4
votes
1answer
79 views

Why are simple SELECTs on InnoDB 100x slower than on MyISAM?

I have quite an annoying problem. I want to use INNODB as my main database engine and give up on MyISAM as I need the former for using galera-cluster for redundancy. I copied (description follows) ...
3
votes
2answers
194 views

Can I update every datetime in bulk?

The current database assumes all times are local to the user. Now we're changing this so the database stores everything in UTC and our application converts the UTC time in the database to the correct ...
1
vote
0answers
63 views

sql query takes too long to execute [closed]

I am having trouble with this query. It takes 10 hours to execute. WITH CONSUM AS ( SELECT C.ID_MEASURER,C.ID_MEASURING_POINT,C.CONSUM_TYPE FROM GCGT_RE_CONSUM_H_E C WHERE C.DAY ...
2
votes
2answers
57 views

Should I drop a foreign key if I use a soft delete?

"ON UPDATE" scenario never happens in my application. As soft delete is used, "ON DELETE" cascade and restrict scenario never happen as well now. Then, should I just drop foreign key because I have ...
0
votes
1answer
28 views

MySQL: What is SQL profiler, does it different for MySQL?

Whenever SQL profiling comes in mind, focus goes to two below sections: GUI tools like - MONyog, Neor Profile SQL set profiling =1; Execute Query; show profiles; show profile; I am really confuse ...
1
vote
1answer
77 views

MySQL: Which join is better between left outer join and inner join

Which join is better peforming if all of them provides the same result? For example, I have a two tables employees(emp_id,name, address, designation, age, sex) and work_log(emp_id,date,hours_wored). ...
0
votes
0answers
38 views

How can I decrease FULLTEXT initialization time?

I'm trying to decrease execution time of the a query. Using SHOW PROFILE, FULLTEXT initialization takes about 0.3, which is too high. Other values are at normal level. How can I decrease FULLTEXT ...
1
vote
2answers
44 views

Optimize rows to columns conversion

I have a big Oracle table (around 40 million rows) that looks like this: ID Name Question Answer Reason 3 Name1 1 Yes blah blah 3 Name1 2 No NA 3 Name1 3 ...
3
votes
2answers
57 views

SQL Server Baseline and Performance Optimization

I've been struggling a little bit around Performance Troubleshooting including baseline and troubleshooting of SQL Performance. Could anyone help with this or point me to where I can possibly get a ...
1
vote
1answer
104 views

Why is this second query more expensive than the first?

While reading Graph Databases book, I came across this excerpt: I can't figure out why the second query is more expensive than the first. Indeed, both filter on the Bob person. May anyone ...
1
vote
2answers
132 views

Optimizing large MySQL SELECT WHERE IN clauses

How can the following SELECT WHERE IN case be optimized? I have a table with over 100 million rows with only 3 columns. The primary key (col1) is a 127 varchar. I am performing a SELECT col1 WHERE ...
6
votes
5answers
539 views

Performance tuning a Great Circle distance calculation

I have a query that I am using to find locations that are within 1km of a known point. To do this, I am using the Spherical Law of Cosines formula with my latitude and longitudes. Currently, the ...
1
vote
1answer
64 views

Running queries directly on DB2 databases

Just have a general query, if it is really fine or safe to run long select queries on RDBMS production Databases specifically DB2? If NO, what are the major risks and issues in executing select ...
0
votes
1answer
51 views

How can I control the order of a query regarding to inner join

I have 3 tables. They have table_a 5m records table_b 20m records table_c 20m records I'm performing the query below. SELECT * FROM table_a a INNER JOIN table_b b ON a.a_id = b.a_id AND ...
1
vote
1answer
57 views

MySQL from table to table data transfer

I've got some problem with my MySQL. I have the database with many many data. Well, there is only one table actually with huge ammount of data, over 1 billion rows. For some reasons I need to create ...
0
votes
1answer
30 views

Why does AttachDBFile make everything slower?

In my ASP.NET app, I had tested a query against a 200.000 rows table with two connection strings, one connect to a remote SQL Server and once use AttachDBFile to attach to a database file in App_Data. ...
1
vote
1answer
58 views

Seeking help to test a use case on sql server memory

This is a question which came out of curiosity to know of how sql server handles memory. Assume I set a very low value for max server memory and I increase my workload like running dbcc checkdb, ...
1
vote
1answer
83 views

How to speed up looped INSERT INTO statements?

