The prior article discussed the Oracle library cache, the difference between a hard parse and a soft parse, and a bit on bind variable processing as well. To review, Oracle hard parsing reads in statistics, utilizes index information and creates an execution plan. Soft parsing already has the execution plan and doesn’t need to revisit the statisticsand […]
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The prior article finished the discussion on hard parsing. This article will take a look at some of the explain plan content then wrap up with what to look for when you have poorly performing SQL. Up to now, we have been discussing how Oracle processes SQL, the hard and soft parse processes, and how […]
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The prior article in this series finished the discussion on hard parsing. This article will take a look at the explain plan and discuss the order of processing and what the steps actually mean. Please be sure to read these articles in the proper order as they each build on the prior article! Let’s review […]
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The prior article started a discussion on the hard parsing process. It left off with the query transformation step. Please read these articles in the proper order as they each build on the prior article. The next step in the hard parse process is the permutations, as shown in the Figure below, taken from the […]
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In a previous article, I discussed the PLAN_TABLE and its role in SQL tuning for Oracle. This article will discuss using this PLAN_TABLE to display SQL execution plans, or explain plans. Technically, the Oracle Hard Parse process produces an execution plan. The explain plan is the visualization of this execution plan. I use the terms synonymously. […]
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This article will discuss the importance of the PLAN_TABLE and how to make sure you are using the correct one. The PLAN_TABLE, shown below, is used to produce SQL Explain Plans. When SQL is submitted to Oracle and processed (details to follow in other articles), an execution plan is created and used to process the […]
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The inventor of the relational model, Dr. Edgar Codd, was of the opinion that “[r]equesting data by its properties is far more natural than devising a particular algorithm or sequence of operations for its retrieval. Thus, a calculus-oriented language provides a good target language for a more user-oriented source language” (“Relational Completeness of Data Base […]
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Lately, the big IT buzzword is cloud solutions. In fact, if you believe all of the hype, most companies are moving en masse from on-premise solutions to cloud-based architectures. On the surface, the cloud-based solution certainly seems to be a more affordable solution that not only reduces the complexities of on-premise build-outs and maintenance, but […]
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Keep a watchful eye on two key configuration parameters to maintain consistent performance. Server virtualization for Oracle databases is here–and it works, so it will be staying. As database administrators, we must adapt to the new architecture, while ensuring database performance and resiliency. A recent client problem involving a handful of critical applications revealed two […]
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Cloud is the next buzz word in the industry. If we were to quiz any CIO on what are some of the big bets they want to make in the next 6-12 months–using cloud will surely be one of them. Why has this new concept has caught on like forest fire? Why are organizations exploring […]
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TNS:could not resolve service name This error, seen as ORA-12154, means SQL*Net could not find the database alias specified for a database connection in the TNSNAMES.ORA file or other naming adapter. The database alias is specified after the “@” character in a database connection string. For example, if the connect string “SYSTEM/MANAGER@PROD” is used, “PROD” […]
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Learn about Oracle database maintenance, including best practices recommended by Oracle ACE and performance experts.
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