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  • Join DELETE in MySql? How to?

    - by Camran
    I have this: $query="DELETE FROM classified, $sql_table WHERE classified.ad_id = '$id' AND classified.classified_id = $sql_table.classified_id AND classified.poster_password='$pass'"; I get this error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE classified.ad_id = 'Bmw_M3_E46_Full_29920' AND classified.cla' at line 1 Any help? As you can see the $sql_table is linked to the classifieds table with the fields classified_id I need to JOIN DELETE somehow. Basically classified table is the main table, then every category has its own tables with vehicle data. classified table has a field called classified_id which is the same as the Here is the full query echoed: DELETE FROM classified, vehicles WHERE classified.ad_id = 'Bmw_M3_E46_410811305' AND classified.classified_id = vehicles.classified_id AND classified.poster_password='some_password' Why isn't this working, Should it be so hard to delete from multiple tables? Thanks

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  • Can I join two tables whereby the joined table is sorted by a certain column?

    - by Ferdy
    I'm not much of a database guru so I need some help on a query I'm working on. In my photo community project I want to richly visualize tags by not only showing the tag name and counter (# of images inside them), I also want to show a thumb of the most popular image inside the tag (most karma). The table setup is as follow: Image table holds basic image metadata, important is the karma field Imagefile table holds multiple entries per image, one for each format Tag table holds tag definitions Tag_map table maps tags to images In my usual trial and error query authoring I have come this far: SELECT * FROM (SELECT tag.name, tag.id, COUNT(tag_map.tag_id) as cnt FROM tag INNER JOIN tag_map ON (tag.id = tag_map.tag_id) INNER JOIN image ON tag_map.image_id = image.id INNER JOIN imagefile on image.id = imagefile.image_id WHERE imagefile.type = 'smallthumb' GROUP BY tag.name ORDER BY cnt DESC) as T1 WHERE cnt > 0 ORDER BY cnt DESC [column clause of inner query snipped for the sake of simplicity] This query gives me somewhat what I need. The outer query makes sure that only tags are returned for which there is at least 1 image. The inner query returns the tag details, such as its name, count (# of images) and the thumb. In addition, I can sort the inner query as I want (by most images, alphabetically, most recent, etc) So far so good. The problem however is that this query does not match the most popular image (most karma) of the tag, it seems to always take the most recent one in the tag. How can I make sure that the most popular image is matched with the tag?

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  • Query broke down and left me stranded in the woods

    - by user1290323
    I am trying to execute a query that deletes all files from the images table that do not exist in the filters tables. I am skipping 3,500 of the latest files in the database as to sort of "Trim" the table back to 3,500 + "X" amount of records in the filters table. The filters table holds markers for the file, as well as the file id used in the images table. The code will run on a cron job. My Code: $sql = mysql_query("SELECT * FROM `images` ORDER BY `id` DESC") or die(mysql_error()); while($row = mysql_fetch_array($sql)){ $id = $row['id']; $file = $row['url']; $getId = mysql_query("SELECT `id` FROM `filter` WHERE `img_id` = '".$id."'") or die(mysql_error()); if(mysql_num_rows($getId) == 0){ $IdQue[] = $id; $FileQue[] = $file; } } for($i=3500; $i<$x; $i++){ mysql_query("DELETE FROM `images` WHERE id='".$IdQue[$i]."' LIMIT 1") or die("line 18".mysql_error()); unlink($FileQue[$i]) or die("file Not deleted"); } echo ($i-3500)." files deleted."; Output: 0 files deleted. Database contents: images table: 10,000 rows filters table: 63 rows Amount of rows in filters table that contain an images table id: 63 Execution time of php script: 4 seconds +/- 0.5 second Relevant DB structure TABLE: images id url etc... TABLE: filter id img_id (CONTAINS ID FROM images table) etc...

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  • How can you tell MYSQL to TRIM the X number of characters, beginning from the Back?

