MySQL database and SQL: Working with Table Fragmentation

You may already know that a table that only undergoes a whole lot of insert operations doesn’t face fragmentation in MySQL database and SQL. Generally, this takes place through an update or a delete operation.

 

Such tasks leave behind gaps among the information that remains in the table and that is the true cause of table fragmentation. Moreover, the database doesn’t immediately replace these spaces that non-insert DML commands liberate.

In this blog, we will discuss how the database management system handles this space for the tables.

MySQL SQL Performance Tuning: Managing Table Fragmentation

In some cases, row storage isn’t contiguous or the rows are divided across multiple blocks. Both of these negatively impact the database, so you will need MySQL SQL performance tuning to reduce the requirement of additional block accesses.

Keep in mind that table fragmentation and file fragmentation are two distinct occurrences. Table fragmentation involves the application of many Data Manipulation Language commands. This is because the resulting free space does not get released by the DML from the table, except if it is under the High-Water Mark (HWM).

High Water Mark is a measure of that DBMSs occupied blocks. Those that lie under the HWM may or may not have data at the moment but they have held it at least once. The database is aware that blocks over this indicator have never contained data. It is why it only reads those that reach up to the HWM during a complete table scan. This value can be reset by a DDL query.

 

Why Table Reorganization Can Help MySQL Database and SQL

This particular task helps deal with three major problems with MySQL Database and SQL:

 

●      Too many chained or migrated rows

●      Sluggish table response time

●      Wasted old space due to non-uniform table growth

There are certain ways to locate a majority of fragmented tables. Look for tables that have a sizable difference in their expected and actual sizes. Such differences usually occur thanks to table fragmentation or old stats that haven’t gone through updates.

If you want to determine and eliminate table fragmentation, you may follow the steps explained briefly below:

1. Bring together important table stats, such as the actual size and stats size. These will help you calculate the exact difference between the two and help you identify the presence of fragmentation. You will require updated stats in dba_tables for this purpose. To verify whether the stats are new, you can go through the last_analyzed value or try collecting table stats.
2. Find out the current table size- if it is smaller than its older size, you can tell it has undergone table fragmentation.
3. Other signs you can look for in the table include the overall size of the table (with fragmentation), what size you may expect in the absence of fragmentation, and the percentage size the DBA may regain once fragmentation is removed. You will require the table and schema names for this.

Final Thoughts

You can still gain performance-related advantages from a large number of fragmented tables with the help of the steps mentioned above.

These will enable you to collect all the necessary statistics that will inform the optimizer on how to build the most favorable execution plan. The plan will ensure MySQL SQL performance tuning for better results during statement execution. 

The Best Ways to Ensure Proper PL SQL Performance Tuning

 

There are many things you can do as a database professional to ensure your PL SQL code runs as it should. Therefore, in this article, we will talk about some good coding practices and offer advice regarding PL SQLperformance tuning.  

The tips presented in this post are extremely reliable; in fact, top experts and experienced database technicians recommend them. They have been aimed at enhancing the execution time and getting the code to run optimally. 

The code you have to tune has to take the least time to run. This is particularly important when the statement consists of several rows and the function is present in a SELECT clause. In such cases, the DBA first analyzes the nature of the function and then checks to see whether the database views will prove more productive. 

The goal behind any kind of optimization, including Oracle SQL performance tuning and optimization, is to prevent users from facing any issues or wait times when using the database. 

In case the function mentioned above has a reference in a WHERE clause, it is important to look into it further. This will help the DBA determine if a function-based index will help run the SQL faster. 

It is also essential to carry out proper coding methods and practices when it comes to functions. That is because functions work best when they only contain a single RETURN clause in the regular (Begin) area present in the code. They can make use of purity features to reduce or eliminate side effects. 

The next thing to consider is tuning every SQL call because SQL, when getting executed from PL/SQL, results in some extra overhead, known as a context switch. The SQL and its output find their source in the SQL engine which is why PL/SQL must request for every row from SQL. 

Several experts are willing to educate newcomers for PL SQLperformance tuning and it certainly helps in this regard as well. They also mention bind variables to boost cursor reuse and decrease hard parsing as much as possible. However, experienced professionals advise against using them too much as they might cause other issues in the execution plan. 

Another element that steadily reduces performance is the bulk processing of information. This is especially true if IN OUT or OUT parameters come into play. For this, it is better to use the NOCOPY alternative that allows the database to pass pointers rather than the entire information itself. That said, the best thing to do in these instances is to simply place all the routines in one package so nothing has to be passed!

