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114 lines
4.1 KiB
Python
114 lines
4.1 KiB
Python
#coding:utf-8
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"""
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ID: issue-6520
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ISSUE: 6520
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TITLE: Efficient table scans for DBKEY-based range conditions
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DESCRIPTION:
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We create table with very wide column and add there about 300 rows from rdb$types, with random data
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(in order to prevent RLE-compression which eventually can reduce number of data pages).
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Then we extract all values of rdb$db_key from this table and take into processing two of them.
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First value has 'distance' from starting db_key = 1/3 of total numbers of rows, second has similar
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distance from final db_key.
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Finally we launch trace and start query with SCOPED expression for RDB$DB_KEY:
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select count(*) from tmp_test_6278 where rdb$db_key between ? and ?
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Trace must contain after this explained plan with "lower bound, upper bound" phrase and table statistics
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which shows number of reads = count of rows plus 1.
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Before fix trace table statistics did not reflect scoped WHERE-expression on RDB$DB_KEY column.
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JIRA: CORE-6278
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FBTEST: bugs.core_6278
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"""
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import pytest
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import re
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from firebird.qa import *
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db = db_factory()
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act = python_act('db')
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expected_stdout = """
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-> Table "TMP_TEST_6278" Full Scan (lower bound, upper bound)
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Reads difference: EXPECTED.
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"""
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test_script = """
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recreate table tmp_test_6278 (s varchar(32700)) ;
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insert into tmp_test_6278 select lpad('', 32700, uuid_to_char(gen_uuid())) from rdb$types ;
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commit ;
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set heading off ;
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set term ^ ;
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execute block returns(
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count_intermediate_rows int
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) as
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declare dbkey_1 char(8) character set octets ;
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declare dbkey_2 char(8) character set octets ;
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declare sttm varchar(255) ;
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begin
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select max(iif( ri=1, dbkey, null)), max(iif( ri=2, dbkey, null))
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from (
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select dbkey, row_number()over(order by dbkey) ri
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from (
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select
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dbkey
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,row_number()over(order by dbkey) ra
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,row_number()over(order by dbkey desc) rd
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from (select rdb$db_key as dbkey from tmp_test_6278)
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)
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where
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ra = (ra+rd)/3
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or rd = (ra+rd)/3
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) x
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into dbkey_1, dbkey_2 ;
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sttm = q'{select count(*) from tmp_test_6278 where rdb$db_key between ? and ?}' ;
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execute statement (sttm) (dbkey_1, dbkey_2) into count_intermediate_rows ;
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suspend ;
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end ^
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set term ; ^
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commit ;
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"""
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trace = ['log_statement_finish = true',
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'print_plan = true',
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'print_perf = true',
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'explain_plan = true',
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'time_threshold = 0',
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'log_initfini = false',
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'exclude_filter = "%(execute block)%"',
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'include_filter = "%(select count)%"',
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]
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@pytest.mark.version('>=4.0')
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def test_1(act: Action, capsys):
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allowed_patterns = [re.compile(' Table "TMP_TEST_6278"', re.IGNORECASE),
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re.compile('TMP_TEST_6278\\s+\\d+', re.IGNORECASE)
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]
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# For yet unknown reason, trace must be read as in 'cp1252' (neither ascii or utf8 works)
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with act.trace(db_events=trace, encoding='cp1252'):
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act.isql(switches=['-q'], input=test_script)
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# Process isql output
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for line in act.clean_stdout.splitlines():
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if elements := line.rstrip().split():
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count_intermediate_rows = int(elements[0])
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break
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# Process trace
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for line in act.trace_log:
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for p in allowed_patterns:
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if p.search(line):
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if line.startswith('TMP_TEST_6278'):
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trace_reads_statistics = int(line.rstrip().split()[1])
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result = ('EXPECTED.' if (trace_reads_statistics - count_intermediate_rows) <= 1
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else f'UNEXPECTED: {trace_reads_statistics - count_intermediate_rows}')
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print(f'Reads difference: {result}')
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else:
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print(line)
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# Check
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act.reset() # necessary to reset 'clean_stdout' !!
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act.expected_stdout = expected_stdout
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act.stdout = capsys.readouterr().out
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assert act.clean_stdout == act.clean_expected_stdout
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