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• Query to find tables modified in the last hour

  - by oalo

  I want to find out which tables have been modified in the last hour in a MySQL database. How can I do this? I am new to MySQL so please try to explain it as simply as you can. thank you!

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• IP address numbers in MySQL subquery

  - by Iain Collins

  I have a problem with a subquery involving IPV4 addresses stored in MySQL (MySQL 5.0). The IP addresses are stored in two tables, both in network number format - e.g. the format output by MySQL's INET_ATON(). The first table ('events') contains lots of rows with IP addresses associated with them, the second table ('network_providers') contains a list of provider information for given netblocks. events table (~4,000,000 rows): event_id (int) event_name (varchar) ip_address (unsigned 4 byte int) network_providers table (~60,000 rows): ip_start (unsigned 4 byte int) ip_end (unsigned 4 byte int) provider_name (varchar) Simplified for the purposes of the problem I'm having, the goal is to create an export along the lines of: event_id,event_name,ip_address,provider_name If do a query along the lines of either of the following, I get the result I expect: SELECT provider_name FROM network_providers WHERE INET_ATON('192.168.0.1') >= network_providers.ip_start ORDER BY network_providers.ip_start DESC LIMIT 1 SELECT provider_name FROM network_providers WHERE 3232235521 >= network_providers.ip_start ORDER BY network_providers.ip_start DESC LIMIT 1 That is to say, it returns the correct provider_name for whatever IP I look up (of course I'm not really using 192.168.0.1 in my queries). However, when performing this same query as a subquery, in the following manner, it doesn't yield the result I would expect: SELECT event.id, event.event_name, (SELECT provider_name FROM network_providers WHERE event.ip_address >= network_providers.ip_start ORDER BY network_providers.ip_start DESC LIMIT 1) as provider FROM events Instead the a different (incorrect) value for network_provider is returned - over 90% (but curiously not all) values returned in the provider column contain the wrong provider information for that IP. Using event.ip_address in a subquery just to echo out the value confirms it contains the value I'd expect and that the subquery can parse it. Replacing event.ip_address with an actual network number also works, just using it dynamically in the subquery in this manner that doesn't work for me. I suspect the problem is there is something fundamental and important about subqueries in MySQL that I don't get. I've worked with IP addresses like this in MySQL quite a bit before, but haven't previously done lookups for them using a subquery. The question: I'd really appreciate an example of how I could get the output I want, and if someone here knows, some enlightenment as to why what I'm doing doesn't work so I can avoid making this mistake again. Notes: The actual real-world usage I'm trying to do is considerably more complicated (involving joining two or three tables). This is a simplified version, to avoid overly complicating the question. Additionally, I know I'm not using a between on ip_start & ip_end - that's intentional (the DB's can be out of date, and such cases the owner in the DB is almost always in the next specified range and 'best guess' is fine in this context) however I'm grateful for any suggestions for improvement that relate to the question. Efficiency is always nice, but in this case absolutely not essential - any help appreciated.

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• How do I write this insert statement in Django?

  - by alex

  newthing = Link(user=request.user,last_updated=datetime.datetime.now()) However, this uses datetime , not the MYSQL "now()". How can I use mysql's now()?

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• How can I write full search index query which will not consider any stopwords?

  - by Avinash

  I have written a query which will perform Full Text search using full search Index in mysql Table. But my problem is that when user searches with "to go" then it will not search anything because of stopwords in mysql. So my question is, how can I write a Full Search query which will ignore the stopwords?

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• Values of generated column not appearing in table

