Latin America Tour 2019 - slow data and sql processing

8. Me connor-mcdonald.com https://linktr.ee/connor

33. 33

43. ~2007

48. 52

57. cursors

58. cursors declare cursor C(p number) is select * from DEPT where DEPTNO = p; begin for rec in C loop … end loop; end; select * from EMPLOYEE where EMPNO > 1234; delete from MY_TABLE; drop table MY_TABLE; begin MY_PROCEDURE(1,2,3); end;

61. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. open process close give me some memory do some stuff using that memory, maybe access other memory here's your memory back 66 Dame un poco de memoria usa la memoria devolver la memoria

62. memory access = controlled access acceso a memoria = acceso controlado

63. a quick primer on (database) memory una cartilla rápida en memoria

64. 66 metaphor

65. 67

66. 71 limited resource lots of people want it concurrent access causes problems it's a complex system recurso limitado mucha gente lo quiere el acceso concurrente causa problemas es un systema complejo

67. 73 same with memory lo mismo con la memoria

68. SGA

69. SGA protected by

70. SGA protected by 1) get latch

71. SGA protected by 1) get latch

72. SGA protected by 2) access memory

73. SGA protected by 2) access memory

74. SGA protected by 3) release latch

75. SGA protected by 3) release latch

76. latch contention

77. SGA protected by someone must wait ... alguien debe esperar

78. active wait activo espere

79. spinning 89 hilado

80. spinning can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ?can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? can I have the latch ? 90

81. latch contention....

82. hurts CPU... 94 duele la CPU

83. hurts concurrency duele la concurrencia

88. "When are we talking about SQL?" "¿Cuándo estamos hablando de SQL?

89. to run a SQL statement para ejecutar una declaración SQ

90. Syntax Validity Optimization Rowsourcing Execution (Fetch) 107

91. Syntax Validity Optimization Rowsourcing Execution (Fetch) SQL> select * 2 frmo emp; frmo emp * ERROR at line 2: ORA-00923: FROM keyword not found where expected 108

92. Syntax Validity Optimization Rowsourcing Execution (Fetch) SQL> select empnoo 2 from emp; select empnoo * ERROR at line 1: ORA-00904: invalid column name

93. Syntax Validity Optimization Rowsourcing Execution (Fetch) PLAN ------------------------------------- SELECT STATEMENT TABLE ACCESS BY INDEX ROWID EMP INDEX RANGE SCAN EMP_PK

94. EMP_PK EMP Syntax Validity Optimization Rowsourcing Execution (Fetch)

95. Syntax Validity Optimization Rowsourcing Execution (Fetch) 112

96. Syntax Validity Optimization Rowsourcing Execution (Fetch)

97. lots of preliminary steps muchos pasos preliminares

98. parsing 103 "compile"

99. lots of memory access 116 mucha memoria de acceso

100. lots of latching ! 117

107. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. parse statement already in library cache ? reuse optimizer info select * from emp where empno = 123 syntactically, semantics OK

108. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. parse statement already in library cache ? reuse optimizer info reuse row source info select * from emp where empno = 123 syntactically, semantics OK

109. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. select surname, firstname from emp where empno = 123 select * from dept where deptno = 4567 select * from customer where locality = 17 select prno from property where reference = 'X123G' select * from dept where deptno = 23 select surname, firstname from emp where empno = 123 select * from customer where locality = 256 select * from organisation where officer = 'OFF876' select surname, firstname from emp where empno = 7632 select * from dept where deptno = 4567 select offender from crimes where crno = 247462 Two full parses avoided library cache

110. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. select surname, firstname from emp where empno = 123 select * from dept where dname = 'SALES' probability of reuse low ? probabilidad de reutilización baja?

111. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. some queries are “nearly the same” 128 select surname, firstname from emp where empno = 123 select surname, firstname from emp where empno = 456 algunas consultas son "casi iguales"

115. select surname, firstname from emp where empno = ? select * from dept where deptno = ? select * from customer where locality = ? select prno from property where reference = ? select * from dept where deptno = ? select surname, firstname from emp where empno = ? select * from customer where locality = ? select * from organisation where officer = ? select surname, firstname from emp where empno = ? select * from dept where deptno = ? select offender from crimes where crno = ? Five full parses avoided library cache

116. demo

117. demo ParseDemo ParseDemoBind

118. "performance still looks ok" "el rendimiento todavía se ve bien"

119. let us use real queries hagámoslo real

120. let's make it real ParseDemo2 nn ParseDemo2Bind nn

121. much more serious mucho Más grave

122. building SQL by concatenation construir SQL por concatenación

123. you'll get hacked

124. select ename from emp where empno = 6543

125. select ename from emp where empno = 6543 select ename from emp where empno = 6543 and 1=0 union all select table_name from all_tables where table_name like '%SECURITY%'

126. select ename from emp where empno = 6543 select ename from emp where empno = 6543 and 1=0 union all select table_name from all_tables where table_name like '%SECURITY%' select ename from emp where empno = 6543 and 1=0 union all select username from app_security where ...

