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.

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6
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125 views

How to do Statistics in Partial Indexes of PostgreSQL efficiently?

This answer motivated think again my following tables but I am still uncertain how to store variables/results from data analysis for quick selection in post-processing. If stored, I think it is well ...
5
votes
0answers
144 views

To partition or not to partition?

Having already read several questions on SO, external blog posts and manual SO: Foreign Key constraint to partitioned table in Pg dba.SE: Different ways of handling FK to partitioned table in Pg ...
5
votes
0answers
134 views

Measure SQL Azure Transaction Rate

We are on SQL Azure v12 Standard/S2 Service Tier and are not satisfied with the performance so I am trying to measure where the bottleneck is. I realize that we could be hitting the limits of the S2 ...
4
votes
0answers
147 views

Performance inner join vs left join involving parallelism

I have a query which takes about 8 hours to finish. Simplified, the query looks something like this: SELECT [Some attributes, inconsequential] FROM RBM.Financial_Events RFE INNER JOIN ...
4
votes
0answers
91 views

How can we improve this PIVOT operation? ( SQL Server 2008 R2 )

We have this query, that runs in 1:10. We need to improve this. This is just a test query, but we will implement this upgrade on our real query. select top 100 * from ( select codCliente ...
4
votes
0answers
2k views

How to properly monitor the number of PostgreSQL database connections?

I tried to use a Nagios script for monitoring the number of database connections on a Postgres database and I reached this problem: these are counted as currently open-connections and measured every 5 ...
3
votes
0answers
424 views

Slow inserts/updates into partitioned table with lot of partitions

I'm designing the partitioning for our new database, but we are facing performance issues in inserting or updating the partitioned table. For simplicity suppose we have one table T, which have an ...
3
votes
0answers
58 views

Why is a max degree of parallelism 1 recommended and used for Sharepoint in SQL Server?

I am new to Sharepoint, but I used to work with SQL Server a lot. I realized that Sharepoint changes some of the SQL Server settings to non default values. One is the max degree of parallelism, why ...
3
votes
0answers
297 views

Are there any known benchmarks/statistics on UnQLite?

I came across UnQLite the other day in Stack Overflow and it has me intrigued for some software I'm working on. However, very few tests have been published on how well it performs. There are plenty of ...
3
votes
0answers
317 views

Slow transactions, many locks

At high load conditions the server app stops responding to client because begin/commit statements are executing very slowly (some take 15 seconds). The queries are simple - insert, update two columns ...
3
votes
0answers
77 views

Can CTE sub-statements be prevented from executing at all?

Through this strategy, time consumed by queries for my application have dropped to extreme lows; however, some queries consume more milliseconds than necessary. The reason why is that upon ...
3
votes
0answers
131 views

Optimizing postgres row overlap constraints involving UUIDs and GIST

For various reasons all my tables have UUIDs as primary keys and I need to exclude duplicate rows where the combination of area_id, user_id, and finished_at <-> started_at window. The only way I ...
3
votes
0answers
74 views

Oracle - physical writes to an index

We have a large UPDATE (affects about 200K records) on a huge table (80M records). Due to a coding mistake, the UPDATE updates the same set of rows (200K) all over again with the exact same value. ...
3
votes
0answers
59 views

Sample a Mysql table to increase performance

we are storing all our clients traffic data in a MySQL 5.1.73 database (MyISAM) and then we use it to generate user and internal statistics/graphs, always searchinng for a client id and a date/hour. ...
3
votes
0answers
662 views

Do OR conditions in Oracle SQL queries spoil index use / cause full table scan?

