tree e9a7da16b3b114cc92e9f6619f24e057a449943e
parent b2798269590d5e87912badff9900dc98e8de2531
author Hongkai Liu <hongkai.liu@ericsson.com> 1491598465 -0400
committer Hugo Arès <hugo.ares@ericsson.com> 1493191737 +0200

Support Jdbc implementation of AccountPatchReviewStore

Provide in gerrit core support for alternative database backends
for AccountPatchReview store.

H2 was used for storing AccountPatchReview. This can become
problematic in large installation since embedded H2 cannot execute
concurrent requests even to the same database. The options related to
multi-thread in H2 are:
- MULTI_THREADED: a long running query blocks the ones in other
threads [1].
- MVCC: This is not production-ready yet, since it is not fully
tested [2].

AccountPatchReviewStore is an extension and a plugin could
implement a jdbc store but this would result in duplicated code
with core H2 implementation. Since core H2 implementation was
almost already compliant to jdbc standard, it's easy to make
jdbc url configurable in gerrit config and make the core support
other database than H2.

One could extend the H2 implementation in plugin, however the
changes on the supper class could lead to breaking plugin
implementation.

[1] http://www.h2database.com/html/features.html#multiple_connections
[2] http://www.h2database.com/html/advanced.html#mvcc

Change-Id: Ie61ac63a72cab71bd907886a794541cb3dea291e