  - by msh210

  I'm using mysql version 5.1.41-3ubuntu12.10 (Ubuntu). mysql> show create table tt\G *************************** 1. row *************************** Table: tt Create Table: CREATE TABLE `tt` ( `pz` int(8) DEFAULT NULL, `os` varchar(8) DEFAULT NULL, `uz` int(11) NOT NULL, `p` bigint(21) NOT NULL DEFAULT '0', `c` decimal(23,0) DEFAULT NULL, KEY `pz` (`pz`), KEY `uz` (`uz`), KEY `os` (`os`), KEY `pz_2` (`pz`,`uz`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 1 row in set (0.00 sec) mysql> select pz,uz,pz*uz, -> if(pz*uz,1,.5), -> left(pz,2) pl,left(lpad(uz,5,0),2) ul, -> p from tt limit 10; +-------+----+-------+----------------+--------+----+--------+ | pz | uz | pz*uz | if(pz*uz,1,.5) | pl | ul | p | +-------+----+-------+----------------+--------+----+--------+ | NULL | 0 | NULL | 0.5 | NULL | 00 | 4080 | | NULL | 0 | NULL | 0.5 | NULL | 00 | 323754 | | 89101 | 0 | 0 | 0.5 | 89 | 00 | 6880 | | 0 | 0 | 0 | 0.5 | 0 | 00 | 11591 | | 89110 | 0 | 0 | 0.5 | 89 | 00 | 72 | | 78247 | 0 | 0 | 0.5 | 78 | 00 | 27 | | 90062 | 0 | 0 | 0.5 | 90 | 00 | 5 | | 63107 | 0 | 0 | 0.5 | 63 | 00 | 4 | | NULL | 0 | NULL | 0.5 | NULL | 00 | 54561 | | 94102 | 0 | 0 | 0.5 | 94 | 00 | 12499 | +-------+----+-------+----------------+--------+----+--------+ So far so good. As you see, 0.5 appears as a value of if(pz*uz,1,.5). The problem is: mysql> select os, -> if(pz*uz,left(pz,2)<=>left(lpad(uz,5,0),2),.5) uptwo, -> if(pz*uz,left(pz,3)<=>left(lpad(uz,5,0),3),.5) upthree, -> sum(p) p,sum(c) c -> from tt t -> group by os,uptwo,upthree order by null; +----+-------+---------+---------+-------+ | os | uptwo | upthree | p | c | +----+-------+---------+---------+-------+ | u | 1 | 1 | 52852 | 318 | | i | 1 | 1 | 7046563 | 21716 | | m | 1 | 1 | 1252166 | 7337 | | i | 0 | 0 | 1830284 | 4033 | | m | 0 | 0 | 294612 | 1714 | | i | 1 | 0 | 911486 | 3560 | | m | 1 | 0 | 145182 | 1136 | | u | 0 | 0 | 12144 | 23 | | u | 1 | 0 | 1571 | 8 | +----+-------+---------+---------+-------+ Although I group by uptwo, 0.5 doesn't appear in that column. What happened to the 0.5 values? Edit: As noted in the comments to Todd Gibson's answer, I also tried it with if(pz*uz,cast(left(pz,2)<=>left(lpad(uz,5,0),2) as decimal),.5) instead of if(pz*uz,left(pz,2)<=>left(lpad(uz,5,0),2),.5), but it, too, didn't work.

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• Does the order of columns in a query matter?

  - by James Simpson

  When selecting columns from a MySQL table, is performance affected by the order that you select the columns as compared to their order in the table (not considering indexes that may cover the columns)? For example, you have a table with rows uid, name, bday, and you have the following query. SELECT uid, name, bday FROM table Does MySQL see the following query any differently and thus cause any sort of performance hit? SELECT uid, bday, name FROM table

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• Will this SQL screw up

  - by Joshua

  I'm sure everyone knows the joys of concurrency when it comes to threading. Imagine the following scenario on every page-load on a noobily set up MySQL db: UPDATE stats SET visits = (visits+1) If a thousand users load the page at same time, will the count screw up? is this that table locking/row locking crap? Which one mysql use.

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• How can I call python module inside versioned package folder?

  - by Yanhua

  I need write python codes which run inside a host application. The python codes should be deployed under a specific folder of the host application. I must put my entry python module under the root of the specific folder. And I want put all my other python codes and c/c++ dll under a sub folder, I prefer to name the sub folder like XXX-1.0, the number is the version of my python codes. The entry python module is just simple call a python module under the sub-folder. By this way different version python codes can be deployed together without collision. May I know it is possible or not? Thanks.

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• How do I run an interactive command line Python app inside of Emacs on Win32?

  - by sludge

  If I use M-x shell and run the interactive Python interpreter, Emacs on Windows does not return any IO. When I discovered M-x python-shell, I regained hope. However, instead of running the interactive Python shell, I want to run a specific Python script that features an interactive CLI. (See Python's cmd module for details). Is there a way of launching a Python script in Emacs that is interactive? (stdout, stdin, stderr)

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• Replace a whole line in a txt file

  - by user302935

  I'am new to Python 3 and could really use a little help. I have a txt file containing: InstallPrompt= DisplayLicense= FinishMessage= TargetName=D:\somewhere FriendlyName=something I have a python script that in the end, should change just two lines to: TargetName=D:\new FriendlyName=Big Could anyone help me, please? I have tried to search for it, but I didnt find something I could use. The text that should be replaced could have different length.

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• MySQL 5.5 (Percona) assertion failure log.. what would cause this?

