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• Optimizing MySQL statement with lot of count(row) an sum(row+row2)...

  - by Zombies

  I need to use InnoDB storage engine on a table with about 1mil or so records in it at any given time. It has records being inserted to it at a very fast rate, which are then dropped within a few days, maybe a week. The ping table has about a million rows, whereas the website table only about 10,000. My statement is this: select url from website ws, ping pi where ws.idproxy = pi.idproxy and pi.entrytime > curdate() - 3 and contentping+tcpping is not null group by url having sum(contentping+tcpping)/(count(*)-count(errortype)) < 500 and count(*) > 3 and count(errortype)/count(*) < .15 order by sum(contentping+tcpping)/(count(*)-count(errortype)) asc; I added an index on entrytime, yet no dice. Can anyone throw me a bone as to what I should consider to look into for basic optimization of this query. The result set is only like 200 rows, so I'm not getting killed there.

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• strange results with /fp:fast

  - by martinus

  We have some code that looks like this: inline int calc_something(double x) { if (x > 0.0) { // do something return 1; } else { // do something else return 0; } } Unfortunately, when using the flag /fp:fast, we get calc_something(0)==1 so we are clearly taking the wrong code path. This only happens when we use the method at multiple points in our code with different parameters, so I think there is some fishy optimization going on here from the compiler (Microsoft Visual Studio 2008, SP1). Also, the above problem goes away when we change the interface to inline int calc_something(const double& x) { But I have no idea why this fixes the strange behaviour. Can anyone explane this behaviour? If I cannot understand what's going on we will have to remove the /fp:fastswitch, but this would make our application quite a bit slower.

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• Django: Set foreign key using integer?

  - by User

  Is there a way to set foreign key relationship using the integer id of a model? This would be for optimization purposes. For example, suppose I have an Employee model: class Employee(models.Model): first_name = models.CharField(max_length=100) last_name = models.CharField(max_length=100) type = models.ForeignKey('EmployeeType') and EmployeeType(models.Model): type = models.CharField(max_length=100) I want the flexibility of having unlimited employee types, but in the deployed application there will likely be only a single type so I'm wondering if there is a way to hardcode the id and set the relationship this way. This way I can avoid a db call to get the EmployeeType object first.

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• Should I make my MutexLock volatile?

  - by sje397

  I have some code in a function that goes something like this: void foo() { { // scope the locker MutexLocker locker(&mutex); // do some stuff.. } bar(); } The function call bar() also locks the mutex. I am having an issue whereby the program crashes (for someone else, who has not as yet provided a stack trace or more details) unless the mutex lock inside bar is disabled. Is it possible that some optimization is messing around with the way I have scoped the locker instance, and if so, would making it volatile fix it? Is that a bad idea? Thanks.

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• Anything wrong with this MySQL quert? takes 10 seconds+ to load

  - by user345426

  I have a search that is taking 10 seconds+ to execute! Keep in mind it is also searching over 200,000 products in the database. I posted the explain and MySQL query here. 1 SIMPLE p ref PRIMARY,products_status,prod_prodid_status,product... products_status 1 const 9048 Using where; Using temporary; Using filesort 1 SIMPLE v ref PRIMARY,vendors_id,vendors_vendorid vendors_vendorid 4 rhinomar_rhinomartnew.p.vendors_id 1 1 SIMPLE s ref products_id products_id 4 rhinomar_rhinomartnew.p.products_id 1 1 SIMPLE pd ref PRIMARY,products,prod_desc_prodid_prodname prod_desc_prodid_prodname 4 rhinomar_rhinomartnew.p.products_id 1 1 SIMPLE p2c ref PRIMARY,ptc_catidx PRIMARY 4 rhinomar_rhinomartnew.p.products_id 1 Using where; Using index 1 SIMPLE c eq_ref PRIMARY PRIMARY 4 rhinomar_rhinomartnew.p2c.categories_id 1 Using where MySQL Query: select p.products_id, p.products_image, p.products_price, p.products_weight, p.products_unit_quantity, s.specials_new_products_price, s.status, pd.products_name, pd.products_img_alt from products p left join vendors v ON v.vendors_id = p.vendors_id left join specials s on s.products_id = p.products_id left join products_description pd on pd.products_id = p.products_id left join products_to_categories p2c on p2c.products_id = p.products_id left join categories c on c.categories_id = p2c.categories_id where ( ( pd.products_name like '%apparel%' ) or p2c.categories_id IN (773, 132, 135, 136, 119, 122, 124, 125, 126, 1749, 1753, 1747, 123, 127, 130, 131, 178, 137, 140, 164, 165, 166, 167, 168, 169, 832, 2045 ) or p.products_id = 'apparel' or p.products_model = 'apparel' or CONCAT(v.vendors_prefix, '-') = 'apparel' or CONCAT( v.vendors_prefix, '-', p.products_id ) = 'apparel' ) and p.products_status = '1' and c.categories_status = '1' group by p.products_id order by pd.products_name

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• PHP speed optimisation.

