Re: hello
On 11/1/15 2:37 PM, בבנייה בבנייה wrote: I trying to leran derby for a project that include it. I want to say that it's very not full , there is much misunderstand for who that not familiar with all issues like class path, start server and more. I think that should at least be a quick and friendly guide for get some order with all the mess. good day,,, Please consult the Getting Started Guide here: http://db.apache.org/derby/docs/10.12/getstart/index.html Thanks, -Rick
Re: hello
On 11/01/2015 11:37 PM, בבנייה בבנייה wrote: I trying to leran derby for a project that include it. I want to say that it's very not full , there is much misunderstand for who that not familiar with all issues like class path, start server and more. I think that should at least be a quick and friendly guide for get some order with all the mess. good day,,, Please see http://www.catb.org/esr/faqs/smart-questions.html -- Regards, Dyre
RE: hello
Try the followin quotation: C:\Program Files\Apache\db-derby-10.8.1.2-bin\lib\derby.jar;C:\Program Files\Apache\db-derby-10.8.1.2-bin\LIB\derbytools.jar; That is the complete path of the jar and no only the directory with the space. Greetings -Mensaje original- De: Bryan Pendleton [mailto:bpendleton.de...@gmail.com] Enviado el: viernes, 25 de mayo de 2012 08:03 p.m. Para: Derby Discussion Asunto: Re: hello C:\java org.apache.derby.tools.sysinfo Error: Could not find or load main class org.apache.derby.tools.sysinfo C:\echo %CLASSPATH% C:\Program Files\Apache\db-derby-10.8.1.2-bin\lib\derby.jar;C:\Program Files \Apache\db-derby-10.8.1.2-bin\LIB\derbytools.jar; Sometimes it is hard to get the quotation marks correct when you have spaces in file names. Why don't you try putting the Derby installation into a different directory, without spaces in the names, for example c:\derby10.8, and see if setting your classpath to point to that directory makes things easier. thanks, bryan
Re: hello
C:\java org.apache.derby.tools.sysinfo Error: Could not find or load main class org.apache.derby.tools.sysinfo C:\echo %CLASSPATH% C:\Program Files\Apache\db-derby-10.8.1.2-bin\lib\derby.jar;C:\Program Files \Apache\db-derby-10.8.1.2-bin\LIB\derbytools.jar; Sometimes it is hard to get the quotation marks correct when you have spaces in file names. Why don't you try putting the Derby installation into a different directory, without spaces in the names, for example c:\derby10.8, and see if setting your classpath to point to that directory makes things easier. thanks, bryan
Re: Hello
When I try to run WwdEmbedded.java there is an error that looks like this: --- C:\Documents and Settings\Zoran\Desktop\DERBYTUTORjava WwdEmbedded Exception in thread main java.lang.NoClassDefFoundError: WwdEmbedded I suspect this is because you didn't set your CLASSPATH environment variable carefully, to include . in the classpath. See step (1) of the instructions at: http://db.apache.org/derby/docs/dev/getstart/twwdactivity3_Setup.html and ensure that you have done: set CLASSPATH=%DERBY_HOME%\lib\derby.jar;. thanks, bryan
Re: Hello
This error can happen if you do not have the current directory in your classpath. Did you follow all the instructions in the Setting up your environment section, including Manually setting the CLASSPATH environment variable? Kim Haase On 12/01/09 12:51, velimzo wrote: I am new in Derby. Here is my problem: I am following Getting Started With Java DB instructions. Problem occures when I try to follow instructions for Run a JDBC program using the embedded driver. I compiled successfully WwdEmbedded.java, not following instructions but with a command javac *.java When I try to run WwdEmbedded.java there is an error that looks like this: --- C:\Documents and Settings\Zoran\Desktop\DERBYTUTORjava WwdEmbedded Exception in thread main java.lang.NoClassDefFoundError: WwdEmbedded Caused by: java.lang.ClassNotFoundException: WwdEmbedded at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClassInternal(Unknown Source) Could not find the main class: WwdEmbedded. Program will exit. - My version of Java is : Java(TM) SE Runtime Environment (build 1.6.0_17-b04) Version of Derby is : Derby 10.5.3.0 Operating System : Windows XP sp3 I am thankful on every answer...