    - by Tim
    How do I write the following in MYSQL? SELECT SUBSTRING(value - (1 TRAILING CHARACTER)) FROM table; Basically substring(value, 2) trims the first letters. But I need to trim the last letters. I can't use substring(value, -4, 3) because I don't know the length of the value. Here's another example: SELECT * FROM table WHERE SUBSTRING(value - (4 TRAILING CHARACTER)) in (SELECT SUBSTRING(value - (1 TRAILING CHARACTER)) FROM table);

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  • Mysql concurrency: what happens if a locked table is accessed?

    - by PixelSapiens
    the question is rather simple but I couldn't find a precise answer: in a myisam db, what happens if a php file locks a table (with an atomic operation, say an INSERT) and another php file tries to access the same table (reading or writing)? Now, while it is obvious that the second session will not be able to access the table, what exactly happens? Does it return some kind of error? Does is wait in queue until it is able to access it? Thanks in advance!

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  • Mysql - Operand should contain 1 column(s) : What's wrong with the query...?

    - by SpikETidE
    Hi everybody.... I am trying to query a database to find the following If a customer searches for a hotel in a city between dates A and B, find and return the hotels in which rooms are free between the two dates. There will be more than one room in each room type(i.e. 5 Rooms in type A, 10 rooms in Type B etc) and we have to query the db to find only those hotels in which there is atleast one room free in atleast one type. This is my table structure.... **Structure for table 'reservations'** reservation_id hotel_id room_id customer_id payment_id no_of_rooms check_in_date check_out_date reservation_date **Structure for table 'hotels'** hotel_id hotel_name hotel_description hotel_address hotel_location hotel_country hotel_city hotel_type hotel_stars hotel_image hotel_deleted **Structure for table 'rooms'** room_id hotel_id room_name max_persons total_rooms room_price room_image agent_commision room_facilities service_tax vat city_tax room_description room_deleted And this is my query $city_search = '15'; $check_in_date = '29-03-2010'; $check_out_date = '31-03-2010'; $dateFormat_check_in = "DATE_FORMAT('$reservations.check_in_date','%d-%m-%Y')"; $dateFormat_check_out = "DATE_FORMAT('$reservations.check_out_date','%d-%m-%Y')"; $dateCheck = "$dateFormat_check_in >= '$check_in_date' AND $dateFormat_check_out <= '$check_out_date'"; $query = "SELECT $rooms.room_id, $rooms.room_name, $rooms.max_persons, $rooms.room_price, $hotels.hotel_id, $hotels.hotel_name, $hotels.hotel_stars, $hotels.hotel_type FROM $hotels,$rooms,$reservations WHERE $hotels.hotel_city = '$city_search' AND $hotels.hotel_id = $rooms.hotel_id AND $hotels.hotel_deleted = '0' AND $rooms.room_deleted = '0' AND $rooms.total_rooms - (SELECT SUM($reservations.no_of_rooms) as tot, $rooms.room_id as id FROM $reservations,$rooms WHERE $dateCheck GROUP BY $reservations.room_id) > '0'"; The number of rooms already reserved in each room type in each hotel will be stored in the reservations table... The query returns the error : Operand should contain 1 column(s) I tried running the sub-query alone but i don't get any result... And i have lost quite some amount of hair trying to de-bug this query from yesterday... What's wrong with this...? Or is there a better way to do what i mentioned above...? Thanks for your time...

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  • MySQL triggers cannot update rows in same table the trigger is assigned to. Suggested workaround?

    - by Cory House
    MySQL doesn't currently support updating rows in the same table the trigger is assigned to since the call could become recursive. Does anyone have suggestions on a good workaround/alternative? Right now my plan is to call a stored procedure that performs the logic I really wanted in a trigger, but I'd love to hear how others have gotten around this limitation. Edit: A little more background as requested. I have a table that stores product attribute assignments. When a new parent product record is inserted, I'd like the trigger to perform a corresponding insert in the same table for each child record. This denormalization is necessary for performance. MySQL doesn't support this and throws: Can't update table 'mytable' in stored function/trigger because it is already used by statement which invoked this stored function/trigger. A long discussion on the issue on the MySQL forums basically lead to: Use a stored proc, which is what I went with for now. Thanks in advance!