  - by Tom Geee

  256GB, 64 Core , AMD running Ubuntu 12.04 with Percona MySQL 5.5.28. Below is the assertion failure. We just had a second assertion failure (different "in file", position, etc) while running a large set of inserts. After the first failure, MySQL restarted after a reboot only - after continuously looping on the same error after trying to recover. I decided to do a mysqlcheck with -o for optimize. Since these are all Innodb tables (very large tables, 60+GB) this would do an alter table on all tables. In the middle of this , the below assertion failure happened again: 121115 22:30:31 InnoDB: Assertion failure in thread 140086589445888 in file btr0pcur.c line 452 InnoDB: Failing assertion: btr_page_get_prev(next_page, mtr) == buf_block_get_page_no(btr_pcur_get_block(cursor)) InnoDB: We intentionally generate a memory trap. InnoDB: Submit a detailed bug report to http://bugs.mysql.com. InnoDB: If you get repeated assertion failures or crashes, even InnoDB: immediately after the mysqld startup, there may be InnoDB: corruption in the InnoDB tablespace. Please refer to InnoDB: http://dev.mysql.com/doc/refman/5.5/en/forcing-innodb-recovery.html InnoDB: about forcing recovery. 03:30:31 UTC - mysqld got signal 6 ; This could be because you hit a bug. It is also possible that this binary or one of the libraries it was linked against is corrupt, improperly built, or misconfigured. This error can also be caused by malfunctioning hardware. We will try our best to scrape up some info that will hopefully help diagnose the problem, but since we have already crashed, something is definitely wrong and this may fail. Please help us make Percona Server better by reporting any bugs at http://bugs.percona.com/ key_buffer_size=536870912 read_buffer_size=131072 max_used_connections=404 max_threads=500 thread_count=90 connection_count=90 It is possible that mysqld could use up to key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 1618416 K bytes of memory Hope that's ok; if not, decrease some variables in the equation. Thread pointer: 0x14edeb710 Attempting backtrace. You can use the following information to find out where mysqld died. If you see no messages after this, something went terribly wrong... stack_bottom = 7f687366ce80 thread_stack 0x30000 /usr/sbin/mysqld(my_print_stacktrace+0x2e)[0x7b52ee] /usr/sbin/mysqld(handle_fatal_signal+0x484)[0x68f024] /lib/x86_64-linux-gnu/libpthread.so.0(+0xfcb0)[0x7f9cbb23fcb0] /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x35)[0x7f9cbaea6425] /lib/x86_64-linux-gnu/libc.so.6(abort+0x17b)[0x7f9cbaea9b8b] /usr/sbin/mysqld[0x858463] /usr/sbin/mysqld[0x804513] /usr/sbin/mysqld[0x808432] /usr/sbin/mysqld[0x7db8bf] /usr/sbin/mysqld(_Z13rr_sequentialP11READ_RECORD+0x1d)[0x755aed] /usr/sbin/mysqld(_Z17mysql_alter_tableP3THDPcS1_P24st_ha_create_informationP10TABLE_LISTP10Alter_infojP8st_orderb+0x216b)[0x60399b] /usr/sbin/mysqld(_Z20mysql_recreate_tableP3THDP10TABLE_LIST+0x166)[0x604bd6] /usr/sbin/mysqld[0x647da1] /usr/sbin/mysqld(_ZN24Optimize_table_statement7executeEP3THD+0xde)[0x64891e] /usr/sbin/mysqld(_Z21mysql_execute_commandP3THD+0x1168)[0x59b558] /usr/sbin/mysqld(_Z11mysql_parseP3THDPcjP12Parser_state+0x30c)[0x5a132c] /usr/sbin/mysqld(_Z16dispatch_command19enum_server_commandP3THDPcj+0x1620)[0x5a2a00] /usr/sbin/mysqld(_Z24do_handle_one_connectionP3THD+0x14f)[0x63ce6f] /usr/sbin/mysqld(handle_one_connection+0x51)[0x63cf31] /lib/x86_64-linux-gnu/libpthread.so.0(+0x7e9a)[0x7f9cbb237e9a] /lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f9cbaf63cbd] Trying to get some variables. Some pointers may be invalid and cause the dump to abort. Query (7f6300004b60): is an invalid pointer Connection ID (thread ID): 876 Status: NOT_KILLED You may download the Percona Server operations manual by visiting http://www.percona.com/software/percona-server/. You may find information in the manual which will help you identify the cause of the crash. 121115 22:31:07 [Note] Plugin 'FEDERATED' is disabled. 121115 22:31:07 InnoDB: The InnoDB memory heap is disabled 121115 22:31:07 InnoDB: Mutexes and rw_locks use GCC atomic builtins .. Then it recovered , without a reboot this time. from the log, what would cause this? I am currently running a dump to see if the problem resurfaces. edit: data partition is all in / since this is a hosted, defaulted file system unfortunately: Filesystem Size Used Avail Use% Mounted on /dev/vda3 742G 445G 260G 64% / udev 121G 4.0K 121G 1% /dev tmpfs 49G 248K 49G 1% /run none 5.0M 0 5.0M 0% /run/lock none 121G 0 121G 0% /run/shm /dev/vda1 99M 54M 40M 58% /boot my.cnf: [client] port = 3306 socket = /var/run/mysqld/mysqld.sock [mysqld_safe] socket = /var/run/mysqld/mysqld.sock nice = 0 [mysqld] skip-name-resolve innodb_file_per_table default_storage_engine=InnoDB user = mysql socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /data/mysql tmpdir = /tmp skip-external-locking key_buffer = 512M max_allowed_packet = 128M thread_stack = 192K thread_cache_size = 64 myisam-recover = BACKUP max_connections = 500 table_cache = 812 table_definition_cache = 812 #query_cache_limit = 4M #query_cache_size = 512M join_buffer_size = 512K innodb_additional_mem_pool_size = 20M innodb_buffer_pool_size = 196G #innodb_file_io_threads = 4 #innodb_thread_concurrency = 12 innodb_flush_log_at_trx_commit = 1 innodb_log_buffer_size = 8M innodb_log_file_size = 1024M innodb_log_files_in_group = 2 innodb_max_dirty_pages_pct = 90 innodb_lock_wait_timeout = 120 log_error = /var/log/mysql/error.log long_query_time = 5 slow_query_log = 1 slow_query_log_file = /var/log/mysql/slowlog.log [mysqldump] quick quote-names max_allowed_packet = 16M [mysql] [isamchk] key_buffer = 16M

