lneves

I've been using postgres for a few years now, I also use MSSQL, MonetDB and MySQL.

Some of the things I miss most frequently are:

- Easy table partitioning.

- Support for "phrase search" in fts.

- MERGE/UPSERT support.

- Columnar storage (and related optimizations) for "OLAP like" workloads.

- EXPLAIN ANALYSE that traces functions.

lneves

14 anni fadiscuss

  find . -type d

edit: for the same output as your command you can use:

  dir -l

lneves

16 anni fadiscuss

I do not think that this is equivalent, it looks like querying complex JSON objects and not "simple" arrays.

From the "Array Element by Position" example:

  db.blogposts.find( { "comments.0.by" : "Abe" } )

PostgreSQL doesn't have JSON support but it does have XML/Xpath support.

If you stored XML documents in PostgreSQL the similar query to the MongoDB one would be something like this:

  select * from blogposts where (xpath('/comments[0]/@by', doc))::text[] = array['Abe']

Yes it's a little more verbose but not terrible so... at least in my opinion.

lneves

16 anni fadiscuss

Yes I've looked at them. I use them every day. The example you posted its difficult to parse because it deals with multidimensional arrays and also populating one in the inner query. The simple, and much more common case of one dimension arrays is very straightforward. Can you show me the equivalent in MongoDB?

About the performance/scalability warning; I don't deal with very large arrays, a couple hundred items max, and when using a GIN index over the array field, search queries are screamingly fast.

lneves

16 anni fadiscuss

<quote>simply because a row can't contain sub-arrays or hashes</quote>

This is not true at all. At least in PostgreSQL you can have arrays and hashes:

http://www.postgresql.org/docs/current/static/arrays.html

http://www.postgresql.org/docs/current/static/hstore.html

lneves

16 anni fadiscuss

I would be interested to know if sports like cycling also have some kind of the negative health impact caused by the long periods of "sitting down".

lneves

17 anni fadiscuss

I want to see it get out :-)

lneves

17 anni fadiscuss

So the brain is, in a way, executing before the data is available (energy in this case).

You can absorb drugs on your mouth: http://silversol.110mb.com/use/sublin.htm

I would think that carbs are also readily absorbed in some quantity without the need of ingesting them.

lneves

17 anni fadiscuss

If your objects have a wide variety of attributes, either you need lots of columns with many of them empty, or you need some sort of attribute table with object-key-value triples. Both are bad relational design, but the structure is inherent in the data. If you're having to use a fixed DB schema, I can't see any way around bad design.

PostgreSQL HStore is very handy in situations such as this: http://www.postgresql.org/docs/8.3/static/hstore.html

lneves

18 anni fadiscuss

An easy way do it would be to extract the term vectors from the query and then find related documents computing the cosine similarity measure.

lneves

18 anni fadiscuss

No way JVM starts in under a second: it's more like 2 full seconds on his hardware.

My machine has lower hardware specs than what the article mentions. This is what i get.

$ java -version

java version "1.6.0_10"

Java(TM) SE Runtime Environment (build 1.6.0_10-b33)

Java HotSpot(TM) 64-Bit Server VM (build 11.0-b15, mixed mode)

$ uname -a

Linux lneves-t61p 2.6.27-9-generic #1 SMP Thu Nov 20 22:15:32 UTC 2008 x86_64 GNU/Linux

$ echo "public class Test{public static void main(String[] args) {System.out.println(\"Hello World\");}}" > Test.java

$ javac Test.java

$ time java Test

Hello World

real 0m0.174s

user 0m0.068s

sys 0m0.016s

It seems that you are wrong.

More likely he had some of JVM in the filesystem cache. Vista/OSX will pre-fetch JVM modules even after you reboot (not sure about Linux) if you run Java software and especially if you have 8GB of RAM...

Do you mean Class Data Sharing?

http://java.sun.com/j2se/1.5.0/docs/guide/vm/class-data-shar...

Lets disable it:

$ time java -Xshare:off Test

Hello World

real 0m0.165s

user 0m0.060s

sys 0m0.040s

Not much of a difference.

lneves

18 anni fadiscuss

Did you read the linked presentation? http://www.commandprompt.com/files/mysql_learn.pdf

lneves

18 anni fadiscuss

This reminds me of the following Penny Arcade cartoon:

http://www.penny-arcade.com/images/2002/20020712l.gif

lneves

18 anni fadiscuss

If you haven't seen it yet, check this presentation about partitioning with PostgreSQL:

http://images.omniti.net/omniti.com/talks/partitions-public....