Re: performance, memory consumption...and a big hello :)
2009/7/29 Dan Armbrust daniel.armbrust.l...@gmail.com: Problem 1: select id_group, count(id) group by id_group This takes a couple of minutes, Is that the entire query? No where clause? I don't think any database is going to use the index when you aren't providing a where clause... especially when you have a count and a group by in there... it has to read the entire table. Well, initially, I would have agreed with you, but after having thought about it for a while and having read a couple of threads in various forums and mailing lists, I think it's not impossible: an index might in fact be useful if all the information is inside it, i.e. the table itself doesn't need to be read. Still, you might be right: I'm not sure yet.
Re: performance, memory consumption...and a big hello :)
2009/7/29 Kristian Waagan kristian.waa...@sun.com: Hello Tomislav, You might want to read this: http://wiki.apache.org/db-derby/StmtExecutionPlan Especially, follow the link for the QueryPlanJoinOrder. ... A new feature has also been introduced into the development trunk, called the XPLAIN style runtime statistics. It may or may not be of interest to you, consult the Derby Tuning Guide for more information. Thanks, Kristian. I had looked in the Derby Tuning Guide and had gotten the distinct impression that the available tools only display information after the query has been executed which was not really what I was looking for. I look forward to future improvements (the XPLAIN statement, for example).
Re: performance, memory consumption...and a big hello :)
2009/7/29 Rick Hillegas richard.hille...@sun.com: Some great work has been put into improving Derby's explain capabilities in the next feature release. In the meantime, you can view Derby query plans by using the SYSCS_UTIL.SYSCS_SET_RUNTIMESTATISTICS() system procedure. Please see the Derby Tuning Guide: http://db.apache.org/derby/docs/10.5/tuning/tuning-single.html#ctundepth13055 As I've already mentioned to Kristian, from what I understood from the Tuning Guide, the information is all available once the query is finished which was quite cumbersome in my case. I was interested in testing a dozen or two combinations with different indexes setups and if each test took a long time (because the query had to be actually executed, rather than just it's plan displayed), it would take forever. I'm glad to hear there are improvements on the way as Derby remains the DB of choice on my project. Have you tried ( id_group1, id ) This index covers your query and is in a useful sort order. If Derby does not use this index on your large data set, then there may be a bug. It would be interesting to see the query plan which Derby follows when you have declared this index. Interesting idea, Rick. At the moment I don't have the Derby instance available, but I did try it out on postgresql. However, I've had no lock: the column order doesn't seem to impact the execution plan: it's invariably a seq. scan...still a nice try, though. I like your methodical, precise analytical approach. :)
Re: performance, memory consumption...and a big hello :)
Thank you both for the comments. Jan, I've kind of taken your advice even before I saw it :), but I tried PostgreSQL, unfortunately, with no obvious improvement. 2009/7/27 Rick Hillegas richard.hille...@sun.com: select id_group, count(id) group by id_group Not to be tiresome, but just to make sure we understand the query: I think you mean id_group1 instead of id_group. Exactly right. It sounds as though you may have created an index on ( id_group1, id ). At first blush, I would expect that index to improve the performance. Did that not happen? That is exactly what I observed. As I told Jan, I've tried it out on PostgreSQL in the meantime because a) I wanted to see how a different RDBMS would behave and b) because derby (it seems) doesn't support the explain command to show the query plan and PostgreSQL does. I've tried the following indexes: (id) (id_group1) (id, id_group1) but postgresql announced a sequential table scan every time and, in fact, seemed to have done exactly that when I executed the query. Either I'm doing something obviously wrong or am assuming something obviously impossible is possible, but I'm inclined to believe the former, rather than the latter which is why I'm writing. :-) Cheers, Tomislav
Re: performance, memory consumption...and a big hello :)
Problem 1: select id_group, count(id) group by id_group This takes a couple of minutes, Is that the entire query? No where clause? I don't think any database is going to use the index when you aren't providing a where clause... especially when you have a count and a group by in there... it has to read the entire table.
