Oracle persistent connections

[Shmuma]

Hello,

This patch changes frontend to initiate persistent connection to oracle database instead of non-persistent ones. Simple benchmark shows about 30000 times connection initiation boost .

Benchmark initiates 20 connections in a loop. Results:

1. ocilogon: 36.6958 seconds,
2. ociplogon: 1.8807 seconds first run,
3. ociplogon: 0.0011 seconds all subsequential runs.

This is especially usefull for oracle 11 which doesn't support hugetlb pages. So new connections performed very slow.

[Aly]

Thank you, applied.