replace ludb with data-store

LuDB has a few disadvantages. 
  1. Most notably disk space. H2 wastes a lot of valuable disk space.
     For my test data set with 44 million entries it is 14 MB 
     (sometimes a lot more; depends on H2 internal cleanup). With 
     data-store it is 15 KB.
     Overall I could reduce the disk space from 231 MB to 200 MB (13.4 %
     in this example). That is an average of 4.6 bytes per entry.
  2. Speed:
     a) Liquibase is slow. The first time it takes approx. three seconds
     b) Query and insertion. with data-store we can insert entries 
        up to 1.6 times faster.

Data-store uses a few tricks to save disk space:
  1. We encode the tags into the file names.
  2. To keep them short we translate the key/value of the tag into 
     shorter numbers. For example "foo" -> 12 and "bar" to 47. So the
     tag "foo"/"bar" would be 12/47. 
     We then translate this number into a numeral system of base 62
     (a-zA-Z0-9), so it can be used for file names and it is shorter.
     That way we only have to store the mapping of string to int.
  3. We do that in a simple tab separated file.

pdb-ui/src/main/java/org/lucares/pdbui/MySpringConfiguration.java

@@ -1,5 +1,6 @@
 package org.lucares.pdbui;
 
+import java.io.IOException;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 
@@ -20,7 +21,7 @@ public class MySpringConfiguration {
 	private static final Logger LOGGER = LoggerFactory.getLogger(MySpringConfiguration.class);
 
 	@Bean
-	PerformanceDb performanceDb(@Value("${db.base}") final String dbBaseDir) {
+	PerformanceDb performanceDb(@Value("${db.base}") final String dbBaseDir) throws IOException {
 		final Path dataDirectory = Paths.get(dbBaseDir);
 
 		LOGGER.info("using database in {}", dataDirectory.toAbsolutePath());

pdb-ui/src/main/java/org/lucares/pdbui/PdbController.java

@@ -9,22 +9,22 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.SortedSet;
 
-import org.lucares.ludb.FieldNotExistsException;
-import org.lucares.ludb.Proposal;
 import org.lucares.pdb.plot.api.PlotSettings;
 import org.lucares.pdbui.domain.AutocompleteProposal;
 import org.lucares.pdbui.domain.AutocompleteProposalByValue;
 import org.lucares.pdbui.domain.AutocompleteResponse;
 import org.lucares.pdbui.domain.PlotRequest;
 import org.lucares.pdbui.domain.PlotResponse;
-import org.lucares.performance.db.CollectionUtils;
 import org.lucares.performance.db.PerformanceDb;
+import org.lucares.performance.db.Proposal;
 import org.lucares.recommind.logs.DataSeries;
 import org.lucares.recommind.logs.InternalPlottingException;
 import org.lucares.recommind.logs.NoDataPointsException;
 import org.lucares.recommind.logs.PlotResult;
 import org.lucares.recommind.logs.Plotter;
+import org.lucares.utils.CollectionUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
@@ -41,7 +41,7 @@ import org.springframework.web.servlet.ModelAndView;
 
 @Controller
 @EnableAutoConfiguration
-public class PdbController implements HardcodedValues, CollectionUtils {
+public class PdbController implements HardcodedValues {
 
 	private static final Logger LOGGER = LoggerFactory.getLogger(PdbController.class);
 
@@ -100,7 +100,7 @@ public class PdbController implements HardcodedValues, CollectionUtils {
 		final int zeroBasedCaretIndex = caretIndex - 1;
 
 		final List<Proposal> proposals = db.autocomplete(query, zeroBasedCaretIndex);
-		final List<Proposal> nonEmptyProposals = filter(proposals, p -> p.getResults() > 0);
+		final List<Proposal> nonEmptyProposals = CollectionUtils.filter(proposals, p -> p.getResults() > 0);
 
 		final List<AutocompleteProposal> autocompleteProposals = toAutocompleteProposals(nonEmptyProposals);
 		Collections.sort(autocompleteProposals, new AutocompleteProposalByValue());
@@ -129,16 +129,12 @@ public class PdbController implements HardcodedValues, CollectionUtils {
 			produces = MediaType.APPLICATION_JSON_UTF8_VALUE //
 	)
 	@ResponseBody
-	List<String> fields(@PathVariable(name = "fieldName") final String fieldName,
+	SortedSet<String> fields(@PathVariable(name = "fieldName") final String fieldName,
 			@RequestParam(name = "query") final String query) {
 
-		try {
-			final List<String> fields = db.getFieldsValues(query, fieldName);
+		final SortedSet<String> fields = db.getFieldsValues(query, fieldName);
 
-			return fields;
-		} catch (final FieldNotExistsException e) {
-			throw new NotFoundException(e);
-		}
+		return fields;
 	}
 
 	private List<AutocompleteProposal> toAutocompleteProposals(final List<Proposal> proposals) {

pdb-ui/src/main/java/org/lucares/pdbui/TcpIngestor.java

@@ -159,7 +159,7 @@ public class TcpIngestor implements Ingestor, AutoCloseable, DisposableBean {
 		}
 	}
 
-	public TcpIngestor(final Path dataDirectory) {
+	public TcpIngestor(final Path dataDirectory) throws IOException {
 		LOGGER.info("opening performance db: " + dataDirectory);
 		db = new PerformanceDb(dataDirectory);
 		LOGGER.debug("performance db open");

pdb-ui/src/test/java/org/lucares/performance/db/ingestor/TcpIngestorTest.java

@@ -14,8 +14,8 @@ import java.util.Map;
 
 import org.lucares.pdb.api.Entry;
 import org.lucares.pdbui.TcpIngestor;
-import org.lucares.performance.db.FileUtils;
 import org.lucares.performance.db.PerformanceDb;
+import org.lucares.utils.file.FileUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.testng.Assert;
@@ -23,8 +23,6 @@ import org.testng.annotations.AfterMethod;
 import org.testng.annotations.BeforeMethod;
 import org.testng.annotations.Test;
 
-import liquibase.exception.LiquibaseException;
-
 @Test
 public class TcpIngestorTest {
 
@@ -42,7 +40,7 @@ public class TcpIngestorTest {
 		FileUtils.delete(dataDirectory);
 	}
 
-	public void testIngestDataViaTcpStream() throws LiquibaseException, Exception {
+	public void testIngestDataViaTcpStream() throws Exception {
 
 		final OffsetDateTime dateA = OffsetDateTime.now();
 		final OffsetDateTime dateB = OffsetDateTime.now();