Rotate Checkpoins

Jakub_Jedelsky

Hi y'all,

I'm trying to find a way how to "rotate" checkpoints which are saved under Catalog/Checkpoints directory. We haven't so many objects in catalog (it can be around 80k) but the size of Checkpoints dir is 3.6 GB and data there are 4 months old. Is it possible to say: "Hey Vertica, throw away these four months old data and crate a new one?"

Version: 6.1.3-8

Thanks.

[Deleted User]

Hi Jakub,

Good question.  I'm curious -- how are you determining that your catalog is only around 80kb?  I'm surprised that you have such a large differential between your checkpoints and your actual catalog.

I don't recall off the top of my head what catalog-checkpoints controls are available in that version of Vertica.  But you can take a look yourself by running the query:

select * from configuration_parameters where parameter_name ilike '%CatalogCheckpoint%';

You should be able to fiddle with the options there to get Vertica to behave more usefully for you.

Adam

Jakub_Jedelsky

Hi Adam,

the size 80k wasn't mean as size in kb but as "number of objects stored in catalog".

Thanks for kick me with 'configuration_parameters' table. As I can see a lot of them aren't documented I found CatalogCheckpointPercent and CatalogCheckpointMinLogSizeKB which are exactly what I need.

Parameter CatalogCheckpointPercent is by default set to 50 (%), that means that Catalog/Txnlog dir has to have 50 or more percent of Catalog/Checkpoints dir size to rotate it. The problem was that the Checkpoints dir had been too big (3.6GB) and trafic too low so Txnlog grows very slowly. I had to change this paarmetr and Txnlog dir shrinks into new (and much more smaller) Checkpoints.