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• PYTHON: ntlm authentication

  - by Svetlana

  Hello!! I'm trying to implement NTLM authentication on IIS (Windows Server 2003) from Windows 7 with python. LAN Manager Authentication Level: Send NTLM response only. Client machine and server are in the same domain. Domain controller (AD) is on another server (also running Windows Server 2003). I recieve 401.1 - Unauthorized: Access is denied due to invalid credentials. Could you please help me find out what is wrong with this code and/or show me the other possible directions to solve this problem (using NTLM or Kerberos)? [python] import sys, httplib, base64, string import urllib2 import win32api import sspi import pywintypes import socket class WindoewNtlmMessageGenerator: def __init__(self,user=None): import win32api,sspi if not user: user = win32api.GetUserName() self.sspi_client = sspi.ClientAuth("NTLM",user) def create_auth_req(self): import pywintypes output_buffer = None error_msg = None try: error_msg, output_buffer = self.sspi_client.authorize(None) except pywintypes.error: return None auth_req = output_buffer[0].Buffer auth_req = base64.encodestring(auth_req) auth_req = string.replace(auth_req,'\012','') return auth_req def create_challenge_response(self,challenge): import pywintypes output_buffer = None input_buffer = challenge error_msg = None try: error_msg, output_buffer = self.sspi_client.authorize(input_buffer) except pywintypes.error: return None response_msg = output_buffer[0].Buffer response_msg = base64.encodestring(response_msg) response_msg = string.replace(response_msg,'\012','') return response_msg fname='request.xml' request = file(fname).read() ip_host = '10.0.3.112' ntlm_gen = WindoewNtlmMessageGenerator() auth_req_msg = ntlm_gen.create_auth_req() auth_req_msg_dec = base64.decodestring(auth_req_msg) auth_req_msg = string.replace(auth_req_msg,'\012','') webservice = httplib.HTTPConnection(ip_host) webservice.putrequest("POST", "/idc/idcplg") webservice.putheader("Content-length", "%d" % len(request)) webservice.putheader('Authorization', 'NTLM'+' '+auth_req_msg) webservice.endheaders() resp = webservice.getresponse() resp.read() challenge = resp.msg.get('WWW-Authenticate') challenge_dec = base64.decodestring(challenge.split()[1]) msg3 = ntlm_gen.create_challenge_response(challenge_dec) webservice = httplib.HTTP(ip_host) webservice.putrequest("POST", "/idc/idcplg?IdcService=LOGIN&Auth=Intranet") webservice.putheader("Host", SHOD) webservice.putheader("Content-length", "%d" % len(request)) webservice.putheader('Authorization', 'NTLM'+' '+msg3) webservice.putheader("Content-type", "text/xml; charset=\"UTF-8\"") webservice.putheader("SOAPAction", "\"\"") webservice.endheaders() webservice.send(request) statuscode, statusmessage, header = webservice.getreply() res = webservice.getfile().read() res_file = file('result.txt','wb') res_file.write(res) res_file.close() [/python] sspi.py is available here: http://www.koders.com/python/fidF3B0061A07CD13BA35FF263E3E45252CFABFAA3B.aspx?s=timer Thanks!

