uniqueidentifier

I'm fairly well versed in SQL server performace but I constanly have to argue down the idea that GUIDs should be used as the default type for Clusterd Primary Keys. Assuming that the table has a fairly low amount of inserts per day (5000 +/- rows / day), what kind of performace issues could we run into? How will page splits affect our seek performance? How often should I reindex (or should I defrag)? What should I set the fill factors to (100, 90, 80, ect)? What if I were inserting 1,000,000 rows per day? I apologize beforhand for all of the questions, but i'm looking to get some backup for

My app generates unique id for each row to index in lucene and save to database. One sutation is if there is and row have the same id,I want to update it,not insert an new row and index. How to do that? This is exactly the purpose of the IndexWrite#updateDocument method. The first argument is the term that must be unique in your index. For example, String id = "42"; Document doc = new Document(); Field field = new Field("id", id, Store.YES, Index.NOT_ANALYZED); doc.add(field); indexWriter.updateDocument(new Term("id", id), doc); will ensure that doc is the only document with id 42 in your

Please give me sample code to generate UUID of long type in java without using timestamp. Thanks A real UUID is 128 bits. A long is 64 bits. This is not just pedantry. UUID stands for Universal Unique IDentifier. The "universal uniqueness" of the established UUID schemes are based on: encoding a MAC address and a timestamp, encoding a hash of a DNS name and a timestamp, or using a 122 bit random number ... which is large enough that the probability of a collision is very very small. With 64 bits, there are simply not enough bits for "universal uniqueness". For instance, the birthday paradox

what's the equivalent of this function in javascript: http://php.net/manual/en/function.uniqid.php Basically I need to generate a random ID that looks like: a4245f54345 and starts with a alphabetic character (so I can use it as a CSS id) Manish Trivedi Try this (Work in php). $prefix = chr(rand(97,121)); $uniqid = $prefix.uniqid(); // $uniqid = uniqid($prefix); Try this for JavaScript:: var n = Math.floor(Math.random() * 11); var k = Math.floor(Math.random() * 1000000); var m = String.fromCharCode(n) + k; Try PHPJS's website, specifically the page for uniqid I have been using this ... I use it

I need a way to uniquely and permanently identify an instance of the JVM from within Java code running in that JVM. That is, if I have two JVMs running at the same time on the same machine, each is distinguishable. It is also distinguishable from running JVMs on other machines and from future executions on the same machine even if the process id is reused. I figure I could implement something like this by identifying the start time, the machine MAC, and the process id, and combining them in some way. I'm wondering if there is some standard way to achieve this. Update : I see that everyone

I was wondering if anybody knew a good way to create a unique random integer id for a primary key for a table. I'm using MySQL. The value has to be integer. byte_slave If your're open to suggestions and you can implement it, use UUIDs. MySQL's UUID() function will return a 36 chars value which can be used for ID . If you want to use integer, still, I think you need to create a function getRandID() that you will use in the INSERT statement. This function needs to use random + check of existing ids to return one that is not used before. Check RAND() function for MySQL. In response to: "Because I