A database structure that can improve the speed of queries at the cost of disk space and slower inserts/updates. It stores a copy of one or more columns but structures the data differently to allow for faster access.

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postgres materialized views and indexes to improve aggregate performance

I have a large table with a number of materialized views used for pre-calculating aggregates. New data is inserted only once a day so think of this as a data warehouse type system. Obviously when I ...
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282 views

non clustered index on same table but the order is different?

I have a table with 5 columns col1...col5 . I need to create a non clustered index on col2,col3,col4. I did, then my boss is asking me to create one more non clustered index on col4,col3,col2. It ...
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575 views

Removing some English token words (such as “are” or “or” etc.) from the system stoplist of full text search?

One of our table has full text catalog on it. It contains some data in a language other than English which makes some words such as "are", "or" useful. There is no stop list defined but these words ...
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227 views

Optimizing for data that does not fit in memory

We have a database that contains around 235 GB of data (calculcated using pg_total_relation_size for each table) on a server with around 77GB of memory. The server is used for nothing else (aside from ...
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57 views

Choice of clustered key when almost all columns would be part of a unique index anyway

I am creating the following table CREATE TABLE dbo.COMM_SHELF_BLOCK_ACCESS ( KeyId uniqueidentifier NOT NULL ROWGUIDCOL CONSTRAINT DF_COMM_SHELF_BLOCK_ACCESS_KeyId default NEWSEQUENTIALID(), ...
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3k views

Compare Indexes/Constraints between two SQL Server databases

I have two databases on one SQL Server that I would like to compare Index/Constraints. The two databases should be identical but I have a suspicion that one database is missing a index or constraints. ...
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99 views

PostgreSQL: Another seq scan where an index scan is expected

Here's the query: SELECT DISTINCT ON(points.track_id) participants.contest_number, points.track_id, points.lat, points.lon, points.alt, points.timestamp, points.h_speed, points....
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42 views

Index on integer column not helping. Help? (EXPLAIN ANALYZE output inside)

The table market_trades has an integer column market_id which takes values from 1 to 5. This seems like a pretty straightforward query to get the number of trades on each market: WITH markets AS ( ...
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37 views

Product table with possible duplicate part numbers from different manufacturers

I am making a database. It has a product(aka component or part) table with a ID, ManufacturerID, and PartNumber. The ID is obviously the primary key and is unique. The ManufacturerID is pulled from ...
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27 views

is there any need to index b again as it is already a under primary

Is there any need to index b again as it is already a under primary- if primary(a,b) and in query we have where b=' '; Is there any need to index(b) again individually because while indexing it ...
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89 views

MySQL from table to table data transfer

I've got some problem with my MySQL. I have the database with many many data. Well, there is only one table actually with huge ammount of data, over 1 billion rows. For some reasons I need to create ...
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127 views

how to use an index on a mysql query with a where clause and a order by

I have a table CREATE TABLE activity ( id INT(10) UNSIGNED AUTO_INCREMENT, subscriberid INT(10) UNSIGNED NOT NULL DEFAULT '0', action VARCHAR(250) NOT NULL DEFAULT '', ip INT(10) UNSIGNED NOT ...
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34 views

Index table for horizontal shard

Lets assume we have a vary amount of clients, which could manage some stuff on our site. Each client has his own table, which is used to store data. For instance: client_1, client_2, ..., client_N. ...
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200 views

How to find the length of multiple column index in MySQL

Is there a way to find out what is the length in bytes for the unique index (NKU) key created through the following command: CREATE TABLE test_ ( testId bigint(20) NOT NULL, name varchar(75) ...
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908 views

Error with Solr DataImporter using Mongodb

I've configured my environment and I've downloading Solr 4.7 The idea is make an indexing my mongodb database. For this I've installed the mongo-connector like appear here: https://github.com/10gen-...
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120 views

How to index WHERE (start_date >= '2013-12-15')

I have a table named items, and inside the table there is a some_date column, with date as the datatype. I was wondering how can I index the some_date column with PostgreSQL SELECT "items".* FROM "...
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324 views

Spliting Datetime into 2 Columns for Restaurant Reservation Schema?

