diff options
Diffstat (limited to 'synapse/storage')
| -rw-r--r-- | synapse/storage/stream.py | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/synapse/storage/stream.py b/synapse/storage/stream.py index 163363c0c2..529ad4ea79 100644 --- a/synapse/storage/stream.py +++ b/synapse/storage/stream.py @@ -77,14 +77,27 @@ def generate_pagination_where_clause( would be generated for dir=b, from_token=(6, 7) and to_token=(5, 3). + Note that tokens are considered to be after the row they are in, e.g. if + a row A has a token T, then we consider A to be before T. This convention + is important when figuring out inequalities for the generated SQL, and + produces the following result: + - If paginating forwards then we exclude any rows matching the from + token, but include those that match the to token. + - If paginating backwards then we include any rows matching the from + token, but include those that match the to token. + Args: direction (str): Whether we're paginating backwards("b") or forwards ("f"). column_names (tuple[str, str]): The column names to bound. Must *not* be user defined as these get inserted directly into the SQL statement without escapes. - from_token (tuple[int, int]|None) - to_token (tuple[int, int]|None) + from_token (tuple[int, int]|None): The start point for the pagination. + This is an exclusive minimum bound if direction is "f", and an + inclusive maximum bound if direction is "b". + to_token (tuple[int, int]|None): The endpoint point for the pagination. + This is an inclusive maximum bound if direction is "f", and an + exclusive minimum bound if direction is "b". engine: The database engine to generate the clauses for Returns: @@ -131,7 +144,9 @@ def _make_generic_sql_bound(bound, column_names, values, engine): names (tuple[str, str]): The column names. Must *not* be user defined as these get inserted directly into the SQL statement without escapes. - values (tuple[int, int]): The values to bound the columns by. + values (tuple[int|None, int]): The values to bound the columns by. If + the first value is None then only creates a bound on the second + column. engine: The database engine to generate the SQL for Returns: |