Collections have also greatly improved in Oracle.  For instance, the BULK COLLECT and FORALL features have become much quicker and have now proven to be the answer to row-at-a-time processing. Moreover, Oracle prefers hitting rows that don’t contain null values, and certain methods, such as the FIRST, the NEXT, and the LAST method, tend to skip null rows. 

DBAs recommend another tip: to keep loop code as short as possible. Combined with good coding methods and single result set processing, this strategy is extremely helpful in Oracle SQL performance tuning and optimization. Also, developers should try not to use EXIT while they are inside the FOR or WHILE loops. 

A majority of experts consider this to be poor coding because it mostly results in unexpected behaviour. The better thing to do is to make use of a single EXIT command and leave the loops simple. It doesn’t only make coding and executing easier, but it also simplifies maintenance in the long run. 

Want to use the FOR loop? You can do it, but avoid declaring the FOR loop subscript. In case it already has a declaration that isn’t a PLS_INTEGER, Oracle will find it necessary to turn it into this format before it executes every single iteration of the loop. For instance, declaring the “i” in “FOR i IN…” will waste time in conversion. 

The key to ensuring lasting results in SQL performance tuning is to use recent coding technologies as they are introduced. It is useful because it will improve the consistency of your code in conjunction with coding practices that exist in other languages. 

Additionally, it becomes more convenient for the Database Administrator to modify the code when they know other experts follow the same practices during code maintenance. For example, all C programming languages have Boolean logic in common. This is why it’s vital for database professionals to conform to certain practices and techniques that will also ensure consistent performance throughout various databases.

Find Out Some of The Benefits of Oracle Database and SQL

 

There are many benefits of learning Oracle and SQL that help you manage data. Oracle and SQL can improve workflow in your company. Many big companies hire data analysts to record, analyze and disseminate data. They are required to have a complete understanding of the goals of the company to use the data. With the help of the SQL programming language, You can manage information and data the way you like. In this article, you will know about the benefits of Oracle database and SQL and learn why it is essential in these times. 

On the other hand, the Oracle database is a unit to retrieve related information to manage data in an environment with many users. Its database server can prevent unauthorized access and provide efficient recovery solutions. It is one of the tools to solve the problems related to information management. Oracle database is the first step towards enterprise grid computing and a cost-effective way to manage information and applications. It can create large pools of industry-standard where you do not depend on large pools of industry-standard and servers.

With the robust architecture, every system can rapidly take peak workloads. The capacity can be allocated from the resource. With the help of Oracle Database and SQL, you can manage your data in a better way. This type of database has logical structures and physical structures that won’t affect access to storage structures.

Advantages of My SQL Database and SQL

Oracle Database and SQL offer different methods of improving the company’s database. However, you can use other servers on the same database with the cluster feature to increase processing power at the same price. It can increase the price and gives you some options to find a suitable database at the price of the server.

Additionally, MySQL Database and SQL are versatile and can run in any operating system. For instance, when you run SQL Server on a window-based machine, it can benefit the way Unix work and keep the standardization of SQL. Unix is not affected by any viruses and can keep the information secure. You can also upgrade it in the future and retain the same data.

Another feature of Oracle is useful for restoring database files during downtimes and outages. It supports online archiving and recovery and is called a user-managed recovery supported by it.

It also uses real application clusters over traditional databases servers due to many reasons. It can scale the database in many instances. It can minimize data redundancy and availability.

SQL allows you to cut needless spending and get on the point when it comes to storing databases. It is not wrong to say that it is an efficient solution. If you are well versed in SQL, you can store and track all essential data and use it effectively.

Some traditional database solutions may track things one at a time, but SQL is not like that and provide data in one place. SQL also allows programming commands and does data analysis to update information whenever needed. In a nutshell, it can streamline data analysis that was not possible earlier.

Learning SQL definitely has many advantages and it helps you stay in touch with changing technologies. SQL language knowledge can help you to lead in the future and gain success. No matter what you want to do, there is no particular time for you to start learning the SQL language. Whether you want to start all over again or enhance your professional skills, you can learn SQL language and move ahead in your career!

Optimization of SQL Queries: Cons of Multiple Storage Engines

Among the big advantages advertised for MySQL includes support for several storage engines. This seems like an excellent advantage at first glance because users gain the advantage of using the same high-level SQL interface, enabling them to save their information in numerous ways.   

Though it may seem quite useful, this advantage comes at a high expense in terms of performance, growth, and operational intricacy. In this post, we will discuss just a few challenges of this particular feature.  