  - by Petah

  Hi, Im wondering about speed optimization in PHP. I have a series of files that are requested every page load. On average there are 20 files. Each file must be read an parsed if they have changed. And this is excluding that standard files required for a web page (HTML, CSS, images, etc). EG - client requests page - server outputs html, css, images - server outputs dynamic content (20+/- files combined and minified). What would be the best way to serve these files as fast as possible?

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• How to check for C++ copy ellision

  - by Steve

  I ran across this article on copy ellision in C++ and I've seen comments about it in the boost library. This is appealing, as I prefer my functions to look like verylargereturntype DoSomething(...) rather than void DoSomething(..., verylargereturntype& retval) So, I have two questions about this Google has virtually no documentation on this at all, how real is this? How can I check that this optimization is actually occuring? I assume it involves looking at the assembly, but lets just say that isn't my strong suit. If anyone can give a very basic example as to what successful ellision looks like, that would be very useful I won't be using copy ellision just to prettify things, but if I can be guaranteed that it works, it sounds pretty useful.

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• MySQL Datefields: duplicate or calculate?

  - by Konerak

  We are using a table with a structure imposed upon us more than 10 years ago. We are allowed to add columns, but urged not to change existing columns. Certain columns are meant to represent dates, but are put in different format. Amongst others: * CHAR(6): YYMMDD * CHAR(6): DDMMYY * CHAR(8): YYYYMMDD * CHAR(8): DDMMYYYY * DATE * DATETIME Since we now would like to do some more complex queries, using advanced date functions, my manager proposed to d*uplicate those problem columns* to a proper FORMATTED_OLDCOLUMNNAME column using a DATE or DATETIME format. Is this the way to go? Couldn't we just use the STR_TO_DATE function each time we accessed the columns? To avoid every query having to copy-paste the function, I could still work with a view or a stored procedure, but duplicating data to avoid recalculation sounds wrong. Solutions I see (I guess I prefer 2.2.1) 1. Physically duplicate columns 1.1 In the same table 1.1.1 Added by each script that does a modification (INSERT/UPDATE/REPLACE/...) 1.1.2 Maintained by a trigger on each modification 1.2 In a separate table 1.2.1 Added by each script that does a modification (INSERT/UPDATE/REPLACE/...) 1.2.2 Maintained by a trigger on each modification 2. On-demand transformation 2.1 Each query has to perform the transformation 2.1.1 Using copy-paste in the source code 2.1.2 Using a library 2.1.3 Using a STORED PROCEDURE 2.2 A view performs the transformation 2.2.1 A separate table replacing the entire table 2.2.2 A separate table just adding the date-fields for the primary keys Am I right to say it's better to recalculate than to store? And would a view be a good solution?

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• In Python, is there a way to call a method on every item of an iterable? [closed]

  - by Thane Brimhall

  Possible Duplicate: Is there a map without result in python? I often come to a situation in my programs when I want to quickly/efficiently call an in-place method on each of the items contained by an iterable. (Quickly meaning the overhead of a for loop is unacceptable). A good example would be a list of sprites when I want to call draw() on each of the Sprite objects. I know I can do something like this: [sprite.draw() for sprite in sprite_list] But I feel like the list comprehension is misused since I'm not using the returned list. The same goes for the map function. Stone me for premature optimization, but I also don't want the overhead of the return value. What I want to know is if there's a method in Python that lets me do what I just explained, perhaps like the hypothetical function I suggest below: do_all(sprite_list, draw)

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• SQL: Optimize insensive SELECTs on DateTime fields

  - by Fedyashev Nikita

  I have an application for scheduling certain events. And all these events must be reviewed after each scheduled time. So basically we have 3 tables: items(id, name) scheduled_items(id, item_id, execute_at - datetime) - item_id column has an index option. reviewed_items(id, item_id, created_at - datetime) - item_id column has an index option. So core function of the application is "give me any items(which are not yet reviewed) for the actual moment". How can I optimize this solution for speed(because it is very core business feature and not micro optimization)? I suppose that adding index to the datetime fields doesn't make any sense because the cardinality or uniqueness on that fields are very high and index won't give any(?) speed-up. Is it correct? What would you recommend? Should I try no-SQL? -- mysql -V 5.075 I use caching where it makes sence.

