Implement rank function for SQLite FTS

This commit is contained in:
Erik Johnston 2015-10-23 13:23:48 +01:00
parent 671ac699f1
commit 0c36098c1f
3 changed files with 30 additions and 2 deletions

View File

@ -17,6 +17,8 @@ from synapse.storage.prepare_database import (
prepare_database, prepare_sqlite3_database
)
import struct
class Sqlite3Engine(object):
single_threaded = True
@ -32,6 +34,7 @@ class Sqlite3Engine(object):
def on_new_connection(self, db_conn):
self.prepare_database(db_conn)
db_conn.create_function("rank", 1, _rank)
def prepare_database(self, db_conn):
prepare_sqlite3_database(db_conn)
@ -45,3 +48,27 @@ class Sqlite3Engine(object):
def lock_table(self, txn, table):
return
# Following functions taken from: https://github.com/coleifer/peewee
def _parse_match_info(buf):
bufsize = len(buf)
return [struct.unpack('@I', buf[i:i+4])[0] for i in range(0, bufsize, 4)]
def _rank(raw_match_info):
"""Handle match_info called w/default args 'pcx' - based on the example rank
function http://sqlite.org/fts3.html#appendix_a
"""
match_info = _parse_match_info(raw_match_info)
score = 0.0
p, c = match_info[:2]
for phrase_num in range(p):
phrase_info_idx = 2 + (phrase_num * c * 3)
for col_num in range(c):
col_idx = phrase_info_idx + (col_num * 3)
x1, x2 = match_info[col_idx:col_idx + 2]
if x1 > 0:
score += float(x1) / x2
return score

View File

@ -54,7 +54,7 @@ CREATE INDEX event_search_ev_ridx ON event_search(room_id);
SQLITE_TABLE = (
"CREATE VIRTUAL TABLE IF NOT EXISTS event_search"
" USING fts3 ( event_id, room_id, key, value)"
" USING fts4 ( event_id, room_id, key, value )"
)

View File

@ -72,7 +72,8 @@ class SearchStore(SQLBaseStore):
)
elif isinstance(self.database_engine, Sqlite3Engine):
sql = (
"SELECT 0 as rank, room_id, event_id FROM event_search"
"SELECT rank(matchinfo(event_search)) as rank, room_id, event_id"
" FROM event_search"
" WHERE value MATCH ?"
)
else: