Questions tagged [performance-tuning]
Improving the performance characteristics of a database application or system.
0
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0answers
30 views
MySQL 5.1.73 Tuning for PHP5.6 Application [on hold]
I have a PHP5.6 application running Symfony 2.x, backed by MySQL 5.1.73. We are currently experiencing latency in our data tier during peak load. During normal operation we see about 2k queries per ...
1
vote
0answers
33 views
Different query plans for same In line Function [duplicate]
I am facing a potential parameter sniffing issue with an In Line function in sql server 2008.
Basically Given the below three queries (same function):
First Query:
DECLARE @SQL NVARCHAR(1000)
...
1
vote
2answers
41 views
Inline function Plan Properties in SQL Server 2008
Currently I use the below two queries to get some properties from the execution plan in stored procedures, the problem arises when I try to run it in a SQL Server 2008 version. Do you know if there is ...
0
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0answers
13 views
MYSQL 5.7 Online DDL (Alter) Statement causing Lock_Wait_Timeout : AWS RDS
We are not able to do updated code publish from application on MySQL 5.7 as it contains ALTER statement on the table which has more than 50 million records and application team escalated that most of ...
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0answers
28 views
Does keyset/cursor pagination scale query performance better than offset pagination?
I am seeing behavior where the query that powers my infinite scrolling list seems to be slowing down as the number of rows grow.
Naturally, I used offset pagination because the library I am using ...
10
votes
3answers
304 views
Converted a Scalar function to a TVF function for parallel execution-Still running in Serial mode
One of my query in was running in serial execution mode after a release and i noticed that two new functions were used in a view which is referenced in the LINQ to SQL Query generated from the ...
0
votes
1answer
22 views
mysql query with 1 derived table and 1 inner join takes forever to load
I tried removing some chunks of code little by little and found out that the condition inside the inner join is the devil. Can someone enlighten me on how to achieve this when I have like 10,000+ rows ...
0
votes
3answers
332 views
Make SQL query “latency proof”
I have developed an application which connects to a database over a WAN.
As long as I'm using the application on my local network, everything works fine.
When I connect over the WAN, the database ...
0
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0answers
32 views
What is the best compaction strategy for overwritable/mutable/upsert-able data?
Suppose I have a Cassandra table like this:
CREATE TABLE keyspace.last_modified (
category text,
subcategory text,
id text,
created_at bigint,
PRIMARY KEY ((category, subcategory, ...
4
votes
2answers
156 views
Slow checkpoint and 15 second I/O warnings on flash storage
Last couple of weeks we've been working on getting to the root cause of what could likely be the cause of the occurrence of these I/O issues and slowdown of the checkpoints.
At first glance it looks ...
0
votes
1answer
77 views
Do Indexes in the T-SQL Data Warehouse automatically go over and optimize into the SSAS Cube?
Do Indexes in the T-SQL Data Warehouse automatically go over and optimize into the SSAS Cube?
I am reading that applying indexes, will transfer into SSAS. I thought SQL and SSAS are totally different ...
0
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1answer
73 views
Performance Metrics: Columnstore Indexes vs SSAS Cubes [closed]
What has faster performance speed: Columnstore Indexes or SSAS Cubes? Are Columnstore indexes proven to be faster than SSAS cubes (SQL Analysis Services)? Have their been any performance studies ...
0
votes
1answer
34 views
Why these Two Queries performace so different?
This is Query 1:
SELECT
A.innings_no AS Inn, bowler, OT.Out_Name AS OutType, Runs
FROM
(SELECT
a.innings_no, a.striker, SUM(b.runs_scored) AS Runs
FROM
ball_by_ball a
...
0
votes
1answer
35 views
Need Help in extended events SQL Server
I have created an extended event as below. I want to know how to query the historical data using T-SQL to see the issues at particular timestamps. The trace is running as of now
CREATE EVENT SESSION [...
0
votes
2answers
35 views
does sequence of columns in where condition matters the sequence of composite key? in Oracle Database
here, In the code where exists clause contains all primary key columns in where, I want to know that the sequence of this columns in it, matters in query performance.
update temp_fd_dtl_svj a
set ...
0
votes
1answer
23 views
Filegroup: [primary] dbcc shrinkfile() need balanced extent counts per file when done
I'm working with a ~1 terabyte db, server 40+cores, memory 500G+, db files on SAN (no control over lun segments), the bottleneck now is file contention. Currently running 2014 but by final "release" ...
