Am 04.09.2011 06:35, schrieb Stas Malyshev:
The ones I'm most worried about are:
1. mysqli_stmt_num_rows() is expected to return number of rows after all
rows were fetched while returning 0 before that. libmysql definitely
Yes, here the test assumes a marginally different behavior. The test
needs an update. No, there is no BC break.
doesn't do that, in full accordance with mysql docs which state row
numbers can't be had for unbuffered queries.
If we do want this new non-portable semantics in mysqlnd, we should have
it in separate test, clearly marked as such, even though I'm not
convinced having such semantics is a good idea at all (would lead to
applications working with mysqlnd and not with libmysql - invitation for
trouble).
Your description of the difference is wrong. You conclusion "invitation
for trouble" must be a joke.
a) The difference
Pseudo-code:
/* identical behavior */
mysqli_stmt_prepare(stmt, "SELECT ...");
mysqli_stmt_execute(stmt)
do {
assert(0 == mysqli_stmt_num_rows(stmt));
} while (mysqli_stmt_fetch(stmt);
/* difference now */
printf("number of rows fetched: %d\n", mysqli_stmt_num_rows());
Output:
libmysql: 0 rows fetched
mysqlnd: <actual_number_of_rows> rows fetched
Difference: mysqlnd lifts a silly libmysql limitation.
b) Practical relevance
bugs.php.net - 0 related reports
https://bugs.php.net/search.php?search_for=mysqli_stmt_num_rowsboolean=0&limit=All&order_by=id&direction=DESC&cmd=display&status=All&bug_type=All&php_os=&phpver=&cve_id=&assign=&author_email=&bug_age=0&bug_updated=0
code.google.com - nobody using the function ?!
http://code.google.com/intl/en-EN/query/#q=mysqli_stmt_num_rows
Code that relies on undefined behavior:
num_rows = 0;
while (mysql_stmt_fetch(stmt)) {
num_rows++;
}
/* Bogus code - does not follow docs */
if (num_rows && 0 !== mysqli_stmt_num_rows(stmt)
printf("Damn, API returns a meaninful value"");
else
printf("Jippie, MySQL folks lifted a limitation");
Worst that could happen is that someone relies on stmt_num_rows() @
mysqlnd here. Relying on any specific behavior is bogus. We are talking
about C libmysql (libmysql vs. mysqlnd) differences here, thus we can
check C API reference: "[...] Otherwise, the row count is unavailable
unless you count the rows as you fetch them. ",
http://dev.mysql.com/doc/refman/5.6/en/mysql-stmt-num-rows.html .
There is no promise made in the documentation that num_rows is set to 0.
"Unavailable" means that it can be set to any value. The return value
can be <num_rows_last_stmt>, 0 (libmysql) or the actual number of rows
(mysqlnd). None of this would violate the documentation.
This leaves us with:
- BC breakage is impossible because behavior is undefined
- update test, issue gone
Ulf
--
PHP Internals - PHP Runtime Development Mailing List
To unsubscribe, visit: http://www.php.net/unsub.php