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• Searching phpbb's 'topic_title' via MYSQL php, but exact match doesn't work

  - by Mint

  $sql = sprintf("SELECT topic_title FROM `phpbb_topics` WHERE `topic_title` LIKE '%%%s%%' LIMIT 20", mysql_real_escape_string('match this title')); Which I run this query in phpMyAdmin the results are: (correct) match this title match this title 002 But when I run that same MYSQL query in PHP I get: (incorrect) match this title 002 I have also tried MATCH AGAINST with the same result with both php and phpMyAdmin: $sql = "SELECT topic_title FROM phpbb_topics WHERE MATCH (topic_title) AGAINST('match this title' IN BOOLEAN MODE)"; Whats going on? I'v been searching all over the place and have found next to no help :(

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• Coldfusion Report Builder - How can you set different datasources externally between prod/staging/de

  - by Smooth Operator

  Coldfusion Report Builder is great. One small issue. We use ANT+CFANT to deploy. When we create the report, say in a datasource called MyApp_dev on a dev box. Everything works great when the report is created. We deploy the report to our staging server, which has a datasource of MyApp_Staging. That server also, may or may not, have the live app working under MyApp_Live. Ant pushes the update to Staging just great. Run the report, crashes and burns. Why? It seems the report is looking for the MyApp_Dev data_source, even though the application is using the MyApp_Staging datasource. In digging around I found a few approaches, I would like to do this one, final, ideal way from the beginning instead of having to go back to do dozens of reports differently when I have a new Aha! moment. 1) Obvious: Pass in the datasource in to the cfreport tag. Doesn't work for ColdFusion Builder Reports as of v8, or v9 as tested on Linux. 2) Most realistic option (but painful) so far: Pass in the query as an object into the ColdFusion Builder report. Let's think about this: Create the Report with the report builder to my heart's content using the RDS, etc on my local box. When I'm done, copy the query into a snippet of code, or into a database column to be dynamically be injected at runtime with correct datasource. Modify my "run report" event to find the query from the database column, insert it into another dynamic cfquery and potentially... evaluate (!?!) it? Fun side is I can set the cfquery datasource to what I would need for each environment. When I modify the report's columns in CF Report Builder, I always have to update the query in the database. Is there a snippet of code that can extract this for me? Hmm. 3) Less than ideal. Suck it up and let all the reports in staging run off the live server. Maybe copy the live data into staging (sans structural changes) to let it seem similar. Are there any eloquent ways to accomplish the above? Thanks in Advance!

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• 'And' operator in Linq

  - by Ani

  I have a query that prints userid in label1 when username is entered.Works fine; but i want to write query for username and password that prints userid. so how can i write it? i tried writing using 'and' operator but dont seems to work. int id = (from auser in lq.logins where auser.username == userNameString //&& auser.Password =pwdString select auser.userid).SingleOrDefault(); label1.Text = id.ToString(); Thanks Ani

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• MySQL search Chinese characters

  - by Jasie

  Hello, Let's say I have a row: ??????? Someone enters as a query: ?? Should I break up the characters in the query, and individually perform a LIKE % % match on each character against the row, or is there any easier way to get a row that contains one of the two characters? FULLTEXT won't work with CJK characters. Thanks!

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• ORA-30036: unable to extend segment by 8 in undo tablespace 'UNDO'

  - by Nitin Gurram

  I am trying to update the table which has millions of records. However my update query will update around 2-3 millions of records. I am facing below error on executing the update query. I googled and found that I need to update the Table Space as DBA But is there any work around for executing the update without actually extending the UNDO table space or something dba is not required UPDATESERVICE SET CREATION_TIME = LAST_UPDATE_TIME WHERE CREATION_TIME is null

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• Determine if an Index has been used as a hint

  - by Joe Bloggs

  In SQL Server, there is the option to use query hints. eg SELECT c.ContactID FROM Person.Contact c WITH (INDEX(AK_Contact_rowguid)) I am in the process of getting rid of unused indexes and was wondering how I could go about determining if an index was used as a query hint. Does anyone have suggestions on how I could do this? Cheers, Joe

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• Active User Tracking, PHP Sessions

  - by Nik

  Alright, I'm trying to work on a function for active user counting in an AJAX based application. I want to express the below SQL Query in correct syntax but I'm not sure how to write it. The desired SQL Query is below: SELECT count(*) FROM active WHERE timestamp > time() - 1800 AND nick=(a string that doesn't contain [AFK]) Now, I do understand that time() - 1800 can be assigned to a variable, but how is timestamp > variable and nick that doesn't contain a string written in SQL?