Using PostgreSQL. The primary driver of this is that while no reservation will exist without a date and time, a user can search for and monitor reservations using a time or date or both. With a ...
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164 views

index for OR operator with different columns

What would be best index for this kind of query: -- id is the PK create table test3(id number,name varchar2(30) not null,lastname varchar2(30) not null); select id from test3 where id=:1 and (name=:...
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299 views

Is searching an alternate index on a partitioned myISAM table concurrent or serial?

I have a myISAM table with 30 partitions. The primary key is a SHA1 hash value, which is also used in the partition selection function. I also have an alternate key - an autoincrement integer. Since ...
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242 views

When to use hashtable over binary search tree vice verse for Database Index

Database Index can be constructed using binary search trees (BST) or HashTables , From my understanding so far , HashTables are superior to BST in terms of time taken for searching and insertions ...
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49 views

What indexes would I create for a query like this?

Here's a query I've got: SELECT "balance_transactions"."fee" FROM "balance_transactions" JOIN charges ON balance_transactions.source = charges.balance_id WHERE "balance_transactions"."account_id" = ...
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1k views

Retrieve Data faster from a huge Oracle Table

I have a huge Oracle table ( ttdinv700 ) which contains almost 20 million rows. I am trying to execute the below query, on the table: select max(ttdinv700.t$trdt) from ttdinv700, ttiitm001 ...
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92 views

Is an explicit KEY redundant if it is covered by a UNIQUE KEY?

I am auditing an application which I've been developing over the course of several weeks. I've noticed this in CREATE TABLE: UNIQUE KEY `baz_3` (`baz`,`foo`,`bar`), KEY `baz` (`baz`), Is the ...
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1k views

Postgres - Optimizing an view dependent on an aggregate function?

I have a table of about 15 million records. Whenever information about a specific charge_id is changed, a new row is added with the current timestamp and the changes. This results in multiple rows ...
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601 views

Should I index before or after importing a dump?

I am using mongodb to persist a very big-size (90G), which has nearly 40,000,000 items. I read and parse this file and insert all items into mongodb (my programming language is perl, batch_insert, and ...
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60 views

Creating an index on table A but with reference to table B

Our company uses a 3rd party application for numerous aspects of the business. One aspect is dealing with customer payments and when selecting a window within the app to list all the payments ever ...
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189 views

Benefit to keeping a record in the database, rather than deleting it, for performance issues?

So I have a client that I am building a Rails app for....I am using PostgreSQL. He made this comment about preferring to hide records, rather than delete them, and given that this is the first time I ...
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2k views

MySQL Cluster - Table is full [Error 1114] while still creating tables

I am trying to forward engineer a MySQL Workbench model with about 100 tables to a development single-node cluster and, while creating the 51th table, I end up getting a "1114 table is full" error, ...
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519 views

optimizing MySQL for traffic analytics system

background : I've developed a URL shortener system like Bitly with same features , so the system also tracks clickers info and represent as graphs to the person who has shorten the link as ...
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327 views

Unused Indexes - Consider Primary Key Constraint Supporting Indexes?

I have given a task to find out the unused indexes in my production environment. I'm using a DMV to find the unused indexes should i include the Primary key Clustered Indexes on it? If a Primary key ...
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333 views

Updating an FTS indexed column returns “Invalid InnoDB FTS Doc ID”

Environment: Ubuntu 12.04 (and 13.04) MySQL 5.6.11 I have a table which has a full text index on it (real table has much more columns and rows): DROP TABLE IF EXISTS articles; CREATE TABLE ...
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3k views

Varchar index - will hashing value make it faster?

I have a VARCHAR(1000) column in a table. It will contain strings that will not be guaranteed to be unique. I have a query that searches this column as part of a WHERE IN clause, the list of values in ...
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141 views

Big jump in search time for Postgres Index query for results with high selectivity

I am doing some performance comparison of databases and lucene for full-text searching. So I use Postgres to create an Index for the data to search: CREATE INDEX bodies_index ON bodies USING gin ...
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2k views

Why PostreSQL 9.2 does not use index scan if it can?