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• MySQL Connection Timeout Issue - Grails Application on Tomcat using Hibernate and ORM

  - by gav

  Hi Guys I have a small grails application running on Tomcat in Ubuntu on a VPS. I use MySql as my datastore and everything works fine unless I leave the application for more than half a day (8 hours?). I did some searching and apparently this is the default wait_timeout in mysql.cnf so after 8 hours the connection will die but Tomcat won't know so when the next user tries to view the site they will see the connection failure error. Refreshing the page will fix this but I want to get rid of the error altogether. For my version of MySql (5.0.75) I have only my.cnf and it doesn't contain such a parameter, In any case changing this parameter doesn't solve the problem. This Blog Post seems to be reporting a similar error but I still don't fully understand what I need to configure to get this fixed and also I am hoping that there is a simpler solution than another third party library. The machine I'm running on has 256MB ram and I'm trying to keep the number of programs/services running to a minimum. Is there something I can configure in Grails / Tomcat / MySql to get this to go away? Thanks in advance, Gav From my Catalina.out; 2010-04-29 21:26:25,946 [http-8080-2] ERROR util.JDBCExceptionReporter - The last packet successfully received from the server was 102,906,722 milliseconds$ 2010-04-29 21:26:25,994 [http-8080-2] ERROR errors.GrailsExceptionResolver - Broken pipe java.net.SocketException: Broken pipe at java.net.SocketOutputStream.socketWrite0(Native Method) ... 2010-04-29 21:26:26,016 [http-8080-2] ERROR util.JDBCExceptionReporter - Already closed. 2010-04-29 21:26:26,016 [http-8080-2] ERROR util.JDBCExceptionReporter - Already closed. 2010-04-29 21:26:26,017 [http-8080-2] ERROR servlet.GrailsDispatcherServlet - HandlerInterceptor.afterCompletion threw exception org.hibernate.exception.GenericJDBCException: Cannot release connection at java.lang.Thread.run(Thread.java:619) Caused by: java.sql.SQLException: Already closed. at org.apache.commons.dbcp.PoolableConnection.close(PoolableConnection.java:84) at org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper.close(PoolingDataSource.java:181) ... 1 more

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• Memory allocation error from MySql ODBC 5.1 driver in C# application on insert statement

  - by Chinjoo

  I have a .NET Wndows application in C#. It's a simple Windows application that is using the MySql 5.1 database community edition. I've downloaded the MySql ODBC driver and have created a dsn to my database on my local machine. On my application, I can perform get type queries without problems, but when I execute a given insert statement (not that I've tried doing any others), I get the following error: {"ERROR [HY001] [MySQL][ODBC 5.1 Driver][mysqld-5.0.27-community-nt]Memory allocation error"} I'm running on a Windows XP machine. My machine has 1 GB of memory. Anyone have any ideas? See code below OdbcConnection MyConn = DBConnection.getDBConnection(); int result = -1; try { MyConn.Open(); OdbcCommand myCmd = new OdbcCommand(); myCmd.Connection = MyConn; myCmd.CommandType = CommandType.Text; OdbcParameter userName = new OdbcParameter("@UserName", u.UserName); OdbcParameter password = new OdbcParameter("@Password", u.Password); OdbcParameter firstName = new OdbcParameter("@FirstName", u.FirstName); OdbcParameter LastName = new OdbcParameter("@LastName", u.LastName); OdbcParameter sex = new OdbcParameter("@sex", u.Sex); myCmd.Parameters.Add(userName); myCmd.Parameters.Add(password); myCmd.Parameters.Add(firstName); myCmd.Parameters.Add(LastName); myCmd.Parameters.Add(sex); myCmd.CommandText = mySqlQueries.insertChatUser; result = myCmd.ExecuteNonQuery(); } catch (Exception e) { //{"ERROR [HY001] [MySQL][ODBC 5.1 Driver][mysqld-5.0.27-community-nt]Memory // allocation error"} EXCEPTION ALWAYS THROWN HERE } finally { try { if (MyConn != null) MyConn.Close(); } finally { } }

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• How to implement Priority Queues in Python?

  - by dragosrsupercool

  Sorry for such a silly question but Python docs are confusing.. . Link 1: Queue Implementation http://docs.python.org/library/queue.html It says thats Queue has a contruct for priority queue. But I could not find how to implement it. class Queue.PriorityQueue(maxsize=0) Link 2: Heap Implementation http://docs.python.org/library/heapq.html Here they says that we can implement priority queues indirectly using heapq pq = [] # list of entries arranged in a heap entry_finder = {} # mapping of tasks to entries REMOVED = '<removed-task>' # placeholder for a removed task counter = itertools.count() # unique sequence count def add_task(task, priority=0): 'Add a new task or update the priority of an existing task' if task in entry_finder: remove_task(task) count = next(counter) entry = [priority, count, task] entry_finder[task] = entry heappush(pq, entry) def remove_task(task): 'Mark an existing task as REMOVED. Raise KeyError if not found.' entry = entry_finder.pop(task) entry[-1] = REMOVED def pop_task(): 'Remove and return the lowest priority task. Raise KeyError if empty.' while pq: priority, count, task = heappop(pq) if task is not REMOVED: del entry_finder[task] return task raise KeyError('pop from an empty priority queue' Which is the most efficient priority queue implementation in python? And how to implement it?

