Re: understanding 'binding' use in clojure.java.jdbc
FWIW, the c.j.jdbc docs have an example of connection pooling: http://clojure.github.com/java.jdbc/doc/clojure/java/jdbc/ConnectionPooling.html On Mon, Dec 3, 2012 at 6:03 AM, Matthias Cords wrote: > Hi, > > I found database connection pools to be the right thing to use with > c.j.jdbc and multiple databases. > > https://clojars.org/org.bituf/clj-dbcp > > (let [conn1 (make-pool-1) > conn2 (make-pool-2)] > (sql/with-connection conn1 > (sql/with-query-results r ["select ..."] > (sql/with-connection conn2 > (sql/do-commands "insert into ...") > > matt > > > > On 10 October 2012 15:03, Stuart Sierra wrote: > >> >> >> On Tuesday, October 9, 2012 10:25:05 PM UTC-4, Sean Corfield wrote: >>> >>> This is why c.j.jdbc is getting an API overall that will expose >>> functions that accept the connection or the db-spec directly (and the old >>> API will be rewritten in terms of the new one for compatibility). >> >> >> Excellent. >> -S >> >> -- >> You received this message because you are subscribed to the Google >> Groups "Clojure" group. >> To post to this group, send email to clojure@googlegroups.com >> Note that posts from new members are moderated - please be patient with >> your first post. >> To unsubscribe from this group, send email to >> clojure+unsubscr...@googlegroups.com >> For more options, visit this group at >> http://groups.google.com/group/clojure?hl=en >> > > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > -- Sean A Corfield -- (904) 302-SEAN An Architect's View -- http://corfield.org/ World Singles, LLC. -- http://worldsingles.com/ "Perfection is the enemy of the good." -- Gustave Flaubert, French realist novelist (1821-1880) -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: understanding 'binding' use in clojure.java.jdbc
Hi, I found database connection pools to be the right thing to use with c.j.jdbc and multiple databases. https://clojars.org/org.bituf/clj-dbcp (let [conn1 (make-pool-1) conn2 (make-pool-2)] (sql/with-connection conn1 (sql/with-query-results r ["select ..."] (sql/with-connection conn2 (sql/do-commands "insert into ...") matt On 10 October 2012 15:03, Stuart Sierra wrote: > > > On Tuesday, October 9, 2012 10:25:05 PM UTC-4, Sean Corfield wrote: >> >> This is why c.j.jdbc is getting an API overall that will expose functions >> that accept the connection or the db-spec directly (and the old API will be >> rewritten in terms of the new one for compatibility). > > > Excellent. > -S > > -- > You received this message because you are subscribed to the Google > Groups "Clojure" group. > To post to this group, send email to clojure@googlegroups.com > Note that posts from new members are moderated - please be patient with > your first post. > To unsubscribe from this group, send email to > clojure+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/clojure?hl=en > -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: understanding 'binding' use in clojure.java.jdbc
On Tuesday, October 9, 2012 10:25:05 PM UTC-4, Sean Corfield wrote: > > This is why c.j.jdbc is getting an API overall that will expose functions > that accept the connection or the db-spec directly (and the old API will be > rewritten in terms of the new one for compatibility). Excellent. -S -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: understanding 'binding' use in clojure.java.jdbc
Yeah, you probably shouldn't rely on this but I think it will still
work. I have done something similar before when reading from 3
databases simultaneously (3 nested with-connection and
with-query-result calls) and I believe (connection) is only called
once when creating the prepared statement.
On Tue, Oct 9, 2012 at 9:24 PM, Sean Corfield wrote:
> No, the inner with-connection binds *db* to db1 so db2 is no longer
> accessible.
>
> This is why c.j.jdbc is getting an API overall that will expose functions
> that accept the connection or the db-spec directly (and the old API will be
> rewritten in terms of the new one for compatibility).
>
> Sean
>
>
> On Tue, Oct 9, 2012 at 2:44 PM, gaz jones wrote:
>>
>> Can you not simply:
>>
>> (jdbc/with-connection db2
>> (jdbc/with-query-results results
>> query
>> {:result-type :forward-only
>>:fetch-size 1000}
>> (jdbc/with-connection db1
>> ;; read and write?
>>)))
>>
>> ?
>
>
>
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Re: understanding 'binding' use in clojure.java.jdbc
On Tue, Oct 9, 2012 at 12:53 PM, Brian Craft wrote: > On Tuesday, October 9, 2012 12:11:28 PM UTC-7, Tassilo Horn wrote: > >> Yes, that's true. Maybe Korma [1] is better suited for this kind of >> operation. >> > Thanks for the link to korma. > Korma is built on c.j.jdbc and may suffer from the same issues...? -- Sean A Corfield -- (904) 302-SEAN An Architect's View -- http://corfield.org/ World Singles, LLC. -- http://worldsingles.com/ "Perfection is the enemy of the good." -- Gustave Flaubert, French realist novelist (1821-1880) -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: understanding 'binding' use in clojure.java.jdbc
No, the inner with-connection binds *db* to db1 so db2 is no longer
accessible.
