Merge pull request #327 from matrix-org/erikj/search
Implement rank function for SQLite FTS
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commit
b8e37ed944
3 changed files with 30 additions and 2 deletions
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@ -17,6 +17,8 @@ from synapse.storage.prepare_database import (
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prepare_database, prepare_sqlite3_database
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)
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import struct
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class Sqlite3Engine(object):
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single_threaded = True
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@ -32,6 +34,7 @@ class Sqlite3Engine(object):
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def on_new_connection(self, db_conn):
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self.prepare_database(db_conn)
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db_conn.create_function("rank", 1, _rank)
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def prepare_database(self, db_conn):
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prepare_sqlite3_database(db_conn)
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@ -45,3 +48,27 @@ class Sqlite3Engine(object):
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def lock_table(self, txn, table):
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return
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# Following functions taken from: https://github.com/coleifer/peewee
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def _parse_match_info(buf):
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bufsize = len(buf)
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return [struct.unpack('@I', buf[i:i+4])[0] for i in range(0, bufsize, 4)]
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def _rank(raw_match_info):
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"""Handle match_info called w/default args 'pcx' - based on the example rank
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function http://sqlite.org/fts3.html#appendix_a
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"""
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match_info = _parse_match_info(raw_match_info)
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score = 0.0
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p, c = match_info[:2]
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for phrase_num in range(p):
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phrase_info_idx = 2 + (phrase_num * c * 3)
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for col_num in range(c):
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col_idx = phrase_info_idx + (col_num * 3)
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x1, x2 = match_info[col_idx:col_idx + 2]
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if x1 > 0:
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score += float(x1) / x2
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return score
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@ -54,7 +54,7 @@ CREATE INDEX event_search_ev_ridx ON event_search(room_id);
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SQLITE_TABLE = (
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"CREATE VIRTUAL TABLE IF NOT EXISTS event_search"
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" USING fts3 ( event_id, room_id, key, value)"
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" USING fts4 ( event_id, room_id, key, value )"
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)
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@ -72,7 +72,8 @@ class SearchStore(SQLBaseStore):
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)
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elif isinstance(self.database_engine, Sqlite3Engine):
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sql = (
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"SELECT 0 as rank, room_id, event_id FROM event_search"
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"SELECT rank(matchinfo(event_search)) as rank, room_id, event_id"
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" FROM event_search"
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" WHERE value MATCH ?"
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)
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else:
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