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• Python coding test problem for interviews

  - by Kal

  I'm trying to come up with a good coding problem to ask interview candidates to solve with Python. They'll have an hour to work on the problem, with an IDE and access to documentation (we don't care what people have memorized). I'm not looking for a tough algorithmic problem - there are other sections of the interview where we do that kind of thing. The point of this section is to sit and watch them actually write code. So it should be something that makes them use just the data structures which are the everyday tools of the application developer - lists, hashtables (dictionaries in Python), etc, to solve a quasi-realistic task. They shouldn't be blocked completely if they can't think of something really clever. We have a problem which we use for Java coding tests, which involves reading a file and doing a little processing on the contents. It works well with candidates who are familiar with Java (or even C++). But we're running into a number of candidates who just don't know Java or C++ or C# or anything like that, but do know Python or Ruby. Which shouldn't exclude them, but leaves us with a dilemma: On the one hand, we don't learn much from watching someone struggle with the basics of a totally unfamiliar language. On the other hand, the problem we use for Java turns out to be pretty trivial in Python (or Ruby, etc) - anyone halfway competent can do it in 15 minutes. So, I'm trying to come up with something better. Surprisingly, Google doesn't show me anyone doing something like this, unless I'm just too dumb to enter the obvious search term. The best idea I've come up with involves scheduling workers to time slots, but it's maybe a little too open-ended. Have you run into a good example? Or a bad one? Or do you just have an idea?

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• Fitting Gaussian KDE in numpy/scipy in Python

  - by user248237

  I am fitting a Gaussian kernel density estimator to a variable that is the difference of two vectors, called "diff", as follows: gaussian_kde_covfact(diff, smoothing_param) -- where gaussian_kde_covfact is defined as: class gaussian_kde_covfact(stats.gaussian_kde): def __init__(self, dataset, covfact = 'scotts'): self.covfact = covfact scipy.stats.gaussian_kde.__init__(self, dataset) def _compute_covariance_(self): '''not used''' self.inv_cov = np.linalg.inv(self.covariance) self._norm_factor = sqrt(np.linalg.det(2*np.pi*self.covariance)) * self.n def covariance_factor(self): if self.covfact in ['sc', 'scotts']: return self.scotts_factor() if self.covfact in ['si', 'silverman']: return self.silverman_factor() elif self.covfact: return float(self.covfact) else: raise ValueError, \ 'covariance factor has to be scotts, silverman or a number' def reset_covfact(self, covfact): self.covfact = covfact self.covariance_factor() self._compute_covariance() This works, but there is an edge case where the diff is a vector of all 0s. In that case, I get the error: File "/srv/pkg/python/python-packages/python26/scipy/scipy-0.7.1/lib/python2.6/site-packages/scipy/stats/kde.py", line 334, in _compute_covariance self.inv_cov = linalg.inv(self.covariance) File "/srv/pkg/python/python-packages/python26/scipy/scipy-0.7.1/lib/python2.6/site-packages/scipy/linalg/basic.py", line 382, in inv if info>0: raise LinAlgError, "singular matrix" numpy.linalg.linalg.LinAlgError: singular matrix What's a way to get around this? In this case, I'd like it to return a density that's essentially peaked completely at a difference of 0, with no mass everywhere else. thanks.

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• oRecordset in ASP.NET mySQL problem

  - by StealthRT

  I have this mySQL code that connects to my server. It connects just fine: Dim MyConString As String = "DRIVER={MySQL ODBC 3.51 Driver};" & _ "SERVER=xxx.com;" & _ "DATABASE=xxx;" & _ "UID=xxx;" & _ "PASSWORD=xxx;" & _ "OPTION=3;" Dim conn As OdbcConnection = New OdbcConnection(MyConString) conn.Open() Dim MyCommand As New OdbcCommand MyCommand.Connection = conn MyCommand.CommandText = "select * from userinfo WHERE emailAddress = '" & theUN & "'"" MyCommand.ExecuteNonQuery() conn.Close() However, i have an old Classic ASP page that uses "oRecordset" to get the data from the mySQL server: Set oConnection = Server.CreateObject("ADODB.Connection") Set oRecordset = Server.CreateObject("ADODB.Recordset") oConnection.Open "DRIVER={MySQL ODBC 3.51 Driver}; SERVER=xxx.com; PORT=3306; DATABASE=xxx; USER=xxx; PASSWORD=xxx; OPTION=3;" sqltemp = "select * from userinfo WHERE emailAddress = '" & theUN & "'" oRecordset.Open sqltemp, oConnection,3,3 And i can use oRecordset as follows: if oRecordset.EOF then.... or strValue = oRecordset("Table_Name").value or oRecordset("Table_Name").value = "New Value" oRecordset.update etc... However, for the life of me, i can not find any .net code that is simular to that of my Classic ASP page!!!!! Any help would be great! :o) David

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• C# Entity FrameWork MySQL Slow Queries Count()

  - by Matthew M.

