Added/Updated tests\bugs\gh_8104_test.py: Checked on 6.0.0.345, 5.0.1…

….1395, 4.0.5.3092 (fetches in req #2 LESS than in req #1).

tests/bugs/gh_8104_test.py

@@ -0,0 +1,116 @@
+#coding:utf-8
+
+"""
+ID:          issue-8104
+ISSUE:       https://github.com/FirebirdSQL/firebird/issues/8104
+TITLE:       Inefficient evaluation of expressions like rdb$db_key <= ? after mass delete
+DESCRIPTION:
+NOTES:
+    [08.05.2024] pzotov
+    Confirmed problem on 6.0.0.344, 5.0.1.1394, 4.0.5.3091 (request #1: 47643; request #2: 115943).
+    Checked on 6.0.0.345, 5.0.1.1395, 4.0.5.3092 (fetches in req #2 LESS than in req #1).
+"""
+
+import pytest
+from firebird.qa import *
+
+TAB_NAME = 'T1'.upper()
+ROWS_CNT = 100000
+
+init_sql = f"""
+    create table {TAB_NAME} (
+        id int not null,
+        val varchar(256)
+    );
+    commit;
+
+    -- fill with some data
+    set term ^;
+    execute block as
+        declare n int = 0;
+        declare s varchar(36);
+    begin
+        while (n < {ROWS_CNT}) do
+        begin
+            n = n + 1;
+            s = uuid_to_char(gen_uuid());
+            insert into {TAB_NAME} (id, val) values (:n, lpad('', 256, :s));
+        end
+    end
+    ^
+    set term ;^
+    commit;
+"""
+
+db = db_factory(init = init_sql)
+act = python_act('db')
+
+@pytest.mark.version('>=4.0.5')
+def test_1(act: Action, capsys):
+
+    get_last_pp_for_table = f"""
+        select p.rdb$relation_id, p.rdb$page_sequence
+        from rdb$pages p join rdb$relations r on p.rdb$relation_id = r.rdb$relation_id
+        where r.rdb$relation_name = '{TAB_NAME}' and p.rdb$page_type = 4
+        order by 2 desc
+        rows 1
+    """
+    rel_id, max_pp = -1, -1
+    with act.db.connect(no_gc = True) as con:
+        cur = con.cursor()
+        cur.execute(get_last_pp_for_table)
+        for r in cur:
+            rel_id, max_pp = r[:2]
+        assert rel_id > 0 and max_pp > 0
+        #--------------------------------
+
+        # Subsequent number of PP that we want to check ('20' in the ticket):
+        ##########
+        chk_pp = 0
+        ##########
+
+        read_records_for_chk_pp = f"""
+            select count(*), min(id), max(id)
+            from t1
+            where
+                rdb$db_key >= make_dbkey({rel_id}, 0, 0, {chk_pp})
+                and rdb$db_key < make_dbkey({rel_id}, 0, 0, {chk_pp+1})
+        """
+
+        fetches_ini = con.info.fetches
+        # read records from selected PP only -- FIRST TIME
+        cur.execute(read_records_for_chk_pp)
+        cur.fetchall()
+        fetches_1 = con.info.fetches - fetches_ini
+
+        #----------------------------------
+
+        # delete records from selected PP and up to the end
+        del_rows_starting_from_chk_pp = f"""
+            delete from t1
+            where rdb$db_key >= make_dbkey({rel_id}, 0, 0, {chk_pp})
+        """
+        con.execute_immediate(del_rows_starting_from_chk_pp)
+
+        #----------------------------------
+
+        fetches_ini = con.info.fetches
+        # read records from selected PP only -- SECOND TIME
+        cur.execute(read_records_for_chk_pp)
+        cur.fetchall()
+        fetches_2 = con.info.fetches - fetches_ini
+
+    expected_msg = 'Fetches ratio expected.'
+
+    if fetches_2 <= fetches_1:
+        print(expected_msg)
+    else:
+        print(f'Fetches ratio between 1st and 2nd requests to PP = {chk_pp} - UNEXPECTED:')
+        print('Request #1:', fetches_1)
+        print('Request #2:', fetches_2)
+
+    act.expected_stdout = f"""
+        {expected_msg}
+    """
+    act.stdout = capsys.readouterr().out
+    assert act.clean_stdout == act.clean_expected_stdout