2026-03-12 20:23:15

tpt/demos/lotsofchildren.sql

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+-- Copyright 2018 Tanel Poder. All rights reserved. More info at http://tanelpoder.com
+-- Licensed under the Apache License, Version 2.0. See LICENSE.txt for terms & conditions.
+
+EXEC EXECUTE IMMEDIATE 'drop table t_children'; EXCEPTION WHEN OTHERS THEN NULL;
+
+CREATE TABLE t_children AS SELECT rownum a, 'zzz' b FROM dual CONNECT BY LEVEL<=1000;
+
+CREATE INDEX i_children ON t_children(a);
+
+-- deliberately gathering a histogram 
+EXEC DBMS_STATS.GATHER_TABLE_STATS(user,'T_CHILDREN',method_opt=>'FOR COLUMNS A SIZE 254');
+
+-- this is the crap setting 
+ALTER SESSION SET cursor_sharing = similar;
+
+@saveset
+
+SET PAGES 0 HEAD OFF TRIMOUT OFF TRIMSPOOL OFF ARRAYSIZE 5000 TERMOUT OFF
+SPOOL tmp_lotschildren.sql
+SELECT 'SELECT COUNT(*) FROM t_children WHERE a = '||TO_CHAR(ABS(DBMS_RANDOM.RANDOM))||';'
+FROM dual CONNECT BY LEVEL <= 100000;
+SPOOL OFF
+
+@loadset
+
+PROMPT Now run @tmp_lotschildren.sql
+
+-- this hack is not working, must use plain SQL instead of plsql
+-- ALTER SESSION SET session_cached_cursors = 0;
+-- ALTER SESSION SET "_close_cached_open_cursors" = TRUE;
+-- ALTER SESSION SET plsql_optimize_level = 0;
+-- 
+-- DECLARE
+--     j NUMBER;
+--     x NUMBER;
+-- BEGIN
+--     EXECUTE IMMEDIATE 'SELECT COUNT(*) FROM t_children WHERE a = '||TO_CHAR(ABS(DBMS_RANDOM.RANDOM)) INTO j;
+--     x:=x+j;
+--     COMMIT;
+-- END;
+-- /
+