0
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0answers
7 views
Performance considerations for a standalone server running Postgres 9.4 on 8 CPU core with 47GB RAM
I'm running:
Postgres 9.4
8 CPU cores
47GB RAM
shared_buffers = 13.8GB
work_mem = 32MB
The server gets its workload from 6 web application nodes which connect using JDBC connection pooling. Each web ...
-3
votes
1answer
73 views
Partitioning and Performance of DB Table [closed]
After partitioning a table the performance of select queries returning large datasets degrades as compared to performance earlier. For small datasets there is no degradation. No change in index is ...
0
votes
2answers
80 views
What kind of SSD to speed up querying a lot of data?
For research purposes I am using a big MariaDB database (~500 GB) with 20 Tables (engine: myISAM) and around 9 Billion rows. Due to missing free storage on my Laptop (16 GB RAM), I put the data on an ...
2
votes
1answer
203 views
Empty Table: Insert into Table WITH (TABLOCK)
We have a clustered index table which is empty. Table has around eg: 20 columns, 50 million rows, around (40GB).
Is it best practice to apply Insert With (TABLOCK) for empty tables such as this? The ...
0
votes
1answer
45 views
Are these stats reasonable? If not, where should I start?
The below is the output result of mysqladmin for our mysql server which has been having consistent problems for months since we switched from a dedicated server to the cloud. In the switch, we ...
2
votes
3answers
713 views
SQL Server: Performance Insert Into vs Select Into
I am hearing different things from colleagues/research. What are good guidelines in performance for, Select Into vs Insert into when creating a temp table? I know difference is minimal for small ...
0
votes
0answers
15 views
any knowledge or experience with dynamic ax [duplicate]
I support a system called "dynamics ax" and sometimes my optimizer picks a good plan, drops it and then picks a bad plan (where the same code is been ran). users who usually wait for 10 seconds start ...
1
vote
1answer
56 views
oracle slow query with diferent user
I have a question with an oracle query that takes almost 20 minutes when it is executed from a schema and yet when it runs as sys users it runs in 1 second maximum ... how is this possible? ... I do ...
1
vote
1answer
102 views
Debug Connection Pool Error
I have been getting the below error.
System.Data.Entity.Core.EntityException: The underlying provider failed on Open. ---> System.InvalidOperationException: Timeout expired. The timeout ...
4
votes
1answer
208 views
why is this left join faster than an inner join?
So I'm tuning this query, and I am pretty sure that in this instance, I can replace an inner join with a left join without affecting the data. However, I'm not entirely sure why this is faster. Here ...
1
vote
1answer
62 views
When to Disable and Recreate Indexes in Data Warehouse ETL?
We are moving data from Staging Database into Kimball Data Warehouse DB.
I am hearing different ideas regarding when to disable and rebuild indexes.
Stage tables are truncated every day for each new ...
2
votes
0answers
52 views
Recommendations around managing large amounts of data that needs to be aggregated (SUM)
I am looking for alternatives to redesign a part of our system that needs to perform cumulative SUMs over large data sets of rows based on user and dates.
How the system works
We are running a web (...
-1
votes
1answer
107 views
Index vs Statistics [duplicate]
In SQL Server, when to create statistics only on a table column instead of index and when create to index (which creates statistics as well automatically)? I mean both improve query performance then ...
2
votes
2answers
99 views
Slow query that includes a WHERE clause with SUBSTRING
I have the following query in SQL Server 2016, as there is no code for the "enter code here" column, I had to do a search with SUBSTRING. But as expected it is slow, the query ends in 00:03:37.
with ...
4
votes
2answers
111 views
CXPACKET wait on SQL Server
Recently I am experiencing performance issue on a SQL Server database and I have two queries that show me the wait as shown below, one of the databases on this server is a member of Always On replica, ...
1
vote
0answers
75 views
pgbench - 20-30% variation in benchmark results (non-repeatable benchmarks)
Problem
I'm trying to use pgbench to help me tune Postgres for my hardware, but I'm seeing a very strange behaviour. I cannot seem to get a stable number for TPS in consecutive runs of pgbench. Since ...
0
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0answers
41 views
RAC DB Slowness - AWR Report
While going through the AWR report found that the row lock waits on indexes and buffer busy waits are more (rest of the stats look normal).
Could someone tell me if we can interpret by the below if ...
