DO NOT USE this for questions targeting Microsoft SQL Server, use the tag sql-server instead. "SQL" is an acronym for "Structured Query Language", it is used in relational database management systems (RDBMS) to query, update, delete, and insert data as well as modify the structure of the database. ...

learn more… | top users | synonyms (1)

7
votes
2answers
7k views

Oracle 11g: performance improvements of inserts

I have a table of 500 millions of rows (and growing) I did the following to improve performance of inserts: On database side: dropped all indexes and constraints disabled logging On application ...
7
votes
1answer
656 views

Is the optimisation fence behaviour of a CTE (WITH query) specified in the SQL:2008 standard? If so, where?

I see frequent references to WITH queries (common table expressions, or CTEs) acting as an optimisation fence, where the server isn't permitted to push filters down into the CTE queries, pull common ...
5
votes
4answers
8k views

Executing a very large SQL file

I have a 830mb .sql file which is a scripted DB. I wish to execute this SQL so it will create and insert data into a database on a hosted server. I cannot get it to open in SQL Server Management ...
5
votes
2answers
5k views

Grouping records based on intervals of time

I have a table with the following schema, and I need to define a query that can group data based on intervals of time (Ex. records per minute) and then provide the sum of the changes to the ...
4
votes
1answer
130 views

Optimizing indexes

I just began optimizing my schemas with indexes (pretty late I guess). I never dealt with huge dataset but I'll be soon coping with about 1 to 5 millions rows. Here is the schema I'm using right now ...
3
votes
1answer
263 views

MySQL fulltext selection performance

I have 1.5M rows in a table. Following is the table create code: CREATE TABLE `jobs` ( `id` INT(8) NOT NULL AUTO_INCREMENT, `job_id` VARCHAR(50) NOT NULL DEFAULT '', `title` VARCHAR(255) ...
3
votes
2answers
586 views

Help with a multi-language medical database

My project is to design a database for medicines in many countries. Medicines have various criteria like composition, price, manufacturer. Database will be multi-language; related to each country. ...
3
votes
3answers
4k views

How? SQL Cluster with multiple active nodes (not failover)

I'm building a new SQL 2008 R2 (Enterprise) Cluster that is backed by an EqualLogic iSCSI SAN. Instead of building a failover cluster (which I have done), I would instead like to setup several nodes ...
2
votes
2answers
5k views

Should I join datetime to a date using cast or range?

This question is a take-off from the excellent one posed here: Cast to date is sargable but is it a good idea? In my case, I am not concerned with the WHERE clause but in joining to an events table ...
2
votes
0answers
395 views

Transform XPath map into XML document using relational data [closed]

Background Most modern databases have XML functions that can be used to extract data in an XML format. I want to avoid the task of manually calling XML functions to extract the data. This problem ...
2
votes
5answers
327 views

How define select, if bridge pair may have 3 players?

Normaly a pair has 2 players, but if there is an odd number of players at the club, one 'pair' has 3 players. Table, members: pair, player_id 1 1 1 2 2 3 2 4 3 5 3 6 4 7 4 8 5 9 5 10 6 11 6 12 6 ...
2
votes
3answers
2k views

Is it normal to use many Triggers?

I have many so-called summary columns throughout my database to count number of rows in other tables. For example, counting the number of comments by a user (a column in the user table). Currently, I ...
2
votes
2answers
3k views

Restore Database script

I have a live database which i would like to create a backup and restore script that will take the "live" database every night, create a back, then drop the existing "testing" database (if any) and ...
0
votes
2answers
433 views

Tsql Query speed slow due to Or within where clause, causing index scan instead of seek

I have been working on making this query work more efficiently. I found that the number of Ors within the where clause are the biggest problem within this query. This query sits in a stored ...
0
votes
3answers
535 views

Can a RDBMS connect to a remote server, execute a select query and copy them into a local table just with SQL commands?

I'm sorry it may sound stupid but I've been wondering about how multiple databases are automated before the virtualization era. Can a DB Adminsitrator make a stored procedure to get data from a remote ...
18
votes
3answers
4k views

Why does ANSI SQL define SUM(no rows) as NULL?

The ANSI SQL standard defines (chapter 6.5, set function specification) the following behaviour for aggregate functions on empty result sets: COUNT(...) = 0 AVG(...) = NULL MIN(...) = NULL MAX(...) = ...
14
votes
1answer
10k views

How do I read Query Cost, and is it always a percentage?

