recreate word table when refreshing counts

The counting touches a large part of the word table, leaving
bloated tables and indexes. Thus recreate the table instead and
swap it in.

lib-sql/tokenizer/icu_tokenizer_tables.sql

@@ -1,40 +0,0 @@
--- SPDX-License-Identifier: GPL-2.0-only
---
--- This file is part of Nominatim. (https://nominatim.org)
---
--- Copyright (C) 2022 by the Nominatim developer community.
--- For a full list of authors see the git log.
-
-DROP TABLE IF EXISTS word;
-CREATE TABLE word (
-  word_id INTEGER,
-  word_token text NOT NULL,
-  type text NOT NULL,
-  word text,
-  info jsonb
-) {{db.tablespace.search_data}};
-
-CREATE INDEX idx_word_word_token ON word
-    USING BTREE (word_token) {{db.tablespace.search_index}};
--- Used when updating country names from the boundary relation.
-CREATE INDEX idx_word_country_names ON word
-    USING btree(word) {{db.tablespace.address_index}}
-    WHERE type = 'C';
--- Used when inserting new postcodes on updates.
-CREATE INDEX idx_word_postcodes ON word
-    USING btree(word) {{db.tablespace.address_index}}
-    WHERE type = 'P';
--- Used when inserting full words.
-CREATE INDEX idx_word_full_word ON word
-    USING btree(word) {{db.tablespace.address_index}}
-    WHERE type = 'W';
--- Used when inserting analyzed housenumbers (exclude old-style entries).
-CREATE INDEX idx_word_housenumbers ON word
-    USING btree(word) {{db.tablespace.address_index}}
-    WHERE type = 'H' and word is not null;
-
-GRANT SELECT ON word TO "{{config.DATABASE_WEBUSER}}";
-
-DROP SEQUENCE IF EXISTS seq_word;
-CREATE SEQUENCE seq_word start 1;
-GRANT SELECT ON seq_word to "{{config.DATABASE_WEBUSER}}";

nominatim/clicmd/refresh.py

@@ -110,7 +110,7 @@ class UpdateRefresh:
 
         if args.word_counts:
             LOG.warning('Recompute word statistics')
-            self._get_tokenizer(args.config).update_statistics()
+            self._get_tokenizer(args.config).update_statistics(args.config)
 
         if args.address_levels:
             LOG.warning('Updating address levels')

nominatim/clicmd/setup.py

@@ -169,7 +169,7 @@ class SetupAll:
         tokenizer.finalize_import(args.config)
 
         LOG.warning('Recompute word counts')
-        tokenizer.update_statistics()
+        tokenizer.update_statistics(args.config)
 
         webdir = args.project_dir / 'website'
         LOG.warning('Setup website at %s', webdir)

nominatim/db/sql_preprocessor.py

@@ -90,6 +90,18 @@ class SQLPreprocessor:
         self.env.globals['postgres'] = _setup_postgresql_features(conn)
 
 
+    def run_string(self, conn: Connection, template: str, **kwargs: Any) -> None:
+        """ Execute the given SQL template string on the connection.
+            The keyword arguments may supply additional parameters
+            for preprocessing.
+        """
+        sql = self.env.from_string(template).render(**kwargs)
+
+        with conn.cursor() as cur:
+            cur.execute(sql)
+        conn.commit()
+
+
     def run_sql_file(self, conn: Connection, name: str, **kwargs: Any) -> None:
         """ Execute the given SQL file on the connection. The keyword arguments
             may supply additional parameters for preprocessing.

nominatim/tokenizer/base.py

@@ -201,7 +201,7 @@ class AbstractTokenizer(ABC):
 
 
     @abstractmethod
-    def update_statistics(self) -> None:
+    def update_statistics(self, config: Configuration) -> None:
         """ Recompute any tokenizer statistics necessary for efficient lookup.
             This function is meant to be called from time to time by the user
             to improve performance. However, the tokenizer must not depend on

nominatim/tokenizer/icu_tokenizer.py

@@ -31,6 +31,11 @@ DBCFG_TERM_NORMALIZATION = "tokenizer_term_normalization"
 
