An evaluation of whether a system works well enough to be fit for purpose. Normally performance refers to the speed with which a system completes an operation or set of operations over time.

learn more… | top users | synonyms

1
vote
1answer
32 views

Perfomance of CREATE INDEX vs CREATE INDEX CONCURRENTLY in PostgreSQL

I know CREATE INDEX CONCURRENTLY is slower, but how many longer it will takes to finish in comparison with the traditional CREATE INDEX? 40% more or much more than that? I am creating an index in a ...
2
votes
2answers
173 views

Select the maximum aggregate value for a limited set of chunked/grouped rows in a large database?

I work on WordPress plugin which implements sitemap functionality. One of the steps is to build an index of sitemap pages for post entries. The logic required is roughly: determine last modified time ...
1
vote
3answers
131 views

Avoid repeated traversing of hierarchical data when parsing a big tree frequently

I have a hierarchical/tree data structure in Oracle/RDBMS where I need to traverse the tree frequently. The tree is huge and therefore parsing it every time will not be efficient. A better way could ...
1
vote
1answer
33 views

Security and Performance Implications of SQL Tuning Advisor

I work on a relatively small development team that works with an Oracle (11g) database. It's recently been requested that all the developers be given the Advisor role so that we can utilize SQL Tuning ...
2
votes
0answers
15 views

How does the use of derived tables speed up sorting?

In the article 45 Ways To Speed Up Firebird Database, it states that Use derived tables to optimize SELECT with ORDER BY/GROUP BY Another way to optimize SQL query with sorting is to ...
1
vote
1answer
149 views

How to find High CPU queries

CPU utilization is very high and the SQL Server process is consuming a lot of CPU. We have run few queries and notice that there are a few SPIDs taking a long time to complete and these queries may be ...
3
votes
1answer
121 views

.Net Application Using Inefficient Query Plan - caused by ARITHABORT setting?

One of our applications is causing a problem in that there is a stored procedure that returns fine in SSMS, in under 1 sec, but in the application its taking anything up to 10 minutes, depending on ...
2
votes
0answers
41 views

Loads of parallel inserts (OLTP) into heap table - Operation stops every now and then for 2-3 seconds

We got an analytics database and as new events are coming in we are adding them into our tempdb. From there we have backend processors that pick up the events and merge them into the right tables, i.e....
0
votes
0answers
17 views

Optimal Number of Queries Per Batch for SQL Server

I am optimizing an application for a scenario where it will import an sql file and execute over 11 million create commands, which have have some expensive subqueries that are outside my control. This ...
2
votes
0answers
99 views

High Performance Relational DB for Fast Read and Fast Write [closed]

I am looking for the best database solution for a high availability, high performance solution that meets the following requirements. Data being read, written and updated is very simple, and small. ...
0
votes
0answers
25 views

improve performance with schema design, a lot join

I'm making a custom cms system for my client, with postgresql, nodejs ... have problem with slow performance issue, when doing select data . (and it is still on localhost/mac nginx and just few data, ...
3
votes
1answer
46 views

Online text based game design - Am I linking the databases correctly?

I'm trying to recreate an old game that I used to play that went offline quite some time ago. I'm doing this as a hobby project for myself with the hope that maybe a few hundred people might enjoy it ...
1
vote
1answer
49 views

Slow MySQL query with Group by

I have a query that is taking a long time to execute minutes and more. The two tables orders and tickets have around 150k records. This is the query: SELECT orders.id, count(distinct tickets.id) ...
3
votes
0answers
57 views

Why would Stolen Memory counter be at a constant high? [duplicate]

I'm trying to understand memory stats a lot better and have been troubleshooting an issue with one of our SharePoint DB servers for a while now. Low PLE, frequent lazy writes, slow performance etc I ...
6
votes
2answers
180 views

ANALYZE TABLE..VALIDATE STRUCTURE runs forever

So, as I've mentioned before, I am a SQL Server DBA/Consultant who is helping out a customer with their Oracle databases. Mostly, I've been able to figure out what I need to and work through things ...
3
votes
0answers
49 views

Postgresql Filter Slows Query

I've got a query like this: SELECT count(*) FROM acs2014_5yr.geoheader as g JOIN tractcache as c ON (c.tract_id = g.state||g.county||g.tract) JOIN tiger2014.tract AS t ON (t.geoid = c.tract_id) ...
4
votes
1answer
67 views

