Questions tagged [index-tuning]
The process of determining which indexes are useful and which are not.
625
questions
4
votes
1answer
40 views
Add INCLUDE term to primary key index in Postgres 11
I work with Postgres 11 and would like to change the index that backs the primary key of a large table (~750 million rows). The primary key is the bigint column id and I would like to include an extra ...
1
vote
1answer
64 views
Is it useful to index a column if it is already the first column in a composite index? [closed]
Suppose I have this table (simplified from my project):
create table BillTax
(
BillID int not null constraint FK_BillTax_Bill foreign key references Bill(BillID),
TaxCode varchar(20) not null,...
0
votes
1answer
26 views
Why is DTA recommending non-clustered indexes that match the clustered Primary Key index?
I'm only vaguely familiar with SQL Server's Database Engine Tuning Advisor (DTA) but I'm using it to suggest recommendations for indexes on my database.
Most of the tables in the database at present ...
-2
votes
1answer
30 views
SQL server index autotuning in Azure
I know SQL server index autotuning available in Azure DB. Which Azure DB version does this work with? Also does this work for AWS SQLdb?
Thanks for your help.
0
votes
1answer
30 views
Optimization for table with text and time columns
I have a simple table with the following columns:
id (int4)
time (timestamp)
name (varchar)
service_name (varchar)
For every service (there are not more than 500 different names), there are a lot of ...
4
votes
1answer
44 views
Delete unused indexes from Microsoft Dynamics CRM Application
So I found tons of unused indexes from our CRM application with this query from Pinal:
SELECT
o.name AS ObjectName
, i.name AS IndexName
, i.index_id AS IndexID
, dm_ius.user_seeks AS UserSeek
, ...
0
votes
0answers
61 views
Reproduce Deadlock in SQL Server
I have identified a deadlock by using Solarwinds, I have noticed that it is happening in a specific table, that table only has a primary key, which tells me that the deadlock makes sense since every ...
14
votes
4answers
1k views
Index Uniqueness Overhead
I've been having an ongoing debate with various developers in my office on the cost of an index, and whether or not uniqueness is beneficial or costly (probably both). The crux of the issue is our ...
0
votes
1answer
69 views
Benefit to additional index with key column moved to includes
Say I have an Index Foo with:
Keys [A, B, C] and Included columns (D, E)
Is there any performance reason to have an additional index Bar with:
Keys [A, B] and Included columns (C, D, E)
My ...
0
votes
0answers
17 views
MongoDB date range index bounds
I have a mongodb (V3.6.10) collection with the following stats&indexes:
{
"ns" : "RepoProd.raiding",
"size" : 145312567936,
"count" : 6776728,
"avgObjSize" : 21442,
"...
0
votes
1answer
42 views
Postgres index not being used
Postgres 9.6.8, a table with 6GB including a jsonb field that is up to 15MB. The query planner is not using any indices btree or gin when querying that table. When I add the same indices to a local/...
1
vote
0answers
51 views
Finding which queries used an index
I'm being asked to provide historical proof before I can maintain indexes - which is fine - over the past year I've kept a table full of index usage statistics for all the tables on the server.
I ...
0
votes
2answers
29 views
No index used warning in WHERE column IS NULL
I'm getting this warning:
No index used in query/prepared statement SELECT * FROM mTable WHERE my_column IS NULL
But the my_column is already indexed.
MariaDB [mytest]> SHOW INDEX FROM mTable;
...
0
votes
1answer
32 views
Indexing every WHERE column?
I tried to turn on MYSQLI_REPORT_ALL | MYSQLI_REPORT_STRICT and now MySQL tells me:
No index used in query/prepared statement...
in some of my app's queries.
Is it really best practice to index ...
0
votes
1answer
56 views
Efficient partition pruning with ORDER BY on same column as PARTITION BY RANGE + LIMIT?
I've set up a table in MariaDB (10.4.5, currently RC) with InnoDB using partitioning by a column of which its value is incrementing-only and new data is always inserted at the end. For this case, ...
1
vote
2answers
30 views
PostgreSQL partial index not used depending on boolean comparison
I need help understanding why a partial index would be used in one query and would not in second one which is effectively the same.
I have the following table:
Column | Type ...
0
votes
0answers
22 views
compund MongoDB index with _id
I have database with few fields:
_id, field0, field1, field2, field3, field4, field5..
