You are committing a file with bug fixes to the SVN, there is an issue with a conflict in the file what does this mean? How do you solve it?

Questions and Answers

Question: You are committing a file with bug fixes to the SVN, there is an issue with a conflict in the file what does this mean? How do you solve it?

Answer:

A conflict happens because changes were made to the same parts of the file in two different branches. You solve a conflict by editing the parts where conflict occurred, remove markers that indicate the conflict and add whatever changes you want to apply. This means that since the last update, some changes have been committed to the SVN (most likely when a project has multiple developers). A simple solution is to revert the current changes and update the copy in progress i.e.

$ svn revert README

Reverted ‘README’

$ svn update README

Second, I may choose to keep my changes and dump the earlier saved changes. This will ensure that all special files formally generated are cleaned up.

Lastly, I can create a new version from both conflicting files. Here I would manually edit the readme file and add or remove any conflicting makers. The new file will be marked as resolved to ensure that subversion enables committing.

Question: How would you find out what files were out of date within SVN and commit those specific files into a revision with a log message via the command line?

Answer:

`svn st` will report which files have local changes.
`svn diff` each file, this avoids accidental white-space checkins

Question: How do you use memcached to optimize mysql queries?

Answer:

Memcache is an object caching system and as such I use it to store queries that are small and yet return small data sets. I use it to create caching scripts. However, based on my experience not all DB queries are suitable for caching especially where the database server caches queries. Here is an example code of how I utilize memcache

//declare a global variable of memcache

global $memcache;

$memcache=new MemCache;

//create a function to get the value into memcache

function getCache($cacheKey){

global $memcache;

return ($memcache) ? $memcache-> get(cacheKey) : false;

}

function setCache($key,$object,$timeout = 60) {

        global $memcache;

        return ($memcache) ? $memcache->set($key,$object,MEMCACHE_COMPRESSED,$timeout) : false;

    }

    # Caching version of mysql_query()

    function mysql_query_cache($sql,$linkIdentifier = false,$timeout = 60) {

        if (($cache = getCache(md5("mysql_query" . $sql))) !== false) {

            $cache = false;

            $r = ($linkIdentifier !== false) ? mysql_query($sql,$linkIdentifier) : mysql_query($sql);

            if (is_resource($r) && (($rows = mysql_num_rows($r)) !== 0)) {

                for ($i=0;$i<$rows;$i++) {

                    $fields = mysql_num_fields($r);

                    $row = mysql_fetch_array($r);

                    for ($j=0;$j<$fields;$j++) {

                        if ($i === 0) {

                            $columns[$j] = mysql_field_name($r,$j);

                        }

                        $cache[$i][$columns[$j]] = $row[$j];

                    }

                }

                if (!setCache(md5("mysql_query" . $sql),$cache,$timeout)) {

                    # If we get here, there isn't a memcache daemon running or responding

                }

            }

        }

        return $cache;

    }

?>

Question: How do you iterate an array in smarty?

Answer:

The following is an iteration of an array in smarty

Array

$data = array(10,11,12);

$smarty->assign('ourname',$data);

?>

{section name=ournames loop=$ourname}

{section ournames $ourname}

  id: {$ourname[ournames]}

{/section}

{section name=foo loop=$ourname step=-1}

{section foo $ourname step=-1}

  {$ourname[foo]}

{/section}

Question: PHP errors are not displaying on the page you are developing. You only have SFTP Access to change files. How do you display the errors?

Answer:

Evaluate files using command-line php. ie: php file.php

Question: What is better and more efficient in development time for a large scale enterprise PHP / MySQL application? Using packages and open source classes or developing your own solutions?

Answer:

Using packages and open source classes (why reinvent the wheel?)

Question: What are the risks of using user inputted data in SQL queries and how to eliminate this risk ?

Answer:

It leaves you open to SQL injection attacks. Eliminate the risk by escaping all user input data

Question: You have been given a specification and been briefed on a project. The specification included work that was already completed for the project but there are many bugs and you did not write this code. What do you do?

Answer:

Study the code, evaluate how easy it is to fix the bugs as compared to writing new code. Select whichever outweighs the other.

Question: There is a bug in your code, what do you do?

Answer:

Debug and fix it, test everything to ensure the fix didn't break other things (automated tests are your friend here)

Question: Recently users are complaining they are being logged out of the site. The site uses sessions and php. Also recently a new webserver was added, bringing the total to 2. What could be causing this and how would it be solved?

Answer:

The two servers may cause users to flip from one server to another. The solution is to petition management, to get a core library upgrade. You replace the SESSION storage mechanism with the database-backed one so either server may load the SESSION. Also I will check all the certs and domain paths first on the COOKIEs, to avoid future problems.

Question: You need to create a search function for a website with over 2.000 searches per second on a record set of 100.000.000 text records. How would you do this assuming data source is in MySQL?

Answer:

There are two options; one, use memcache or two, set the express caching on the MYSQL server. Whichever provides the least response time should be adopted.

Question: You need to integrate an external website's data that does not have an API - describe this process.

Answer:

Have the site send you files containing the data in a structured format such as xml, json. Parse these files to extract whatever data you need

Question: You've written a news service in PHP that needs to be used by many external websites. How would you allow those websites to use your functions to display the news on their site?

Answer:

Create a Web service (e.g. using soap protocol) that returns xml, json etc.

Question: You want to create an AJAX suggestion box that displays in real time suggestions related to the content of the search text field. Describe how this process would work.

Answer:

 Implement on key release action, this ensures that as the user types on the text field every character is parsed to the database (using Ajax, and a return of results using json) and filtered accordingly and the return is based on the typed characters. Similar to how Facebook search button works. Really simple to implement.

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