Cons of Multiple Storage Engines in Oracle\MySQL Databases 

Consider the following setbacks due to the support provided for multiple storage engines in Oracle queries - 

• Conversions – Every storage engine contains its unique format for storing data, so MySQL performance tuning requires plenty of copying and conversions when it needs to access the information. This has a substantial impact on performance in comparison with a “zero-copy” design, where users may stream information from memory when it can be accommodated there. Optimizer and Execution Storage engines are not created equal especially if you look at In-Memory storage engines vs Distributed ones. 

• Managing many different instances in query optimizer - Certain tasks and cases like clustering by The primary key in Innodb, the memory-based characteristics of the MEMORY storage engine and the distributed nature of NDB tend to get more complicated than necessary. This is due to the need to cater to several use cases that keep MySQL from exploiting the proper performance potential of either of the storage engines. 

• Integration and Synchronization - The upper-most level at the MySQL side that includes .frm and binary log files require synchronization with storage engine transactions. This, in turn, takes up significant performance overhead and gets rather complicated. Also, despite MySQL doing numerous fsync() calls for each transaction commit just to remain on the safe side, many tasks still aren’t completely safe. For example, .frm files can be retrieved from the internal data dictionary in case of a crash at an inopportune moment. 

• Transaction Assistance - There are several combinations of locks that users need to manage on higher levels and inside storage engines. They also have to deal with varying locking strategies owned by storage engines, which can lead to plenty of surprises if they choose to venture into the cross storage engine transactions.

• Backup - Backing up data across storage engines can be frustrating due to their differences. While some of these storage engines are distributed, others use the memory, which means even versatile approaches such as LVM backup could fail in some situations.  

Query Optimization & Multiple Storage Engines - Final Thoughts

It is interesting to note that a single storage engine is more than sufficient for over ninety-five percent of applications that use SQL tuning for Oracle. Moreover, most users already prefer to use only one storage engine instead of mixing multiple of them because of the hindrances mentioned above. 

At the same time, this doesn’t mean users should give up flexibility altogether. For instance, administrators can enable InnoDB tables that don’t log changes, which will increase the rate of update operations. They may also lock those tables in memory to make sure the in-memory performance doesn’t get unpredictable.

Oracle Database and SQL: Know More about Them

Prior to our discussion about the various functions and features that databases have to offer, we need to understand what they are and why we require them in the first place. This blog is aimed at discussing all these aspects in order to develop a sound understanding of Oracle database and SQL performance tuning in the long run. 

What is the Oracle Database and SQL Required for?

Data on a computer needs to be stored somewhere in order to be accessed whenever it will be needed in the future. From basic information related to the goings-on at a retail store, such as employee information, customer’s purchase history, transaction details, etc., to the employee records at an organization, data can be stored in different formats depending on the nature of the information - letters, digits, audio, video, images, and so on. 

One of the first ideas to occur in terms of data recording is opening up a spreadsheet. However, large amounts of information are much more convenient to store in a way that makes it easier to access any piece of it within a fraction of a second. 

And that way is a database. Moreover, when you have thousands of records to store at a single place, where some of that information may also be sensitive, you need a mode of data storage that is not only safe for private data but also prevents you from entering the exact same information repeatedly (duplication of data). 

A database is a well-organized system of storing your data with a set of rules decided by the user. The rules and structures defining the data are shifted as per the organization’s requirements. For instance, some may need to store a greater amount of data, whereas others may not have a large quantity of data but the amount of information that they have is sensitive and needs protective measures.

These aspects are managed by the database in the background to ensure that the data is completely secure and accessible only to certain individuals with the right credentials. Also, data integrity is established along with reliable means to retrieve said information in a fast, reliable manner. Such a robust way of storing information makes Oracle database and SQL a useful means of storage for business organizations of all sizes, which is also because of its ability to serve several users simultaneously and keeping data safe in case of hardware and technical difficulties that lead to system crashes. 

Oracle Database and SQL: Performance Tuning for DBMS

In larger organizations, it is common to own multiple databases, and a database management system like Oracle database and SQL is one of the best ways to conveniently manage them at the same time. Like databases, one organization can also have more than one DBMS due to their varying features and the organization’s specific requirements in each department. 

The following are some of the different types of Database Management Systems available these days - 

• RDBMS (Relational Database Management System)
• NoSQL Database System
• Object-Oriented Database System
• Network Database System
• Hierarchical Database System

RDBMS like Oracle database and MySQL is the most commonly used ones by organizations at present. They do a lot to improve data operations in an organization but need to be ‘tuned’ from time to time. 

This basically means that their performance can be affected by a few factors which experts knowledgeable in this regard, known as database administrators, are tasked to keep an eye on. SQL performance tuning is easy with the help of tools designed specifically for this task, such as those by Tosska Technologies Limited.

