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Added/Updated tests\bugs\gh_7687_test.py: Checked on 5.0.0.1169. See notes.
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‎tests/bugs/gh_7687_test.py‎

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#coding:utf-8
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"""
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ID: issue-7687
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ISSUE: https://github.com/FirebirdSQL/firebird/issues/7687
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TITLE: Add LEVEL column to PLG$PROF_RECORD_SOURCES and PLG$PROF_RECORD_SOURCE_STATS_VIEW
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DESCRIPTION:
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Test creates master-detail tables and view 'v_test' for them.
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Then we create auxiliary view 'vp_rec_stats' to see profiler data.
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Running query to 'v_test' will add data to profiler snapshot tables so that we must have ability
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to reconstruct the whole EXPLAINED PLAN of that query, i.e. with top-level and all subsequent access paths.
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This reconstruction is performed by recursive query which first gets records with 'parent_record_source_id is null'
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(and all these records always have LEVEL = 0), and then goes down according to the principle:
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"give be lines with level that be bigger but CLOSEST to current one". This is achieved by applying dense_rank()
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function, see 'ranked_level' column usage and notes below.
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NOTES:
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[25.08.2023] pzotov
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1. We can NOT use "next level must be current one plus 1" in recursive part of query that reconstructs explained plan!
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This is because some access paths can be 'splitted' onto one or several 'sub-paths' by LF character, thus they are looked
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to be somewhat as 'multi-line' parts. Every LF in such case causes LEVEL to be "sinlently" increased by 1, so lines
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AFTER this "complex" access path will have LEVEL that differs from source for MORE than 1.
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Here is example of such data (there is NO record with LEVEL = 3):
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STTM_ID LEVEL REC_ID PAR_ID ACC_PATH SQL_TEXT
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======= ======= ======= ======= ================================================== ==================================================
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5760 0 1 <null> Select Expression select first 1 r.* from rdb$database r order by 1
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5760 1 2 1 -> First N Records select first 1 r.* from rdb$database r order by 1
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5760 2 3 2 -> Refetch
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-> Sort (record length: 36, key select first 1 r.* from rdb$database r order by 1
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5760 4 4 3 -> Table "RDB$DATABASE" as "R" Full Scan select first 1 r.* from rdb$database r order by 1
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This was implemented intentionally with purpose to make reconstruction of indents easier.
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Because of that, view that queries PLG$PROF_ tables must use "dense_rank()over(order by t.level)".
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2. We have to make additional (preliminary) call to rdb$profiler.start_session() / .finish_session() BEFORE test in order to create view
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that is based on profiler snapshot tables. Otherwise error raises:
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SQLSTATE = 42S02 / ... / -Table unknown / -PLG$PROF_RECORD_SOURCE_STATS_VIEW
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See: doc/sql.extensions/README.profiler.md
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"Snapshot tables (as well views and sequence) are automatically created in the first usage of the profiler"
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3. Currently there is problem with distinguish 'blocks' from profiler data that corresponds to sub-queries: there is no column that applies
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to the whole block and lines that belong (by hierarchy) to subquery can be displayed either before or after lines that relate to 'main'
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part of query. Although it seems that subquery is mostly displayed *after* main part.
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Because of that, it was decided for now to leave expected output as it is produced by current FB versions.
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If future runs will show that subquery part "jumps" randomly (from "top" to "bottom") than only presense of top-level access paths
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will be checked (without requirement to their concrete order).
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4. In order to see indents properly (including case if they will change in size) we have to prefix each line ('#' character is used).
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Checked on 5.0.0.1169.