I created index on as follows:
db.usertable.createIndex( { _id: 1, field1:1} )
The expected that a query ...
3
votes
0answers
30 views
Will my database index be more performant with a smaller varchar size?
We're using Mysql 5.7
We have an index over a varchar(255) column in a table of ~ 500M rows.
select distinct varchar_column from table yields seven results, with the max length 21.
A DBA consultant ...
1
vote
0answers
58 views
How does mysql optimizer works?
I have two tables t_core_blueprints,t_ci.
CREATE TABLE `t_core_blueprints` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(100) COLLATE utf8_unicode_ci NOT NULL,
`last_modified_on` ...
3
votes
2answers
86 views
Database design that requires an index over two tables
Using PostgreSQL (currently 9.6, but upgrades are possible), I currently have the following database layout where customers can order products, which are themselves sorted into categories (products ...
1
vote
1answer
23 views
Azure SQL Server - Cannot get rid of the sort operator
I'm using Azure SQL Server (Microsoft SQL Azure (RTM) - 12.0.2000.8 Apr 3 2019 13:27:00 Copyright (C) 2019 Microsoft Corporation), Premium tier 4 (500 DTUs).
Query: offer progress has a history ...
2
votes
3answers
161 views
Why does sql server prefer the nonclustered index over the clustered index?
I am trying to speed up a table and as I was experimenting I ran into this (what I think is) odd occurrence. I created a clustered index and a nonclustered index that should be the same thing. However,...
1
vote
0answers
27 views
Spatial index unused on nested set
I'm using the nested set architecture to store URL hierarchies in the following InnoDB table on MySQL 5.7. From my research, I've learnt that using a SPATIAL index will significantly speed up any ...
0
votes
2answers
60 views
How to index/optimize sum of two columns in PostgreSQL?
We have a database where one table contains serialized temporary data that needs to be kept for various times (usually between tens of minutes and two weeks). We also have a low priority background ...
1
vote
2answers
109 views
What is the best practice when an index with key/include columns are inversed for a second index on the same table
I have an index on a table of the form:
NONCLUSTERED INDEX [IDX1] ON [TABLE]
(
[COL_ID_A] ASC
)
INCLUDE
(
[COL_ID_B]
)
For a different query on the same table MSSMS proposes the following ...
2
votes
1answer
101 views
How to optimize the execution of query that takes too long
I am working with a query that is taking around 53 minutes to execute, which I feel is excessive.
Maria DB version: Server version: 10.1.38-MariaDB-1~stretch mariadb.org
The declaration of the ...
0
votes
1answer
91 views
Is MongoDB index creation single threaded?
I have rather big dataset - 2TB of text data, 18.000 millions of lines.
Each document is same: 5 fields: 4 strings + 1 integer.
All fields should be indexed and searched by.
That is: array of 3 ...
1
vote
0answers
46 views
Background index creation resource provisioning
I have a long running background index creation running in MongoDB. However, the CPU and RAM usage is below 30%.
Is there a way to allocate more resources to the index creation process or is it ...
0
votes
1answer
58 views
Optimizer choosing a bad index
I have a pretty simple select statement,
select column 4 from table_x where column1=:1 and column2=:2 and column3=:3
Columns 1,2 and 3 make up the primary key on the table.
For some reason, ...
1
vote
1answer
88 views
Query Index question
I am trying to figure out how I can index this query below. The table is 155 columns. It has a clustered index on the column which is not in the query. The query is dynamically created from out of the ...
2
votes
3answers
72 views
Identify proper index for group and order by date and hour (2 columns)
PostgreSQL 10.4
I have a table that has already an index on date column. Current query plan is doing a Bitmap Heap Scan using the existing date index. I would like to add a new index for this query, ...
3
votes
1answer
29 views
Is PRIMARY(ColumnA, ColumnB) + INDEX(ColumnB) + PARTITIONING(ColumnB) redundant?
I have a big table (30 millions rows) defined like this:
CREATE TABLE `drawing` (
`id` int unsigned NOT NULL,
`artist` int unsigned NOT NULL,
`imageUrl` text NOT NULL,
`uploadDate` timestamp NOT ...
1
vote
1answer
107 views
Index Optimization for Datetime comparing day of week and hour
I have a table of sensor observations with obs_ts timestamp, sensor_id text, sensor_val int, and to fill in gaps with data we have models by day of week and hour of day: model_id int, hour_of_day int, ...
