Added/Updated tests\bugs\gh_8291_test.py: Checked on 6.0.0.502-d2f4cf6, 5.0.2.1542-ab50e20 (intermediate builds).

tests/bugs/gh_8291_test.py

@@ -0,0 +1,82 @@
+#coding:utf-8
+
+"""
+ID:          issue-8291
+ISSUE:       https://github.com/FirebirdSQL/firebird/issues/8291
+TITLE:       NULLs should be skipped during index navigation when there's no lower bound and matched conditions are known to ignore NULLs
+DESCRIPTION:
+    Test uses script from ticket. We compare number of indexed reads with threshold - see variable MAX_ALLOWED_IDX_READS.
+    BEFORE fix value of indexed was 500002 (both on 5.x and 6.x), after fix it became 886 (using default page_size = 8k).
+NOTES:
+    [25.10.2024] pzotov
+    Confirmed problem on 6.0.0.485, 5.0.2.1519.
+    Checked on 6.0.0.502-d2f4cf6, 5.0.2.1542-ab50e20 (intermediate builds).
+"""
+
+import pytest
+from firebird.qa import *
+
+############################
+MAX_ALLOWED_IDX_READS = 1000
+############################
+
+init_sql = """
+    create table test (id int);
+
+    set term ^;
+    execute block as
+        declare n int = 1000000;
+        declare i int = 0;
+    begin
+        while (i < n) do
+        begin
+            insert into test(id) values( iif(mod(:i, 2) = 0, null, :i) );
+            i = i + 1;
+        end
+    end^
+    set term ;^
+    commit;
+
+    create index test_id on test(id);
+    commit;
+"""
+db = db_factory(page_size = 8192, init = init_sql)
+
+act = python_act('db')
+
+#-----------------------------------------------------------
+
+@pytest.mark.version('>=5.0.2')
+def test_1(act: Action, capsys):
+    msg_prefix = 'Number of indexed reads:'
+    expected_txt = 'EXPECTED'
+    idx_reads = {}
+    with act.db.connect() as con:
+        cur = con.cursor()
+        cur.execute("select rdb$relation_id from rdb$relations where rdb$relation_name = 'TEST'")
+        test_rel_id = cur.fetchone()[0]
+        idx_reads[test_rel_id] = 0
+
+        for x_table in con.info.get_table_access_stats():
+            if x_table.table_id == test_rel_id:
+                idx_reads[test_rel_id] = -x_table.indexed
+
+        cur.execute('select count(*) from (select id from test where id < 3 order by id)')
+        data = cur.fetchall()
+
+        for x_table in con.info.get_table_access_stats():
+            if x_table.table_id == test_rel_id:
+                idx_reads[test_rel_id] += x_table.indexed
+            
+        # BEFORE fix value of indexed was 500002. After fix: 886
+        if idx_reads[test_rel_id] < MAX_ALLOWED_IDX_READS:
+            print(f'{msg_prefix} {expected_txt}')
+        else:
+            print(f'{msg_prefix} UNEXPECTED: {idx_reads[test_rel_id]} - greater than threshold = {MAX_ALLOWED_IDX_READS}.')
+
+    act.expected_stdout = f"""
+        {msg_prefix} {expected_txt}
+    """
+
+    act.stdout = capsys.readouterr().out
+    assert act.clean_stdout == act.clean_expected_stdout