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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25 views

SQL Server doesn't use expected index

Running a query generated from Entity Framework gives me a poorly performing execution plan. It scans the documents table several times, to ultimately return 15 rows. If I run the same query, adding ...
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1answer
34 views

Check if an index exists by comparing columns

We are currently using ALL_IND_COLUMNS to check if an index exists by its name or the columns it is using. The problem is that we can only check if the index exists with columns in a specific order. ...
3
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1answer
35 views

Help with indexing narrow table with many millions of rows

I have a good amount of experience with SQL Server, but not much with indexes and I fear I'm a little bit out of my depth in trying to figure out how to correctly structure a table that has 100+ ...
3
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1answer
259 views

Adding new key(s) to enable partitioning, INSERT performance?

I have a table to storage GPS coordinates with multiple (~30) inserts per second (from 50 different devices) during 12 hours per day, so the table is growing fast, to improve the SELECT speed I was ...
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1answer
20 views

optimize my query mysql

I have the following query: SELECT DISTINCT d.movieName, d.castName, d.movieImdbId, f.year, f.posterLink FROM director_movie as d LEFT JOIN film_info as f ON d.movieImdbId = f.ImdbId WHERE d.castName ...
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10 views

How do I recover from MySQL InnoDB table/index corruption?

While trying to upgrade a database (in place) I got the following error. The server starts up and everything seems to be fine, except that the table mentioned in the message is no longer accessible. ...
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2answers
1k views

Adding index to large mysql tables

I have a table | base_schedule_line_items | CREATE TABLE base_schedule_line_items ( id int(10) unsigned NOT NULL AUTO_INCREMENT, installment int(10) unsigned NOT NULL, on_date date ...
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3answers
721 views

Should I separate frequently updated columns?

I have a users table that contains users' information and a column named credits that is frequently updated. On index page I'm showing list of users with basic user information but I don't need ...
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1answer
49 views

PostgreSQL CREATE INDEX memory requirement

I've got 6GB of RAM on my laptop and for a test I'm creating a 50mil-rows table in PostgreSQL 9.3. I then want to create an index on the table. The table and the resulting index together (or twice ...
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1answer
16 views

How to get the spatial index in CREATE TO script?

Is it possible to get the spatial index using the create to script using SQL Server 2012? When I write out a table using SCRIPT TABLE AS > CREATE TO in Microsoft SQL Server Management Studio 2012, I ...
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1answer
71 views

Increase performance WITHOUT adding indexes [on hold]

I'm having a rather large table (350MB, 1.3M rows) and there are dozens of queries arriving at this table every second. Most queries are super-fast thanks to indexes - but some others aren't. ...
2
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1answer
126 views

Best Indexing Strategy for Query with Equality[A], Range[B], Group By[C], AND Order By[count(P)]

I have a poorly performing query: SELECT user_id, count(item_id) as count FROM table items WHERE category = 'magazine' AND created_at > 1384754400 GROUP BY user_id ORDER BY count(item_id) desc ...
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11 views

Best way to profile SQL Server [on hold]

We are developing an email campaign web application for my company. The application is in .Net and we are using Microsoft SQL Server 2012 Web Edition (64-bit). When a big campaign is going out we ...
2
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1answer
42 views

How to determine cost/benefit of adding an index?

According to Craig Ringer: While it's usually a good idea to create an index on (or including) your referencing-side foreign key columns, it isn't required. Each index you add slows DML operations ...
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1answer
64 views

Sybase ASA: Saving and dropping all foreign keys and most Primary Keys for (Bulk) Insert

Background Information: I am trying to migrate from an ASA 12 Database, to a ASA 12 Database by using a Remote Server. I have to migrate a lot of Rows (not all), spread over a lot of tables (not ...
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1answer
323 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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1answer
3k views

MySQL requires FORCE INDEX on huge table and simple SELECTs

We have an application which stores articles from different sources in a MySQL table and allows users to retrieve those articles ordered by date. Articles are always filtered by source, so for client ...
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2answers
239 views

Minimizing Indexed Reads with Complex Criteria

I'm optimizing a Firebird 2.5 database of work tickets. They're stored in a table declared as such: CREATE TABLE TICKETS ( TICKET_ID id PRIMARY KEY, JOB_ID id, ACTION_ID id, STATUS str256 ...
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1answer
23 views

Does a database update force index rebuild regardless of updated field?

With MySQL (InnoDB), I understand that having indexes slow down UPDATE queries. I would like to know if this happens regardless of what fields are updated. For example, if I have a table with 20 ...
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1answer
25 views

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 ...
2
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1answer
19 views

MySQL table indexes change location

Is it possible to move the MySQL Table indexes to another location rather than "datadir" ? for example a ssd drive or memory partition ?
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2answers
89 views

Using sp_BlitzIndex - Diagnosed as “Index Hoarder: Addicted to nulls” [duplicate]

Context: MS SQL Server 2012 In using Kendra Little's awesome tool, sp_BlitzIndex, a number of tables were diagnosed as "Index Hoarder: Addicted to nulls". I'm not looking for a debate over NULLs and ...
2
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1answer
520 views

Use GIN to index bit strings

I'm trying to extend PostgreSQL to index bit strings up to 1000 bits. (These bit strings are created by quantization of high-dimensional vectors, so for each dimension up to 4 bits are assigned). ...
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69 views

Duplicate Key Entry

I've got a problem on SQL Server 2008 where I'm getting a duplicate key entry error on a process that's worked fine in the past. What is really weird is that if I drop the clustered index, insert the ...
3
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1answer
74 views

Multi-row insert vs multiple single row inserts

In my app I do multi-row inserts when I can just because it reduces the number of round trips between the db and the app. However, I was curious, is there any other advantages? For example, if ...
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1answer
32 views

schema for mysql database with 30million rows

We am building a SaaS backend for restaurants. We integrate directly with POS, so each POS keeps sending customer orders that we store in a following table in mysql. CREATE TABLE name ( `id` ...
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1answer
26 views

Does PGStrom calculate relational comparisons?

