Why are certain types of prepared queries using PDO in PHP with MySQL slow?

Question

When using SELECT * FROM table WHERE Id IN ( .. ) queries with more than 10000 keys using PDO with prepare()/execute(), the performance degrades ~10X more than

Answer 1

Don't have any experience with PDO so can't help with that but this method is pretty performant, although it's a bit ugly in places ;)

PHP

query($sql);

echo sprintf("Fetched %d rows in %s secs
", 
    $conn->affected_rows, number_format(microtime(true) - $startTime, 6, ".", ""));

$result->close();
$conn->close();

?>

Results

select count(*) from product;
count(*)
========
1000000

Fetched 1000 rows in 0.014767 secs
Fetched 1000 rows in 0.014629 secs

Fetched 2000 rows in 0.027938 secs
Fetched 2000 rows in 0.027929 secs

Fetched 5000 rows in 0.068841 secs
Fetched 5000 rows in 0.067844 secs

Fetched 7000 rows in 0.095199 secs
Fetched 7000 rows in 0.095184 secs

Fetched 10000 rows in 0.138205 secs
Fetched 10000 rows in 0.134356 secs

MySQL

drop procedure if exists list_products_by_id;

delimiter #

create procedure list_products_by_id
(
in p_prod_id_csv text,
in p_show_explain tinyint unsigned
)
proc_main:begin

declare v_id varchar(10);
declare v_done tinyint unsigned default 0;
declare v_idx int unsigned default 1;

    create temporary table tmp(prod_id int unsigned not null)engine=memory; 

    -- split the string into tokens and put into a temp table...

    if p_prod_id_csv is not null then
        while not v_done do
            set v_id = trim(substring(p_prod_id_csv, v_idx, 
                if(locate(',', p_prod_id_csv, v_idx) > 0, 
                        locate(',', p_prod_id_csv, v_idx) - v_idx, length(p_prod_id_csv))));

                if length(v_id) > 0 then
                set v_idx = v_idx + length(v_id) + 1;
                        insert ignore into tmp values(v_id);
                else
                set v_done = 1;
                end if;
        end while;
    end if;

    if p_show_explain then

        select count(*) as count_of_tmp from tmp;

        explain
        select p.* from product p
        inner join tmp on tmp.prod_id = p.prod_id order by p.prod_id;

    end if;

    select p.* from product p
        inner join tmp on tmp.prod_id = p.prod_id order by p.prod_id;

    drop temporary table if exists tmp;

end proc_main #

delimiter ;