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• Need help with this SQL

  - by Bragaadeesh

  Hi guys, I am very very new to mysql. I am trying to execute the following query. update share set holder = 22 where SHARE_ID IN (select SHARE_ID from SHARE WHERE holder=1 LIMIT 10) When I try to execute the above query I am getting this error #1235 - This version of MySQL doesn't yet support 'LIMIT & IN/ALL/ANY/SOME subquery'

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• What is the Dojo equivalent of jQuery's scope attribute?

  - by joolss

  Hi. I'm a Dojo n00b. In jQuery, a DOM node or jQuery object can be passed as an attribute in a query, which sets the scope: var myScope = $('#someDiv'); $('a',myScope).addClass('red'); $('li',myScope).css('display','inline'); Now, in Dojo I can chain several .query()s after each other, but what should I do if I have a certain DOM node - not a nodeList - that I want to use as a scope? KTHNX

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• MySQL - Using an alias in a subquery with WHERE clause

  - by gaoshan88

  I have a feeling I am completely borking this MySQL query but I'll ask anyway. I am wondering why I get the warning Unknown column 'FOO', and how I can get this query to work properly, in 'where clause' when I run the following: SELECT sample_id as FOO FROM tbl_test WHERE sample_id = 521 AND sample_id IN ( Select sample_id FROM tbl_test WHERE sample_id = FOO GROUP BY sample_id )

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• CQRS - Should a Command try to create a "complex" master-detail entity?

  - by Simon Crabtree

  I've been reading Greg Young and Udi Dahan's thoughts on Command Query Responsibilty Separation and a lot of what I read strikes a chord with me. My domain (we track vehicles which are doing deliveries) has the concept of a Route which contains one or more Stops. I need my customers to be able to set these up in our system by calling a webservice, and then be able to retrieve information about a Route and how the vehicle is progressing. In the past I would have "cut-down" DTO classes which closely resemble my domain classes, and the customer would create a RouteDto with an array of StopDto(s), and call our CreateRoute webmethod, passing in the RouteDto. When they query our system by calling the GetRouteDetails method, I would return exactly the same objects to them. One of the appealing aspects of CQRS is that the RouteDto might have all manner of properties that the customer wants to query, but have no business setting when they create a Route. So I create a separate CreateRouteRequest class which is passed in when calling the CreateRoute "command", and a Route DTO class which gets returned as a query result. class Route{ string Reference; List<Stop> Stops; } But I need my customer to provide me with Route AND Stop details when they create a route. As I see it I could either... Give my CreateRouteRequest class a Stops(s) property which is an array of "something" representing the data they need to provide about each stop - but what do I call this class? It's not a Stop as that's what I'm calling the list of DTO inside my Route DTO, but I don't like "CreateStopRequest". I also wonder if I'm stuck in a CRUD mindset here thinking in terms of master-detail information and asking the customer to think like that too. class CreateRouteRequest{ string Reference; ... List<CreateStopRequest> Stops; } or They call CreateRoute, and then make a number of calls to an AddStopToRoute method. This feels a bit more "behavioural" but I'm going to lose the ability to treat creating a route including its stops as a single atomic command. If they create a Route and then try to add a Stop which fails due to some validation problem they're going to have a partially correct Route. The fact that I can't come up with a good name for the list of "StopCreationData" objects I'd be working with in option 1, makes me wonder if there's something I'm missing.

