![]() How do we actually fix this, for real? If you did ALTER COLUMN, you’d just change the datatype, that would rewrite the whole table. But it's the fastest way to fix this right away. ![]() It might also not look aesthetically pleasing in your URL structure, for example. So if, downstream in your application, you're parsing integers and you're not expecting the sign in front of the number, that could be a problem. Of course, the downside is that you suddenly have negative values as your IDs. You could, in most cases, just run this one command and the problem will be at least - in that very moment - fixed and your application will be online again. Now, what you're doing is to tell the sequence to instead count down and to have the next value be minus one and then count down from minus one to negative 2.1 billion. When this happens to you, when you're in a pinch, the best fast fix that I've seen is using negative numbers. So you see, very much a problem that can happen in real life and in real world situations! Using negative numbers I've actually had issues in the past myself where I was in a car and suddenly got paged and I had to actually take my laptop out - I wasn't driving - and I actually had to fix something, as production was down because suddenly new integer values could no longer be assigned. Let's say this happens to you and you're either at 93% or maybe you're at 99%. A column percent, this is the physical data type in the table, and how much more space there is to have values assigned.A sequence percent, which refers to how much more space there is in the sequence itself, so the sequence maximum.It checks the database for this type of problem, and it looks at the last sequence values using the pg_sequence_last_value function, and then says: “is the last value close to the maximum of that particular data type?” Jesse's query has two outputs it produces: In his blog post, Jesse shows a useful query. How to avoid integer sequence overflow in Postgres For example, again, you've reached that 2.1 billion mark, and the next value that would be assigned would go outside of the four byte range for the integer.īefore we jump into how to fix the situation, let's take a step back and see how we can avoid running into this in the first place. This will happen when a sequence could technically give you more values, but the data type in the physical table is too small. This is when the sequence itself cannot assign more because the sequence maximum has been reached. The nextval: reached maximum value of sequence error.What we mean by integer overflow is that we have a data type like a four byte integer that has a maximum of 2.1 billion values, and once you have a sequence that keeps counting up and it reaches that 2.1 billion value, it actually will start erroring out. In this blog post, Jesse Soyland from the Crunchy Data team describes how they've helped their customers navigate problems around integer overflow. Let's jump in! What happens when a sequence reaches max value in Postgres? What we have discussed in this episode of 5mins of Postgres Is integer sequence overflow actually a realistic problem? ![]() What happens when a sequence reaches max value in Postgres?
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