Sorry, I'm probably confusing you by getting off topic.
I think memLZF just stores it compressed in memory. To compress it for
transfer over the wire you want to alter this line to say
conn.createStatement().execute(
"script to 'memFS:script.sql COMPRESSION GZIP'");
To read it back you need to do the opposite process, I assume you write
to the file in-memory with something like
os = FilePath.get("memFS:script.sql").newOutputStream();
then write to the output stream to populate the in-memory file.
then
conn.createStatement().execute("runscript memFS:script.sql COMPRESSION
GZIP");
I'm not sure how to clear the in-memory file to get that memory back or
how long it lasts in memory?
You might be safer just using SCRIPT TO, read the script from the result
set, then transfer, then execute the script manually without using
RUNSCRIPT... This in-memory file stuff might just be complicating it,
but I think it's pretty nifty! :)
On 2/01/2014 10:40 PM, Rob Oaks wrote:
Just to be clear (and keeping in mind that I'm new to H2!), to run the
in-memory script would I use:
conn.createStatement().execute("runscript
FilePath.get('memFS:script.sql')");
Can I also substitute memLZF for memFS so that the compressed version
of the string is being sent over the wire?
On Thursday, January 2, 2014 6:39:21 AM UTC-5, Thomas Mueller wrote:
Hi,
> SCRIPT TO mem:myobject COMPRESSION GZIP
You can do that already, using the H2 file system abstraction:
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import org.h2.store.fs.FilePath;
import org.h2.util.IOUtils;
public class TestSimpleDb {
public static void main(String[] args) throws Exception {
Connection conn = DriverManager.getConnection(
"jdbc:h2:mem:test");
conn.createStatement().execute(
"create table test(id int) as select 1");
conn.createStatement().execute(
"script to 'memFS:script.sql'");
InputStream in = FilePath.get(
"memFS:script.sql").newInputStream();
byte[] script = IOUtils.readBytesAndClose(in, -1);
System.out.println(new String(script, "UTF-8"));
}
}
Or you can just run "script" and process the result set.
Regards,
Thomas
On Thu, Jan 2, 2014 at 12:14 PM, Ryan How <rh...@exemail.com.au
<javascript:>> wrote:
On 2/01/2014 6:40 PM, Thomas Mueller wrote:
> Would be nice if there was some java in-memory file abstraction
I don't understand, you can already use the file system
abstraction of H2. You can also use databases that persist to
an in-memory file system, using the database URL
jdbc:h2:memFS:test or jdbc:h2:memLZF:test. See also
http://h2database.com/html/advanced.html#file_system
<http://h2database.com/html/advanced.html#file_system>
I meant that because RUNSCRIPT reads from a file or a URL, it
would be good to be able to pass it file object that just
points to an in memory string. Nothing H2 specific, just a way
to use the java file API for accessing custom data structures.
So he could do something like SCRIPT TO mem:myobject
COMPRESSION GZIP, which would put the compressed data into
some byte[] and then transfer it, and then RUNSCRIPT
mem:myobject COMPRESSION GZIP which reads from the byte array.
Would save all the custom compressing / uncompressing and
manually executing the SQL statements. Not that it would be
hard...
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