As it is AFAIK not documented anyhwere and also far away from being
obvious, here is a short tutorial for the RPM hackers on how to migrate
the RPM DB of RPM 5 between Berkeley-DB and SQLite.

The obvious pre-requisite for an in-place migration obviously is that
RPM 5 was built with _both_ Berkeley-DB _and_ SQLite, of course. In our
newer RPM 5 world-order this is just a matter of having SQLite installed
under /path/to/sqlite and then build RPM with the Autoconf option set
"--with-db=internal --with-sqlite=/path/to/sqlite"

After you have this "multi-DB-lingual" RPM available, here is how one
can migrate from Berkeley-DB to SQLite and vice versa:

1. start with a standard Berkeley-DB RPM DB:

| $ /tmp/rpm/bin/rpm --initdb
| $ /tmp/rpm/bin/rpm --import pubkeys/JBJ-GPG-KEY
| $ /tmp/rpm/bin/rpm -qai
| Name        : gpg-pubkey                   Relocations: (not relocatable)
| Version     : 2039b291                          Vendor: (none)
| Release     : 3dbaae72                      Build Date: Thu Jun 28 11:20:48 2007
| Install Date: Thu Jun 28 11:20:48 2007      Build Host: localhost
| Group       : Public Keys                   Source RPM: (none)
| Size        : 0                                License: pubkey
| Signature   : (none)
| Summary     : gpg(Jeff Johnson (ARS N3NPQ) <jbj@redhat.com>)
| [...]
| $ file /tmp/rpm/var/lib/rpm/*
| /tmp/rpm/var/lib/rpm/Group:          Berkeley DB (Btree, version 9, little-endian)
| /tmp/rpm/var/lib/rpm/Installtid:     Berkeley DB (Btree, version 9, little-endian)
| /tmp/rpm/var/lib/rpm/Name:           Berkeley DB (Btree, version 9, little-endian)
| /tmp/rpm/var/lib/rpm/Packagecolor:   Berkeley DB (Hash, version 8, little-endian)
| /tmp/rpm/var/lib/rpm/Packages:       Berkeley DB (Btree, version 9, little-endian)
| /tmp/rpm/var/lib/rpm/Providename:    Berkeley DB (Btree, version 9, little-endian)
| /tmp/rpm/var/lib/rpm/Provideversion: Berkeley DB (Btree, version 9, little-endian)
| /tmp/rpm/var/lib/rpm/Pubkeys:        Berkeley DB (Hash, version 8, little-endian)

2. migrate RPM DB from Berkeley-DB to SQLite:

| $ /tmp/rpm/bin/rpm --rebuilddbapi 4 --rebuilddb
| $ file /tmp/rpm/var/lib/rpm/*
| /tmp/rpm/var/lib/rpm/Group:          SQLite 3.x database
| /tmp/rpm/var/lib/rpm/Installtid:     SQLite 3.x database
| /tmp/rpm/var/lib/rpm/Name:           SQLite 3.x database
| /tmp/rpm/var/lib/rpm/Packagecolor:   SQLite 3.x database
| /tmp/rpm/var/lib/rpm/Packages:       SQLite 3.x database
| /tmp/rpm/var/lib/rpm/Providename:    SQLite 3.x database
| /tmp/rpm/var/lib/rpm/Provideversion: SQLite 3.x database
| /tmp/rpm/var/lib/rpm/Pubkeys:        SQLite 3.x database
| $ /tmp/rpm/bin/rpm --dbapi 4 -qai
| Name        : gpg-pubkey                   Relocations: (not relocatable)
| Version     : 2039b291                          Vendor: (none)
| Release     : 3dbaae72                      Build Date: Thu Jun 28 11:20:48 2007
| Install Date: Thu Jun 28 11:20:48 2007      Build Host: localhost
| Group       : Public Keys                   Source RPM: (none)
| Size        : 0                                License: pubkey
| Signature   : (none)
| Summary     : gpg(Jeff Johnson (ARS N3NPQ) <jbj@redhat.com>)
| [...]
| -----END PGP PUBLIC KEY BLOCK-----

3. migrate RPM DB back from SQLite to Berkeley-DB:

| $ /tmp/rpm/bin/rpm --dbapi 4 --rebuilddbapi 3 --rebuilddb
| $ file /tmp/rpm/var/lib/rpm/*
| /tmp/rpm/var/lib/rpm/Group:          Berkeley DB (Btree, version 9, little-endian)
| /tmp/rpm/var/lib/rpm/Installtid:     Berkeley DB (Btree, version 9, little-endian)
| /tmp/rpm/var/lib/rpm/Name:           Berkeley DB (Btree, version 9, little-endian)
| /tmp/rpm/var/lib/rpm/Packagecolor:   Berkeley DB (Hash, version 8, little-endian)
| /tmp/rpm/var/lib/rpm/Packages:       Berkeley DB (Btree, version 9, little-endian)
| /tmp/rpm/var/lib/rpm/Providename:    Berkeley DB (Btree, version 9, little-endian)
| /tmp/rpm/var/lib/rpm/Provideversion: Berkeley DB (Btree, version 9, little-endian)
| /tmp/rpm/var/lib/rpm/Pubkeys:        Berkeley DB (Hash, version 8, little-endian)
| $ /tmp/rpm/bin/rpm -qai
| Name        : gpg-pubkey                   Relocations: (not relocatable)
| Version     : 2039b291                          Vendor: (none)
| Release     : 3dbaae72                      Build Date: Thu Jun 28 11:20:48 2007
| Install Date: Thu Jun 28 11:20:48 2007      Build Host: localhost
| Group       : Public Keys                   Source RPM: (none)
| Size        : 0                                License: pubkey
| Signature   : (none)
| Summary     : gpg(Jeff Johnson (ARS N3NPQ) <jbj@redhat.com>)
| [...]

Yours,
                                       Ralf S. Engelschall
                                       rse@engelschall.com
                                       www.engelschall.com