SQL Plan Management Oracle- How to Create SQL Plan Baselines

Have you ever experienced performance regressions because of some drastic changes in the execution plan? If so, then we have brought to you a smart solution known as SQL Plan Management (SPM). SQL plan management Oracle is a deterrent mechanism that allows the optimizer to automatically handle execution plans while assuring that the database utilizes only verified and known plans.

The execution plan mainly changes because of several system changes. For instance, you might have changed a few optimizer-related parameters or updated stats for some objects manually or automatically. The more substantial change is the database upgrade. These changes can lead to the generation of new execution plans for many of your SQL statements. While some new plans are improvements, some of them are worse that leads to performance regression.

SQL Plan Management (SPM)

SPM enables database users to manage stable yet optimal performance for a set of SQL statements. Further, it incorporates the positive features of plan stability and adaptability, while simultaneously dodging their shortcomings. SPM has two key objectives:

●Offering performance improvement by gracefully accepting database changes, and

●Preventing performance regressions in the face of any changes in the database system. 

A managed SQL statement has an enabled SPM system. SQL plan management Oracle can be controlled manually either partially or wholly or be configured to work automatically. SPM prevents performance regressions by allowing the detection of plan changes for managed SQL statements. For this purpose, SPM manages, on disk, a plan history that comprises distinct execution plans generated for every maintained SQL statement.

Oracle optimizer’s advanced version, SPM aware optimizer uses, accesses, and manages information stored in a repository called the SMB (SQL Management Base). The plan history lets the SPM aware optimizer to identify whether the produced best-cost plan utilizing the cost-based method is a brand new plan or not. A brand new plan outlines a plan changes that can cause a performance regression.

The SPM aware optimizer doesn’t pick a brand new best-cost plan. Instead, it picks from a set of accepted plans called an SQL plan baseline that represents a subset of the plan history. These accepted plans have been either designated to hold good performance or verified to not cause a performance regression. A brand new plan is combined with the plan history as a non-accepted plan. Later, an SPM utility determines its performance and holds it as an accepted plan if it improves the performance or as a non-accepted plan if it reduces the performance.

The plan performance verification method ascertains both plan adaptability and stability. A SQL plan baseline can be created in several ways-

1.     Using a SQL Tuning Set (STS);

2.     From the cursor cache;

3.     Using a staging table; and

4.     Automatically.

SQL plan baselines from STS

If you are upgrading your Oracle Server, you might have an existing STS containing some or all your SQL statements. This STS might include a plan that works satisfactorily.

SQL Plan Baselines from the Cursor Cache

For any cursor that is present in the cache, SQL plan baselines can be automatically created. This lets you create SQL plan baselines for all every statement whose text is similar to the specified string. Various overloaded variations of such function enable you to filter on other cursor features.

SQL plan baselines using a staging table

If you have SQL plan baselines, you can export them to another system. Firstly, create a staging table and pack the SQL plan baselines you need to export. This will pack all SQL plan baselines for statements that match the certain filter. MY_STGTAB, the staging table is a regular table that you must export to the production system with the use of Datapump Export.

On the production system, for creating the SQL plan baselines, you can now unpack the staging table. You must note that the filter for unpacking the staging table isn’t mandatory, it’s optional. Plus, it may be distinct from the one utilized during packing which implies that various SQL plan baselines can be packed into a staging table and selectively unpack only a subset of them on the target system.

Creating SQL plan baselines automatically

SQL plan baselines can also be created automatically for every statement that is repeatable by setting the parameter optimizer_capture_sql_plan_baselines to TRUE (Note: default is FALSE). For any statement, the first plan captured is accepted automatically and becomes part of the SQL plan baseline. Therefore, you must enable this parameter only when you are certain that the default plans perform well. The automatic plan capture mode can only be used when the previous database version is upgraded to a new one.

By now, we expect that you have understood how SQL plan management oracle can be used to create SQL plan baseline. Also, SPM is one of the best oracle SQL query optimization techniques that avoid performance regression.

Top 5 Best Practices To Improve SQL Database Performance Tuning

Database Tuning refers to a group of activities used for homogenizing and optimizing the performance of a database. Usually, it protrudes with query tuning but describes the design of the database files, configuration of the databases’ environment such as CPU, operating systems, etc., and configuration of the DBMS (Database Management System) application. 

Mainly, the database performance tuning is done to maximize the use of system resources so that application or the system works faster and efficiently as possible. Most systems are designed in a way that they can manage their use of system resources. However, in order to improve their efficiency, there still exists room for improvement which can be done by configuring the database and the DBMS and customizing their settings.

