Sunday, July 23, 2017

Dark Intelligence (Transformation #1), by Neal Asher

book cover I loved this book about the far future where humanity is ruled by benevolent AIs and vicious technological wars are being fought with xenophobic alien races. The greatest quality of Dark Intelligence is how it managed to define a world of varying degrees of power and intelligence that somehow manage to coexist without straining suspension of disbelief. I also liked that throughout the book there were hints on various hidden truths in the story, but Neal Asher didn't simply spoil the ending with them, nor did said ending rely solely on disclosing the twists that were glimpsed from those hints. The style of the writing was focused, easy to read, capturing the reader in the world the author created. I finished the book in just two days.

The subject of the story is also one that is very dear to my heart: what is the meaning of identity and personal purpose in life when anything can be changed, altered by either yourself or others, sometimes god like intelligences that just don't see galactic life as any more interesting than we would an ant hill. And while the book is part of a series set in a universe that Asher wrote a bunch of books about, the story is quite stand alone and can be read with pleasure without fear of a cliffhanger ending ruining it all. I liked it and probably I will try other books from the series and from this author.

Tea from an Empty Cup (Artificial Reality Division #1), by Pat Cadigan

book cover It was difficult for me to finish Tea From An Empty Cup. While it was a rather classic cyberpunk novel, which I usually enjoy, I felt it was obsolete in a way that could not be fixed. You know, like when designers or artists try to imagine how computers will be in the future. Only after reading it I realized it was written in 1998, so it was normal for that time and age to misunderstand how humans behave in networked environments, but still... even if the subject was a bit interesting, I actually had to make an effort to go through with it. I think the reason for why I didn't like the book was that the characters were paper thin. Concerned to describe a chaotic virtual reality world in which anything is possible and nothing is regulated (although everything is billed), Pat Cadigan forgot to make us feel anything for the protagonists. And considering that this is a story about how technology is affecting our perception of identity, it made the book unpalatable.

Imagine a Matrix in which people enter voluntarily because the real world is boring by comparison. They create their own intricate fantasies that go well beyond the basic human needs like food or sex and focus on social cues that the participants struggle to constantly redefine and grab for themselves. In this, Pat Cadigan was spot on. However, other than this simple idea that nowadays is ubiquitous on the Internet via the various social networks, the book is nothing but a boring detective story, complete with the "normal" policeman character that enters this virtual world as a complete noob and somehow solves the case. The action is very inconsistent and the feeling I got from the flow of the plot was one of a dream sequence where stuff is cool just by merely being defined as such. At no time while reading the book I was enticed by the scenes in the story.

The concepts inside the book are interesting, but explored very little. The author seems to be under the impression that by merely listing them, the story will somehow become interesting by association, an ironic parallel with the characters in the book. Just think that this book was published at the same time The Matrix movie was released. The difference in quality between the two stories is just too big.

Thursday, July 13, 2017

In Java, two Integer objects with the same value are not == to each other, most of the time

Today I've discovered, to my dismay, that two Integer objects with the same value compared with the == operator may return false, because they are different objects. So you need to use .equals (before you check for null, of course). I was about to write a scathing blog entry on how much Java sucks, but then I discovered this amazing link: Java gotchas: Immutable Objects / Wrapper Class Caching that explains that the Integer class creates a cache of 256 values so that everything between -128 and 127 is actual equal as an instance as well.

Yes, folks, you've heard that right. I didn't believe it, either, so I wrote a little demo code:
Integer i1 = Integer.valueOf(1);
Integer i2 = Integer.valueOf(1);
boolean b1 = i1 == i2; // true

i1 = Integer.valueOf(1000);
i2 = Integer.valueOf(1000);
boolean b2 = i1 == i2; // false

i1=1;
i2=1;
boolean b3 = i1 == i2; // true

i1=1000;
i2=1000;
boolean b4 = i1 == i2; // false

i1=126;
i2=126;
boolean b5 = i1 == i2; // true

i1++;
i2++;
boolean b6 = i1 == i2; // true

i1++;
i2++;
boolean b7 = i1 == i2; // false

i1 = 2000;
i2 = i1;
boolean b8 = i1 == i2; // true

i1++;
i1--;
boolean b9 = i1 == i2; // false


I now submit to you that "sucks" applies to many things, but not to Java. A new term needs to be defined for it, so that it captures the horror above in a single word.

