query-performance

On our SQL SERVER 2008 R2 database we have an COUNTRIES referential table that contains countries. The PRIMARY KEY is a nvarchar column: create table COUNTRIES( COUNTRY_ID nvarchar(50) PRIMARY KEY, ... other columns ) The primary key contains values like 'FR', 'GER', 'US', 'UK', etc. This table contains max. 20 rows. We also have a SALES table containing sales data: create table SALES( ID int PRIMARY KEY COUNTRY_ID nvarchar(50), PRODUCT_ID int, DATE datetime, UNITS decimal(18,2) ... other columns ) This sales table contains a column named COUNTRY_ID , also of type nvarchar (not a primary key).

I have a SQL query Like SELECT Column1, Column2, Column3, **ufn_HugeTimeProcessFunction**(Column1, Column2, @Param1) As Column4 From Table1 This ufn_HugeTimeProcessFunction function run against large table (in terms of number of rows) and there are several calculation behind to return value. Am I able to force the SQL compiler to run that function in another thread (process)? Edited : Basically that function get the data from 3 different databases. That's why I am planing to run it "in parallel", moreover it is not possible to change the indexes on the other databases If the server computer on

My server application makes multiple connections to MySQL through separate threads. Each connection fires a SELECT query and fetches result which the application then caters back to its connected users. I am using InnoDB. To my surprise I found it a very weird that if I increase number of connections to MySQL, query performance deteriorates and result fetch time also increases. Below is a table showing same. This data is produced when I had 3333 records in MySQL table and the SELECT query based on random parameters given to it fetches around 450 records out of them. Each record has around 10

I've got a PostgreSQL array of strings as a column in a table. I created an index using the GIN method. But ANY queries won't use the index (instead, they're doing a sequential scan of the whole table with a filter). What am I missing? Here's my migration: class CreateDocuments < ActiveRecord::Migration def up create_table :documents do |t| t.string :title t.string :tags, array: true, default: [] t.timestamps end add_index :documents, :tags, using: 'gin' (1..100000).each do |i| tags = [] tags << 'even' if (i % 2) == 0 tags << 'odd' if (i % 2) == 1 tags << 'divisible by 3' if (i % 3) == 0 tags

I have this process that has to make a series of queries, using pl/pgsql: --process: SELECT function1(); SELECT function2(); SELECT function3(); SELECT function4(); To be able to execute everything in one call, I created a process function as such: CREATE OR REPLACE FUNCTION process() RETURNS text AS $BODY$ BEGIN PERFORM function1(); PERFORM function2(); PERFORM function3(); PERFORM function4(); RETURN 'process ended'; END; $BODY$ LANGUAGE plpgsql The problem is, when I sum the time that each function takes by itself, the total is 200 seconds, while the time that the function process() takes

I need to FULL OUTER JOIN multiple tables. I know how to FULL OUTER JOIN two tables from here . But I have several tables, and I can't apply it over them. How can I achieve it? My SQL code, below: INSERT INTO table ( customer_id ,g01 ,g02 ,g03 ,has_card ,activity ) SELECT sgd.customer_id, sgd.g01,sgd.g02,sgd.g03,sc.value, a.activity FROM s_geo_data sgd LEFT JOIN s_category sc ON sc.customer_id = sgd.customer_id UNION SELECT sgd.customer_id, sgd.g01,sgd.g02,sgd.g03,sc.value, a.activity FROM s_geo_data sgd RIGHT JOIN s_category sc ON sc.customer_id = sgd.customer_id UNION SELECT sgd.customer_id,