 LOG = logging.getLogger()
 
+WORD_TYPES =(('country_names', 'C'),
+             ('postcodes', 'P'),
+             ('full_word', 'W'),
+             ('housenumbers', 'H'))
+
 def create(dsn: str, data_dir: Path) -> 'ICUTokenizer':
     """ Create a new instance of the tokenizer provided by this module.
     """
@@ -62,7 +67,8 @@ class ICUTokenizer(AbstractTokenizer):
 
         if init_db:
             self.update_sql_functions(config)
-            self._init_db_tables(config)
+            self._setup_db_tables(config, 'word')
+            self._create_base_indices(config, 'word')
 
 
     def init_from_project(self, config: Configuration) -> None:
@@ -80,9 +86,7 @@ class ICUTokenizer(AbstractTokenizer):
         """ Do any required postprocessing to make the tokenizer data ready
             for use.
         """
-        with connect(self.dsn) as conn:
-            sqlp = SQLPreprocessor(conn, config)
-            sqlp.run_sql_file(conn, 'tokenizer/legacy_tokenizer_indices.sql')
+        self._create_lookup_indices(config, 'word')
 
 
     def update_sql_functions(self, config: Configuration) -> None:
@@ -100,24 +104,35 @@ class ICUTokenizer(AbstractTokenizer):
         self.init_from_project(config)
 
 
-    def update_statistics(self) -> None:
+    def update_statistics(self, config: Configuration) -> None:
         """ Recompute frequencies for all name words.
         """
         with connect(self.dsn) as conn:
-            if conn.table_exists('search_name'):
-                with conn.cursor() as cur:
-                    cur.drop_table("word_frequencies")
-                    LOG.info("Computing word frequencies")
-                    cur.execute("""CREATE TEMP TABLE word_frequencies AS
-                                     SELECT unnest(name_vector) as id, count(*)
-                                     FROM search_name GROUP BY id""")
-                    cur.execute("CREATE INDEX ON word_frequencies(id)")
-                    LOG.info("Update word table with recomputed frequencies")
-                    cur.execute("""UPDATE word
-                                   SET info = info || jsonb_build_object('count', count)
-                                   FROM word_frequencies WHERE word_id = id""")
-                    cur.drop_table("word_frequencies")
+            if not conn.table_exists('search_name'):
+                return
+
+            with conn.cursor() as cur:
+                LOG.info('Computing word frequencies')
+                cur.drop_table('word_frequencies')
+                cur.execute("""CREATE TEMP TABLE word_frequencies AS
+                                 SELECT unnest(name_vector) as id, count(*)
+                                 FROM search_name GROUP BY id""")
+                cur.execute('CREATE INDEX ON word_frequencies(id)')
+                LOG.info('Update word table with recomputed frequencies')
+                cur.drop_table('tmp_word')
+                cur.execute("""CREATE TABLE tmp_word AS
+                                SELECT word_id, word_token, type, word,
+                                       (CASE WHEN wf.count is null THEN info
+                                          ELSE info || jsonb_build_object('count', wf.count)
+                                        END) as info
+                                FROM word LEFT JOIN word_frequencies wf
+                                  ON word.word_id = wf.id""")
+                cur.drop_table('word_frequencies')
             conn.commit()
+        self._create_base_indices(config, 'tmp_word')
+        self._create_lookup_indices(config, 'tmp_word')
+        self._move_temporary_word_table('tmp_word')
+
 
 
     def _cleanup_housenumbers(self) -> None:
@@ -219,16 +234,81 @@ class ICUTokenizer(AbstractTokenizer):
             self.loader.save_config_to_db(conn)
 