Buffer Cache Size when Page Life Expectancy Drops

I'm troubleshooting an issue with one of our SharePoint databases, essentially huge drops in PLE which I think are caused by increased I/O activity (I see increased reads, writes and lazy writes at ...
3
votes
2answers
219 views

IN Clause - performance difference between listing values and query

I changed this query SELECT ... FROM linkedServer.DB.Schema.Table1 t1 LEFT JOIN linkedServer.DB.Schema.Table2 t2 ON t1.ORDER_ID = t2.ORDER_ID WHERE t1.BRANCH_ID NOT IN ( '009991', '009992', '...
1
vote
1answer
64 views

Does schema binding views affect performance?

Does schemabinding views affect performance in SQL Server or is just to prevent accidental changes?
23
votes
1answer
437 views

Logical reads different when accessing the same LOB data

Here are three simple tests that read the same data, yet report very different logical reads: Setup The following script creates a test table with 100 identical rows, each containing an xml column ...
1
vote
0answers
22 views

How to design for scalable set operations?

This is the requirement for an educational application to teach words to language learners: Learner can declare that he/she knows a given word Learner can memorize the given word (to be managed by ...
0
votes
2answers
86 views

Search entire database

Recently I was working on the database of an application that had no documentation and the database did not have any foreign keys. I needed to create a script to enforce a 10 year retention policy. It ...
0
votes
1answer
51 views

How to make a query on multiple columns without writting all possible permutations?

I'm at my first question on stackexchange, as i have a few days since I struggle on this matter: I want to make a complex query(PLSQL) on a table that has col1,col2,col3,col4,col5 having values like (...
0
votes
2answers
27 views

Quick and easy ways to check SQL/DB performance [closed]

We host a web application for customers, sometimes they call in and complain of slowness. I was asked to have a list of things to check from network down to the application. For SQL, can any suggest ...
0
votes
1answer
29 views

MySQL 5.6 performance_schema not showing queries from application

I'm seeing a strange problem with perfromance_schema... it seems queries are not getting logged as I expect them to be. For example, this is what I get: mysql> SELECT `SCHEMA_NAME`, `DIGEST_TEXT`, ...
5
votes
3answers
395 views

Why set Auto Update Statistics to False?

I've just inherited about 20 instances of SQL Server, as part of a wider acquisition project. I'm in the process of assessing performance and I don't like the way maintenance plans have been ...
0
votes
2answers
36 views

AlwaysOn Async read takes more time when compared to that of Sync secondary [closed]

AlwaysOn Async read takes more time when compared to that of Sync secondary (by a small fraction). Is this expected behaviour? I was under the impression that ASYNC must be faster than the SYNC.
4
votes
1answer
116 views

Slow Delete's of LOB data in SQL Server

I have a tables for logging, and a stored procedure to purge old data that has very slow DELETE performance, beyond what makes sense to me. I am looking for how to modify the tables or DELETE ...
0
votes
1answer
62 views

Maximum number of TEXT/BLOB columns per table/performance of table with many of them?

I've created a system that generically imports CSVs into a database table with metadata columns for keeping track of when a CSV record has been changed, and it allows filtering on CSV columns instead ...
6
votes
2answers
314 views

Are cursors/While loops the only way to make administrative changes to multiple databases?

I specifically want a programmable way to change the recovery model of all the databases on a server, and i know this solution can be applied to all 'Alter Database' commands. While I know SMO in ...
0
votes
1answer
71 views

Same query same data different server different query plan

I have a query that hits a view, which references other views etc...several levels down. The query plan is a bit complex. I run the query on 2 different servers. On both servers, the number of rows ...
3
votes
1answer
70 views

Amazing improvement of script execution speed when split - not understood

I have an ETL job that merges data into about 20 columns of a fact table, all integer non-null (default 0) columns. There are 8 merge statements to completely update all the columns and they involve ...
3
votes
1answer
78 views

Execution time with warm up cache

I have a query that takes around 1 second on first execution and 15-50 ms after running the same query again. The only difference between EXPLAIN outputs is that the second execution contains a lot of ...
1
vote
1answer
49 views

SPID Change for a process?