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  • rake db:create gives some problem when used from limited account

    - by Xinxua
    I am using mysql 5.1 and mysql gems version is 2.73 This is giving the following error message when I try to run it from a limited account in my XP. If try it using the admin account, it works fine. I think this is wierd because it cannot be the problem of mysql gem. (in F:/Temp/wassup) !!! The bundled mysql.rb driver has been removed from Rails 2.2. Please install the mysql gem and try again: gem install mysql. rake aborted! 5: Access is denied. - C:/Program Files/Ruby/lib/ruby/gems/1.8/gems/mysql-2.7. 3-x86-mswin32/ext/mysql.so (See full trace by running task with --trace) I need to work from the limited account. Can anyone let me know why is this happening?

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  • How can I make a web-based "table" select like a spreadsheet? (rectangular area vs row-wrap selecti

    - by Dax
    I want to make a table that displays on a webpage, but one requirement is to make it easy to copy and paste into a spreadsheet. Normal HTML tables selection behavior is obviously different from how a spreadsheet like Excel selects -- when you select multiple rows it wraps around instead of selecting a rectangular area. Is there any way to make HTML table behave like a spreadsheet in this regard, or is the only way to resort to a Flash table or something similar?

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  • MySQL Table structure of thumb UP & DOWN for comments system ?

    - by Axel
    Hello, i already created a table for comments but i want to add the feature of thumb Up and Down for comments like Digg and Youtube, i use php & mysql and i'm wondering What's the best table scheme to implement that so comments with many likes will be on the top. This is my current comments table : comments(id,user,article,comment,stamp) Note: Only registred will be able to vote, so there isn't need to restrict the votes by IP Thanks

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  • The maximum row size for the used table type, not counting BLOBs, is 65535. You have to change some columns to TEXT or BLOBs

    - by Matthew Chambers
    Hello I am getting the below message on a table i am trying to create The maximum row size for the used table type, not counting BLOBs, is 65535. You have to change some columns to TEXT or BLOBs Anyone know the answer to this please -- Table warrington_central.job -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS warrington_central.job ( id MEDIUMINT(8) UNSIGNED NOT NULL AUTO_INCREMENT , alias_title VARCHAR(255) NOT NULL , reference_number VARCHAR(100) NOT NULL , title VARCHAR(255) NOT NULL , primary_category SMALLINT(5) UNSIGNED NOT NULL , secondary_category SMALLINT(5) UNSIGNED NOT NULL , tertiary_category SMALLINT(5) UNSIGNED NULL , address_id BIGINT(20) UNSIGNED NOT NULL , geolocation_id BIGINT(20) UNSIGNED NULL , company VARCHAR(255) NOT NULL , description VARCHAR(10000) NOT NULL , skills_required VARCHAR(10000) NOT NULL , job_type TINYINT(2) UNSIGNED NOT NULL , experience_months_required TINYINT(2) UNSIGNED NOT NULL , experience_years_required TINYINT(2) UNSIGNED NOT NULL , salary_range VARCHAR(30) NOT NULL , extra_benefits_above_salary VARCHAR(500) NOT NULL , available_from DATE NULL , available_to DATE NULL , extra_location_details VARCHAR(1000) NOT NULL , contact_email VARCHAR(100) NOT NULL , contact_phone_number VARCHAR(20) NOT NULL , contact_mobile_number VARCHAR(20) NOT NULL , terms_conditions_application VARCHAR(5000) NOT NULL , link_to_profile ENUM('0','1') NOT NULL , created_on DATETIME NOT NULL , updated_on DATETIME NOT NULL , updated_by BIGINT(20) UNSIGNED NOT NULL , add_contact_form ENUM('0','1') NOT NULL , admin_package_id TINYINT(1) UNSIGNED NOT NULL , package_start_date DATETIME NOT NULL , package_end_date DATETIME NULL , package_comment VARCHAR(500) NOT NULL , viewable_to_members_only ENUM('0','1') NOT NULL , advertise_to DATETIME NULL , show_comment ENUM('0','1') NOT NULL , hits BIGINT(20) UNSIGNED NOT NULL DEFAULT 0 , visible ENUM('0','1') NOT NULL DEFAULT '0' , approved ENUM('I/* large SQL query (3.9 KB), snipped at 2,000 characters / / SQL Error (1118): Row size too large. The maximum row size for the used table type, not counting BLOBs, is 65535. You have to change some columns to TEXT or BLOBs */ SHOW WARNINGS;