  Hello, I'm having a serious issue with MySQL and Entity Framework 4.0. I have dropped a Table onto the EF Designer surface, and everything seems OK. However, when I perform a query in the following fashion: using(entityContext dc = new entityContext()) { int numRows = dc.myTable.Count(); } The query that is generated looks something like this: SELECT `GroupBy1`.`A1` AS `C1` FROM (SELECT Count(1) AS `A1` FROM (SELECT `pricing table`.`a`, `pricing table`.`b`, `pricing table`.`c`, `pricing table`.`d`, `pricing table`.`e`, `pricing table`.`f`, `pricing table`.`g`, `pricing table`.`h`, `pricing table`.`i` FROM `pricing table` AS `pricing table`) AS `Extent1`) AS `GroupBy1` As should be evident, this is an excruciatingly unoptimized query. It is selecting every single row! This is not optimal, nor is it even possible for me to use MySQL + EF at this point. I have tried both the MySQL 6.3.1 [that was fun to install] and DevArt's dotConnect for MySQL and both produce the same results. This table has 1.5 million records.. and takes 6-11s to execute! What am I doing wrong ? Is there any way to optimize this [and other queries] to produce sane code like: SELECT COUNT(*) FROM table ? Generating the same query using SQLServer takes virtually no time and produces sane code. Help! Thanks! Matthew

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• Asynchronous background processes in Python?

  - by Geuis

  I have been using this as a reference, but not able to accomplish exactly what I need: http://stackoverflow.com/questions/89228/how-to-call-external-command-in-python/92395#92395 I also was reading this: http://www.python.org/dev/peps/pep-3145/ For our project, we have 5 svn checkouts that need to update before we can deploy our application. In my dev environment, where speedy deployments are a bit more important for productivity than a production deployment, I have been working on speeding up the process. I have a bash script that has been working decently but has some limitations. I fire up multiple 'svn updates' with the following bash command: (svn update /repo1) & (svn update /repo2) & (svn update /repo3) & These all run in parallel and it works pretty well. I also use this pattern in the rest of the build script for firing off each ant build, then moving the wars to Tomcat. However, I have no control over stopping deployment if one of the updates or a build fails. I'm re-writing my bash script with Python so I have more control over branches and the deployment process. I am using subprocess.call() to fire off the 'svn update /repo' commands, but each one is acting sequentially. I try '(svn update /repo) &' and those all fire off, but the result code returns immediately. So I have no way to determine if a particular command fails or not in the asynchronous mode. import subprocess subprocess.call( 'svn update /repo1', shell=True ) subprocess.call( 'svn update /repo2', shell=True ) subprocess.call( 'svn update /repo3', shell=True ) I'd love to find a way to have Python fire off each Unix command, and if any of the calls fails at any time the entire script stops.

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• Python: How to execute a SQL file or command

  - by Mestika

  Hi, I have this Python script: import sys import getopt import timeit import random import os import re import ibm_db import time from string import maketrans runs=5 queries=50 file = open("results.txt", "a") for r in range(5): print "Run %s\n" % r os.system("python reads.py -r1 -pquery1.sql -q50 -sespec") file.write('END QUERY READ 01') file.close() os.system("python query_read_02.py") Everything here is working, it is creating the results.txt file, it run the os.system("python reads.py...") file and that file is doing everything it's suppose to, but the problem comes when go and run the query_read_02.py file. In this file, it should execute a SQL command or a SQL file on my database, so I can create an index and see what the performance of that input is, but how do i do it? I create the connection to the database in the reads.py file, but it's hard to create the queries in there because I doesn't keep track of which file it has reached, it just execute commands from what the parameters are. I hope I've explained myself clear enough, otherwise please let me know. I just want to execute a SQL command or file which each query_read_0x.py file. Sincerely Mestika

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• Activate a python virtual environment using activate_this.py in a fabfile on Windows

