Bug #12229 Updated: implicit_flush (off) causes mysql to see into the future

ID: 12229 User updated by: php-man@qcn.com.au Reported By: php-man@qcn.com.au Status: Open Bug Type: MySQL related Operating System: RedHat 7.1 PHP Version: 4.0.6 New Comment: In addition; After removing debugging code (which included a top-of-script database open, loop'd fetch-array, close ... a heap of "echo"s with relevant stages/values .. and a few var_dumps) the implicit_flush=On is no longer keeping the script predictable. I can't believe I'm the only person experiencing these difficulties/bugs (if they are legitimate) ... have I done something catastrophically wrong? I would suspect a php error (on my part) if the error was consistant/predictable .. but the only time this has been predictable has been either under php3 (where the code has existed for 2years) or with my own debug code and implicit_flush on in php4 (which I now can no longer reproduce) ... very frustrating. Any help/info appreciated ... I can run test code if it will help. Previous Comments: ------------------------------------------------------------------------ [2001-07-18 07:22:24] php-man@qcn.com.au I'll be the first to admit that this is weird ... but, after 11hours of debugging and recompiling I can safely say that while implicit_flush is off, mysql_query returns some odd (pre-emptive) results; I have run an old database system (php3.0.12/mysql3.22.26a (sitting on RH6.0)) for a couple of years .. I wanted to put that onto a new RH7.1 box (php4.04pl1-9/mysql3.23.36-1). Whith the same database structure, and the same php code (bar the mysql_affected_rows() "link id" mod) I was seeing future mysql updates being entered into the database before current php decisions, ie; Table "tbl" has 1 record. In that record, field "fldx"=0, field "fldt"=0. if we query the database, in one instance, and do nothing more; select * from tbl, echo field "fldx" .. the screen output is the value 0. if we add to that php program/script a function call to a function containing further mysql queries - including updates to the field we echo at the top of this script (above); function whatever (condition parameters) { $time = 995454806 update tbl set fldt=$time where (conditions) and fldt=0 if affected rows > 0 { select * from tbl where (conditions) if number rows > 0 { fetch array (to retrieve fldx) if fldx == 2 { delete from tbl where (conditions) (interim work on other tables) return } else { update tbl set fldx=2 where (conditions) (interim work on other tables) update tbl set fldt=0 where (conditions) and fldt=$time return } } } return } then the onscreen output for fldx is "2". It is as though we had gone through the program with the stored fldx value of "0", switching through the conditions appropriately, then updating our record (fldx) with a "2", before we proceed through the php (from the top), outputting our "2" then randomly tripping condition 1 (no affected rows), or randomly tripping condition fldx==2, causing the record to be prematurely deleted, or randomly (far less frequently than the prior) occuring correctly. ... almost as if the output caching was occuring *between* PHP and MySQL ... not between PHP and the User .. (?) Since I had thought it was version problems with PHP/MySQL, I have compiled up and am now running php4.06 and mysql3.23.39 -- where the problem persisted. I have since verified that the /etc/php.ini setting "implicit_flush" when set to "on" under the newer software, does return my code to the former php3/expected logic. Very strange indeed. ------------------------------------------------------------------------ Edit this bug report at http://bugs.php.net/?id=12229&edit=1