I have a query on Oracle 11g of the following type, which results in a series of highly inefficient full table scans: select t.Id, t.ObjectId, t...[other Tasks columns] , od1...[ObjectData1 ...
3
votes
0answers
501 views

Poor performance in my pgpool cluster

I've configured a postgres cluster with pgpool2 using the following link. The replication seems to be ok, but I ran some benchmarks (pg_bench) and the performance is lower than a single node, for ...
3
votes
0answers
556 views

Fastest way to get the length of the intersection of two text arrays in PostgreSQL

This is what I am currently using: CREATE OR REPLACE FUNCTION array_intersect(a1 anyarray, a2 anyarray) RETURNS anyarray AS $$ select array ( select unnest($1) intersect select unnest($2) order by 1 ...
3
votes
0answers
2k views

Oracle high Paging Faults

What are the reasons that lead to terrible high Paging faults. The following is the topas information and background about the Environment. OS: AIX 6.1 Softwares: Oracle 11gR2 Paging Space:30720 ...
2
votes
0answers
42 views

Error in loading data using DB2 load command in DB2 10.5

I have a IBM DB2 database in our application. We have a monthly Java batch process which loads data in the tables using "load Replace" sql command. Around millions of record will be updated every ...
2
votes
0answers
24 views

Implications of many materialized views in Postgres?

I'm working on a system that includes a scheduling component, which has support for recurring events. After reading many, many posts on storing recurring events, it was suggested that they be ...
2
votes
0answers
57 views

Postgres: CREATE INDEX, but very slowly, to reduce performance hit on rest of database?

I have a large production PostgreSQL (9.1) database running on Ubuntu Linux. It is currently being queried and used. However there is another use I need later, and I will need to create a large ...
2
votes
0answers
46 views

Simple insert with Wait_Info = WRITELOG()

We have a query ( the same as some questions I made here ). a simple insert: INSERT INTO [My_Ttable]([IDChamada],[Evento], [Resposta],[IDTarifador],[ProximoEvento],[NomeDaMaquina],[DataMaquina]) ...
2
votes
0answers
58 views

Query that can benefit from index, cluster or hash-cluster

I'm trying to find a equi-join query that shows a decent performance bump when I use an index, cluster or hash-cluster structure on my data. I initially need to run the query on unstructured data ...
2
votes
0answers
36 views

SQL Server Performance : isolate different databases under same engine

I have SQL Server 2014 installed onto a machine with two different users and two catalogs, each of them accessed by a different user (each user is strictly tied to his catalog). Is it possible that a ...
2
votes
0answers
93 views

Transaction log bloat when writing to table on replicated database with parameterized filter

We are observing abnormally large log writes whenever we update a table that is used for parameterized filter in a merge replication. There are a number of join filters as well. When executing a ...
2
votes
0answers
81 views

Performance Implications of Explicit Collation Conversions across Linked Servers

I locally host host databases from two vendors on two different SQL instances, but on the same network. These servers frequently communicate with each other (through joins and whatnot), so we have ...
2
votes
0answers
64 views

Is it possible to trace queries that never complete with SQL Server 2008 R2?

Running SQL Server 2008 R2. We have some queries that typically take less than one second to complete, but, occasionally, they are taking longer than 30 seconds which causes a client timeout. ...
2
votes
0answers
195 views

Case Statements, subqueries, and datediff

First time posting on this website so please let me know if you require any other information. This first section of code worked perfectly and resulted in correct information. [Field 1] = (CASE ...
2
votes
0answers
2k views

How to resolve RESOURCE_SEMAPHORE and RESOURCE_SEMAPHORE_QUERY_COMPILE wait types

We are trying to figure out root cause of slow running sql server queries hitting/fetching data from one of the database , size 300 GB, hosted on server with below configuration: Windows server ...
2
votes
0answers
73 views

SQL - Optimize table population with dynamic queries

I need to optimize the following pl/sql procedure. So, fundamentally my question is: There is a way you can do a bulk insert in a pl/sql that could be more efficient than loop through an associative ...
2
votes
0answers
280 views

Excessive CPU Usage caused by long running query?

We have been getting intermittent excess CPU usage at 100%. There is not a whole amount running on the system. We also get warning of Batch Requests/sec above threshold.: 1030, which would seem to ...
2
votes
0answers
178 views

Oracle: separate column histograms for partitions

I have a partitioned table like MY_TABLE(PART_KEY, DATE_KEY, ...) with a local partitioned index on (PART_KEY, DATE_KEY). When I collect stats on the table, I end up with a HEIGHT BALANCED histogram ...
2
votes
0answers
154 views

Find Most active databases that can be offloaded from a busy server

I am in the process of identifying the most active databases on the server and will be moving the databases off the current server to alleviate the load. The reason to do it is that our servers are ...
2
votes
0answers
1k views

Mysql slow writes

i have a strange problem with mysql. My selects goes fast. My insert/create/delete/drop/update go very slow. I have done some tests on 2 machines. My old machine and my new machine. Old is worst ...
2
votes
0answers
80 views

Performance of database with transactional data

There are lots of row modifications (several thousands of rows per minute) in our PostgreSQL database that stores transactional data. We have a problem because PostgreSQL runs vacuuming process and ...
2
votes
0answers
626 views

How to calculate running total based on dynamic values?