  - by Rudy Lattae

  I have a Fabric task that needs to access the settings of my Django project. On Windows, I'm unable to install Fabric into the project's virtualenv (issues with Paramiko + pycrypto deps). However, I am able to install Fabric in my system-wide site-packages, no problem. I have installed Django into the project's virtualenv and I am able to use all the " python manage.py" commands easily when I activate the virtualenv with the "VIRTUALENV\Scripts\activate.bat" script. I have a fabric tasks file (fabfile.py) in my project that provides tasks for setup, test, deploy, etc. Some of the tasks in my fabfile need to access the settings of my django project through "from django.conf import settings". Since the only usable Fabric install I have is in my system-wide site-packages, I need to activate the virtualenv within my fabfile so django becomes available. To do this, I use the "activate_this" module of the project's virtualenv in order to have access to the project settings and such. Using "print sys.path" before and after I execute activate_this.py, I can tell the python path changes to point to the virtualenv for the project. However, I still cannot import django.conf.settings. I have been able to successfully do this on *nix (Ubuntu and CentOS) and in Cygwin. Do you use this setup/workflow on Windows? If so Can you help me figure out why this wont work on Windows or provide any tips and tricks to get around this issue? Thanks and Cheers. REF: http://virtualenv.openplans.org/#id9 | Using Virtualenv without bin/python Local development environment: Python 2.5.4 Virtualenv 1.4.6 Fabric 0.9.0 Pip 0.6.1 Django 1.1.1 Windows XP (SP3)

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• Error Log states that I have MySQL connect error, yet script runs fine

  - by rob - not a robber

  Hello All, First, thanks for all the help I've received so far from StackOverflow. I've learned much. Once again, I'm posing a rudimentary question that I've searched on, but cannot find the exact answer to. Here or on PHP.net. It's sort of like what this guy asked, but not exactly: http://stackoverflow.com/questions/288603/mysql-throwing-query-error-yet-finishing-query-just-fine-why So, I saw my errorlog ballooning up when I checked my site directory and opened to notice that a bunch of errors have been recorded since I wrote this new Admin area. I know something is obviously awry with my scripting for the error to be thrown, but the weird thing is, the script actually runs through and pulls all the data I need without breaking. The log contains: PHP Warning: mysql_query() [function.mysql-query]: Access denied for user 'someuser'@'localhost' (using password: NO) in /home/mysite/adminconsole.php on line 15 I don't get that because that very line is where I setup my connection... the exact same way I do it everywhere else on the site with no problem. After that error, I have these thrown at the same time [09-Apr-2010 08:44:18] PHP Warning: mysql_query() [function.mysql-query]: A link to the server could not be established in /home/mysite/adminconsole.php on line 15 [09-Apr-2010 08:44:18] PHP Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /home/mysite/adminconsole.php on line 16 From what I read in the other guys thread, the problem is the contents of the query maybe? Maybe my query is malformed? Thanks so much for any guidance you can provide. -Rob

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• mysql-python stopped working

  - by MAC

  This is a rather dumb question but i'am looking at a bizarre situation. I am running fedora and have python 2.6.5 installed. The other day i installed MySQL-python using yum (because i do not have the setuptools module so i cannot build it from source). Anyway yesterday i wrote my entire data access layer in python and it was running fine, i did test it. Today however it gives me an ImportError: No module named MySQLdb The only thing i ever changed was i installed eclipse and pyDev. Any ideas on what went wrong and how i fix it. I tried removing and re-installing MySql-python but that did not help. I did the following import sys print sys.path And it shows me all the paths which are basically pertaining to /usr/local/lib/python2.6 However i was trying to find where the MySQLdb module is installed and it seems that its installed in /usr/lib/python2.5/sitepackages Now i have no idea why it got installed there and why it was working earlier and why it stopped working now. Any ideas on how i should fix it. I did try copying the site-packages folder over to the python2.6 folder but that did not work Help!!

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• How to group data changes by operation with MySQL triggers

  - by Jan-Henk

  I am using triggers in MySQL to log changes to the data. These changes are recorded on a row level. I can now insert an entry in my log table for each row that is changed. However, I also need to record the operation to which the changes belong. For example, a delete operation like "DELETE * FROM table WHERE type=x" can delete multiple rows. With the trigger I can insert an entry for each deleted row into the log table, but I would like to also provide a unique identifier for the operation as a whole, so that the log table looks something like: log_id operation_id tablename fieldname oldvalue newvalue 1 1 table id 1 null 2 1 table type a null 3 1 table id 2 null 4 1 table type a null 5 2 table id 3 null 6 2 table type b null 7 2 table id 4 null 8 2 table type b null Is there a way in MySQL to identify the higher level operation to which the row changes belong? Or is this only possible by means of application level code? In the future it would also be nice to be able to record the transaction to which an operation belongs. Another question is if it is possible to capture the actual SQL query, besides using the query log. I don't think so myself, but maybe I am missing something. It is of course possible to capture these at the application level, but the goal is to keep intrusions to the application level code as minimal as possible. When this is not possible with MySQL, how is this with other database systems? For the current project it is not an option to use something other than MySQL, but it would be nice to know for future projects.

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