Mysqli query performance multi-query

Question 1

EDIT : So now, the conclusion: (test case below)

You cannot control the execution of subsequent statements of a multi-statement query.
You can therefore not use multi_query() in the way you wanted to.

Execute them all, or execute none.

Regarding
Multi_query #2 "current for benchmark" How to remove duplicate fields in result set after next_result()?

Use fetch_assoc() or fetch_array(MYSQLI_ASSOC) (both practically the same) instead of fetch_array().

About multi_query():

I recently worked on a program using the MySQL C API, which mysqli uses, too.
About multiple-statement query support the documentation states:

Executing a multiple-statement string can produce multiple result sets or row-count indicators. Processing these results involves a different approach than for the single-statement case: After handling the result from the first statement, it is necessary to check whether more results exist and process them in turn if so. To support multiple-result processing, the C API includes the mysql_more_results() and mysql_next_result() functions. These functions are used at the end of a loop that iterates as long as more results are available. Failure to process the result this way may result in a dropped connection to the server.

(emphasize added)

This leads to the conclusion, that aborting a multiple-statement query is not an intended feature.

Moreover, I didn't find any resource explaining when subsequent queries are actually executed.
Calling next_result() doesn't neccessarily mean that the query hasn't been executed already.

EDIT : TEST CASE

To prove what I previously assumed, I created a test case:

<?php
$db = new mysqli('localhost', 'root', '', 'common');
$query = 'SELECT NOW() as time;';
$query .= 'SELECT NOW() as time;';
$query .= 'SELECT NOW() as time;';
$query .= 'SELECT NOW() as time;';

if($db->multi_query($query)) {
    // Current time
    echo "'multi_query()' executed at:\n\t\t"
        .date('Y-m-d H:i:s')."\n";

    // First result
    if($result = $db->store_result()) {
        $i = 1;

        $row = $result->fetch_assoc();
        echo "'NOW()' of result $i:\n\t\t".$row['time']."\n";
        $result->free();
        // Wait 5 seconds
        sleep(5);

        // Subsequent results
        while($db->more_results() && $db->next_result()) {
            $result = $db->store_result();
            $row = $result->fetch_assoc();
            $i++;
            echo "'NOW()' of result $i:\n\t\t".$row['time']."\n";
            // Wait 5 seconds
            sleep(5);
            $result->free();
        }
    }
}
$db->close();
?>

This results in:

'multi_query()' executed at:
        2013-05-10 10:18:47
'NOW()' of result 1:
        2013-05-10 10:18:47
'NOW()' of result 2:
        2013-05-10 10:18:47
'NOW()' of result 3:
        2013-05-10 10:18:47
'NOW()' of result 4:
        2013-05-10 10:18:47

Given that, it is obvious that all four statements of the query were executed directly after the call to multi_query().
If they were only executed after calling next_result() there would be a 5 second delay caused by sleep(5) calls I added between the loop iterations.

Question 2

Try to use index in getting count. Like for example COUNT(pageid). It will speed up your query.

Update

You can also try this link for further explanation

Question 3

Please run following query in mysql and check your query run time :

CREATE INDEX pagidIndex ON af_ban (pageid(11));
CREATE INDEX pagidFeedIndex ON af_freefeed (pageid(11));
CREATE INDEX viewsIndex ON af_freefeed (views(11));

Question 4

i am checking one table to see if user is banned, then if not, i am getting row for the id and updating it's view count by 1.

The following query may help you to update the view count. I assume that you already know the page_id.

UPDATE af_freefeed SET views=views+1 WHERE page_id=%s and page_id not in (select page_id from af_ban WHERE page_id=%s);

Question 5

You could try something along these lines:

$sql = sprintf("SELECT af_freefeed.pageid FROM af_freefeed left join af_ban ".
               "on (af_freefeed.pageid = af_ban.pageid) ".
               "where af_freefeed.pageid = %s and ".
               "af_ban.pageid is null limit 1", $pageid);

to replace your first two queries.

The existence of a record in the results should indicate an unbanned user requesting the resource. Then you can do your update your views.

Hope this helps.