problem: GetVulnerabilities is slow

create a partial index on the host_creds table where result is not
blank.

This drops the query GetVulnerabilities runs from a second or two to
almost zero.

Author: JustinAzoff

sshauditor/store.go

@@ -54,6 +54,7 @@ UPDATE sqlite_master SET SQL=REPLACE(SQL, 'priority', 'scan_interval') WHERE nam
 PRAGMA writable_schema=0;
 UPDATE credentials set scan_interval=14 where scan_interval == 0;
 UPDATE host_creds set scan_interval=14 where scan_interval == 0;
+CREATE INDEX IF NOT EXISTS host_creds_vulnerable ON host_creds (result) WHERE result != '';
 `
 
 type Host struct {