Today, we are going to learn some of the best practices implemented by the DBAs and developers to improve SQL query performance or database performance. Here you go-

Creating Optimized Indexes

Indexing acts as a backbone for any RDBMS (relational database management system). No index directly impacts the functioning of a SELECT statement, while the queries will slow down if you put an excess of indexes. The fields and their order in indexing play a vital role during the database performance tuning. While indexing, the most important information to consider is the number of unique values present in a column of the table. For instance, thousands of first names in a column might maximize specific SELECT statements but it also introduce extra index retrieval time due to the big index pages. Therefore, it’s essential to optimize the index to balance between the two processing times. 

Pre-determine the Expected Growth

Indexes create a negative impact on DML (INSERT, UPDATE, and DELETE) queries. When an index is created, the data for indexed columns gets stored on the disk. When the values in the indexed column are changed or new rows of data are inserted into the table, the database needs to reorganize the data storage to create room for the new rows. The reorganization of data storage can take extra troll on DML queries. However, if you need new rows in any table on a frequent basis, you need to specify the expected growth for an index. Also, the terminology for the predetermined growth varies in every database.

Select Limited Data

The less data you retrieve, the faster the query runs. Instead of filtering on the client, add as much filters you can on the server-end. As a result, less data will be sent on the wire and you will get results much faster. Try to eradicate any computed or obvious columns.

Avoid Foreign Key Constraints

The term is mainly used for ensuring data integrity. But, in turn, it affects the performance of your database. So, if your first priority includes performance, you need to modify the process of database performance tuning. The best example of a database avoiding the foreign key constraints is the system tables containing meta-data information about the user databases. However, it is seen that most users are concerned about data integrity. In such cases, they perform the data integrity process in the application layer and use foreign key only in development or QA environment as an error detection feature. This method will not affect the database performance and the data integrity is also protected. 

No Indexes before Loading Data

Dropping indexes on a table before loading a large quantity of data allows the INSERT statement to run faster. Once the insert is completed, it can be re-indexed. You can use a temporary table to load data when thousands of rows in an online system is being inserted. Also, ensure that this temp table doesn’t contain any index. 

SQL Performance Tuning for Developers: 3 Practical Tips

When you are working with large scale data, then even the most minor change made by you in the database may have a dramatic impact on the performance. The impact could be both positive and negative. In such situations, SQL performance tuning can be an incredibly challenging task.

Typically, a Database Administrator or DBA handles most of the SQL performance tunings in mid-sized and large companies. However, most of the companies with DBAs strive hard to work in sync with developers. The problem-solving modes of both the teams are different which often leads to conflict among the co-workers.

As a result, companies have to depart them and let them work separately with their own techniques. However, for better performance tuning, both teams need to work together for an effective result. In this blog, we are going to learn three important tips that will help in tuning SQL performance tuning.

Top Three Experimented Techniques for SQL Performance Tuning

 Without much ado, let us look at these three important tips to tuning:

Tip 1: Generation of an Actual Execution Plan

An SQL Server Management tool is crucial for generating graphical execution plans as well as for creating indexes. One can generate the actual execution plan only after the queries run. But the question arises- how will you generate it?

You need to simply click on ‘Include Actual Execution Plan’ or CTRL + M before running your query. Later on, a new tab will appear namely ‘Execution Plan’ where you will find a missing index. Ultimately, you have to right-click and select the ‘Missing Index Details’ in the execution plan and you’re all done.

Tip 2: Indexing

Through indexing, you can effectively tune your SQL performance. However, most of the developers often neglect it during the development process. An index is a data structure that provides efficient access of ordered records and random rapid lookups to upgrade the speed of data retrieval operations.

It implies that once an index has been created, you can sort or select your rows even faster. Furthermore, indexes also define the unique index or primary key to ascertain no other columns hold the same value.

Tip 3: Discover Slow Queries with SQL DMVs

DMV (Dynamic Management Views) are built into SQL Server and is one of the most significant features of SQL Server. They are in dozens and render a wide range of information pertaining to various topics. Several DVMs offer data about execution plans, recent queries, query stats, and more. These data can be combined together to obtain some astonishing insights.

Final Thoughts

So, for the next time, you need to improve the SQL performance tuning, you will have these three essential techniques at your fingertip. However, there are several other tips as well that can upgrade to the performance of your SQL server.

But before opting for any SQL tuning products, you must ensure the type of SQL performance functionality the product has built-in. There are several SQL tuning products available in the market but they aren’t useful to you until you have an in-depth knowledge of the same.

Tosska provides a one-button-solution tool to automatically tune the SQL statements without the need for users’ intervention. It offers various other tools to cope up with different issues related to SQL performance tuning. Therefore, you must look once into its products.