I currently use the following statement, for 10,000 rows it takes about 150 seconds. I tried removing the index on the target table, but this didn't help. Running the loop without the INSERT INTO ...
2
votes
1answer
82 views

Will adding more indexes speed up using RedGate SQL DATA compare?

We want to use RedGate's SQL Data Compare to migrate user data from one DB to a DB on a completely different provider. This will be a time-sensitive operation as we do not want our site offline for ...
0
votes
0answers
35 views

more queries vs storing results in database

Environment: Embedded (smartphones) Data Structures: Object Table A: id, field1, field2... Object Table B: id, field1, field2... Object Table C: id, field1, ... , Object A, Object B ... many ...
1
vote
1answer
136 views

Optimistic Paging and separate query for COUNT?

I am using SQL SERVER 2012 FETCH/OFFSET after searching a lot that this will give me the best performance. But for paging to work, I need a Total count. There are 2 ways to achieve this. 1) Paging ...
0
votes
1answer
46 views

How can I rewrite the following removing the date_format function?

I have a table with a column when that is of type datetime. I am doing the following filter which can not use and index: AND DATE_FORMAT(t1.when, '%Y-%m-%d') <= LAST_DAY(now() - interval 1 month ) ...
1
vote
2answers
63 views

Oracle result cache behaviour

Oracle by default caching the query results and function results(Buffer cache). I have noticed this with AutoTrace utility, where the physical reads are huge on first execution, but from next ...
1
vote
1answer
174 views

Inserting to table: Insert rows with Left Outer Join or Insert rows then Update?

I have a table of Orders and another table of Deliveries. The Orders table will contain a reference to the Deliveries table if there is a corresponding row. Not every row in Orders will have a row in ...
0
votes
0answers
41 views

Sql Server Standard VS Enterprise

I have been bench-marking SQL Server Enterprise and Standard, Enterprise is using Partitioning by month on the table. The table only has 3 fields, Date-time (DateTimeOffeset(3)), Value (integer in the ...
3
votes
2answers
145 views

Enhance performance of update query

I have a query that is running against a table with 50 million rows. The phone number is stored as a CHAR(10) and an ETL process is changing the phone number if it has certain values. We are seeing ...
2
votes
1answer
80 views

How to monitor load on database server

Could anybody please suggest me a way to monitor the load on my database server? What perfmon counters should I monitor on daily basis and confirm that load on the server is increasing day by day [or] ...
9
votes
3answers
2k views

When a previously-fast SQL query starts running slow, where do I look to find the source of the issue?

Background I have a query running against SQL Server 2008 R2 that joins and/or left-joins about 12 different "tables". The database is fairly large with many tables over 50 million rows and about 300 ...
11
votes
1answer
1k views

GO After every T-SQL statement

What is the reasoning behind using the GO statement after every SQL statement? I understand that GO signals the end of batch and/or allows the reputation of statements but what advantage does it have ...
0
votes
0answers
43 views

query comes in slow query when log_queries_not_using_indexes is enabled

This query comes in slow query log when log_queries_not_using_indexes is enabled. SELECT a.id, d.id AS city_id, d.city FROM booking a, sub_area_master b, area_master c, city_master d WHERE ...
0
votes
1answer
1k views

How index work in oracle? [duplicate]

I want to understand : How index work in oracle. How they are stored in the disk. How they increase the efficiency of a query? By third point I means how Index contribute to the efficiency of ...
1
vote
0answers
170 views

Postgres database zero down time production deployment

I need some idea about how I can deploy a financial application in production environment using PostgreSQL DB with zero down time. I have two servers in Master-Slave design. Currently I am giving ...
0
votes
0answers
133 views

Mysql View Performance on Aggregate Functions

I've a table that contains weekly statistical infos. ex. Society - Week - Year - Data AAA Inc - 1 - 2014 - 10250 AAA Inc - 2 - 2014 - 5235 BBB Inc - 2 - 2014 - 3210 ... Over this table i need to ...
6
votes
2answers
226 views

Should I nest dependent outer joins in SQL Server?

