Merging to installations is possible!
sorry for my late reply. it’s no easy task and is very time consuming, it’s not implemented but possible 
essentials:
- every piwik installation must use the same version
- every piwik installtion has the Site Migration plugin installed
additional info:
- the ID of an imported (migrated) site is the next free ID from the table “site”
- site ID’s are only used in the tables “site”, “log_visit” and “log_link_visit_action”
- disable browser triggers for Piwik archiving
so you start with 3 installations (in my case, they are all on one webserver):
D:\INETPUB
\---piwik_2
+---piwik_1
\---piwik_3
PIWIK_1
5 Profiles (id1, id2, id3, id4, id5)
old data
Url: https://piwik.example.com/piwik_1
Db: piwik_1
Db Prefix: piwik_1
PIWIK_2
5 Profiles (id1, id2, id3, id4, id5),
aktive, production data
Url: https://piwik.example.com/
Db: piwik_2
Db Prefix: piwik_2
PIWIK_3
0 Profiles
should become the new production environment
Url: https://piwik.example.com/piwik_3
Db: piwik_3
Db Prefix: piwik_3
tracking code on all Websites actual points to https://piwik.example.com/piwik.js
step by step description:
1.) migrate idsite=1 from PIWIK_1 to PIWIK_3
navigate on the commandline to d:\inetpub\piwik_2\piwik_1
start here site migration to piwik 3, command should look similar:
d:\inetpub\piwik_2\piwik_1>php.exe .\console migration:site 1 --skip-archive-data -H 127.127.127.127 -U root -P pass -N piwik_3 --db-prefix=piwik_3_
now there is a new entry in Db “piwik_3.piwik_3_site” with ID=1, like in the PIWIK_1 Environment.
autoincrement of “idsite” in “piwik_3.piwik_3_site” is set to 2, any new site migrated to PIWIK_3 gets the ID=2!
2.) on the Website of Profile 1 change the JS Tracking Code
Change that all future requests go to PIWIK_3 (beware of proxies and caching of JS code!!)
example old tracking code:
var _paq = _paq || [];
_paq.push(["setDocumentTitle", document.domain + "/" + document.title]);
_paq.push(['setCustomUrl', location.href.toLowerCase()]);
_paq.push(['trackPageView']);
_paq.push(['enableLinkTracking']);
(function() {
var u="//piwik.example.com/";
_paq.push(['setTrackerUrl', u+'piwik.php']);
_paq.push(['setSiteId', 1]);
var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s);
})();
new tracking code:
var _paq = _paq || [];
_paq.push(["setDocumentTitle", document.domain + "/" + document.title]);
_paq.push(['setCustomUrl', location.href.toLowerCase()]);
_paq.push(['trackPageView']);
_paq.push(['enableLinkTracking']);
(function() {
var u="//piwik.example.com/piwik_3/";
_paq.push(['setTrackerUrl', u+'piwik.php']);
_paq.push(['setSiteId', 1]);
var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s);
})();
3.) migrate missing Data from PIWIK_2 to PIWIK_3
if there are no new requests in the PIWIK_2 Db, it’s time to migrate the missing Data.
navigate on the commandline to d:\inetpub\piwik_2\ and start the site Migration, you import now PIWIK_2 ID=1 and the command looks nearly like the command in step one.
please note, the only difference is the working path, destination is the same.
d:\inetpub\piwik_2\>php.exe .\console migration:site 1 --skip-archive-data -H 127.127.127.127 -U root -P pass -N piwik_3 --db-prefix=piwik_3_
now there are two entries in the table site:
mysql> SELECT idsite, name, main_url, ts_created FROM piwik_3.piwik_3_site;
+--------+-------------------------+-------------------------------+---------------------+
| idsite | name | main_url | ts_created |
+--------+-------------------------+-------------------------------+---------------------+
| 1 | Example www.example.com | http://www.example.com | 2013-03-14 16:20:00 |
| 2 | Example www.example.com | http://www.example.com | 2014-10-30 13:33:37 |
+--------+-------------------------+-------------------------------+---------------------+
2 rows in set (0.00 sec)
4.) merge the profiles
update “idsite” in “piwik_3.piwik_3_log_visit” and “piwik_3.piwik_3_log_link_visit_action”
UPDATE piwik_3.piwik_3_log_visit SET idsite=1 WHERE idsite=2;
UPDATE piwik_3.piwik_3_log_link_visit_action SET idsite=1 WHERE idsite=2;
5.) delete redundant profiles, update autoincrement and run core:archive
DELETE FROM piwik_3.piwik_3_site WHERE idsite=2;
ALTER TABLE piwik_3.piwik_3_site AUTO_INCREMENT=2;
d:\inetpub\piwik_3\>php.exe .\console core:archive --url=https://piwik.example.com/piwik_3/ --force-idsites=1
voila. all data in one profile!
