PostgreSQL has two functions that are not standard SQL, but are very helpful in certain situations : GREATEST and LEAST. PostgreSQL does not have scalar functions for MIN and MAX (those are aggregate functions that operate on all rows in a query), but GREATEST and LEAST accomplish that and then some. Both allow for more …
There have been a handful of times over the last few years where I have needed to take time series data, and group the runs of data together to determine when a certain value changed, and how long it stayed that way. Every time I do this, I have to go back and figure out …
TL:DR; takeaways: These seem very obvious, but with rushed deadlines, and “it works well enough”, these things are sometimes overlooked. Use the right data type for the job. If the documentation says VARCHAR when the values are always integers, maybe you should use INT. Generate a proper primary key when you can, skip indexes that …
For years I have relied on a simple property “show-sql=true” to see Hibernate’s generated SQL. This option is fairly limited: it bypasses the logging framework in the rest of my apps (SLF4J) it doesnt show parameters, just question marks it doesn’t show any timing information Frustrated at these limitations, I set out to understand all …
At work we have a copy of the zip-codes.com Business database, which I tend to reference somewhat frequently due to the nature of projects I work on. Today I needed a list of postal codes from major metro areas, which would be used to drive a test data generator. The data generator has access to …
Sql Quickie: Find zipcodes near the center of a region Read More »
Over the last couple of weeks, I have been spending some time troubleshooting performance issues in some of our Java-based RESTful services. This week I came across one that required some different steps to troubleshoot. First, the tl;dr – our JDBC driver (jTDS) converts CHAR to NCHAR, which causes an index SCAN on a CHAR …
Troubleshooting a SQL Server Implicit Conversion Issue Read More »