How to cache maven local repo between Travis builds

caching is allowed only for private repos or public repos that use "Using container-based infrastructure".

Steps:
1. instruct travis to use "container-based infrastructure"
2. instruct travis what folder you need to cache

Official documentation:
http://docs.travis-ci.com/user/workers/container-based-infrastructure/#Routing-your-build-to-container-based-infrastructure
http://docs.travis-ci.com/user/caching/#Arbitrary-directories


Results: that caching speedup build on ~3-4 minutes for each jdk.

Example: https://github.com/checkstyle/checkstyle/blob/master/.travis.yml

Force Oracle to recalculate execution plan for a table

Steps to force Oracle to recalculate execution plan for tables:

EXEC DBMS_STATS.GATHER_TABLE_STATS('<Schema_name>','<Table_name>'); 

-- deprecated approach

ANALYZE table <SCHEMA_NAME>.<TABLE_NAME> compute statistics;

and, DBMS_STATS.GATHER_TABLE_STATS is preferable (source: link, oracle-link)

Optimization for SqlDeveloper

Update file:
<sqldeveloper folder>/sqldeveloper/bin/sqldeveloper.conf

With content:

# from https://forums.oracle.com/forums/thread.jspa?messageID=9773884
AddVMOption -XX:PermSize=128M
AddVMOption -XX:MaxGCPauseMillis=50
AddVMOption -XX:GCPauseIntervalMillis=200
AddVMOption -Xms50M
AddVMOption -Xmx300M
AddVMOption -XX:MinHeapFreeRatio=10
AddVMOption -XX:MaxHeapFreeRatio=10

AddVMOption -XX:+AggressiveOpts
AddVMOption -XX:+UseStringCache
AddVMOption -XX:+OptimizeStringConcat
AddVMOption -XX:+ScavengeBeforeFullGC
AddVMOption -XX:+UseConcMarkSweepGC
AddVMOption -XX:+UseCompressedOops

# from https://blogs.oracle.com/angelo/entry/improving_the_performance_of_jdeveloper
AddVMOption -XX:+UseGCOverheadLimit

Work experience should be better.