PIWIK_1
5 Profiles (id1, id2, id3, id4, id5)
old data
PIWIK_2
5 Profiles (id1, id2, id3, id4, id5),
aktive, production data for id2-id5
PIWIK_3
1 Profile (id1)
aktice only for id1
so back to step one. and proceed with id=2 from PIWIK_1
migrate PIWIK_1(ID=2) to PIWIK_3(ID=2)
change JS Code
migrate PIWIK_2(ID=2) to PIWIK_3(ID=3)
merge PIWIK_3(ID=3) with PIWIK_3(ID=2)
clean DELETE PIWIK_3(ID=3)
repeat.
if every profile is migrated, change the Piwik config.ini of the PIWIK_2 Website to use the PIWIK_3 database.
finaly change the JS tracking code.
hints:
if you have problems with the php “memory_limit”, try to start the script with “php.exe -d Memory_limit=-1” or increase the script execution time
if the processing takes to long, try to split the import with the “–date-from” and “–date-to” Option. or start core:archive with --force-date-range.
be familiar with the options of “core:archive” and “migration:site”
D:\inetpub\piwik>c:\php\php .\console migration:site -h
Usage:
migration:site [--skip-archive-data] [--skip-log-data] [-H|--db-host="..."] [-U|--db-username="..."] [-P|--db-password="..."] [-N|--db-name="..."] [--db-prefix[="..."]] [--db-port="..."] [-F|--date-from="..."] [-T|--date-to="..."] idSite
Arguments:
idSite Site id
Options:
--skip-archive-data Skip migration of archived data
--skip-log-data Skip migration of log data
--db-host (-H) Destination database host
--db-username (-U) Destination database username
--db-password (-P) Destination database password
--db-name (-N) Destination database name
--db-prefix Destination database table prefix
--db-port Destination database port (default: "3306")
--date-from (-F) Start date from which data should be migrated
--date-to (-T) Start date from which data should be migrated
--help (-h) Display this help message
--quiet (-q) Do not output any message
--verbose (-v|vv|vvv) Increase the verbosity of messages: 1 for normal output, 2 for more verbose output and 3 for debug
--version (-V) Display this application version
--ansi Force ANSI output
--no-ansi Disable ANSI output
--no-interaction (-n) Do not ask any interactive question
--piwik-domain Piwik URL (protocol and domain) eg. "http://piwik.example.org"
--xhprof Enable profiling with XHProf
D:\inetpub\piwik>c:\php\php .\console core:archive -h
Usage:
core:archive [--url="..."] [--force-all-websites] [--force-all-periods[="..."]] [--force-timeout-for-periods[="..."]] [--skip-idsites[="..."]] [--force-idsites[="..."]] [--force-periods[="..."]] [--force-date-last-n="..."] [--force-date-range[="..."]] [--concurrent-requests-per-website[="..."]] [--disable-scheduled-tasks] [--accept-invalid-ssl-certificate]
Options:
--url Mandatory option as an alternative to '--piwik-domain'. Must be set to the Piwik base URL.
For example: --url=http://analytics.example.org/ or --url=https://example.org/piwik/
--force-all-websites If specified, the script will trigger archiving on all websites.
Use with --force-all-periods=[seconds] to also process those websites that had visits in the last [secon
ds] seconds.
Launching several processes with this option will make them share the list of sites to process.
--force-all-periods Limits archiving to websites with some traffic in the last [seconds] seconds.
For example --force-all-periods=86400 will archive websites that had visits in the last 24 hours.
If [seconds] is not specified, all websites with visits in the last 604800 seconds (7 days) will be archived.
--force-timeout-for-periods The current week/ current month/ current year will be processed at most every [seconds].
If not specified, defaults to 3600.
--skip-idsites If specified, archiving will be skipped for these websites (in case these website ids would have been archived).
--force-idsites If specified, archiving will be processed only for these Sites Ids (comma separated)
--force-periods If specified, archiving will be processed only for these Periods (comma separated eg. day,week,month)
--force-date-last-n This script calls the API with period=lastN. You can force the N in lastN by specifying this value.
--force-date-range If specified, archiving will be processed only for periods included in this date range. Format: YYYY-MM-DD,YYYY-MM-DD
--concurrent-requests-per-website When processing a website and its segments, number of requests to process in parallel (default: 3)
--disable-scheduled-tasks Skips executing Scheduled tasks (sending scheduled reports, db optimization, etc.).
--accept-invalid-ssl-certificate It is _NOT_ recommended to use this argument. Instead, you should use a valid SSL certificate!
It can be useful if you specified --url=https://... or if you are using Piwik with force_ssl=1
--help (-h) Display this help message
--quiet (-q) Do not output any message
--verbose (-v|vv|vvv) Increase the verbosity of messages: 1 for normal output, 2 for more verbose output and 3 for debug
--version (-V) Display this application version
--ansi Force ANSI output
--no-ansi Disable ANSI output
--no-interaction (-n) Do not ask any interactive question
--piwik-domain Piwik URL (protocol and domain) eg. "http://piwik.example.org"
--xhprof Enable profiling with XHProf
Help:
* It is recommended to run the script with the option --url=[piwik-server-url] only. Other options are not required.
Try --piwik-domain if --url does not work for you.
* This script should be executed every hour via crontab, or as a daemon.
* You can also run it via http:// by specifying the Super User &token_auth=XYZ as a parameter ('Web Cron'),
but it is recommended to run it via command line/CLI instead.
* If you have any suggestion about this script, please let the team know at feedback@piwik.org
* Enjoy!
D:\inetpub\piwik>