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• sql to compare two strings in MS access

  - by tksy

  I am trying to compare a series of strings like the following rodeo rodas carrot crate GLX GLX 1.1 GLX glxs the comparision need not be case sensitive i am trying to write a sql where i am updating the first string with the second string if they match approximately. Here except the second string all the other examples match. I would like to write a query which updates the strings except the second one. is this possible directly in a query in ACCESS thanks

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• ColdFusion's cfquery failing silently

  - by johnthexiii

  I have a query that retrieves a large amount of data. <cfsetting requesttimeout="9999999" > <cfquery name="randomething" datasource="ds" timeout="9999999" > SELECT col1, col2 FROM table </cfquery> <cfdump var="#randomething.recordCount#" /> <!---should be about 5 million rows ---> I can successfully retrieve the data with python's cx_Oracle and using sys.getsizeof on the python list returns 22621060, so about 21 megabytes. ColdFusion does not return an error on the page, and I can't find anything in any of the logs. Why is cfdump not showing the number of rows? Additional Information The reason for doing it this way is because I have about 8000 smaller queries to run against the randomthing query. In other words when I run those 8000 queries against the database it takes hours for that process to complete. I suspect this is because I am competing with several other database users, and the database is getting bogged down. The 8000 smaller queries are getting counts of col1 over a period of col2. SELECT count(col1) as count WHERE col2 < 20121109 AND col2 > 20121108 According to Adam Cameron's suggestions. cflog is suggesting that the query isn't finishing. I tried changing the queries timeout both in the code and in the CFIDE/administrator, apparently CF9 no long respects the timeout attribute, regardless of what I tried I couldn't get the query to timeout. I also started playing around with the maxrows attribute to see if I could discern any information that way. when maxrows is set to 1300000 everything works fine when maxrows is 1400000 or greater I get this error when maxrows is 2000000 I observe my original problem Update So this isn't a limit of cfquery. By using QueryNew then looping over it to add data and I can get well past the 2 million mark without any problems. I also created a ThinClient datasource using the information in this question, I didn't observe any change in behavior. The messages on the database end are SQL*Net message from client and SQL*Net more data to client I just discovered that by using the thin client along with blockfactor1="100" I can retrieve more rows (appx. 3000000).

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• A better way to delete a list of elements from multiple tables

  - by manyxcxi

  I know this looks like a 'please write the code' request, but some basic pointer/principles for doing this the right way should be enough to get me going. I have the following stored procedure: CREATE PROCEDURE `TAA`.`runClean` (IN idlist varchar(1000)) BEGIN DECLARE EXIT HANDLER FOR NOT FOUND ROLLBACK; DECLARE EXIT HANDLER FOR SQLEXCEPTION ROLLBACK; DECLARE EXIT HANDLER FOR SQLWARNING ROLLBACK; START TRANSACTION; DELETE FROM RunningReports WHERE run_id IN (idlist); DELETE FROM TMD_INDATA_INVOICE WHERE run_id IN (idlist); DELETE FROM TMD_INDATA_LINE WHERE run_id IN (idlist); DELETE FROM TMD_OUTDATA_INVOICE WHERE run_id IN (idlist); DELETE FROM TMD_OUTDATA_LINE WHERE run_id IN (idlist); DELETE FROM TMD_TEST WHERE run_id IN (idlist); DELETE FROM RunHistory WHERE id IN (idlist); COMMIT; END $$ It is called by a PHP script to clean out old run history. It is not particularly efficient as you can see and I would like to speed it up. The PHP script gathers the ids to remove from the tables with the following query: $query = "SELECT id, stop_time FROM RunHistory WHERE config_id = $configId AND save = 0 AND NOT(stop_time IS NULL) ORDER BY stop_time"; It keeps the last five run entries and deletes all the rest. So using this query to bring back all the IDs, it determines which ones to delete and keeps the 'newest' five. After gathering the IDs it sends them to the stored procedure to remove them from the associated tables. I'm not very good with SQL, but I ASSUME that using an IN statement and not joining these tables together is probably the least efficient way I can do this, but I don't know enough to ask anything but "how do I do this better?" If possible, I would like to do this all in my stored procedure using a query to gather all the IDs except for the five 'newest', then delete them. Another twist, run entries can be marked save (save = 1) and should not be deleted. The RunHistory table looks like this: CREATE TABLE `TAA`.`RunHistory` ( `id` int(11) NOT NULL auto_increment, `start_time` datetime default NULL, `stop_time` datetime default NULL, `config_id` int(11) NOT NULL, [...] `save` tinyint(1) NOT NULL default '0', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=0 DEFAULT CHARSET=utf8;

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• How to retrieve the rows (with maximum value in a field) having a another common field ?

  - by Ashraf Bashir

  I have a table; let it be called table1; with the following fields and data I need a query that returns the record with the maximum value in Field3 for each group of records having the same value in Field2. So that the query returns: How could this be done using SQL queries ?

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