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"""
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import os
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import pytest
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from firebird.qa import *
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db = db_factory()
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act = python_act('db') #, substitutions=[('[ \t]+', ' ')])
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@pytest.mark.version('>=5.0')
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def test_1(act: Action, capsys):
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test_sql = f"""
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create table tmain(id int primary key using index tmain_pk, x int);
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create table tdetl(id int primary key using index tdetl_pk, pid int references tmain using index tdetl_fk, y int, z int);
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insert into tmain(id,x) select row_number()over(), -100 + rand()*200 from rdb$types rows 100;
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insert into tdetl(id, pid, y,z) select row_number()over(), 1+rand()*99, rand()*1000, rand()*1000 from rdb$types;
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commit;
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create index tmain_x on tmain(x);
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create index tdetl_y on tdetl(y);
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create index tdetl_z on tdetl(z);
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set statistics index tdetl_fk;
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commit;
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out nul;
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-- This is needed in order to create view based on snapshot 'plg$prof_*' tables:
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select rdb$profiler.start_session('profile session 0') from rdb$database;
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out;
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create view vp_rec_stats as
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select
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cast(t.statement_id as smallint) as sttm_id
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,cast(t.level as smallint) as level
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,cast(t.record_source_id as smallint) as rec_id
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,cast(t.parent_record_source_id as smallint) as par_id
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,substring('#' || lpad('', 4*t.level,' ') || replace( replace(t.access_path, ascii_char(13), ''), ascii_char(10), ascii_char(10) || '#' || lpad('', 4*t.level,' ') ) from 1 for 320) as acc_path
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,substring( cast(t.sql_text as varchar(255)) from 1 for 50 ) as sql_text
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,dense_rank()over(order by t.level) as ranked_level
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from plg$prof_record_source_stats_view t
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join plg$prof_sessions s
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on s.profile_id = t.profile_id and
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s.description = 'profile session 1'
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;
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execute procedure rdb$profiler.finish_session(true);
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commit;
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create view v_test as
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select m4.id, d4.y, d4.z
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from tmain m4
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cross join lateral (
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select y, z
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from tdetl dx
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where
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dx.pid = m4.id
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and m4.x between dx.y and dx.z
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) d4
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where exists(select count(*) from tdetl dy group by dy.pid having count(*) > 2);
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out nul;
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select rdb$profiler.start_session('profile session 1') from rdb$database;
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-- Test query for which we want to see data in the profiler tables:
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-- ##########
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select * from v_test;
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out;
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execute procedure rdb$profiler.finish_session(true);
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commit;
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set transaction read committed;
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set count on;
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set list off;
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set heading off;
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-- ##############################################
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-- Output data from profiler.
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-- NB-1: each line is prefixed with '#' character in order to see indents.
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-- NB-2: 'level' column can not be used for joining in recursive part because of 'gaps'!
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-- Instead, 'ranked_level' is used fo this:
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-- ##############################################
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with recursive
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r as (
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select sttm_id, level, t.ranked_level, rec_id, par_id, acc_path --, sql_text
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from vp_rec_stats t
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where
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t.par_id is null and t.sql_text not containing 'rdb$profiler.start_session'
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UNION ALL
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select t.sttm_id, t.level, t.ranked_level, t.rec_id, t.par_id, t.acc_path --, t.sql_text
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from vp_rec_stats t
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join r on t.sttm_id = r.sttm_id and t.ranked_level = r.ranked_level + 1 and r.rec_id = t.par_id
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)
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select acc_path from r;
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"""
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act.expected_stdout = f"""
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#Select Expression
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# -> Filter (preliminary)
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# -> Nested Loop Join (inner)
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# -> Table "TMAIN" as "V_TEST M4" Full Scan
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# -> Filter
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# -> Table "TDETL" as "V_TEST D4 DX" Access By ID
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# -> Bitmap And
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# -> Bitmap
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# -> Index "TDETL_FK" Range Scan (full match)
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# -> Bitmap
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# -> Index "TDETL_Y" Range Scan (upper bound: 1/1)
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#Sub-query (invariant)
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# -> Filter
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# -> Aggregate
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# -> Table "TDETL" as "V_TEST DY" Access By ID
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# -> Index "TDETL_FK" Full Scan
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Records affected: 10
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"""
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act.isql(input = test_sql, combine_output = True)
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assert act.clean_stdout == act.clean_expected_stdout
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act.reset()

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