I have heard mixed information on this and am hoping for a canonical or expert opinion. If I have multiple LEFT OUTER JOINs , each dependent on the last, is it better to nest them? For a contrived ...
0
votes
1answer
228 views

What is the Difference between IN and Not IN performance wise?

I am new to database.I am having doubt that what is the difference between IN and NOT IN performance wise. When I am using IN, takes less time for the same query(Logically same query) when I use NOT ...
0
votes
1answer
208 views

Improve Insert performance for 200 Million rows

How can the following insert statement be improved - which varies from 20mins on certain days to 70-140mins on most other days. SELECT DISTINCT od.SourceID, od.OrderID, od.OrderLineNo, ...
0
votes
0answers
72 views

Order before Group

I have this query: SELECT HOTEL.hotelname AS NAME, HOTEL.`boardbasis` AS board, HOTEL.`engine`, HOTEL.`itemcode`, Group_concat(Round(((hotel.cheapestprice / 2) + ...
3
votes
1answer
47 views

How to show the related (suggested) keywords?

We do a program for cataloging images by assigning keywords (tags) to them. An image has the following keywords "John", "Jane", "Portrait". Another image has the following keywords "John", "Jane", ...
2
votes
3answers
326 views

MySQL query extremely slow after server restart

I am managing a very large database for a custom application I wrote to keep track of visitors. The DB server was rebooted for the first time in over a year - not even to install any updates, but ...
2
votes
1answer
73 views

How can I compare the server impact of transaction replication

We are developing a system that must extract data from an existing SQL Server 2008 R2 cluster. One of our design goals is to limit the performance impact on that cluster as much as is practical. ...
2
votes
0answers
48 views

Identical query & instance but other execution plans & performance [duplicate]

I have 2 identical queries . One is executed with parameters, the other is executed with hardcoded values. Somehow sql server is creating 2 different execution plans for the 2 queries. The first one ...
0
votes
1answer
148 views

Does the recovery model affect query speed?

Would using the Full Recovery model make something like a long running DELETE operation slower than it would be under the Simple Recovery model?
5
votes
1answer
152 views

Why would SQL cast have to be expensive if used on a join column?

I see that sql join internally functions always on some of the three basic operations : nested loops join, merge join and hash join. From multiple articles on the internet I see SQL casting is said ...
1
vote
1answer
119 views

Slow queries related to subqueries using aggregation

Here's a simplified version of the queries I am running: select ... from editions join edition_events on edition_events.edition_id = editions.id join events on events.id = ...
0
votes
0answers
156 views

how I can set tmp_table_size for 16GB long table?

I am posting the same question as I posted in SO, but somebody advice me to post it here. I have a 16GB big table with 8 partition. And RAM 4 GB. I am running a query - SELECT ...
0
votes
0answers
14 views

how I can set tmp_table_size for 16GB long table? [duplicate]

I have a 16GB big table with 8 partition. And RAM 4 GB. I am running a query - SELECT c.eveDate,SUM(c.dataVolumeDownLink)+SUM(c.dataVolumeUpLink) FROM cdr c WHERE c.evedate>='2013-10-01' GROUP ...
0
votes
1answer
44 views

Suggest performance tradeoffs

I have a an inner query that needs outer query column values as input. It looks something like this CREATE TABLE TISSET( COL1 int ,COL2 int,COL3 int) INSERT INTO TISSET VALUES (1,1,1); INSERT ...
0
votes
1answer
69 views

SQL Server 2000 Replication, Performance, and Query Priorities

I'm a developer and wanting to confirm the following: Does anyone here have experience with SQL Server Replication (transactional) on 2000? We are trying to convince the DBAs to allow this in a ...
0
votes
0answers
46 views

Recommended plan for 0min RTO and RPO

I have a Windows Server 2008R2 Server, running SQL Server 2008R2 SP2. The server currently only does a full backup once daily. The server's operational hours are between 8am and 5pm. The server's new ...
0
votes
1answer
64 views

Does size of one particular column in a database affect query performance?

I have a table user_list CREATE TABLE IF NOT EXISTS `user_list` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `username` varchar(40) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL, `email` ...