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Amazon DynamoDB: a r(el)ational Glossary

By Franck Pachot

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There are many NoSQL databases. And, because SQL is an ISO standard, “No SQL” also means “No Standard”. Many have a similar API and similar objects, but with completely different names. Today, NoSQL databases are used as an additional datastore for some well-defined use cases for which a hashed key-value store fits better than a relational table. And it quickly became “Not Only SQL” as it is complementary to RDBMS databases using SQL. But at the origin, the idea was to replace the RDBMS databases, refusing the SQL API, and then inventing a “No SQL” data store. When you want to replace something rather than proposing something new, you often adopt the same language to make it look similar. And this why, in my opinion we find some relational database terms like “Table” and “Index”. But they have a different meaning. Here is a dictionary where I try to explain the DynamoDB artifacts and differentiate from their Relational and SQL meaning.

Oracle 18c – select from a flat file

By Franck Pachot

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This post is the first one from a series of small examples on recent Oracle features. My goal is to present them to people outside of Oracle and relational databases usage, maybe some NoSQL players. And this is why the title is “select from a flat-file” rather than “Inline External Tables”. In my opinion, the names of the features of Oracle Database are invented by the architects and developers, sometimes renamed by Marketing or CTO, and all that is very far from what the users are looking for. In order to understand “Inline External Table” you need to know all the history behind: there were tables, then external tables, and there were queries, and inlined queries, and… But imagine a junior who just wants to query a file, he will never find this feature. He has a file, it is not a table, it is not external, and it is not inline. What is external to him is this SQL language and what we want to show him is that this language can query his file.

Video : Online Conversion of a Non-Partitioned Table to a Partitioned Table in Oracle 12.2 Onward

Today’s video demonstrates the online conversion of a non-partitioned table to a partitioned table. This functionality was introduced in Oracle 12.2.

The examples in the video are taken from this article.

Video : Online Segment Shrink for Tables : Free Unused Space

In today’s video we’ll give a demonstration of how to shrink tables that contain a lot of free space. As I say in the video, this is not something you should do regularly. It’s only necessary if you’ve done some drastic one-off maintenance, like a large data purge maybe.

There are a few articles this relates to.

Largest Tables Including Indexes and LOBs

Just a quick code snippit. I do a lot of data pumps to move schemas between different databases; for example taking a copy of a schema to an internal database to try to reproduce a problem. Some of these schemas have some very large tables. The large tables aren’t always needed to research a particular problem.

Here’s a quick bit of SQL to list the 20 largest tables by total size – including space used by indexes and LOBs. A quick search on google didn’t reveal anything similar so I just wrote something up myself. I’m pretty sure this is somewhat efficient; if there’s a better way to do it then let me know! I’m posting here so I can reference it in the future. :)

Largest Tables Including Indexes and LOBs

Just a quick code snippit. I do a lot of data pumps to move schemas between different databases; for example taking a copy of a schema to an internal database to try to reproduce a problem. Some of these schemas have some very large tables. The large tables aren’t always needed to research a particular problem.

Here’s a quick bit of SQL to list the 20 largest tables by total size – including space used by indexes and LOBs. A quick search on google didn’t reveal anything similar so I just wrote something up myself. I’m pretty sure this is somewhat efficient; if there’s a better way to do it then let me know! I’m posting here so I can reference it in the future. :)

Largest Tables Including Indexes and LOBs

Just a quick code snippit. I do a lot of data pumps to move schemas between different databases; for example taking a copy of a schema to an internal database to try to reproduce a problem. Some of these schemas have some very large tables. The large tables aren’t always needed to research a particular problem.

Here’s a quick bit of SQL to list the 20 largest tables by total size – including space used by indexes and LOBs. A quick search on google didn’t reveal anything similar so I just wrote something up myself. I’m pretty sure this is somewhat efficient; if there’s a better way to do it then let me know! I’m posting here so I can reference it in the future. :)