Wednesday, July 12, 2017

Microsoft SQL Server table partitioning

Tonight I went to an ADCES presentation about SQL table partitioning, a concept that allows for a lot of flexibility while preserving the same basic interface for a table one would use for a simpler and less scalable application. The talk was very professionally held by Bogdan Sahlean and you should have been there to see it :)

He talked about how one can create filegroups on which a table can be split into as many partitions as needed. He then demonstrated the concept of partition switching, which means swapping two tables without overhead, just via metadata, and, used in the context of partitions, the possibility to create a staging table, do stuff on it, then just swap it with a partition with no downtime. The SQL scripts used in the demo can be found on Sahlean's blog. This technology exists since SQL Server 2005, it's not something terribly new, and features with similar but limited functionality existed since SQL Server 2000. Basically the data in a table can be organized in separate buckets and one can even put each partition on a different drive for extra speed.

Things I've found interesting, in no particular order:
  • Best practice: create custom filegroups for databases and put objects in them, rather than in the primary (default) filegroup. Reason: each filegroup is restored separately,
    with the primary being the first and the one the database restore waits for to call a database as online. That means one can quickly restore the important data and see the db online, while the less accessed or less important data, like archive info, loaded afterwards.
  • Using constraints with CHECK on tables is useful in so many ways. For example, even since SQL Server 2000, one could create tables on different databases, even different servers, and if they are marked with not overlapping checks, one can not only create a view that combines all data with UNION ALL, but also insert into the view. The server will know which tables, databases and servers to connect to. Also, useful in the partition presentation.
  • CREATE INDEX with a DROP_EXISTING hint to quickly recreate or alter clustered indexes. With DROP_EXISTING, you save one complete cycle of dropping and recreating nonclustered indexes. Also, if specifying a different filegroup, you are effectively moving the data in a table from a filegroup to another.
  • Finally, the SWITCH TO partition switching can be used to quickly swap two tables, since from Sql Server 2005 all tables are considered partitioned, with regular ones just having one partition. So one creates a table identical in structure with another, does whatever with it, then just uses something like this: ALTER TABLE Orders SWITCH PARTITION 1 TO OrdersHistory PARTITION 1; to swap them out, with minimal overhang.

Monday, July 10, 2017

Memory Mapped Files in .NET 4.0

Just a heads up on a technology than I had no idea existed. To get the details read this 2009 (!!! :( ) article.

Basically you define a MemoryMappedFile instance from a path or a file reader, then create one or more MemoryMappedViewAccessors, then read or write binary data. The data can be structures, by using the generic Read/Write<[type]> methods.

Drawbacks: The size of the file has to be fixed, it cannot be increased or decreased. Also the path of the file needs to be on a local drive, it can't be on a network path.
Advantages: Fast access, built in persistency, the most efficient method to share data between processes.

Friday, July 07, 2017

NullPointerException in Java when using null values in a switch statement

Fuck Java! Just fuck it! I have been trying for half an hour to understand why a NullPointerException is returned in a Java code that I can't debug. It was a simple String object that was null inside a switch statement. According to this link states that The prohibition against using null as a switch label prevents one from writing code that can never be executed. If the switch expression is of a reference type, that is, String or a boxed primitive type or an enum type, then a run-time error will occur if the expression evaluates to null at run time.

Friday, June 30, 2017

Central Station, by Lavie Tidhar

Book cover Central Station describes a very interesting cyberpunk style of future, where amazing yet commonplace technology mixes with the traditional and with the local culture in a world in which the Solar System has been colonized. And then the book ends. Lavie Tidhar manages to imagine all of this creative world, but doesn't succeed on making the book more than the collection of short stories it actually is. That doesn't mean the book is not worth reading or that other works from the author will not benefit from the world building in it, but it feels like a missed opportunity. The book is short, it describes interactions between a surprisingly small and somehow related people and then it just ends with none of the threads in it being resolved in any way. The main character remains as the background city of Central Station, former Tel Aviv.

The writing style is also a bit heavy. It is descriptive, a little pretentious, but it might have felt like that because I was reading in the subway or when going to sleep and I wasn't in the mood for intellectual work. Even so I believe that a lighter style with more attention to story development would have benefited this book.

Bottom line: I liked the story immediately and felt betrayed after it abandoned me right when I was intrigued enough to seek closure. It is worth a read and I hope Tidhar expands the world in other stories beyond the insular location of the book. I am also looking forward to reading other things from the same author.