Re: performance, memory consumption...and a big hello :)
Tomi N/A wrote: Thank you both for the comments. Jan, I've kind of taken your advice even before I saw it :), but I tried PostgreSQL, unfortunately, with no obvious improvement. 2009/7/27 Rick Hillegas richard.hille...@sun.com: select id_group, count(id) group by id_group Not to be tiresome, but just to make sure we understand the query: I think you mean id_group1 instead of id_group. Exactly right. It sounds as though you may have created an index on ( id_group1, id ). At first blush, I would expect that index to improve the performance. Did that not happen? That is exactly what I observed. As I told Jan, I've tried it out on PostgreSQL in the meantime because a) I wanted to see how a different RDBMS would behave and b) because derby (it seems) doesn't support the explain command to show the query plan and PostgreSQL does. Hello Tomislav, You might want to read this: http://wiki.apache.org/db-derby/StmtExecutionPlan Especially, follow the link for the QueryPlanJoinOrder. This feature of Derby isn't what I would call the most user friendly, but with some effort it should give you the information you need. A new feature has also been introduced into the development trunk, called the XPLAIN style runtime statistics. It may or may not be of interest to you, consult the Derby Tuning Guide for more information. Regards, -- Kristian I've tried the following indexes: (id) (id_group1) (id, id_group1) but postgresql announced a sequential table scan every time and, in fact, seemed to have done exactly that when I executed the query. Either I'm doing something obviously wrong or am assuming something obviously impossible is possible, but I'm inclined to believe the former, rather than the latter which is why I'm writing. :-) Cheers, Tomislav
Re: performance, memory consumption...and a big hello :)
Hi Tomislav, Some more comments inline... Tomi N/A wrote: Thank you both for the comments. Jan, I've kind of taken your advice even before I saw it :), but I tried PostgreSQL, unfortunately, with no obvious improvement. 2009/7/27 Rick Hillegas richard.hille...@sun.com: select id_group, count(id) group by id_group Not to be tiresome, but just to make sure we understand the query: I think you mean id_group1 instead of id_group. Exactly right. It sounds as though you may have created an index on ( id_group1, id ). At first blush, I would expect that index to improve the performance. Did that not happen? That is exactly what I observed. As I told Jan, I've tried it out on PostgreSQL in the meantime because a) I wanted to see how a different RDBMS would behave and b) because derby (it seems) doesn't support the explain command to show the query plan and PostgreSQL does. Some great work has been put into improving Derby's explain capabilities in the next feature release. In the meantime, you can view Derby query plans by using the SYSCS_UTIL.SYSCS_SET_RUNTIMESTATISTICS() system procedure. Please see the Derby Tuning Guide: http://db.apache.org/derby/docs/10.5/tuning/tuning-single.html#ctundepth13055 I've tried the following indexes: (id) This index doesn't contain the id_group1 column, so a probe of the base row would always be needed. A sequential scan of the heap would be faster than a series of probes. (id_group1) Same situation for this index. (id, id_group1) This is a covering index for the query. That is, it carries both of the columns you need. That eliminates the need for probes of the heap. However, the index is not in the order you want (sorted by the grouping column). So an expensive sort would be needed. but postgresql announced a sequential table scan every time and, in fact, seemed to have done exactly that when I executed the query. Have you tried ( id_group1, id ) This index covers your query and is in a useful sort order. If Derby does not use this index on your large data set, then there may be a bug. It would be interesting to see the query plan which Derby follows when you have declared this index. Hope this helps, -Rick Either I'm doing something obviously wrong or am assuming something obviously impossible is possible, but I'm inclined to believe the former, rather than the latter which is why I'm writing. :-) Cheers, Tomislav
Re: performance, memory consumption...and a big hello :)
Hi Tomislav, Some comments inline... Tomi N/A wrote: Hi everyone, first of all, it's great to have a RDBMS like derby around! Now, on to the 2 problems I'm trying to resolve... Situation: 1 table, 15+ million rows, 4 integer values (id, id_group1, id_group2, id_group3), 750MB size on disk, derby in network mode Problem 1: select id_group, count(id) group by id_group Not to be tiresome, but just to make sure we understand the query: I think you mean id_group1 instead of id_group. This takes a couple of minutes, basically regardless of what I tried with indexes. I'd like it to take 10s if possible. Problem 2: It seemed to me that the query triggers a sequential scan (I see a lot of disk activity) and so I created a disk in memory and restored the database to this disk, expecting the query to be close to instantaneous. Better, but still horrible (80 sec). Which brings me to the crux of the 2nd problem: this in-memory exercise was without indexes, so I tried to create some (id_group1 and id for a start). However, the indexes seem to be _huge_ at 300-400MB each and spike at about 700MB before the index is completely created - I was quite surprised to see the indexes ttake more than several dozen MB. So, is there a way to reduce index size? And would any kind of indexes help the type of query I'm interested in? It sounds as though you may have created an index on ( id_group1, id ). At first blush, I would expect that index to improve the performance. Did that not happen? Thanks, -Rick (Machine: Ubuntu Jaunty, 1.7GHz Pentium M, 2GB RAM, 5400 rpm disk) Thanks, Tomislav -- www.PanBI.org: business intelligence everywhere!