0
votes
1answer
125 views
sp_WhoIsActive waiting resource
I have a huge query in SQL Server 2016 – when I run the query for a subset of records, it completes in 15 minutes. When I extrapolate it to total number of records, it is supposed to be complete in 1 ...
0
votes
1answer
183 views
TSQL or SSIS for Direct Insert Speed Performance
I am moving data from Table A into Table B. Tables have the exact same DDL, table structure, and are straight inserts. We are Not transforming or modifying data.
If TSQL Server and SSIS have the ...
3
votes
1answer
162 views
Identify Query Waiting on resources
I have some query with CXCONSUMER wait time when i ran sp_whoisactive as shown in the screenshot below.
When i checked the status it is suspended.That means it is waiting for some process to release ...
1
vote
1answer
120 views
Microsoft Optimal method for columns into 1 word: XML Raw or Concat
What is fastest, performance method to make columns into one word? Does Microsoft have recommendation, or is there performance Big-O studies on FOR XML RAW vs Concat?
Company has multiple tables with ...
1
vote
2answers
230 views
Is NEWSEQUENTIALID unique within a database for Many tables?
Is NEWSEQUENTIALID unique within a database? We plan many tables in a database with NEWSEQUENTIALID, inserting simultaneously and want to ensure every guid will be unique, regardless if they are in ...
0
votes
1answer
72 views
powerful VPS but slow MS SQL- why? [closed]
VPS (Contabo) : 10 cores (Xeon E5 2.2GHz), 60 GB RAM, SSD, MS SQL Web Edition (configured to use 10 CPUs), Windows Server 2016
When running SQL takes ~32GB of RAM,
When I execute SQL a stored ...
0
votes
1answer
115 views
Update sys.job$ set this_date=:1 where job=:2 as one of the most time-consuming queries - oracle
I am currently helping some organization with their Oracle database performance. They are using Oracle 11gR2 Standard Edition in Windows 2008. As there are no enterprise performance packages ...
0
votes
1answer
41 views
Oracle 9i historical long queries since instance startup
please I would like to know any query that shows the queries or the top 10 queries that take more time to finish since the beginning of the instance with user and the sql sentence, I have seen several ...
0
votes
3answers
335 views
Create Slowly Changing Dimension table from Repeated Data
I am receiving transaction snapshot data from a file, it contains a history of repeated data. Currently trying to find Slowly Changing Dimensions on table with [ProductId] Business Key. Many ...
0
votes
1answer
83 views
Loading 400 Million Records into MySQL Hangs on “Sending Data”
I have a large dataset of approximately 420 million records and I was able to load them into a temporary table in a timely manner of about 15 minutes using a LOAD DATA INFILE statement. Super awesome. ...
0
votes
2answers
28 views
MariaDB “EXECUTE AS” or User Impersonation
With MariaDB, is there a way to impersonate a user execution context when connected with a higher privileged account?
For instance, when connected with a "MasterUser" execute a SELECT using the more ...
6
votes
2answers
399 views
SQL Staging Tables: Primary Key Clustered or Heap
We are taking legacy flat txt files and inserting them into stage tables with SSIS.The question arose whether table should have primary clustered key index or not. This is direct flat file import with ...
1
vote
1answer
181 views
SSIS Data Source: Embedded Queries, Stored Procedures, or Functions
We are moving data from OLTP server into Data Warehouse server, utilizing SSIS to conduct this.
When writing queries from the OLTP Data Source, it it better to utilize?
1) Inline Embedded queries
2)...
0
votes
2answers
35 views
Index columns on pre-production?
If I understand correctly, indexing a column will increase SELECT speed but decrease INSERT speed.
Say your app is new and you have identified columns which are good candidates for indexing (based on ...
0
votes
1answer
36 views
Query Locks Table And Takes Long Time to Run
I have a query that can take a long time to run. I tried running the same query in a test server and it runs very quick.
However, in production it seems to hang and causes blocking of other queries.
...
1
vote
1answer
39 views
SQL Except Statement and Add in One more column
How do I conduct a Except statement and Add in one more column?
Three tables with the exact same structure. (CustomerTransaction1,CustomerTransaction2, CustomerTransactionDiff)
I want the LoadDate ...
3
votes
1answer
335 views
Memory Pressure in SQL Server - Enable LPIM or not?
I have slow query execution in my SQL Server 2016.
Server configurations:
Total Physical Memory : 128 GB
SQL server Max Memory : 102 GB
Transaction replication is enabled.
Database Size:1.6 TB
...
