yandex-qatools#127

 - additional postgres parameters support added

src/main/java/ru/yandex/qatools/embed/postgresql/EmbeddedPostgres.java

@@ -36,6 +36,7 @@ public class EmbeddedPostgres implements AutoCloseable {
             "--locale=C",
             "--lc-collate=C",
             "--lc-ctype=C");
+    private static final List<String> DEFAULT_POSTGRES_PARAMS = asList();
     private final String dataDir;
     private final IVersion version;
     private PostgresProcess process;
@@ -161,14 +162,34 @@ public String start(IRuntimeConfig runtimeConfig) throws IOException {
      */
     public String start(IRuntimeConfig runtimeConfig, String host, int port, String dbName, String user, String password,
                         List<String> additionalParams) throws IOException {
+        return start(runtimeConfig, host, port, dbName, user, password, additionalParams, DEFAULT_POSTGRES_PARAMS);
+    }
+
+    /**
+     * Starts up the embedded postgres
+     *
+     * @param runtimeConfig    required runtime configuration
+     * @param host             host to bind to
+     * @param port             port to bind to
+     * @param dbName           name of the database to initialize
+     * @param user             username to connect
+     * @param password         password for the provided username
+     * @param additionalInitDbParams additional database init params (if required)
+     * @param additionalPostgresParams additional postgresql params (if required)
+     * @return connection url for the initialized postgres instance
+     * @throws IOException if an I/O error occurs during the process startup
+     */
+    public String start(IRuntimeConfig runtimeConfig, String host, int port, String dbName, String user, String password,
+                        List<String> additionalInitDbParams, List<String> additionalPostgresParams) throws IOException {
         final PostgresStarter<PostgresExecutable, PostgresProcess> runtime = PostgresStarter.getInstance(runtimeConfig);
         config = new PostgresConfig(version,
                 new AbstractPostgresConfig.Net(host, port),
                 new AbstractPostgresConfig.Storage(dbName, dataDir),
                 new AbstractPostgresConfig.Timeout(),
                 new AbstractPostgresConfig.Credentials(user, password)
         );
-        config.getAdditionalInitDbParams().addAll(additionalParams);
+        config.getAdditionalInitDbParams().addAll(additionalInitDbParams);
+        config.getAdditionalPostgresParams().addAll(additionalPostgresParams);
         PostgresExecutable exec = runtime.prepare(config);
         this.process = exec.start();
         return formatConnUrl(config);

src/main/java/ru/yandex/qatools/embed/postgresql/PostgresProcess.java

@@ -207,6 +207,7 @@ protected List<String> getCommandLine(Distribution distribution, PostgresConfig
                         "-h", config.net().host(),
                         "-D", config.storage().dbDir().getAbsolutePath()
                 ));
+                ret.addAll(config.getAdditionalPostgresParams());
                 break;
             case "pg_ctl": //NOSONAR
                 ret.addAll(asList(exe.executable().getAbsolutePath(),

src/main/java/ru/yandex/qatools/embed/postgresql/config/AbstractPostgresConfig.java

@@ -27,6 +27,7 @@ public abstract class AbstractPostgresConfig<C extends AbstractPostgresConfig> e
     protected final Credentials credentials;
     protected List<String> args = new ArrayList<>();
     protected List<String> additionalInitDbParams = new ArrayList<>();
+    protected List<String> additionalPostgresParams = new ArrayList<>();
 
     protected AbstractPostgresConfig(AbstractPostgresConfig config, Command postgres) {
         this(config.version, config.net(), config.storage, config.timeout(), config.credentials, new SupportConfig(postgres));
@@ -78,7 +79,6 @@ public C withAdditionalInitDbParams(List<String> additionalInitDbParams) {
         return (C) this;
     }
 
-
     /**
      * You may add here additional arguments for the {@code initdb} executable.<br/>
      * <p>
@@ -100,6 +100,25 @@ public List<String> getAdditionalInitDbParams() {
         return additionalInitDbParams;
     }
 
+    /**
+     * You may add here additional arguments for the {@code postgres} executable.<br/>
+     * <p>
+     * Example.<br>
+     * to use custom number of maximum connection.<br/>
+     * <pre>
+     * getAdditionalPostgresParams().addAll(
+     *      java.util.Arrays.asList(
+     *          "-c", "max_connections=11"
+     * )
+     * </pre>
+     * @return The list of additional parameters for the {@code postgres} executable.<br/>
+     * Not {@code null}.<br>
+     * @see <a href="https://www.postgresql.org/docs/9.6/static/config-setting.html#AEN32659">Parameter Interaction via the Shell</a>
+     */
+    public List<String> getAdditionalPostgresParams() {
+        return additionalPostgresParams;
+    }
+
     public static class Storage {
         private final File dbDir;
         private final String dbName;