 
-    def _init_db_tables(self, config: Configuration) -> None:
+    def _setup_db_tables(self, config: Configuration, table_name: str) -> None:
+        """ Set up the word table and fill it with pre-computed word
+            frequencies.
+        """
+        with connect(self.dsn) as conn:
+            with conn.cursor() as cur:
+                cur.drop_table(table_name)
+            sqlp = SQLPreprocessor(conn, config)
+            sqlp.run_string(conn, """
+                CREATE TABLE {{table_name}} (
+                      word_id INTEGER,
+                      word_token text NOT NULL,
+                      type text NOT NULL,
+                      word text,
+                      info jsonb
+                    ) {{db.tablespace.search_data}};
+                GRANT SELECT ON {{table_name}} TO "{{config.DATABASE_WEBUSER}}";
+
+                DROP SEQUENCE IF EXISTS seq_{{table_name}};
+                CREATE SEQUENCE seq_{{table_name}} start 1;
+                GRANT SELECT ON seq_{{table_name}} to "{{config.DATABASE_WEBUSER}}";
+            """, table_name=table_name)
+
+
+    def _create_base_indices(self, config: Configuration, table_name: str) -> None:
         """ Set up the word table and fill it with pre-computed word
             frequencies.
         """
         with connect(self.dsn) as conn:
             sqlp = SQLPreprocessor(conn, config)
-            sqlp.run_sql_file(conn, 'tokenizer/icu_tokenizer_tables.sql')
+            sqlp.run_string(conn,
+                            """CREATE INDEX idx_{{table_name}}_word_token ON {{table_name}}
+                               USING BTREE (word_token) {{db.tablespace.search_index}}""",
+                            table_name=table_name)
+            for name, ctype in WORD_TYPES:
+                sqlp.run_string(conn,
+                                """CREATE INDEX idx_{{table_name}}_{{idx_name}} ON {{table_name}}
+                                   USING BTREE (word) {{db.tablespace.address_index}}
+                                   WHERE type = '{{column_type}}'
+                                """,
+                                table_name=table_name, idx_name=name,
+                                column_type=ctype)
+
+
+    def _create_lookup_indices(self, config: Configuration, table_name: str) -> None:
+        """ Create addtional indexes used when running the API.
+        """
+        with connect(self.dsn) as conn:
+            sqlp = SQLPreprocessor(conn, config)
+            # Index required for details lookup.
+            sqlp.run_string(conn, """
+                CREATE INDEX IF NOT EXISTS idx_{{table_name}}_word_id
+                  ON {{table_name}} USING BTREE (word_id) {{db.tablespace.search_index}}
+            """,
+            table_name=table_name)
+
+
+    def _move_temporary_word_table(self, old: str) -> None:
+        """ Rename all tables and indexes used by the tokenizer.
+        """
+        with connect(self.dsn) as conn:
+            with conn.cursor() as cur:
+                cur.drop_table('word')
+                cur.execute(f"ALTER TABLE {old} RENAME TO word")
+                for idx in ('word_token', 'word_id'):
+                    cur.execute(f"""ALTER INDEX idx_{old}_{idx}
+                                      RENAME TO idx_word_{idx}""")
+                for name, _ in WORD_TYPES:
+                    cur.execute(f"""ALTER INDEX idx_{old}_{name}
+                                    RENAME TO idx_word_{name}""")
             conn.commit()
 
 
+
+
 class ICUNameAnalyzer(AbstractAnalyzer):
     """ The ICU analyzer uses the ICU library for splitting names.
 

nominatim/tokenizer/legacy_tokenizer.py

@@ -210,7 +210,7 @@ class LegacyTokenizer(AbstractTokenizer):
             self._save_config(conn, config)
 
 
-    def update_statistics(self) -> None:
+    def update_statistics(self, _: Configuration) -> None:
         """ Recompute the frequency of full words.
         """
         with connect(self.dsn) as conn:

test/python/cli/conftest.py

@@ -38,10 +38,10 @@ class DummyTokenizer:
     def finalize_import(self, *args):
         self.finalize_import_called = True
 
-    def update_statistics(self):
+    def update_statistics(self, *args):
         self.update_statistics_called = True
 