I'm currently studying for SQL 70-433 (the Microsoft Certification exam), and I'm getting very confused about the "query cost" performance metric. According to any documentation I could find via ...
12
votes
1answer
331 views

Why does subquery use parallelism and join doesn't?

Why does SQL server use parallelism when running this query which uses a subquery but it doesn't when using a join? The join version runs in serial and takes around 30 times longer to complete. Join ...
10
votes
3answers
149 views

Combining separate ranges into largest possible contiguous ranges

I'm trying to combine multiple date ranges that may or may not overlap into the largest possible contiguous date ranges. For example: Data: CREATE TABLE test ( id SERIAL PRIMARY KEY NOT NULL, ...
10
votes
4answers
4k views

Benefits of using backtick (`) in MySQL queries?

In MySQL we can create queries with or without the backtick (`) symbol. Example: SELECT * FROM TEST; SELECT * FROM `TEST`; Both works fine in mysql-console. Is there any technical difference ...
7
votes
2answers
1k views

How to find parent rows that have indentical sets of child rows?

Suppose I have structure like this: Recipes Table: RecipeID Name Description RecipeIngredients Table: RecipeID IngredientID Quantity UOM What are some good ways for ...
7
votes
4answers
3k views

Multiple operations using WITH

Is there a way to execute multiple operations using the WITH statement? Something like WITH T AS ( SELECT * FROM Tbl ) BEGIN OPEN P_OUTCURSOR FOR SELECT * FROM T; SELECT COUNT(*) INTO ...
6
votes
2answers
1k views

Slow ORDER BY with LIMIT

I have this query: SELECT * FROM location WHERE to_tsvector('simple',unaccent2("city")) @@ to_tsquery('simple',unaccent2('wroclaw')) order by displaycount I'm happy with it: "Sort ...
6
votes
1answer
817 views

adding an order by to this query returns faster than without, why?

Any ideas on why adding a sort to this query returns considerably faster than without the order by? I would expect the opposite so what could make this happen? SELECT TOP (500) ...
5
votes
1answer
11k views

Syntax of INNER JOIN nested inside OUTER JOIN vs. query results

TLDR; If you look at the 2 execution plans, is there an easy answer to which is better? I purposefully did NOT create indexes so it's easier to see what's happening. Following up on my previous ...
5
votes
1answer
1k views

Mysql sub query returns more than 1 row

SELECT * FROM wp_posts WHERE ID IN ( (SELECT courses FROM wp_category WHERE CatID =401) OR (SELECT meta_value FROM wp_postmeta WHERE post_id IN (SELECT courses FROM wp_category WHERE CatID =401) ...
5
votes
1answer
2k views

Send email when certain Data is being inserted in MS SQL Server

I realize that there is an integrated email notification system in SQLServer, where I can configure it to send an email using my organization's Exchange server. I want to use that to send email on ...
5
votes
1answer
481 views

Dealing with temp tables when I have not control over db variables

I have no control over things like tmp_table_size and max_heap_table_size, and so as our tables grow the time taken by queries requiring temp tables is growing geometrically. I am wondering if there ...
4
votes
2answers
398 views

Is a Postgres long-running query aborted if the connection is lost/broken?

If I open a connection to Postgres and issue a long-running query, and then break the connection (e.g., kill the client process that opened the connection), will the long-running query continue to ...
4
votes
3answers
4k views

GROUP BY one column, while sorting by another in PostgreSQL

How can I GROUP BY one column, while sorting only by another. I'm trying to do the following: SELECT dbId,retreivalTime FROM FileItems WHERE sourceSite='something' GROUP BY seriesName ...
4
votes
2answers
584 views

Order of columns in a compound index in PostgreSQL (and query order)

I have a table with 50K rows. It is actually a PostGIS table. The query has 4 parts (1 mandatory) (3 Optional) intersection box (a geography rectangle) with 4 lat,long (I use st_intersects) ...
4
votes
1answer
14k views

Split/explode comma delimited string field into SQL query

I have field id_list='1234,23,56,576,1231,567,122,87876,57553,1216' and I want to use it to search IN this field: SELECT * FROM table1 WHERE id IN (id_list) id is integer id_list is varchar/text ...
4
votes
1answer
22k views

temporary table inside procedure oracle

I'm in a situation right now. I'm migrating several procedures from Mysql 5.0 to Oracle 11g. Mysql procedures allow me to: 1. Create temporary tables 2. Insert data into temporary tables / Query these ...
4
votes
3answers
730 views

Full Text Search With PostgreSQL

i have a table with this rows: Stickers ------------------------------------------------------ ID | Title |Keywords (ts_vector) ------------------------------------------------------ ...
4
votes
1answer
531 views

How to Update same table on deletion in MYSQL?