127. 144

128. you'll get hacked ... ... really easily! muy fácil!

129. #1 hacking app .....

130. #1 hacking app ..... Google

131. it takes 5 minutes to hack you se necesita 5 minutos

132. for fast, secure SQL ... para rápido seguro SQL

133. ... always bind user input siempre vincula la entrada del usuario

135. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. parse statement already in library cache ? reuse optimizer info reuse row source info select * from emp where empno = 123 syntactically, semantics OK Yes! Yes! ??? ???

139. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. scott@mydb> select * 2 from EMP 3 where EMPNO = :b1 anna@mydb> select * 2 from EMP 3 where EMPNO = :b1 SQL> desc anna.emp Name Null? Type ----------------- -------- ------------ EMPNO NOT NULL NUMBER(4) ENAME VARCHAR2(10) JOB VARCHAR2(9)

143. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. open process close give me some memory do some stuff using that memory, maybe access other memory here's your memory back 163 Dame un poco de memoria usa la memoria devolver la memoria

151. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. library cache select * from emp cursor 1 select * from dept cursor 2 select * from emp where ... cursor 3 pstmt_all_emp = con.prepareStatement("select * from emp");

152. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. emplist(String[] args) { if "first time" { else "reset the pointer, re-execute" } library cache select * from emp cursor 1 select * from dept cursor 2 select * from emp where ... cursor 3 pstmt_all_emp = con.prepareStatement("select * from emp");

166. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. procedure MY_PROC is cursor c_emp is select * from emp; begin open c_emp; fetch c_emp into …; close c_emp; end; select * from emp procedure MY_PROC is begin select * into … from dept where … end; select * from dept …

176. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. SQL> select * 2 from EMP 3 where … SQL> update EMP 2 set … 3 where … SQL> select * 2 from EMP 3 where … SQL> insert into 2 EMP 3 values (…) SQL> select * 2 from CUSTOMER 3 / SQL> select max(EMP) 2 from DEPT SQL> delete 2 from DEPT 3 /

178. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. • Get latch • Search along list of blocks in memory • Read block • Extract row of interest • Release latch • Give row back to client "fetch a row" 198 Obtener el pestillo Buscar en la lista de bloques en la memoria Leer bloquear Extraer fila de interés Liberar el pestillo Devolver la fila al cliente

183. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. rs = stmt.executeQuery("..."); while(rs.next()) { v1 = rs.getInt(1); v2 = rs.getString(2); ... } • Get latch • Walk along list • Get block • Extract single row • Release latch • Give row back to client • Get latch (again) • Walk along list (again) • Get block (again) • Extract single row • Release latch (again) • Give row back to client (again) Row #1 Row #2 • Get latch (again) • Walk along list (again) • Get block (again) • Extract single row • Release latch (again) • Give row back to client (again) Row #3 203

187. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. "fetch a row" •Get latch •Walk along list •Get block •Pin the block •Release latch •Give row 1 back to client •Give row 2 back to client •Give row 3 back to client … •Give row n to client •Get latch •Walk along list •Remove my pin on the block •Release latch “and .. I may need many rows from this block”

201. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. SQL> select * from v$mystats 2 where name like '%pga%' 3 / NAME VALUE ------------------------------ ---------- session pga memory 501534672 session pga memory max 501534672

204. Copyright © 2018, Oracle and/or its affiliates. All rights reserved. SQL> declare . . . 9 begin 10 open c; 11 loop 12 fetch c 13 bulk collect 14 into r limit 100; 15 exit when c%notfound; . . . 19 / Elapsed: 00:00:08.17 NAME VALUE ------------------------------ ---------- session pga memory 625912 session pga memory max 625912

214. Thank you! connor-mcdonald.com https://linktr.ee/connor Gracias!

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