My PosgreSQL planner (9.2) does not pick index and rather choose to do seq scan. Here is my table. The index I am talking about is name_left_prefix cwu=# \d web_city; ...
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413 views

SQL Index order and performance based on cardinality and data

I've been working quite a bit on a query that's not operating very efficiently on a DB2 database. The thing will return up to 30k rows or so and take up to 10 seconds. I've been working on getting ...
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579 views

Mysql - How to Optimize Retrieval Time in a Table

I have query which has 200 million Records in a single table. I am using BTree indexes in my table: mysql> select COUNT(DISTINCT id) from [tablename] where [columname] >=3; +------------------...
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333 views

I would like to query a range of criteria on multiple columns in MySQL

I have 3 columns in a mysql table. I'm using Innodb engine. I want to be able to search for some values on those columns and also anything close to those values. For example : We have 3 columns as "...
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431 views

Why do MySQL MyISAM table indexes go out of date?

I have few MyISAM tables, where only the auto_increment primary key is up to date with the number of columns, but not other indexes. Any idea, why this happens?
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201 views

Consolidating indexes

I have one big table that is used to generate business intelligence cube. Currently it has around 40M rows and 55 columns. A lot of the cube dimensions are generated by running 'select distinct' on a ...
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74 views

MySql include partition key in index?

Please look at the following Mysql table: http://pastebin.com/b0NDSbdz I've partitioned the table by sent_at and I'm making sure that most of the queries pass sent_at. do I need to include sent_at in ...
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401 views

Simplify and optimize a complex query

Our site has a chronological event feed that uses MySQL. We have noticed that some of the queries tend to run for quite a bit longer than others. For example, some queries for our heaviest users take ...
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471 views

Mongodb multikey index and $all in queries

I have such structure of documents in my products collection: { title: 'Samsung Galaxy S III', category_id: ObjectId("50bcc2f0b910a6c1936a4424"), properties: [ { title: 'OS', ...
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1k views

InnoDB, What would cause: “db1/tableABC contains 6 indexes inside InnoDB, which is different from the number of indexes 5 defined in MySQL”

MySQL 5.5.24 . We have InnoDB tables that grew almost by double (from 50GB to 100GB - file-per-table enabled) in a few weeks due to a project we are working on. The tables were freshly dumped and ...
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139 views

Simple Slow Query Not Using Indexes

I have a slow query running on a large forum. The EXPLAIN synopsis: mysql> EXPLAIN SELECT COUNT(post_thanks.id) as thanked, post_thanks.postid, post.title, post.dateline FROM ...
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1k views

Issues on defining a PK on a nvarchar column and indexing the FK referring this PK

Someone from the team, has defined two reference tables with a few records in each, and has defined the PK of these tables on a column of type nvarchar(255). The value exists in this columns are ...
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How to interpret this “db.explain()” for this mongodb query

db.tablebusiness.find({ "LongitudeLatitude" : { "$within" : { "$centerSphere" : [[106.772835, -6.186753], 0.0089967464101566] } }, "indexContents" : { "$all" : ["warung"] }, "Prominent" : { "$gte" : ...
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Repair with keycache in mysql runs EVERY time. Can't even log why it's happening

I have a MyISAM table w/ ~1million rows and two indexes - one's a three-column key, and the other is a spatial index for bounded SELECT statements on a separate point column. My insert statements ...
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245 views

What is the performance difference between local text index and domain text index in oracle?

What is the performance difference between local text index and domain text index in oracle? Also what is the cost of rebuilding the domain text index when I have to split just one partition? Does the ...
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2k views

At which frequency run CTXSYS.CTX_DDL.OPTIMIZE_INDEX(…) on a fulltext index?

I've been told to run periodically CTXSYS.CTX_DDL.OPTIMIZE_INDEX(...) on some fulltext indexes, with no more information, in particular at which frequency this task should be run. I guess that it ...
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959 views

PostgreSQL 8.4 hangs on create table, reindex

I have a rather small database(200Mb) which was running on ubuntu 10.10/amazon ec2 fine for a year almost but today I ran into the following problem: When I create a table that references other table ...