows something like this:
> 
> static void php_mysql_do_query_general(zval **query, zval **mysql_link, 
> int link_id, zval **db, int use_store, zval *return_value TSRMLS_DC)
> ...
> ...
> ..
> 
>                     mysql_result = mysql_use_result(&mysql->conn);
>                                 while ((row = 
> mysql_fetch_row(mysql_result))) {
>                                         if (!strcmp("ALL", row[1])) {
>                                                 
> php_error_docref("http://www.mysql.com/doc" TSRMLS_CC, E_WARNING, "Your 
> query requires a full tablescan (table %s, %s rows affected
> ). Use EXPLAIN to optimize your query.", row[0], row[6]);

This piece of code is part of the trace_mode only used for select 
queries where it prefixes the query with "EXPLAIN ". That's why it 
checks for "ALL" in row[1] (and a few lines later for "INDEX"). The rows 
it gets are the output of the EXPLAIN query.

-- 
Jigal van Hemert
skype:jigal.van.hemert
msn: jigal at xs4all.nl
http://twitter.com/jigalvh