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Category Archives: Oracle

Testing solution to MERGE with sequence NEXTVAL

In my last blogpost (“Strange behavior in MERGE with sequence NEXTVAL”) I had a link to article written by Bob Jankovsky. In this article is suggest solving the issue with MERGE and nextvalue by returning the nextvalue from a function. In this blogpost I’ll do some tests and see how this behaves (regarding timings).

Posted 21 December 2023 † Lasse Jenssen § ‡ Comments (0) °

Strange behavior in MERGE with sequence NEXTVAL

Today we learned the following: “When using a sequence in a MERGE statement, the nextvalue is generated for all rows both updated and inserted (hence all rows in the source).” Our initial reaction was that this must be a bug, but is it really?

Posted 20 December 2023 † Lasse Jenssen § DBA § Internals § Performance ‡ Comments (0) °

Use default parameter/setting (row) if not set specific for entity

The other day I was asked about the following: “We have a table VARIABLE and Variable entity. A new requirement is to restrict availability of a limited number of these entities to chosen customers.” I replied: “The volumes?” And the response was: “Quite low – now around 70 rows, it might slightly exceed 100 in […]

Posted 19 May 2022 † Lasse Jenssen § ‡ Comments (0) °

SQL Developer, Database Copy and TRUNCATING unwanted tables

I just experienced something scary with SQL Developer and the “Database Copy” utility. One table in production was truncated by a mistake. I have always been a little against using the SQL Developer functionality “Database Copy …” in production, but for this one task during deployment of a new release, this customer (including me) have […]

Posted 05 April 2022 † Lasse Jenssen § DBA § SQL Developer ‡ Comments (0) °

Copy schema with data pump when using editions

We have just been through a relatively tricky situation, trying to copy our test schemas from our Oracle 12c database to the new Oracle 19c test database. We were trying to use data pump to copy the schemas. The copy was ordered from operation, and the schemas was exported and imported as ordered. Before importing  […]

Posted 18 November 2020 † Lasse Jenssen § ‡ Comments (0) °

The NUMBER datatype without precision

Lately I have seen projects using the NUMBER datatype for table columns without setting precision and scale. When I see this I always question “Is this intentional or did they just happen to forget to set the values?”. This is the problem with using implicit configuration/settings. You don’t really know if it was a mistake […]

Posted 15 July 2019 † Lasse Jenssen § SQL ‡ Comments (0) °

Redundant NOT NULLs in DDL

I often see DDLs with NOT NULL definitions which is really redundant. When I see such DDLs I really question “do the writer really know what he or she is doing”. They might not hurt you application, but why set them if they are redundant? (If you know I reason please comment) Example: CREATE TABLE […]

Posted 13 July 2019 † Lasse Jenssen § Database Design § Performance § SQL ‡ Comments (0) °

Java and JDBC for Oracle DBAs – Part 6: Spring-boot, JPA and Hibernate

In the last article we looked at Spring-boot and accessed the database using the JdbcTemplate class.Today we’ll rewrite the same application but by using JPA and Hibernate instead. The Spring Initializr web page have changed a little since the last time, so the first part will be a little different. Part 1: Install/setup Oracle database […]

Posted 18 March 2019 † Lasse Jenssen § ‡ Comments (0) °