3
votes
1answer
136 views
What is the best index strategy or query SELECT when performing a search/lookup BETWEEN IP address (IPv4 and IPv6) ranges?
Question: Is there a better indexing strategy or query SELECT that I can use for looking up one large data set against another large data set? Or, should I look at placing the lookup dimension table ...
5
votes
2answers
129 views
Why are partial PostgreSQL HASH indices not smaller than full indices?
I want to create the most efficient index for a sparsely populated column. I only need equality operations, so a HASH index should be beneficial.
Now I'm wondering why a partial HASH index isn't ...
3
votes
1answer
356 views
Redundant indexes in SQL Server
I am currently going through all indexes in our data warehouse as a performance tuning exercise. Several of these indexes are not used in the system stats, and I am considering removing them to reduce ...
1
vote
1answer
42 views
Advice on fine-tuning query and index for performance
Currently my query is as below:
select id_request,username_request
from darkhast_follower
where darkhast_follower.id_request != '9762952594'
AND darkhast_follower.status =0
AND NOT exists (...
-1
votes
2answers
167 views
Queries key look up [closed]
SELECT Col1, Col2, Col3, Col4, Col5, Col6, Col25...
FROM Tabl1
WHERE ( Col30 IS NOT NULL
AND Col28 <> @P0
AND DATEDIFF(
dd,
Col31,
...
1
vote
2answers
82 views
PostgreSQL: hstore trgm search on fixed key
I have a table of products with custom properties for each product. So I have props::hstore column in my table. I want the user to be able to search products by key/value by first selecting the key ...
0
votes
0answers
46 views
Slow query with order by join table
I have a SQL with multiple join left, because some data is empty.
However, I need to sort the data using a string column from a join table.
I thought about creating an index for this table, but this ...
2
votes
3answers
444 views
Struggling to create an efficient index for this query
I am struggling to create an index for a query and unfortunately I cannot change the query at all as it part of an ERP system. The problem is this query has over 1m reads and sometimes a duration of ...
7
votes
1answer
392 views
Index help for bad Query on fairly big table (2m)
I am looking for some assistance please. I have a query that is running against a fairly big table (2 million records).
I have been trying to get the indexes working efficiently. There are a few ...
0
votes
1answer
62 views
SQL Server indexes Work Sometimes [duplicate]
So I have the following indexes on my table:
CREATE NONCLUSTERED INDEX [$5] ON [dbo].[Record Link]
(
[Company] ASC,
[Record ID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, ...
0
votes
1answer
25 views
Performance recommendations stuck on 'Validating'
I have been tasked with migrating a 'database from hell' to Azure SQL. It has some complicated and long-running queries (20 seconds on the S6 tier, >600 seconds on S4 tier) and I'd like to optimise ...
2
votes
2answers
167 views
Enlighten me about INCLUDE on indexes
Well, After reading Erik Darling's post Filtered Indexes: Just Add Includes I'm really curious and sad about how I use INCLUDES:
He gives some examples and etc. about INCLUDE, but I'm confused about ...
0
votes
1answer
44 views
Why are bulk multi-column key queries so slow in MySQL?
(For this question, I am using AWS/Aurora MySQL with a reasonably-spec'd RDS instance)
Consider the following schema:
Table T:
col0: the usual autoincrement primary key
col1: varchar
...
1
vote
0answers
226 views
Creating index on a big text column in postgres
We are talking about postgresql 9.5 on windows with a database which has UTF8 encoding and "English_United States.1252" (default) LC_COLLATE and LC_CTYPE.
The column is of type text and it is used ...
2
votes
1answer
172 views
PostgreSQL performance with (col = value or col is NULL)
This question deals with PostgreSQL 9.5 query performance.
The table is:
CREATE TABLE big_table
(
id integer NOT NULL,
flag bigint NOT NULL,
time timestamp with timezone NOT NULL,
val ...
-1
votes
1answer
60 views
Composite index and Normal index,redundant/duplicate index - Incurred Performance penalty [closed]
Need suggestion on below indexes, whether our composite index is enough and can the normal index be removed.
Scenario - We have ix4 and ix6 indexes as below, please review and advise if ix4 is ...
1
vote
1answer
62 views
Is there any benefit to having both an ordered and unordered index on the same column in postgres?
I have inherited a postgres database where there are two identical indexes except for their order:
CREATE INDEX avail_time_ix ON table (availability_time);
CREATE INDEX avail_time_dc_ix ON table (...
