Re: Index split WAL reduction

Here's an updated patch, with a high key related bug and *_desc
functions fixed. And an updated crashtest.sh as well.

Heikki Linnakangas wrote:
> Hi,
>
> Currently, an index split writes all the data on the split page to WAL.
> That's a lot of WAL traffic. The tuples that are copied to the right
> page need to be WAL logged, but the tuples that stay on the original
> page don't.
>
> Here's a patch to do that. It needs further testing, I have used the
> attached crude crashtest.sh to test the basics, but we need to test the
> more obscure cases like splitting non-leaf or root page.
>
> On a test case that inserts 10000 rows in increasing key order with a
> 100 characters wide text-field as key, the patch reduced the total
> generated WAL traffic from 45MB to 33MB, or ~ 25%. Your mileage may
> vary, depending on the tuple and key sizes, and the order of inserts.
>
> Anyone see a problem with this?

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com