Hi Giacomo,
1) Which version of MonetDB are you using? Environment?
2) What do you mean by "the client hangs"?
Best,
Wenjian
On Tue, Dec 22, 2015 at 10:46 PM, Giacomo Bergami wrote: Now I'm trying to follow the example given in this wiki:
https://www.monetdb.org/wiki/TPCH_Example and
https://www.monetdb.org/Documentation/Manuals/SQLreference/Explain. I tried to perform in the mclient the following query, where with the
first statement I try to initialize the sql module. mal>s := sql.start();
mal>_2 := sql.mvc(); but after the second command, the client hangs and does not me allow to
perform the query.
Is there any way to overcome this problem? Thanks again. ________________________________
Da: users-list [users-list-bounces+giacomo.bergami2=unibo.it@monetdb.org]
per conto di Lefteris [lsidir@gmail.com]
Inviato: mercoledì 16 dicembre 2015 17.20
A: Communication channel for MonetDB users
Oggetto: Re: Performing a direct access to MonetDB's BAT tables via MAL Hi, in the MAL level the fastest and best access to a BAT is still subselect
if you are looking for a value and fetch if you are interested in the value
to a specific position (aka oid). Lefteris On Wed, Dec 16, 2015 at 4:45 PM, Giacomo Bergami <
giacomo.bergami2@unibo.itmailto:giacomo.bergami2@unibo.it> wrote:
Good Morning/Evening everyone. My aim is to direcly access to the BAT column store representation of
MonetDB through the standard libraries (MAPI/JDBC) - if possible. I know
that each SQL query gets rewrited into a BAT algebra expression, but in my
case I want to access to a single value per time (e.g. I want to access to
the value stored in the i-th row and in the column labelled "j" of a given
table) and maybe in this case the direct access is quicker than performing
the whole SQL query. I've already tried to use the mclient with the MAL language and read the
documentation, and I tried to use the client with something like this: mdb.start();
bbp.open();
bbp.prelude();
a := bbp.bind("fx", "size"); where "fx" should be the name of the table and "size" one of its
attributes. But unfortunately I do not know how to search for a specific
row-key and to get the correspondant value, and AFAIK i have to get the id
of the column "size". Thanks in advance,
Giacomo Bergami
____________________________
Giacomo Bergami, Ph.D Student
University of Bologna
https://www.unibo.it/sitoweb/giacomo.bergami2
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