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  • How to SELECT the last 10 rows of an SQL table which has no ID field?

    - by Edward Tanguay
    I have an MySQL table with 25000 rows. This is an imported CSV file so I want to look at the last ten rows to make sure it imported everything. However, since there is no ID column, I can't say: SELECT * FROM big_table ORDER BY id DESC What SQL statement would show me the last 10 rows of this table? The structure of the table is simply this: columns are: A, B, C, D, ..., AA, AB, AC, ... (like Excel) all fields are of type TEXT

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  • SQL help - find the table that has 'somefieldId' as the primary key?

    - by Kettenbach
    Hello All, How can I search my sql database for a table that contains a field 'tiEntityId'. This field is referenced in a stored procedure, but I am unable to identify which table this id is a primary key for? Any suggestions? I currently look through stored procedure definitions for references to text by using something like this Declare @Search varchar(255) SET @Search='[10.10.100.50]' SELECT DISTINCT o.name AS Object_Name,o.type_desc FROM sys.sql_modules m INNER JOIN sys.objects o ON m.object_id=o.object_id WHERE m.definition Like '%'+@Search+'%' ORDER BY 2,1 Any SQL guru's out there know what I need to use to find the table that contains the field, 'preferably the table where that field is the Primary Key. Thanks so much for any tips. Cheers, ~ck in San Diego

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  • Is it possible to keep mysql migration running without keeping connection open?

    - by taw
    ALTER TABLE can easily take a few days - and during this time there's a non-negligible chance of connection getting terminated due to network problems. Is it possible to start ALTER TABLE (or CREATE TABLE ... SELECT ...; or some other very long running query) and leave it running without keeping connection open all the time? (the obvious solution of screen + console mysql client won't easily work as there's no ssh running on that server, only mysqld).

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  • Removing "Using temporary; Using filesort" from this MySQL select+join+group by query

    - by claytontstanley
    I have the following query: select t.Chunk as LeftChunk, t.ChunkHash as LeftChunkHash, q.Chunk as RightChunk, q.ChunkHash as RightChunkHash, count(t.ChunkHash) as ChunkCount from chunksubset as t join chunksubset as q on t.ID = q.ID group by LeftChunkHash, RightChunkHash And the following explain table: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE subsets ref PRIMARY,IDIndex,SubsetIndex SubsetIndex 767 const 522014 "Using where; Using temporary; Using filesort" 1 SIMPLE subsets eq_ref PRIMARY,IDIndex,SubsetIndex PRIMARY 771 sotero.subsets.Id,const 1 "Using where; Using index" 1 SIMPLE c ref IDIndex IDIndex 4 sotero.subsets.Id 12 "Using where" 1 SIMPLE c ref IDIndex IDIndex 4 sotero.subsets.Id 12 note the "using temporary; using filesort". When this query is run, I quickly run out of RAM (presumably b/c of the temp table), and then the HDD kicks in, and the query slows to a halt. I thought it might be an index issue, so I started adding a few that sort of made sense: Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment chunks 0 PRIMARY 1 ChunkId A 17796190 NULL NULL BTREE chunks 1 ChunkHashIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 IDIndex 1 Id A 1483015 NULL NULL BTREE chunks 1 ChunkIndex 1 Chunk A 243783 NULL NULL BTREE chunks 1 ChunkTypeIndex 1 ChunkType A 2 NULL NULL BTREE chunks 1 chunkHashByChunkIDIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByChunkIDIndex 2 ChunkId A 17796190 NULL NULL BTREE chunks 1 chunkHashByChunkTypeIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByChunkTypeIndex 2 ChunkType A 261708 NULL NULL BTREE chunks 1 chunkHashByIDIndex 1 ChunkHash A 243783 NULL NULL BTREE chunks 1 chunkHashByIDIndex 2 Id A 17796190 NULL NULL BTREE But still using the temporary table. The db engine is MyISAM. How can I get rid of the using temporary; using filesort in this query? Just changing to InnoDB w/o explaining the underlying cause is not a particularly satisfying answer. Besides, if the solution is to just add the proper index, then that's much easier than migrating to another db engine.