Re: performance, memory consumption...and a big hello :)
Hi Tomi, maybe give try to H2 database. For simple usages as yours I found it better. Jan On Fri, Jul 24, 2009 at 10:23 PM, Tomi N/Ahef...@gmail.com wrote: Hi everyone, first of all, it's great to have a RDBMS like derby around! Now, on to the 2 problems I'm trying to resolve... Situation: 1 table, 15+ million rows, 4 integer values (id, id_group1, id_group2, id_group3), 750MB size on disk, derby in network mode Problem 1: select id_group, count(id) group by id_group This takes a couple of minutes, basically regardless of what I tried with indexes. I'd like it to take 10s if possible. Problem 2: It seemed to me that the query triggers a sequential scan (I see a lot of disk activity) and so I created a disk in memory and restored the database to this disk, expecting the query to be close to instantaneous. Better, but still horrible (80 sec). Which brings me to the crux of the 2nd problem: this in-memory exercise was without indexes, so I tried to create some (id_group1 and id for a start). However, the indexes seem to be _huge_ at 300-400MB each and spike at about 700MB before the index is completely created - I was quite surprised to see the indexes ttake more than several dozen MB. So, is there a way to reduce index size? And would any kind of indexes help the type of query I'm interested in? (Machine: Ubuntu Jaunty, 1.7GHz Pentium M, 2GB RAM, 5400 rpm disk) Thanks, Tomislav -- www.PanBI.org: business intelligence everywhere!
performance, memory consumption...and a big hello :)
Hi everyone, first of all, it's great to have a RDBMS like derby around! Now, on to the 2 problems I'm trying to resolve... Situation: 1 table, 15+ million rows, 4 integer values (id, id_group1, id_group2, id_group3), 750MB size on disk, derby in network mode Problem 1: select id_group, count(id) group by id_group This takes a couple of minutes, basically regardless of what I tried with indexes. I'd like it to take 10s if possible. Problem 2: It seemed to me that the query triggers a sequential scan (I see a lot of disk activity) and so I created a disk in memory and restored the database to this disk, expecting the query to be close to instantaneous. Better, but still horrible (80 sec). Which brings me to the crux of the 2nd problem: this in-memory exercise was without indexes, so I tried to create some (id_group1 and id for a start). However, the indexes seem to be _huge_ at 300-400MB each and spike at about 700MB before the index is completely created - I was quite surprised to see the indexes ttake more than several dozen MB. So, is there a way to reduce index size? And would any kind of indexes help the type of query I'm interested in? (Machine: Ubuntu Jaunty, 1.7GHz Pentium M, 2GB RAM, 5400 rpm disk) Thanks, Tomislav -- www.PanBI.org: business intelligence everywhere!
Re: Hello my dear Friend
Michael Segel: Just out of curiosity, is anyone else getting this spam? I got pretty much the exact same 419, yes. He used hotmail when I got one, but apparently switched to yahoo before he sent one to you. =) Does Apache archive these mail groups on their site? Is it set up to stop robot trawlers from walking down these paths? There are gmane archives here: http://news.gmane.org/gmane.comp.apache.db.derby.user And apache mod_mbox archives here: http://mail-archives.eu.apache.org/mod_mbox/db-derby-user The gmane archives seem to hide email addresses pretty well, but the mod_mbox archives only hide (parts of) the email addresses in the web view, the raw messages still contain real unchanged email addresses. -- Anders Morken My opinions may have changed, but not the fact that I am right!
Re: Hello i have some problem with database username and password can any one solve it
umakanth mandela wrote: Hello, I have been using derby and i want to set the password for derby database. it is accepting the password attribute but sencond time it is opening the database even if provide the wrong password Hi, Umakanth, Authentication is off by default, which is why a wrong password works. Turn authentication on by setting this property: derby.connection.requireAuthentication=true If you want to use Derby's built-in authentication, also set this: derby.authentication.provider=BUILTIN Here are some references: http://db.apache.org/derby/docs/dev/devguide/cdevcsecure36127.html http://db.apache.org/derby/docs/dev/devguide/cdevcsecure21547.html regards, -jean
