The MonetDB/SQL tutorial is based on the material published in the book J.R. Bruijn, F.S. Gaastra and I. Schaar, Dutch-Asiatic Shipping in the 17th and 18th Centuries, which gives an account of the trips made to the East and ships returned safely (or wrecked on the way). A total of 8000 records are provided. They include information about ship name and type, captain, the arrival/departure of harbors along the route, personnel accounts, and anecdotal information.
shell> monetdbd create /path/to/mydbfarm shell> monetdbd start /path/to/mydbfarm shell> monetdb create voc shell> monetdb release voc shell> mclient -u monetdb -d voc password:<monetdb> Welcome to mclient, the MonetDB/SQL interactive terminal (Oct2014-SP1) Database: MonetDB v11.19.7 (Oct2014-SP1), 'mapi:monetdb://localhost:50000/voc' Type \q to quit, \? for a list of available commands auto commit mode: on sql>SELECT 'hello world'; +---------------+ | single_value | +===============+ | hello world | +---------------+ 1 tuple (0.530ms)
sql>\q
The command \q or end-of-file <Ctrl-d> signal terminates the connection with the server. Exploring the wealth of functionality offered by MonetDB/SQL is best started using a toy database. For this we use the VOC database which provides a peephole view into the administrative system of an early multi-national company, the Vereenigde geoctrooieerde Oostindische Compagnie (VOC for short - The (Dutch) East Indian Company) established on March 20, 1602. Download the VOC dataset voc_dump.zip (542K) gz (519K) bz2 (371K) which is a compressed file with SQL statements. After the file has been extracted, load its contents into MonetDB using mclient. Before you load the VOC data set, it is advised to introduce a user different from the omnipresent default monetdb. The new user is given his own schema for the MonetDB database. Assuming you have started MonetDB with SQL module, proceed as follows:
shell> mclient -u monetdb -d voc password:<monetdb> sql>CREATE USER "voc" WITH PASSWORD 'voc' NAME 'VOC Explorer' SCHEMA "sys"; sql>CREATE SCHEMA "voc" AUTHORIZATION "voc"; sql>ALTER USER "voc" SET SCHEMA "voc"; sql>\q
To illustrate the use of the newly created account and schema, the following example connects and creates a table, which is dropped afterwards by aborting the transaction.
shell> mclient -u voc -d voc
password:<voc>
sql>START TRANSACTION;
auto commit mode: off
sql>CREATE TABLE test (id int, data varchar(30));
operation successful (0.722ms)
sql>\d
TABLE voc.test
sql>\d test
CREATE TABLE "voc"."test" (
"id" INTEGER,
"data" VARCHAR(30)
);
sql>CREATE TABLE "voc"."test" ("id" int, "data" varchar(30));sql>ROLLBACK; auto commit mode: on sql>\d
Importing the voc_dump.sql file into the database can be done using the textual client interface. Some alternative ways are as follows:
1: shell> mclient -u voc -d voc voc_dump.sql password:<voc>
2:shell> mclient -u voc -d voc < voc_dump.sql password:<voc>
3:shell> mclient -u voc -d voc password:<voc> sql> \< voc_dump.sql
The VOC data set contains data for around 8000 voyages.
sql>\d TABLE voc.craftsmen TABLE voc.impotenten TABLE voc.invoices TABLE voc.passengers TABLE voc.seafarers TABLE voc.soldiers TABLE voc.total TABLE voc.voyages
Let's check out the data we just loaded. First, count the number of rows the voyages table.
sql>SELECT count(*) FROM voyages; +------+ | L1 | +======+ | 8131 | +------+
The set consists of 8 tables, which are all bound to each other using FOREIGN KEY relationships. The voyages table is the main table, which all others refer to. Every table, except invoices has a PRIMARY KEY defined over the columns number and number_sup. Since the invoices table holds zero or more invoices per voyage (identified by number, number_sub) a PRIMARY KEY constraint is not possible. The tables craftsmen, impotenten, passengers, seafarers, and soldiers all share the same columns. We can define a VIEW that combines them all into one big table, to make them easier to access.
sql>CREATE VIEW onboard_people AS SELECT * FROM ( SELECT 'craftsmen' AS type, craftsmen.* FROM craftsmen UNION ALL SELECT 'impotenten' AS type, impotenten.* FROM impotenten UNION ALL SELECT 'passengers' AS type, passengers.* FROM passengers UNION ALL SELECT 'seafarers' AS type, seafarers.* FROM seafarers UNION ALL SELECT 'soldiers' AS type, soldiers.* FROM soldiers UNION ALL SELECT 'total' AS type, total.* FROM total ) AS onboard_people_table;
The new view will show up and we can just use it as a normal table, to for instance calculate the number of records for each group of people:
sql>\d TABLE voc.craftsmen TABLE voc.impotenten TABLE voc.invoices VIEW voc.onboard_people TABLE voc.passengers TABLE voc.seafarers TABLE voc.soldiers TABLE voc.total TABLE voc.voyages
sql>SELECT type, COUNT(*) AS total FROM onboard_people GROUP BY type ORDER BY type; +------------+-------+ | type | total | +============+=======+ | craftsmen | 2349 | | impotenten | 938 | | passengers | 2813 | | seafarers | 4468 | | soldiers | 4177 | | total | 2467 | +------------+-------+
Let's see how many impotenten we have in the dataset:
sql>SELECT count(*) FROM impotenten; +------+ | L1 | +======+ | 938 | +------+
It is possible to play with the set in many ways, to find out several things that took place during the voyages of the ships, or the money that was earned. A few examples are shown below:
sql>SELECT COUNT(*) FROM voyages WHERE particulars LIKE '%_recked%'; +------+ | L1 | +======+ | 358 | +------+
sql>SELECT chamber, CAST(AVG(invoice) AS integer) AS average FROM invoices WHERE invoice IS NOT NULL GROUP BY chamber ORDER BY average DESC; +---------+---------+ | chamber | average | +=========+=========+ | A | 282996 | | Z | 259300 | | H | 150182 | | R | 149628 | | D | 149522 | | E | 149518 | | null | 83309 | +---------+---------+ sql>CREATE VIEW extended_onboard AS SELECT number, number_sup, trip, trip_sup, onboard_at_departure, death_at_cape, left_at_cape, onboard_at_cape, death_during_voyage, onboard_at_arrival, death_during_voyage - left_at_cape AS death_at_arrival FROM onboard_people;
sql>\d TABLE voc.craftsmen VIEW voc.extended_onboard TABLE voc.impotenten TABLE voc.invoices VIEW voc.onboard_people TABLE voc.passengers TABLE voc.seafarers TABLE voc.soldiers TABLE voc.total TABLE voc.voyages
