Importing geonames data into Firebird

First cut at schema for geonames table

  GEONAMEID BIGINT NOT NULL,
  NAME VARCHAR(200) NOT NULL,
  ASCIINAME VARCHAR(200),
  ALTERNATENAMES BLOB SUB_TYPE 1,
  LATITUDE DOUBLE PRECISION,
  LONGITUDE DOUBLE PRECISION,
  FEATURE_CLASS CHAR(1),
  FEATURE_CODE VARCHAR(10),
  COUNTRY_CODE CHAR(2),
  CC2 VARCHAR(60),
  ADMIN1_CODE VARCHAR(20),
  ADMIN2_CODE VARCHAR(80),
  ADMIN3_CODE VARCHAR(20),
  ADMIN4_CODE VARCHAR(20),
  POPULATION BIGINT,
  ELEVATION INTEGER,
  DEM INTEGER,
  TIMEZONE VARCHAR(40),
  MOD_DATE DATE,
  CONSTRAINT PK_GEONAMES PRIMARY KEY (GEONAMEID)

Import via XMLWizard works fine, but need to improve speed when applying updates.