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-SQLite is the first extension that makes use of SPL automatically by simply
-enabling both.
-
-SQLite offers four access strategies:
-1) sqlite_query + sqlite_fetch_array
-2) sqlite_unbuffered_query + sqlite_fetch_array
-3) sqlite_query + iterators (sqlite_current)
-4) sqlite_unbuffered_query + iterators (sqlite_current)
-5) sqlite_array_query
-
-1) and 3) do "over eager evaluating" since they fetch all rows directly.
-
-2) does "eager evaluating". It always fetches the next row but doesn't
-keep the current row, so that it must be stored elsewhere if it must be
-accessed more then once. For instance this happens when you need to access
-columns separately.
-
-4) does "eager evaluating". But in contrast to 2) it keeps the current row
-hence its name.
-
-There is no efficient way for "lazy or just in time evaluating" so 4) should
-be the best case. And 4) also enables the foreach trick.
-
-5) does a full buffered fetch and returns the complete result into an array.
-As long as you only have a few rows in your result this is very fast and of
-course it is very flexible since you can access any column/row as often you
-like and in any order you like. But it needs to store the full result what
-is called "eager evaluating".
-
-Speedwise analysis:
-
-I compared a database using a table of round about 200 rows with 3 columns.
-I measured the case where 10 rows are returned, since i guess this is a
-value often taken as default list size in web applications. However i did
-that 10 times because the loop initialization is the slowest part of foreach
-overloading. Since we are only interested in the relative effect foreach
-overloading has i stiped the setup part and used a query result iteration
-that does nothing. That means i run 'php -h' in the profiler first and then
-profiled every single case. For completeness i also computed the values
-including the setup process.
-
-Method, without setup, with setup
-1) 100.00% 100.00%
-2) 89.32% 97.16%
-3) 88.35% 96.90%
-
-Furthermore i did some more checks and found out that the loop process using
-foreach overloading (2) takes a constant time while it seems that the time
-needed to add more rows to the array increases with the number of rows being
-already in the array. As a result (2) is faster than (3) after round about 45
-rows.
-
-The loop codes used:
-
-1) Unbuffered query
-
-<?php
-$dbname = dirname(__FILE__).'/profile.sqlite';
-$db = sqlite_factory($dbname);
-
-for ($i = 0; $i < 10; $i++) {
- $res = $db->unbuffered_query("SELECT idx, name, size from files LIMIT 10", SQLITE_NUM);
- while ($res->has_more()) {
-// var_dump($res->current());
- $res->current();
- $res->next();
- }
-}
-echo "DONE!\n";
-?>
-
-2) Unbuffered query using foreach overloading
-
-<?php
-$dbname = dirname(__FILE__).'/profile.sqlite';
-$db = sqlite_factory($dbname);
-
-for ($i = 0; $i < 10; $i++) {
- foreach($db->unbuffered_query("SELECT idx, name, size from files LIMIT 10", SQLITE_NUM) as $row) {
-// var_dump($row);
- }
-}
-echo "DONE!\n";
-?>
-
-3) Array query method
-
-<?php
-$dbname = dirname(__FILE__).'/profile.sqlite';
-$db = sqlite_factory($dbname);
-
-for ($i = 0; $i < 10; $i++) {
- foreach($db->array_query("SELECT idx, name, size from files LIMIT 10", SQLITE_NUM) as $row) {
-// var_dump($row);
- }
-}
-echo "DONE!\n";
-?> \ No newline at end of file