Leveraging Prepared Statements to Improve Performance

In the post on prepared statement the statements were prepared each time a row is received, which seems like a waste of CPU. After all, the tables do not change, so it should be perfectly OK to just prepare the statement once, save it away in prepared form, and then reuse it for each row …
Continue reading Leveraging Prepared Statements to Improve Performance

Reading and writing types

One drawback of the current design is that all the tags and all the fields are stored in a JSONB structure. JSON is a great format if you want to have an open format where you can add new fields as necessary and even have more structured data than what you have in plain columns, …
Continue reading Reading and writing types

Using prepared statements through the SPI

In the previous post, you could see how to use the server programming interface to execute statements that modified the database. This was done by creating a statement containing the all the data that needed to be inserted, but that also meant generating a string from already parsed data, which seems like a waste of …
Continue reading Using prepared statements through the SPI

The Server Programming Interface

In the previous post you could see how to parse a packet and construct a complex data type from it by creating a set-returning function. This function returned a table of rows, but it did not insert it into the database. In this post you will see how to insert the data into the database …
Continue reading The Server Programming Interface

Creating JSON Values

In the previous post, you could see how to create set-returning functions that returns several rows of a table and we returned rows consisting of the timestamp, the metric, and two JSONB values: one for the tags and one for the fields. There were, however, no coverage of what JSONB is, how it differs from JSON, and how to construct them in your code. This post is going to answer those questions.

Parsing InfluxDB Line Protocol

In the previous post you could see how to create a background worker that received data over a socket as well as how to spawn a new background worker. In this post you will see how to write a simple parser for the InfluxDB Line Protocol and also get an introduction into PostgreSQL Memory Contexts and the Set-Returning Function (SRF) interface and learn how to write a function that returns multiple tuples.

It’s all in the Background

In contrast to MySQL—which is a multi-thread database system—PostgreSQL is a multi-process database system. In multi-process systems you have a process tree with several processes that interact to share the work, but only a single thread for each process. Multi-process and multi-thread systems both have advantages and disadvantages, some of which are discussed in this post. Since PostgreSQL is a multi-process system, the focus will be on PostgreSQL and multi-process systems.

In this post you will see how to add a background worker to the extension and how to spawn new background workers.

This post assume that you’re familiar with C programming and also familiar with programming for Linux. In particular, you need to know about processes, signals, and sockets in Linux: what they are, how they work, and what they are used for.

The Nobel Art of Writing PostgreSQL Extensions

Some things in the PostgreSQL code base is very straightforward, while other things can be more tricky to follow. I find that some areas are always not well-documented and understanding the rationale and reasoning behind a solution can require some research.

If you’re a developer that is interested in database internals and database implementations in general—or PostgreSQL internals in particular—this blog is for you.

In this post you will get an introduction to the structure of extensions and how to write an extension with a simple C function returning a complex type.