I need to calculate the running total in which the target column is changing along with the time. Its something which aws does. Charging based for only what you use. So how do I aggregate sum of ...
2
votes
0answers
91 views

How can one improve the performance of a query that selects on a low cardinality column in MySQL?

I have a "State" column that has a low cardinality (three possible value), on which most of my queries perform an equality selection (WHERE col = 'blah') AFAIK you need something like a bitmap index ...
2
votes
0answers
831 views

MySQL: Improve performance for one row insert into table with unique constraint

I have a table with ~ 40 mil records, with a unique index on the url collumn, of type varchar(255). Now the insert speed is about 30/s, is this expected? how could I improve it? I can't use bulk ...
2
votes
0answers
140 views

How To Analyse Index Scans

I am using merge replication with SQL Server 2012. During a sync using a merge agent there are a large number of index scans. I can see this by running a profile capturing SCAN:Started and ...
1
vote
0answers
11 views

Improve performance of query with multiple group by column and count function in select

Brief Background of issue We have a aggregate table to store activities of competitors and this table have currently 3 Million activities and we need to retrieve data from this table group by ...
1
vote
0answers
20 views

Disable/Remove Table Index for INSERT Performance

I am doing a database maintenance where I have to add new fields to a table with over 10GB of data about (20 million rows). To solve that I renamed tableA to be old_tableA and created a new table ...
1
vote
0answers
47 views

MySQL 5.6 Performance Tuning Issue

I have read and try lots of things about MySQL optimization and tuning. I tried most of them one by one according to our needs but nearly I got nothing. I am doing my test using some simulation ...
1
vote
0answers
16 views

PostgreSQL: Improve system performance, KNN modification with GiST Index

In my PostgreSQL 9.5beta2, Postgis 2.2.0 compiled by Visual C++ build 1800, 64-bit I am running a Nearest-Neighbor-Query with the additional complication of unique assignment. I am running this on ...
1
vote
0answers
37 views

SQL Server 2012 AG replication issues

We just went away from SQL Serer clusters in SQL Server 2008 to SQL Server 2012 with AG – have five servers with replicas in a secondary datacenter and syncing over a dedicated eline/LAN layer 2 ...
1
vote
0answers
33 views

Multiple columns VS one big-capacity-column?

I have a table like this: // table_A +--------+---------------+------------+ | id | short-text | long-text | +--------+---------------+------------+ int(11) varchar(200) text ...
1
vote
0answers
28 views

PostgreSQL long transaction on a table performance

We have a long processing pipeline running on PostgreSQL 9.0. Is it faster or slower to perform many operations on a single table within one transaction, versus doing auto-commit for each operation? ...
1
vote
0answers
33 views

Improving PostgreSQL cluster performance

I am trying to cluster my table faster. The table is 27 GB worth of data, and has one index using a point geometry which is 19 GB in size. I am seeing about 5.5 hours to cluster the table. I am ...
1
vote
0answers
24 views

PostgreSQL: labels vs columns

I have a data structure similar to this: date foo bar baz boo ---------------------------------------- 2015-11-18 1 null 2.5 81.0 2015-11-19 1 78.4 12.8 ...
1
vote
0answers
73 views

Mongodb Huge Number of Open Connections and Write Locks

We are seeing around 800 open connections to our Mongodb. To clarify our issue: We have 5 different clients who write the data into Mongodb. Each of these clients - write four different type of ...
1
vote
0answers
49 views

Inexplicable differences between 2 almost identical databases on the same server

Our situation is as follows: We've got 1 MySQL (5.5.44) database server. The server hosts 2 databases. 1 database is the production database. The other is a copy database that gets copied from ...