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  1. MariaDB Server
  2. MDEV-17534

Implement fast path for ASCII range in strnxfrm_onelevel_internal()

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    Description

      During benchmarking, Axel revealed a bottleneck inside MY_FUNCTION_NAME(strnxfrm_onelevel_internal) in ctype-uca.ic.

      The problem is that calling my_uca_scanner_init_any() followed by a loop of MY_FUNCTION_NAME(scanner_next)() calls is costly.

      Under terms of this task we'll add a fast path for the ASCII range into this strnxfrm_onelevel_internal().

      • In the best scenario, when the input string is a pure ASCII, the execution will not even reach my_uca_scanner_init_any().
      • In a worse scenario, when there is an ASCII prefix followed by a non-ASCII suffix, the ASCII part will be processed faster.

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          Task - A task that needs to be done. MDEV-16413 test performance of distinct range queries

          • Major - Major loss of function.
          • Closed

          Activity

            bar Alexander Barkov added a comment -

            Micro-benchmark statistics

            SET @a=CONCAT(REPEAT(_utf8'a' COLLATE utf8_unicode_ci, 360));
            		 
            SELECT BENCHMARK(500000, WEIGHT_STRING(@a,1024,960,128));

            Macro-benchmark statistics for short range ORDER BY queries

            DROP TABLE IF EXISTS t1;
            		 
            CREATE TABLE t1 (pk SERIAL, field CHAR(120) CHARACTER SET utf8 COLLATE utf8_unicode_ci);
            		 
            INSERT t1 (field)
            		 
            WITH  RECURSIVE int_seq AS (
            		 
              SELECT 1 AS val
            		 
              UNION ALL
            		 
              SELECT val + 1
            		 
              FROM int_seq
            		 
              WHERE val < 1000
            		 
            ) SELECT CONCAT('a',val%255,REPEAT('b',100)) FROM int_seq;
            		 
            DROP PROCEDURE IF EXISTS p1;
            		 
            DELIMITER $$
            		 
            CREATE PROCEDURE p1()
            		 
            BEGIN
            		 
              DECLARE a INT DEFAULT 100000;
            		 
              WHILE (a > 0)
            		 
              DO
            		 
                SELECT field INTO @a FROM t1 WHERE pk BETWEEN 1 AND 11 ORDER BY field LIMIT 1;
            		 
                SET a=a-1;
            		 
              END WHILE;
            		 
            END;
            		 
            $$
            		 
            DELIMITER ;
            		 
            CALL p1;

            bar Alexander Barkov added a comment - Micro-benchmark statistics SET @a=CONCAT(REPEAT(_utf8 'a' COLLATE utf8_unicode_ci, 360)); SELECT BENCHMARK(500000, WEIGHT_STRING(@a,1024,960,128)); 0.77 before MDEV-17534 0.44 after MDEV-17534 Macro-benchmark statistics for short range ORDER BY queries DROP TABLE IF EXISTS t1; CREATE TABLE t1 (pk SERIAL, field CHAR (120) CHARACTER SET utf8 COLLATE utf8_unicode_ci); INSERT t1 (field) WITH RECURSIVE int_seq AS ( SELECT 1 AS val UNION ALL SELECT val + 1 FROM int_seq WHERE val < 1000 ) SELECT CONCAT( 'a' ,val%255,REPEAT( 'b' ,100)) FROM int_seq; DROP PROCEDURE IF EXISTS p1; DELIMITER $$ CREATE PROCEDURE p1() BEGIN DECLARE a INT DEFAULT 100000; WHILE (a > 0) DO SELECT field INTO @a FROM t1 WHERE pk BETWEEN 1 AND 11 ORDER BY field LIMIT 1; SET a=a-1; END WHILE; END ; $$ DELIMITER ; CALL p1; 6.36 before MDEV-17534 6.22 after MDEV-17534

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              bar Alexander Barkov
              bar Alexander Barkov
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                Updated:
                Resolved:

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