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  • Is the time cost constant when bulk inserting data into an indexed table?

    - by SiLent SoNG
    I have created an archive table which will store data for selecting only. Daily there will be a program to transfer a batch of records into the archive table. There are several columns which are indexed; while others are not. I am concerned with time cost per batch insertion: - 1st batch insertion: N1 - 2nd batch insertion: N2 - 3rd batch insertion: N3 The question is: will N1, N2, and N3 roughly be the same, or N3 N2 N1? That is, will the time cost be a constant or incremental, with existence of several indexes? All indexes are non-clustered. The archive table structure is this: create table document ( doc_id int unsigned primary key, owner_id int, -- indexed title smalltext, country char(2), year year(4), time datetime, key ix_owner(owner_id) }

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  • Dataset holds a table called "Table", not the table I pass in?

    - by dotnetdev
    Hi, I have the code below: string SQL = "select * from " + TableName; using (DS = new DataSet()) using (SqlDataAdapter adapter = new SqlDataAdapter()) using (SqlConnection sqlconn = new SqlConnection(connectionStringBuilder.ToString())) using (SqlCommand objCommand = new SqlCommand(SQL, sqlconn)) { sqlconn.Open(); adapter.SelectCommand = objCommand; adapter.Fill(DS); } System.Windows.Forms.MessageBox.Show(DS.Tables[0].TableName); return DS; However, every time I run this code, the dataset (DS) is filled with one table called "Table". It does not represent the table name I pass in as the parameter TableName and this parameter does not get mutated so I don't know where the name Table comes from. I'd expect the table to be the same as the tableName parameter I pass in? Any idea why this is not so? EDIT: Important fact: This code needs to return a dataset because I use the dataRelation object in another method, which is dependent on this, and without using a dataset, that method throws an exception. The code for that method is: DataRelation PartToIntersection = new DataRelation("XYZ", this.LoadDataToTable(tableName).Tables[tableName].Columns[0], // Treating the PartStat table as the parent - .N this.LoadDataToTable("PartProducts").Tables["PartProducts"].Columns[0]); // 1 // PartsProducts (intersection) to ProductMaterial DataRelation ProductMaterialToIntersection = new DataRelation("", ds.Tables["ProductMaterial"].Columns[0], ds.Tables["PartsProducts"].Columns[1]); Thanks

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  • Fixing "Lock wait timeout exceeded; try restarting transaction" for a 'stuck" Mysql table?

    - by Tom
    From a script I sent a query like this thousands of times to my local database: update some_table set some_column = some_value I forgot to add the where part, so the same column was set to the same a value for all the rows in the table and this was done thousands of times and the column was indexed, so the corresponding index was probably updated too lots of times. I noticed something was wrong, because it took too long, so I killed the script. I even rebooted my computer since them, but something stuck in the table, because simple queries take a very long time to run and when I try dropping the relevant index it fails with this message: Lock wait timeout exceeded; try restarting transaction It's an innodb table, so stuck the transaction is probably implicit. How can I fix this table and remove the stuck transaction from it?

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  • mysql does not utilize my cpu and ram enough?