-    def update_word_tokens(self):
+    def update_word_tokens(self, *args):
         self.update_word_tokens_called = True
 
 

test/python/tokenizer/test_icu.py

@@ -7,7 +7,6 @@
 """
 Tests for ICU tokenizer.
 """
-import shutil
 import yaml
 import itertools
 
@@ -32,8 +31,6 @@ def test_config(project_env, tmp_path):
     sqldir.mkdir()
     (sqldir / 'tokenizer').mkdir()
     (sqldir / 'tokenizer' / 'icu_tokenizer.sql').write_text("SELECT 'a'")
-    shutil.copy(str(project_env.lib_dir.sql / 'tokenizer' / 'icu_tokenizer_tables.sql'),
-                str(sqldir / 'tokenizer' / 'icu_tokenizer_tables.sql'))
 
     project_env.lib_dir.sql = sqldir
 
@@ -204,16 +201,14 @@ def test_update_sql_functions(db_prop, temp_db_cursor,
 
 def test_finalize_import(tokenizer_factory, temp_db_conn,
                          temp_db_cursor, test_config, sql_preprocessor_cfg):
-    func_file = test_config.lib_dir.sql / 'tokenizer' / 'legacy_tokenizer_indices.sql'
-    func_file.write_text("""CREATE FUNCTION test() RETURNS TEXT
-                            AS $$ SELECT 'b'::text $$ LANGUAGE SQL""")
-
     tok = tokenizer_factory()
     tok.init_new_db(test_config)
 
+    assert not temp_db_conn.index_exists('idx_word_word_id')
+
     tok.finalize_import(test_config)
 
-    temp_db_cursor.scalar('SELECT test()') == 'b'
+    assert temp_db_conn.index_exists('idx_word_word_id')
 
 
 def test_check_database(test_config, tokenizer_factory,
@@ -224,19 +219,20 @@ def test_check_database(test_config, tokenizer_factory,
     assert tok.check_database(test_config) is None
 
 
-def test_update_statistics_reverse_only(word_table, tokenizer_factory):
+def test_update_statistics_reverse_only(word_table, tokenizer_factory, test_config):
     tok = tokenizer_factory()
-    tok.update_statistics()
+    tok.update_statistics(test_config)
 
 
-def test_update_statistics(word_table, table_factory, temp_db_cursor, tokenizer_factory):
+def test_update_statistics(word_table, table_factory, temp_db_cursor,
+                           tokenizer_factory, test_config):
     word_table.add_full_word(1000, 'hello')
     table_factory('search_name',
                   'place_id BIGINT, name_vector INT[]',
                   [(12, [1000])])
     tok = tokenizer_factory()
 
-    tok.update_statistics()
+    tok.update_statistics(test_config)
 
     assert temp_db_cursor.scalar("""SELECT count(*) FROM word
                                     WHERE type = 'W' and

test/python/tokenizer/test_legacy.py

@@ -238,19 +238,19 @@ def test_check_database_bad_setup(test_config, tokenizer_factory, monkeypatch,
     assert tok.check_database(False) is not None
 
 
-def test_update_statistics_reverse_only(word_table, tokenizer_factory):
+def test_update_statistics_reverse_only(word_table, tokenizer_factory, test_config):
     tok = tokenizer_factory()
-    tok.update_statistics()
+    tok.update_statistics(test_config)
 
 
-def test_update_statistics(word_table, table_factory, temp_db_cursor, tokenizer_factory):
+def test_update_statistics(word_table, table_factory, temp_db_cursor, tokenizer_factory, test_config):
     word_table.add_full_word(1000, 'hello')
     table_factory('search_name',
                   'place_id BIGINT, name_vector INT[]',
                   [(12, [1000])])
     tok = tokenizer_factory()
 
-    tok.update_statistics()
+    tok.update_statistics(test_config)
 
     assert temp_db_cursor.scalar("""SELECT count(*) FROM word
                                     WHERE word_token like ' %' and