potiuk commented on code in PR #27912:
URL: https://github.com/apache/airflow/pull/27912#discussion_r1032648381
##########
airflow/providers/common/sql/hooks/sql.py:
##########
@@ -234,7 +266,42 @@ def run(
"""
Runs a command or a list of commands. Pass a list of sql
statements to the sql parameter to get them to execute
- sequentially
+ sequentially.
+
+ The method will return either single query results (typically list of
rows) or list of those results
+ where each element in the list are results of one of the queries
(typically list of list of rows :D)
+
+ For compatibility reasons, the behaviour of the DBAPIHook is somewhat
confusing.
+ In cases, when multiple queries are run, the return values will be an
iterable (list) of results
+ - one for each query. However, in certain cases, when single query is
run - the results will be just
+ the results of that query without wrapping the results in a list.
+
+ The cases when single query results are returned without wrapping them
in a list are when:
+
+ a) sql is string and last_statement is True (regardless what
split_statement value is)
+ b) sql is string and split_statement is False
+
+ In all other cases, the results are wrapped in a list, even if there
is only one statement to process:
+
+ a) always when sql is iterable (regardless what last_statement value
is)
+ b) when sql is string, split_statement is True and last_statement is
False
Review Comment:
Ah yeah. Mental shortcut. "Iterable of string statements" now.
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