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Bug #70092 pg_field_type() is too slow
Submitted: 2015-07-17 21:16 UTC Modified: 2015-07-25 20:17 UTC
Votes:1
Avg. Score:5.0 ± 0.0
Reproduced:1 of 1 (100.0%)
Same Version:1 (100.0%)
Same OS:0 (0.0%)
From: yohgaki@php.net Assigned: yohgaki (profile)
Status: Closed Package: PostgreSQL related
PHP Version: master-Git-2015-07-17 (Git) OS:
Private report: No CVE-ID: None
 [2015-07-17 21:16 UTC] yohgaki@php.net
Description:
------------
Somehow pg_field_type() became very slow. Other functions that share the same code pg_field_name()/etc is not affected.



Test script:
---------------
<?php
$db = pg_connect('host=localhost') or die('Cannot connect db');
$res = pg_query('SELECT * FROM test');

$start = microtime(true);
for ($i = 0; $i < 10000; $i++) {
    pg_field_type($res, 1);
}
echo 'pg_field_type(): '.(microtime(true)-$start)."\n";


$start = microtime(true);
for ($i = 0; $i < 10000; $i++) {
    pg_field_name($res, 1);
}
echo 'pg_field_name(): '.(microtime(true)-$start)."\n";

$start = microtime(true);
for ($i = 0; $i < 10000; $i++) {
    pg_field_size($res, 1);
}
echo 'pg_field_type(): '.(microtime(true)-$start)."\n";






Expected result:
----------------
pg_filed_type() should be as fast as pg_filed_name()/etc

Actual result:
--------------
PHP 7 and master
[yohgaki@dev PHP-master]$ ./php-bin ../t.php
pg_field_type(): 3.1048510074615
pg_field_name(): 0.0023491382598877
pg_field_type(): 0.0014290809631348

PHP 5.6
[yohgaki@dev PHP-master]$ php ../t.php
pg_field_type(): 0.0019080638885498
pg_field_name(): 0.0013489723205566
pg_field_type(): 0.0010430812835693



Patches

pg_field_type (last revision 2015-07-25 14:04 UTC by cmb@php.net)

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History

AllCommentsChangesGit/SVN commitsRelated reports
 [2015-07-17 21:17 UTC] yohgaki@php.net
-Assigned To: +Assigned To: yohgaki
 [2015-07-25 12:41 UTC] cmb@php.net
-Status: Assigned +Status: Verified
 [2015-07-25 12:41 UTC] cmb@php.net
For some reason the buffering of the field names in
get_field_name() does not work, and so for each call to
pg_field_type() the else clause ("hash all oids")[1] is executed
again.

[1] <https://github.com/php/php-src/blob/php-7.0.0beta2/ext/pgsql/pgsql.c#L2349>
 [2015-07-25 14:04 UTC] cmb@php.net
The following patch has been added/updated:

Patch Name: pg_field_type
Revision:   1437833083
URL:        https://bugs.php.net/patch-display.php?bug=70092&patch=pg_field_type&revision=1437833083
 [2015-07-25 14:05 UTC] cmb@php.net
-Status: Verified +Status: Analyzed
 [2015-07-25 14:05 UTC] cmb@php.net
Simply setting the length of the smart_string's zend_string to
zero[1] won't work, because that causes the same zend_string to be
used as key of the list hashtable again and again. Instead it
seems that the smart_string's zend_string has to be free (see the
attached patch "pg_field_type").

Yasuo, please have a look at this issue.

[1] <https://github.com/php/php-src/blob/php-7.0.0beta2/ext/pgsql/pgsql.c#L2371>
 [2015-07-25 19:28 UTC] yohgaki@php.net
@cmb

Thanks! I thought it seems freeing is required, too. I'll check the behavior using gdb later.
 [2015-07-25 20:17 UTC] yohgaki@php.net
Simply freed smart_str instead of setting length to 0.

PHP7/master without --enable-debug
[yohgaki@dev PHP-master]$ ./php-bin ../t.php
pg_field_type(): 0.0013771057128906
pg_field_name(): 0.00064301490783691
pg_field_type(): 0.00048398971557617

Fedora22's PHP 5.6
[yohgaki@dev PHP-master]$ php ../t.php
pg_field_type(): 0.0018699169158936
pg_field_name(): 0.0012152194976807
pg_field_type(): 0.0011649131774902
 [2015-07-25 20:29 UTC] yohgaki@php.net
Automatic comment on behalf of yohgaki
Revision: http://git.php.net/?p=php-src.git;a=commit;h=62515a1dbb6132051d657ce4df7cc5da32b1a039
Log: Fixed Bug #70092 pg_field_type() is too slow
 [2015-07-25 20:29 UTC] yohgaki@php.net
-Status: Analyzed +Status: Closed
 [2015-08-04 20:54 UTC] ab@php.net
Automatic comment on behalf of yohgaki
Revision: http://git.php.net/?p=php-src.git;a=commit;h=62515a1dbb6132051d657ce4df7cc5da32b1a039
Log: Fixed Bug #70092 pg_field_type() is too slow
 [2016-07-20 11:37 UTC] davey@php.net
Automatic comment on behalf of yohgaki
Revision: http://git.php.net/?p=php-src.git;a=commit;h=62515a1dbb6132051d657ce4df7cc5da32b1a039
Log: Fixed Bug #70092 pg_field_type() is too slow
 
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