This is why c.j.jdbc is getting an API overall that will expose functions
that accept the connection or the db-spec directly (and the old API will be
rewritten in terms of the new one for compatibility).
Sean
On Tue, Oct 9, 2012 at 2:44 PM, gaz jones wrote:
> Can you not simply:
>
> (jdbc/with-connection db2
> (jdbc/with-query-results results
> query
> {:result-type :forward-only
>:fetch-size 1000}
> (jdbc/with-connection db1
> ;; read and write?
>)))
>
> ?
>
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Re: understanding 'binding' use in clojure.java.jdbc
Can you not simply:
(jdbc/with-connection db2
(jdbc/with-query-results results
query
{:result-type :forward-only
:fetch-size 1000}
(jdbc/with-connection db1
;; read and write?
)))
?
On Tue, Oct 9, 2012 at 2:53 PM, Brian Craft wrote:
>
> On Tuesday, October 9, 2012 12:11:28 PM UTC-7, Tassilo Horn wrote:
>>
>> Brian Craft writes:
>>
>> Hi Brian,
>>
>> > If (read-stuff) is not lazy, then this looks pretty simple: all the
>> > data is loaded in memory & returned to (write-stuff). If the data is
>> > large you wouldn't want it all in memory. What then? Could you make
>> > read-stuff return a lazy sequence? My impression after a brief
>> > experiment is that this doesn't work: when the inner with-connection*
>> > returns, the db connection is closed. A lazy sequence from
>> > (read-stuff) then can't be evaluated w/o throwing an error.
>>
>> Yes, that's true. Maybe Korma [1] is better suited for this kind of
>> operation.
>>
>
> Damn. I was hoping there was some lispy fp thing I was missing here, but
> *db* really is just a global variable that fails in the same way that
> globals fail in all languages.
>
> Thanks for the link to korma.
>
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Re: understanding 'binding' use in clojure.java.jdbc
On Tuesday, October 9, 2012 12:11:28 PM UTC-7, Tassilo Horn wrote: > > Brian Craft > writes: > > Hi Brian, > > > If (read-stuff) is not lazy, then this looks pretty simple: all the > > data is loaded in memory & returned to (write-stuff). If the data is > > large you wouldn't want it all in memory. What then? Could you make > > read-stuff return a lazy sequence? My impression after a brief > > experiment is that this doesn't work: when the inner with-connection* > > returns, the db connection is closed. A lazy sequence from > > (read-stuff) then can't be evaluated w/o throwing an error. > > Yes, that's true. Maybe Korma [1] is better suited for this kind of > operation. > > Damn. I was hoping there was some lispy fp thing I was missing here, but *db* really is just a global variable that fails in the same way that globals fail in all languages. Thanks for the link to korma. -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: understanding 'binding' use in clojure.java.jdbc
Brian Craft writes: Hi Brian, > If (read-stuff) is not lazy, then this looks pretty simple: all the > data is loaded in memory & returned to (write-stuff). If the data is > large you wouldn't want it all in memory. What then? Could you make > read-stuff return a lazy sequence? My impression after a brief > experiment is that this doesn't work: when the inner with-connection* > returns, the db connection is closed. A lazy sequence from > (read-stuff) then can't be evaluated w/o throwing an error. Yes, that's true. Maybe Korma [1] is better suited for this kind of operation. Bye, Tassilo [1] http://sqlkorma.com -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: understanding 'binding' use in clojure.java.jdbc
On Tuesday, October 9, 2012 11:32:18 AM UTC-7, Tassilo Horn wrote: > > Brian Craft > writes: > > > How would I do an operation involving two databases? I'd need to call > > with-connection* from with-connection*? How would I then read from one > > & write to the other? > > I've never used the jdbc lib, but essentially it should be something > along the lines of > > (let [db1 (connect-to-db1) > db2 (connect-to-db2)] > (with-connection* db2 > (write-stuff (with-connection* db1 (read-stuff) > > If (read-stuff) is not lazy, then this looks pretty simple: all the data is loaded in memory & returned to (write-stuff). If the data is large you wouldn't want it all in memory. What then? Could you make read-stuff return a lazy sequence? My impression after a brief experiment is that this doesn't work: when the inner with-connection* returns, the db connection is closed. A lazy sequence from (read-stuff) then can't be evaluated w/o throwing an error. -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: understanding 'binding' use in clojure.java.jdbc
Brian Craft writes: > How would I do an operation involving two databases? I'd need to call > with-connection* from with-connection*? How would I then read from one > & write to the other? I've never used the jdbc lib, but essentially it should be something along the lines of (let [db1 (connect-to-db1) db2 (connect-to-db2)] (with-connection* db2 (write-stuff (with-connection* db1 (read-stuff) Bye, Tassilo -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