    - by vick
    Hello Everyone! I am importing a 2.5gb csv file to a mysql table. My storage engine is innodb. Here is the script: use xxx; DROP TABLE IF EXISTS `xxx`.`xxx`; CREATE TABLE `xxx`.`xxx` ( `xxx_id` int(10) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(128) NOT NULL, `yy` varchar(128) NOT NULL, `yyy` varchar(64) NOT NULL, `yyyy` varchar(2) NOT NULL, `yyyyy` varchar(10) NOT NULL, `url` varchar(64) NOT NULL, `p` varchar(10) NOT NULL, `pp` varchar(10) NOT NULL, `category` varchar(256) NOT NULL, `flag` varchar(4) NOT NULL, PRIMARY KEY (`xxx_id`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; set autocommit = 0; load data local infile '/home/xxx/raw.csv' into table company fields terminated by ',' optionally enclosed by '"' lines terminated by '\r\n' ( name, yy, yyy, yyyy, yyyyy, url, p, pp, category, flag ); commit; Why does my PC (core i7 920 with 6gb ram) only consume 9% cpu power and 60% ram when running these queries?

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  • Currently using View, Should I use a hard table instead?

    - by 1001010101
    I am currently debating whether my table, mapping_uGroups_uProducts, which is a view formed by the following table: CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`localhost` SQL SECURITY DEFINER VIEW `db`.`mapping_uGroups_uProducts` AS select distinct `X`.`upID` AS `upID`,`Z`.`ugID` AS `ugID` from ((`db`.`mapping_uProducts_Products` `X` join `db`.`productsInfo` `Y` on((`X`.`pID` = `Y`.`pID`))) join `db`.`mapping_uGroups_Groups` `Z` on((`Y`.`gID` = `Z`.`gID`))); My current query is: SELECT upID FROM uProductsInfo \ JOIN fs_uProducts USING (upID) column \ JOIN mapping_uGroups_uProducts USING (upID) -- could be faster if we use hard table and index \ JOIN mapping_fs_key USING (fsKeyID) \ WHERE fsName="OVERALL" \ AND ugID=1 \ ORDER BY score DESC \ LIMIT 0,30; which is pretty slow. (for 30 results, it requires about 10 secondes). I think the reason for my query being so slow is definitely due to the fact that that particular query relies on a VIEW which has no index to speed things up. +----+-------------+----------------+--------+----------------+---------+---------+---------------------------------------+-------+---------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+----------------+--------+----------------+---------+---------+---------------------------------------+-------+---------------------------------+ | 1 | PRIMARY | mapping_fs_key | const | PRIMARY,fsName | fsName | 386 | const | 1 | Using temporary; Using filesort | | 1 | PRIMARY | <derived2> | ALL | NULL | NULL | NULL | NULL | 19706 | Using where | | 1 | PRIMARY | uProductsInfo | eq_ref | PRIMARY | PRIMARY | 4 | mapping_uGroups_uProducts.upID | 1 | Using index | | 1 | PRIMARY | fs_uProducts | ref | upID | upID | 4 | db.uProductsInfo.upID | 221 | Using where | | 2 | DERIVED | X | ALL | PRIMARY | NULL | NULL | NULL | 40772 | Using temporary | | 2 | DERIVED | Y | eq_ref | PRIMARY | PRIMARY | 4 | db.X.pID | 1 | Distinct | | 2 | DERIVED | Z | ref | PRIMARY | PRIMARY | 4 | db.Y.gID | 2 | Using index; Distinct | +----+-------------+----------------+--------+----------------+---------+---------+---------------------------------------+-------+---------------------------------+ 7 rows in set (0.48 sec) The explain here looks pretty cryptic, and I don't know whether I should drop view and write a script to just insert everything in the view to a hard table. ( obviously, it will lose the flexibility of the view since the mapping changes quite frequently). Does anyone have any idea to how I can optimize my schema better?

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  • Can I join between two MySQL tables stores on separate machines?

