Vaccum or compact unused space from an h2 database (especially for datomic)

compact-datomic-dev.sh

#!/bin/sh

# Uses the h2 jar in a datomic distribution to give raw SQL access
# to the h2 database datomic "dev" storage uses.
# The 'SHUTDOWN COMPACT' command in particular performs all
# vaccum-like compaction of the h2 database file to remove
# unused blocks from deleted (garbage-collected) segments.

DATOMIC_HOME=${DATOMIC:-$HOME/lib/datomic/current}
DATOMIC_ADMIN_PASSWORD=${1:?Storage admin password must be provided}
DATOMIC_DATA_DIR=${2:-/usr/local/var/data/datomic/dev-internal}

echo $DATOMIC_HOME/lib/h2*.jar

exec java -server -XX:+UseParallelGC -cp ${DATOMIC_HOME}/lib/h2*.jar \
  org.h2.tools.Shell \
  -url "jdbc:h2:${DATOMIC_DATA_DIR}/db/datomic;IFEXISTS=TRUE;" \
  -user '' -password "$DATOMIC_ADMIN_PASSWORD" \
  -sql 'SHUTDOWN COMPACT;'