In my Database I have a table: Employee with recursive association, an employee can be boss of other employee. Following is query I used to create table: CREATE TABLE IF NOT EXISTS `Employee` ...
4
votes
3answers
1k views

How can I write a proper query to JOIN all of these tables without duplicates?

Let's say I have four tables: TABLE: players COLUMNS: id, first_name, last_name TABLE: passing_stats COLUMNS: id, year, passing_yards (several other passing columns) TABLE: rushing_stats ...
4
votes
2answers
402 views

Running different instances of SQL Server from different networks on one box

I want to be able to run SQLSMS and select an instance to connect to but the instances are on different networks. I remotely log on to our server and from there, I want to be able to access our ...
4
votes
1answer
13k views

Invalid use of a side-effecting operator 'INSERT' within a function - Multiple Inserts in Function

If this is not the right forum please let me know and move it for me. I've just got a bunch of inserts like this toward the end of my scalar function: INSERT INTO [Raptor].[dbo].[UserRole] ...
4
votes
3answers
5k views

Stored procedure executes too long

We use SQL Server 2008. When I am watching in SQL Server Profiler I found some queries that take for example 20 seconds. The same query (in a stored procedure) when executed in SQL Server Management ...
3
votes
2answers
105 views

How to get the sum of a particular item id in a column

Item ItemName PackageID Specifics brandname GRNQty UnitPric GRNValue 102814742801 ALL BRAN FLAKES 1PKT Bran. KELLOGS 7 15.9 111.3 102814742801 ALL BRAN ...
3
votes
2answers
710 views

PostgreSQL joining using JSONB

I have this SQL: CREATE TABLE test(id SERIAL PRIMARY KEY, data JSONB); INSERT INTO test(data) VALUES('{"parent":null,"children":[2,3]}'); INSERT INTO test(data) ...
3
votes
2answers
310 views

How slow is slow in postgres?

I'm working with postgres for the first time. I have a lot of experience with small / medium size data analysis (i.e. things that fit in ram and can be analyzed in R, Stata, Matlab, etc.), but am now ...
3
votes
1answer
2k views

PostgreSQL list of integers separated by comma or integer array for performance?

As per subject, I have a field which is varchar in which i store some numbers separated by commas. The list grows and shrinks based on clients choices. I then use it in queries to check if a ...
3
votes
3answers
3k views

In Microsoft SQL Server 2008, syntax generates the error “The Parallel Data Warehouse (PDW) features are not enabled.”

I have the following virtual column generated from an aggregate over a sorted partition, MIN(picture_id) OVER ( PARTITION BY [360_set] ORDER BY picture_id ASC ) However, when I execute that, I get ...
3
votes
1answer
5k views

Moving postgresql data directory

I moved postgresql's data directory by following the following steps: Stop postgres cp -a source_data_directory destination_data_directory export PGDATA=destination_data_directory Changing data ...
3
votes
2answers
968 views

How to split a string to and get info from another table in mysql

I have a system to assign score for each sentence stored in a column: TABLE 1: word_scores word score this 3 is 4 a 5 test 1 another 0 sentence 8 TABLE 2: ...
3
votes
1answer
8k views

Joining 3 tables using SQL Query?

I'm having problems joining three tables. It works well when I use the same query for joining two tables (after removing LEFT OUTER JOIN C ON B.No = C.No). However, it doesn't work when I use three ...
2
votes
2answers
131 views

Call UPSERT function multiple times to different inputs

I have a function: merge_vehicles(vid, cid, vname, reg_no, name, name_1st) Can i call it multiple times on inputs like (2335, 55, '246BDH', '246BDH', '811', 1), (2336, 55, '038THX', '038THX', ...
2
votes
1answer
211 views

Select data based on records created_at column

I have two tables Keywords, ProjectReports: http://sqlfiddle.com/#!15/06ae3/1 As you can see in that example everything works fine, but I want to get more data from those 2 tables and I don't know ...
2
votes
2answers
23k views

SQL Update column with data from another table

I am working on complicated problem, but I will simplify it to this problem. I have two tables A [ID, column1, column2, column3] B [ID, column1, column2, column3, column4] and i want to update ...