    - by CuriousCoder
    I have a relatively light query that needs information from a local MySQL table along with another MySQL table which is stored on a physically separate machine (on the same network). I'm keen to avoid setting up replication just to facilitate this light query that only needs executed once a day. Is there any way that I can join with a table on a remote machine using one query? Or run a SELECT INTO into a local table. Notes I'm using C# & .NET 4.

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  • How can I determine when an InnoDB table was last changed?

    - by David M
    I've had success in the past storing the (heavily) processed results of a database query in memcached, using the last update time of the underlying tables(s) as part of the cache key. For MyISAM tables, that last changed time is available in SHOW TABLE STATUS. Unfortunately, that's usually NULL for InnoDB tables. In MySQL 4.1, the ctime for an InnoDB in its SHOW TABLE STATUS line was usually its actual last update time, but that doesn't seem to be true for MySQL 5.1. There is a DATETIME field in the table, but it only shows when a row has been modified - it cannot show the deletion time of a row that's not there anymore! So, I really cannot use MAX(update_time). Here's the really tricky part. I have a number of replicas that I do reads from. Can I figure out the state of the table that doesn't rely on when the changes have actually been applied? My conclusion after working on this for a while is that it's not going to be possible to get this information as cheaply as I'd like. I'm probably going to cache data until the time that I expect the table to change (it's updated once a day), and let the query cache help out where it can.

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  • Can MySQL reasonably perform queries on billions of rows?

    - by haxney
    I am planning on storing scans from a mass spectrometer in a MySQL database and would like to know whether storing and analyzing this amount of data is remotely feasible. I know performance varies wildly depending on the environment, but I'm looking for the rough order of magnitude: will queries take 5 days or 5 milliseconds? Input format Each input file contains a single run of the spectrometer; each run is comprised of a set of scans, and each scan has an ordered array of datapoints. There is a bit of metadata, but the majority of the file is comprised of arrays 32- or 64-bit ints or floats. Host system |----------------+-------------------------------| | OS | Windows 2008 64-bit | | MySQL version | 5.5.24 (x86_64) | | CPU | 2x Xeon E5420 (8 cores total) | | RAM | 8GB | | SSD filesystem | 500 GiB | | HDD RAID | 12 TiB | |----------------+-------------------------------| There are some other services running on the server using negligible processor time. File statistics |------------------+--------------| | number of files | ~16,000 | | total size | 1.3 TiB | | min size | 0 bytes | | max size | 12 GiB | | mean | 800 MiB | | median | 500 MiB | | total datapoints | ~200 billion | |------------------+--------------| The total number of datapoints is a very rough estimate. Proposed schema I'm planning on doing things "right" (i.e. normalizing the data like crazy) and so would have a runs table, a spectra table with a foreign key to runs, and a datapoints table with a foreign key to spectra. The 200 Billion datapoint question I am going to be analyzing across multiple spectra and possibly even multiple runs, resulting in queries which could touch millions of rows. Assuming I index everything properly (which is a topic for another question) and am not trying to shuffle hundreds of MiB across the network, is it remotely plausible for MySQL to handle this? UPDATE: additional info The scan data will be coming from files in the XML-based mzML format. The meat of this format is in the <binaryDataArrayList> elements where the data is stored. Each scan produces = 2 <binaryDataArray> elements which, taken together, form a 2-dimensional (or more) array of the form [[123.456, 234.567, ...], ...]. These data are write-once, so update performance and transaction safety are not concerns. My naïve plan for a database schema is: runs table | column name | type | |-------------+-------------| | id | PRIMARY KEY | | start_time | TIMESTAMP | | name | VARCHAR | |-------------+-------------| spectra table | column name | type | |----------------+-------------| | id | PRIMARY KEY | | name | VARCHAR | | index | INT | | spectrum_type | INT | | representation | INT | | run_id | FOREIGN KEY | |----------------+-------------| datapoints table | column name | type | |-------------+-------------| | id | PRIMARY KEY | | spectrum_id | FOREIGN KEY | | mz | DOUBLE | | num_counts | DOUBLE | | index | INT | |-------------+-------------| Is this reasonable?

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