Hello all
Since Apache Derby has been retired, Apache SIS will need to migrate to
another database for embedded EPSG data [1]. Two possibilities are HSQL
or H2. A comparison on the H2 web site [2] suggests that H2 is generally
faster, but this is not necessarily the primary concern for EPSG data.
H2 seems to consume more memory than Derby but less than HSQL. The JAR
file size of H2 (2.6 Mb) is larger than HSQL (1.6 Mb), but still smaller
than Derby (3.4 Mb). The support of ANSI SQL is sufficient for SIS
needs in all those databases. Tables are persisted on disk by default in
H2 while they tables are in-memory by default in HSQL. While HSQL can be
configured, the default behavior of H2 is more conform to SIS needs.
Is there any opinion about what should be the replacement for Derby in
Apache SIS? I would like this change to be done for the next SIS
release, tentatively in the next 2 weeks. If hearing no opinion, I'm
inclined toward H2.
Martin
[1]https://issues.apache.org/jira/browse/SIS-631
[2]https://www.h2database.com/html/performance.html