I prefer index calculation and comparison be executed on the GPU. I have stumbled upon PGStrom. It seems one could infer that it will calculate index comparisons, but the claim doesn't seem to be ...
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1answer
32 views

Does remove document automatically remove the index that reference this document?

I am wondering if removing the document will automatically update the index if this document is referenced?
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2answers
79 views

What Columns to create Indexes on?

I have a table , which contains upto 20 columns. The data is selected, inserted, and deleted by 3 columns: Username, StartDate, and EndDate. These 3 columns are NOT unique. The table is a ...
0
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1answer
163 views

MySQL - Indexes deleted, reduced column size but table size increases

Here is the original table definition which contains 107547934 (~107.5M) rows CREATE TABLE `twitter_tweets` ( `id_str` varchar(100) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL ...
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1answer
135 views

MySQL is using wrong index

This is my table: - user_id INT (foreign key on `user` with the reference `id`) - question_id INT (foreign key on `question` with the reference `id`) - option_id INT (foreign key on `option` with the ...
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1answer
8 views

Record in table won't show in form

I have an Access 2010 database that has "frmCatalog" which is sourced from the Catalog table. The Catalog table shows a record with the primary key "Acq" = "5203." But the form does not show 5203. ...
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1answer
105 views

Should one always VACUUM ANALYZE before REINDEXing in PostgreSQL 8.4?

Early in the morning every day a pgAgent job refreshes the contents of table A from table B on my PostgreSQL 8.4 database. Table A contains around 140k records across 91 columns and has two indexes - ...
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30 views

How best to index large table with many index keys

In our datawarehouse load, we bring data in the following manner. 1. from source to stage 2. stage to a consolidation layer 3. from consolidation layer to operational data store (ODS) ...
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1answer
63 views

Does the order of a mysql multi-column MySQL index matter - if you're always using all columns in the query?

I'm aware that when you define a MySQL index that the order of the fields matters if the query is only using part of the index, as described here. But if your query is always going to use all columns ...
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3answers
339 views

Mysql - How to Optimize Retrieval Time in a Table

I have query like this! 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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1answer
37 views

Does view take advantage of table indexes

I have a table with a clustered index and 2 non clustered index. Now, in my view I am selecting everything from my table create view dbo.MyView as Select * from MyTable Now, when I am using this ...
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2answers
169 views

mysql need help optimizing query

I have a table containing servers logs, and another table containing rules to match certain and drop them. The logs tables contains around 1 million rows, and there are about 20-30 rules. The ...
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2answers
85 views

Why postgres is using an odd index with no relation to the query

(Debian 7, Postgres 9.3, dedicated machine with huge cache) I have one big table called process_data (14gb) and another tiny lookup table called process_location. I'm doing a query between these two ...
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1answer
167 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 ...
0
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1answer
29 views

MySQL uses intersection instead compound index

I have compound index on following columns: (country_id, lazy, has_avatar, inactive, gender, id, age, challenge_count) When I run following query: SELECT COUNT(*) FROM `user_profile` WHERE ...
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2answers
51 views

Solution on a complex sub select query SQL Server

I created a SQL query that requires me to pull data from 2 separate databases, and I noticed that what I did is this: Select *, (Select Z.f From DatabaseZ.TblZ Z where Z.w = A.w) as valueZA, ...
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1answer
40 views

What happens if an index build is cut half way through?

Today I ran a create NC index but stopped the execution after running for 1 hour 46 minutes. The main reason being I started to get worried about the disk space getting lower. It consumed roughly 10 ...
0
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1answer
448 views

Improve MySQL Query Performance - Too many records

I am using MySQL RDMS for a contact management system. Now a days my database grew in size and contains more than 1 million records. Checking duplicate phone numbers became a big issue during ...
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1answer
48 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 ...
2
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2answers
73 views

What is difference between is_unique column and is_unique_constraint columns in sys.indexes

We have two columns is_unique and is_unique_constraint for unique constraints in sys.indexes and I want to clarify few concepts based on these two columns Create statement for both types of ...
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0answers
27 views

MySQL table partition strange behavior (slow query suddenly)

(I asked this question in "stack overflow" and was recommended to ask in here). (MySQL version: 5.6.15) I have a huge table (Table_A) with 10M rows, in entity-attribute-value model. It has a ...
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1answer
644 views

Slow insert with MySQL full-text index

I use a full-text index in a MySQL table, and each insert into this table takes about 3 seconds. It seems that MySQL rebuilds (a part) of the full text index after each insert/update. Is this right? ...
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21 views

Join does not not use index in PostgreSQL?

I have a statement that selects from two tables news and status. It seems that the index on the column status of the table news is not used. This table has about 70.000 rows and the query costs too ...
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0answers
26 views

MySQL not using multicolumn index on self join

I'm trying to optimise a query that performs an inner join with itself. The table size is currently 10GB ~50 million rows. /* Count all occurrences between start and end site id of a given speed ...