Tag: query

Feed: Planet MySQL; Author: Kristian Köhntopp; My task is to collect performance data about a single query, using PERFORMANCE_SCHEMA (P_S for short) in MySQL, to ship it elsewhere for integration with other data. In a grander scheme of things, I will need to define what performance data from a query I am actually interested in. I will also need to find a way to attribute the query (as seen on the server) to a point in the codebase of the client, which is not always easy when an ORM or other SQL generator is being used. And finally I will ... Read More

Feed: Planet MySQL; Author: Vitess; Originally posted at Andres’s blog.Traditional query optimizing is mostly about two things: first, in which order and from where to access data, and then how to then combine it.You have probably seen the tree shapes execution plans that are produced from query planning. I’ll use an example from the MySQL docs, using FORMAT=TREE which was introduced in MySQL 8.0:mysql> EXPLAIN FORMAT=TREE -> SELECT * -> FROM t1 -> JOIN t2 -> ON (t1.c1 = t2.c1 AND t1.c2 < t2.c2) -> JOIN t3 -> ON (t2.c1 = t3.c1)G *************************** 1. row *************************** EXPLAIN: -> Inner hash ... Read More

Feed: Planet MySQL; Author: MyDBOPS; Aurora has a salient feature “Parallel query“, Which will be more beneficial for analytical workload environments. Before going to deep dive on this particular feature, let us understand the basis of Aurora. Aurora Archiecture Key feature The key feature of Aurora is simple data synchronisation among the nodes. The sync latency will be too low when compared to RDS because the synchronisation is happening on storage volumes among the nodes. Also all the server will available in different zone, even when a zone goes down we can able to maintain will other server present in ... Read More

Feed: Planet PostgreSQL. This post is about postgres JDBC (PGJDBC) prepared statements, the setting prepareThreshold, and the performance implication of it. A prepared statement is statement that is defined so that it's variables can be set, and executed. An example: PreparedStatement p = c.prepareStatement("select i from t where i = ?"); p.setInt(1,99); rs=p.executeQuery(); Enter fullscreen mode Exit fullscreen mode 1: definition of a prepared statement p.2: set ('bind') the first variable of p as 99.3: execute prepared statement p. In order to execute prepared statement p again, all that needs to be done is 2 for a new value, and ... Read More

Feed: Planet MySQL; Author: Alena Subotina; August 26th, 2021 We are glad to announce the updated version of dbForge Query Builder for MySQL. The tool offers users a great solution to build, generate, and handle MySQL queries from simple to complex in a visual and easy-to-use interface. In this version, the team focused on the Data Reporting and Analysis feature that allows for fast and efficient data processing, evaluation, reporting, and visualization. What’s new in Query Builder for MySQL v5.0: Data ReportsMaster-Detail BrowserPivot Tables Data Reports dbForge Query Builder for MySQL now supports building data reports and allows customizing them ... Read More

Feed: Planet PostgreSQL. This is a series of blogposts intended to look into how postgres query execution works, so you can get a better understanding, and understand what is happening and what you see. This post is looking at JDBC. In the previous posts I described how query execution works when postgres is used with the psql (Yugabyte: ysqlsh) CLI tool. These tools use the postgres 'simple query protocol'. The simple query protocol uses a single method of communicating with a postgres backend, and always performs the mandatory steps of parsing, rewriting, planning and execution for the execution of a ... Read More

Feed: Planet PostgreSQL. With MVCC databases, a transaction sees a virtual snapshot of committed data, as of the beginning of the statement (in READ COMMITED) or the transaction (in REPEATABLE READ or SERIALIZABLE). In Oracle 9i , this capability has been enhanced so that we can define a snapshot that is even earlier. This was called Flashback Query. Let's see something that, in PostgreSQL, can be equivalent in some cases. I'll run multiple concurrent sessions for this example psql -v PROMPT1="$((1+$(jobs|wc -l)))%R%x%# " Enter fullscreen mode Exit fullscreen mode This connects psql and sets the prompt to the job number ... Read More

Feed: AWS Big Data Blog. If you use data lakes in Amazon Simple Storage Service (Amazon S3) and use SAP HANA as your transactional data store, you may need to join the data in your data lake with SAP HANA in the cloud, SAP HANA running on Amazon Elastic Compute Cloud (Amazon EC2), or with an on-premises SAP HANA, for example to build a dashboard or create consolidated reporting. In such use cases, Amazon Athena Federated Query allows you to seamlessly access the data from SAP HANA database without building ETL pipelines to copy or unload the data to the S3 data ... Read More

Feed: Planet PostgreSQL. This is a series of blogposts intended to look into how postgres query execution works, so you can get a better understanding, and understand what is happening and what you see. This post is looking at simple protocol usage of an anonymous code block using plpgsql. Anonymous code is plpgsql code. Procedures and functions generally are written in plpgsql too, and therefore follow the same pattern. In the previous posts I described how simple query execution works, and how that can be optimized with prepared statements, which allow you to do some of the work (parse and ... Read More

Feed: Planet PostgreSQL. This is a series of blogposts intended to look into how postgres query execution works, so you can get a better understanding, and understand what is happening and what you see. This post is looking at simple query protocol prepare and execute usage. In the previous post I described the execution of queries using the simple protocol, for which the important bit here is that is sends the execution request/command in a single logical request. A common way with SQL databases to improve performance is to hold a cursor and re-execute it with different variables. The idea ... Read More