I recently attended the NoSQL conference in London and think I have a better idea now how to answer the original question. I also wrote a blog post, and there are a couple of other good ones. Key points: We have accumulated probably 30 years knowledge of adminstering relational databases, so shouldn’t replace them without … Read more
Most of the answers here are on the right track. However, a row is not a tuple. Tuples* are unordered sets of known values with names. Thus, the following tuples are the same thing (I’m using an imaginary tuple syntax since a relational tuple is largely a theoretical construct): (x=1, y=2, z=3) (z=3, y=2, x=1) … Read more
I will summarize my thoughts from my blog post – A lesson in address storage (on archive.org). On my current project [I work for a logistics company] we’re storing international addresses. I’ve done research on addresses all over the world in the design of this portion of the database. There’s a lot of different formats. … Read more
First, Solr doesn’t use B-trees. A Lucene (the underlying library used by Solr) index is made of a read-only segments. For each segment, Lucene maintains a term dictionary, which consists of the list of terms that appear in the segment, lexicographically sorted. Looking up a term in this term dictionary is made using a binary … Read more
Let’s start with the definition of a wide column database. Its architecture uses (a) persistent, sparse matrix, multi-dimensional mapping (row-value, column-value, and timestamp) in a tabular format meant for massive scalability (over and above the petabyte scale). A relational database is designed to maintain the relationship between the entity and the columns that describe the … Read more
If we want to see the columns names of the table in HiveQl, the following hive conf property should be set to true. hive> set hive.cli.print.header=true; If you prefer to see the column names always then update the $HOME/.hiverc file with the above setting in the first line.. –Hive automatically looks for a file named … Read more
Sack your contractor. Okay, seriously, this isn’t standard practice. This can be seen simply because all RDBMS that I have ever worked with implement NULL, logic for NULL, take account of NULL in foreign keys, have different behaviour for NULL in COUNT, etc, etc. I would actually contend that using ‘Z’ or any other place … Read more
So I’ve been trying to figure out the real bottom-line when it comes to NoSQL vs RDBMS myself, and always end up with a response that doesn’t quite cut it. In my search there are really 2 primary differences between NoSQL and SQL, with only 1 being a true advantage. ACID vs BASE – NoSQL … Read more
Since postgres is a lot more sane than MySQL, there are not that many “tricks” to report on 😉 The manual has some nice performance tips. A few other performance related things to keep in mind: Make sure autovacuum is turned on Make sure you’ve gone through your postgres.conf (effective cache size, shared buffers, work … Read more
Solution: make index a string (because strings, in essence, have infinite “arbitrary precision”). Or if you use an int, increment index by 100 instead of 1. The performance problem is this: there is no “in between” values between two sorted items. item index —————– gizmo 1 <<—— Oh no! no room between 1 and 2. … Read more