On SQL Server 2012 can a process SPID change mid-operation? We have a very unique query that we've been monitoring (production, but controlled testing) and have seen it at different intervals with ...
6
votes
2answers
181 views

Does table size matter?

I have a table like this (with more columns though): CREATE TABLE [dbo].[MyTable]( [SnapKey] [int] NOT NULL, [SnapDt] [smalldatetime] NOT NULL, [Company] [varchar](4) NOT NULL, [...
14
votes
2answers
398 views

LOB_DATA, slow table scans, and some I/O questions

I have a rather big table with one of the columns being an XML data with an average size of XML entry being ~15 kilobytes. All other columns are regular ints, bigints, GUIDs etc. To have some concrete ...
2
votes
2answers
79 views

Filtering UNION ALL result is much slower than filtering each subquery

(edit: see end for a simpler example) I'm searching in a table named "cases" (135k rows, 29 columns). Some of the rows in this table have a type of parent-child relationship (of different types), ...
1
vote
0answers
33 views

problem with column oriented dbms features

I am currently looking for a free(or at least low cost) column oriented DBMS with really good compression abilities (at least 10:1 ratio) and fast response time. Having evaluated multiple open source ...
0
votes
0answers
60 views

Sql Server Stored Procedure calling table-valued function - Performance

I'm using Sql Server 2012 and I have a stored procedure that does about 15 left joins and one of those joins is a CROSS APPLY to a table-valued function. The first 14 left joins are not gonna restrict ...
0
votes
2answers
26 views

Good reason to convert LONGTEXT column to smaller width if field is smaller?

We have a database that uses a LONGTEXT type for a column that does not need that much space. The maximum row size currently has about 6500 characters and that's with a few million inserts so it's ...
3
votes
1answer
81 views

Finding hash match aggregate

After reading following blogs, I understand that hash match aggregate causes blocking. Using appropriate indexes it can be made as stream aggregate. Blocking/non-blocking aggregate operators The ...
3
votes
1answer
97 views

Improving mongodb read throughput for tiny database

I am given to understand that MongoDB will essentially perform like it is pulling records from memory if the working set is small. I wrote a simple MongoDB test program that inserts just one record ...
2
votes
0answers
47 views

Clustered index on a fact table

I'm trying to work out what field(s) to use for the clustered index of my fact tables (which all have a similar structure). I'll use FactSales as an example: CREATE TABLE dbo.FactSales ( ...
1
vote
2answers
34 views

Mysql Query Take Longer To Prcoess On My Dedicated Server Than My Local Server

One of my MySQL queries takes a very long time to process on my live server compared with my development server. My live server (Windows dedicated server) is more powerful than my local (development) ...
2
votes
1answer
56 views

Possible causes that a MySQL/MariaDB query is slow under some table conditions

I am having a strange issue with a slow query under certain conditions: I have made a few tests and was able to isolate the issue to one single table called products_description (all the tables are ...
1
vote
2answers
52 views

Database logging optimization and maintenance in SQL Server

One of the Web applications I am working on, uses NLog to log debug and error context information in the database. Basically, it performs a moderate number of inserts (I appreciate some tens of ...
1
vote
0answers
53 views

SQL Server 2008R2 - BAK file backup performance issue

Just note I'm not a DBA or anything close to that. Problem: We are using SQL Server 2008 R2. We have 32 databases and backup to local disk (3PAR) using SQL Server maintenance plan. Normally it ...
0
votes
1answer
42 views

Storing mail in database, data type

I've found pretty poor informations about mail databases. My need is to archive mail messages downloaded from a normal pop3 or imap account: I am an ordinary user and I do not own the server, but ...
0
votes
0answers
47 views

Improving query performance involving similarity and full-text search

I have been trying to improving the performance of this query involving similarity and to_tsquery. I have a table (440,000 rows, PostgreSQL 9.5.2) with the following characteristics: test_db=> \d ...
3
votes
1answer
43 views

Performance schema: 'stage/sql/Sending data'

Background I am using MariaDB 10.0 but MySQL 5.6 answers are also of interest. Two machines cloned from the same image, same MariaDB configuration as far as I could tell, same dataset. One machine ...